TWI316966B - Brake disc having high temper softening resistance and superior toughness - Google Patents

Description

1316966 IX. Description of the Invention: [Technical Field] The present invention relates to a disc for disc brakes of locomotives, automobiles, bicycles, and the like, and particularly relates to a friction portion of a brake pad. Brake disc with high quenching hardness and high temper:softening resistance and excellent toughness. The term "excellent temper softening resistance" as used in the present invention means that the tempering softening resistance is high, and the degree of softening after the high temperature due to the friction heat (friction heat) maintained during braking is small and can be maintained. The characteristics of the appropriate hardness close to the initial stage. [Prior Art] The function of the disc brakes for locomotives, automobiles, bicycles, etc., is to brake by suppressing the rotation of the wheels by the friction between the brake discs and the brake pads. Therefore, the brake disc preferably has a proper hardness. If the hardness is too soft, the brake is ineffective and will wear out quickly due to friction with the brake pad. On the other hand, if it is too hard, brake squeal will occur. The appropriate hardness of the brake disc is recommended to be in the hardness range of HRC32~38. Here, the HRC is a Rockwell C Hardness according to JIS Z 2245. Brake disc materials have always been considered based on the viewpoint of hardness and corrosion resistance, which is «the use of MartensiUc steel. In the past, the use of sus 42〇J2 (JIS z 4 such as 〇, such as the high carbon content of the Ma Tian scattered iron stainless steel for quenching and tempering treatment, but the tempering treatment load is large, so in recent years, more inclined to use Japanese patents It can be directly revealed in the case of the singularity of the singularity of the singularity of the singularity of the singularity of the singularity of the singularity of the singularity of the singularity of the singularity of the singularity of the singularity of the singularity of the singularity The use of low-carbon 麻田散铁-based stainless steel brake disc materials. In recent years, based on the consideration of global environmental maintenance, the improvement of fuel efficiency of locomotives and production has attracted attention: fuel efficiency, mitigation The weight of the vehicle is effective, so look at the weight of the vehicle: ., light brakes (brake medlanism) disc brakes are also no exception

In order to reduce the weight of the vehicle, it is necessary to reduce the size (thinning) of the brake disc. X However, the miniaturization and thinning of the brake disc will result in a heat capacity (h^ is low and the temperature of the brake disc caused by the frictional heat during braking is large. Therefore, with such miniaturization and thinning tendency, When braking: the brake disc: the degree will reach 6 〇 rc or more 'Because of the material, due to the brake (four) durability has reduced concerns, so the temper softening resistance is still excellent temper softening resistance brake disc For this expectation, for example, in Japanese Patent Laid-Open No. 2^2_146, a low-carbon 麻田散铁-based stainless steel plate containing: one of: canine heart erosion, ν, Zr or Two or more types can be effectively suppressed: the softening due to the temperature rise in the use of the dish (four), and the suppression of the hard low 0 Japanese & Patent No. 3315974 (Special opening 200 2206E II, J proposes a dish brake Recording steel, adding or recombining Ti, v, B in addition to Nb, and thereby effectively suppressing t 312XP / invention manual (supplement) / 95-12/95 mi 08 1316966 Also, in Japanese patents In the publication No. 2002-121656, it has been proposed to: by making C, N, Ni, Cu, Mn, Cr in steel The GP value of the relational expression of the content of Si, Mo, V, Ti, and A1 is adjusted to 50 «) or more, and contains an appropriate amount of Nb and V, so that the deterioration of the material due to the temperature rise during use is hardly caused. In the technique described in Japanese Laid-Open Patent Publication No. 2002-146489, Japanese Patent No. 3315974, and JP-A-2002-121656, it is necessary to add a relatively large amount of cost. Expensive alloying elements, not only the disc type and the brake are expensive to manufacture, but also have a problem that the hardness is drastically reduced when kept at 600 ° C for a long time (1 hour). Moreover, the brake disc is an important part of safe driving. It is necessary to have high toughness that does not cause embrittlement cracks. It is an object of the present invention to provide a brake disc which can advantageously solve the problems of the prior art, has suitable quenching hardness, and has high temper softening resistance, and is softened for tempering. [Technical Disclosure] The inventors of the present invention have achieved a tempering softening resistance against a brake disc of a granulated stainless steel-based stainless steel plate in order to achieve the above problems. An in-depth review of various factors was made. The result was found to be: "prior-austenite grain diameter" of the brake disc by using a low-carbon ramie-dispersed stainless steel of a specific composition as a material for the brake disc. When it is 8 /zm or more, it can obtain appropriate quenching hardness and can significantly improve temper softening resistance. Figure 1 shows that 0.055% C~0.1% Si-12%Cr-1.5%Mn-0.01%N-the rest is The effect of the average particle size of the old Worthite body particles on the temper softening resistance of the low-carbon 麻田散铁-based stainless steel composed of Fe (all of which is % by mass). Quenching system 312XP / invention manual (supplement) / 95-12/9513: 7108 8 1316966 under the + fire heating temperature, the material is divided into four (four) riding field cold::: (^; ° ^ = two is the old 7) average of the grain The particle size is one in the case of quenching temperature, one in the case of work, and 12 (four) in the case of 1 (10)C. In the evaluation of the two-stage resistance of the third phase between the rcs, the quenched test piece is air-cooled after the temperature of the hour, and the surface is measured after the surface is removed. It is estimated from the hardness of HRC. It can be seen from Fig. 1 that the average particle size of the old Worthite body particles is 8 (four) or more, and it is maintained at a high HRC27 or higher. Hardness. The mechanism for stupid this phenomenon has not been understood so far, and the inventors have considered the following. = In the fire process, the alloy elements diffuse to the grain boundary and are easily precipitated, and are woven into coarse precipitates. The metal having fine old r particles The group has a short distance from the alloy such as Cr to the old 7 grain boundary. Therefore, the element can easily reach the old r grain boundary to form a coarse precipitate. The formation of the fine precipitate will be reduced by two: Because the contribution to the precipitation strengthening is small, it does not help to increase the temper softening resistance. In the second aspect, the metal elements such as r and Nb in the metal structure with coarse grains have a long distance from the old and grain boundaries. It is difficult to reach the core grain boundary with alloy elements such as back = Cr and Nb. Fine precipitation of nitrogen compounds, etc.) will be precipitated in the old grain r. The fine precipitate in the granule becomes a resistance of the displacement movement (disi〇cati〇n 312XP/invention specification (supplement)/95-12/95137108 9 1316966 motion) and can suppress the decrease in hardness at the time of tempering, so In the metal structure of the coarse old T grain, the temper softening resistance will increase. Moreover, we have found that if the old gamma particle size is too large, the average particle size of the old r particles must be set to less than 15/ΖΠ1 because it is easily embrittled. The present invention has been completed based on the above findings and further reviewed. 'In other words, the gist of the present invention is as follows: (1) A brake disc excellent in temper softening resistance and excellent in character, characterized in that the composition thereof satisfies the following formula (1) and formula (2) • 5Cr +10Si + 15Mo+30Nb-9Ni-5Mn-3Cu-225N-270C<45...(1) 〇. 03^ {C+N-(13/92)Nb}^〇. 〇9 ...(2) ( Here, Cr, Si, Mo, Nb, Ni, Μη, Cu, N, and C are contained in the content (mass w) of each element: c: 01% or less, Si: i (10) or less: Μη: 2. G % below, ··· 1G. 5~15 summer N: 1% or less (3)0 in mass%), the rest is Fe and unavoidable impurities, and the average grain size of the old Wotian body particles is 8"m or more and less than 15 (4) Ma Tian's loose iron organization 0 (2) The brake disc in (1), which further includes the above components

Cu: 0.0 U or more and less than (% by mass). (3) If the brake disc in (1) or (2) is at 6 〇〇t: keep it small • The hardness after tempering is 27 or more in URC. ‘(4) As for the financial instrument in (1), it is further advanced in the above-mentioned composition—Cu: 1. 0%~3·0% (% by mass). There are (5) #j车盘(1), which is further in addition to the aforementioned components.

Nb : 0. 02% ~ 〇. 6% (% by mass). There are 312XP / invention manual (supplement) / 95·12/95137108 10 1316966 analysis (out of the brake disc, which goes further to the precipitation _ precipitates all (four), meet the following formula (3), "magic ratio, (precipitation _ 〇 5<(Precipitation Nb/All Nb)s 0. 7 . . . (In this case, Nb is precipitated and all Nb is % by mass). (7) The tray of any of the items of (5) and (8), a before. In addition, the step further includes Cu: 〇. 〇 〇 5% (% by mass)., ', Cheng (8) as in (4) to (7), the brake disc in the item, which is tempered in _ Xiaoyan The hardness after the HRC is 30 or more. The brake disc of 1 牛^^(1) to (9) is further advanced from the above-mentioned composition - y 3 has Co·〇.〇1 ΐΐ·〇% (% by mass)〇 =1) For the brake disc of any of items (1) to (1〇), the step further includes a step selected from the group consisting of Ti: 〇.〇2~〇3%, v:〇〇2~〇3: 2: :::°. Grab, h: °. °"·戕(all are % by mass) or (10) such as (1) to (9), the one that is in the 1st, which goes further than the above - Contains one or two kinds selected from Β: 0·_5~〇. 咖%, Ca. 〇·0005~0. 0050%. According to the present month, the composition of the composition and the size of the old Worth field In the range of suitable rolls, it is easy and inexpensive to manufacture with suitable quenching hard HRC32 38' and excellent temper softening resistance with high temper softening resistance and = 312XP / invention manual (supplement) / 95-12/ 95137108 11 1316966 2 Different brake discs can exert excellent effects in the industry. [Only the method of application] The manufacturing steps of the brake discs are usually as follows: = First, the punching of the raw material of the Ma Tian loose iron is not recorded. =The disc of the specified size is used as the material for the brake disc. Pure, the brake is used for the opening of the material (for the frictional heat dissipation generated when the vehicle is used), and then the material for the brake disc is used. The predetermined region (that is, the friction portion of the brake pad portion) is quenched, that is, it is cooled by high-frequency induction heating (q) and then quenched by qUenching temperature. The treatment is performed so that the predetermined area (friction portion) is made into the granulated iron structure and adjusted to the desired hardness. Then, the coating is applied to the surface of the disc or the punched section as needed, and then removed by quenching by grinding or the like. At The layer of oxides of the formed friction portion is used as a product of the brake disc. # In the present invention, the raw material is a low-carbon 麻田散铁-based stainless steel sheet having a composition satisfying specific conditions. The low-carbon 麻田散铁 is used. A stainless steel plate, preferably, is composed to satisfy the following formula (1) and formula (2) 5Cr+10Si+15Mo+30Nb-9Ni-5Mn-3Cu-225N-270C<45.. (1) 0. 03^ {C+N-(13/92)Nb}^0. 09 (2) • (here, Cr, Si, Mo, Nb, Ni, Μη, Cu, N, C are elements The content of the content (mass «) contains C: 0.1% or less, Si: 1. 〇% or less, Μη: 2. 0% or less, Cr: 10. 5 to 15. 0%, N: 0.1% The following steel sheets (both in mass %). Further, the "steel plate" referred to in the present invention also includes a steel strip. 312XP/Invention Manual (Supplement)/95·12/951371〇8 12 1316966 Further, the steel plate may be either a hot rolled steel sheet or a cold rolled steel sheet. = The reason for the composition range (4) of the raw materials used in the present invention is as follows. In the following, the mass % in the composition is only referred to as %. c : 〇·1% or less c is an element that determines the hardness of the brake disc after quenching together with N. It is preferable to contain G.G1% or more in this month, and α Q 3% or more is preferable; The right 3 has more than 〇. 1% 'will form a thick one. The carbides, which become the original rust of rust, are not only reduced in boxing but also reduced in secret. 1, secret, tolerant I" Health perspective 1 ’ c must be limited to 0.1% or less. Also, in terms of corrosion resistance, it is better to use less than 05%. N : 0.1% or less N is the same element as C to determine the hardness of the brake disc after quenching. Further, N forms a fine & nitride ((4)) in a temperature range of 500 to 700 ° C to enhance temper softening resistance by precipitation hardening. In order to obtain such effects, N is preferably contained in an amount of 0.03% or more. On the other hand, if it is more than o.u, the toughness is lowered, so it is limited to 0.1% or less in the present invention.

Cr : 10. 5-15. 0%

Cr is a useful element for improving corrosion resistance (characterized by stainless steel), and it is necessary to contain 1 5% or more in order to secure sufficient corrosion resistance. On the other hand, if it contains more than 15.0%, the workability and toughness will decrease. 0%。 Therefore, the cr is limited to 10. 5~15. 0%. The 5% or less is preferable, and it is preferable to use it as a viewpoint of the corrosion resistance. Si ·· 1 · 〇% or less 312XP/Invention Manual (supplement)/95·12/95137108 13 1316966

Sl is an effective element as a deoxidizer, and it is preferably contained in an amount of more than 05%. Further, 'Si is an element which can stabilize the ferrite phase, and an excess of more than 1.0% causes a decrease in hardenability to lower the quenching hardness and even lower the toughness. Therefore, the Si whisker is limited to 1. 〇% or less. The 5% or less is preferred. Μ : 2. 2. 2. 2. 2. 2. 2. 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系 系On the other hand, excess of more than 2. G% will reduce the fiscal balance. Therefore, Μη must be limited to 2.0% or less. Further, in terms of improving the hardenability, it is preferable to use I or more, and more preferably 1 to 5% or more. In the local Mingzhong, the above basic components shall be within the above range and satisfy the following (1) and formula (2): 5Cr+10Si+15Mo+30Nb-9Ni-5Mn-3Cu-225N-270C<45...(1) 〇. 03^ {C+N-(13/92)Nb}^〇. 〇9 (2) • (here, Cr, Si, Mo, Nb, Ni, Μη, Cu, N, C are The content of each element (mass «). In addition, in the calculation of the value of the middle term of the formula (1), the value of the middle term of the formula (2) is less than 01. 01% of Cu, less than 0. 02% Nb, less than 1% of M〇, and less than 0.10% of Ni are not included and are calculated as zero. "(1) is a condition for ensuring excellent quenching stability. Here, quenching stability "Excellent" means that 75% by volume of the Worth Field (1) phase is formed during quenching and heating. When a bonfire is cooled faster than air cooling, the Worthfield body phase is transformed into the Mita iron phase and stabilized. , so it can be confirmed 312XP / invention manual (supplement) / 95-12/95137108 14 1316966 to maintain the specified quenching hardness, the Worth field area is wide, can use a wide range of quenching heating temperature. (1) When the left side is 45 or more, the Vostian body phase cannot be heated when the quenching 2 is heated. It is 75 vol% or more, or the generated temperature range is extremely narrow, so that the stable quenching hardness cannot be ensured. Therefore, the right side value of the formula (1) is limited to less than 45. (2) The formula is such that the bonfire hardness becomes the specified appropriate range. The hardness of the inner part - the hardness of quenching has a greater correlation with the amount of C and N. On the other hand, if c, N and Nb combine to form Nb, Nb nitride, it will not help Therefore, the hardness after quenching should be considered by subtracting the amount of C and N from the amount of c and N in the steel and the amount of C and N consumed by the conversion. The intermediate term of (2) is less than 0·03. In the case, the hardness of the brake disc will be less than the lower limit of the appropriate range (HRC32). On the other hand, if it exceeds 〇. 〇9, it will become higher than the upper limit (HRC38). Therefore, the formula (2) The value of the intermediate term is limited to the range of 0.03 to 0.09. The raw materials used in the present invention are further adjusted to be P: 0.04% or less, S: 0, except for the above-mentioned basic component range. 010% or less, A1 : 〇. 2% or less is preferable. P : 0. 04% or less P is a factor that lowers hot workability. It is better to reduce as much as possible, but if the excessive reduction will lead to high manufacturing costs, it is better to use 04. 04% as the upper limit. Also, from the viewpoint of manufacturability, P is 0.03% or less. It is better. S : 0. 010% or less s is the same as P, which reduces the hot workability. It is better to reduce it as much as possible. However, if it is excessively reduced, the manufacturing cost will be too high, so 0.010% 312xp/invented Manual (supplement) / 95-12/95137108 15 1316966 is preferred as the upper limit. Also, the following is better. For the viewpoint of the past, P is 0. 005% A1 : 0. 2% or less is added as a deoxidizer, and is added as a deoxidizer, but if it is not used, it is used as a steel. In the steel, 'there will be _ sex, J will avoid the cause, and the second will remain in the following Α toughness. Therefore, Α1 is limited to 〇. 2% Majia. Also, I went to I曰 for the book of money-resistant. 0砚以下为1, preferably 0. 05% or less. In addition to the fact that the soil is formed into a knife, the viewpoint of corrosion resistance, etc., can be further increased into H Cuu~ under full shoulder, and full of the above formula (1)

Cu·0.01 to less than 1.0% ^ The element having an effect of improving the durability is preferably an amount which is more than UU and less than h(10) which can be transmitted to the effect as needed. In addition, the consideration of Bo's is determined to be no, and 5% is preferable. Further, in the case where Cu is contained in combination, if the content exceeds 〇·(10), the toughness is deteriorated, so u is preferably limited to a range of 5%. The raw material is made into the above-mentioned basic component or further added to the composition selected in the range of the knives described later, and the quenching treatment to be described later is performed at the friction portion with the brake pad, so that the average particle diameter of the old r particles is 8 #m or more. The granulated iron structure of the granules, which is less than 15/ζιη, can be used as a tempering softening resistance brake disc having a hardness of HRC27 or higher after being tempered at 6 〇〇t:1 hour. The average particle size of the old r particles: 8 // m or more and less than 15 # m In the brake disc of the present invention, the hardness after maintaining the tempering treatment for 6 hours or more for 6 hours or more can be maintained as HRC2 7 The above 'old grain average particle 312XP / invention manual (supplement) / 95-12/95137108 16 1316966 control must be 8 / zm or more. If the average particle size of the old r particles is not sufficient, as described above, the precipitation of fine precipitates in the old r particles is small, and the increase in temper softening resistance is small. X, if the old 7 grains are 15 " m or more, the breaking unit of the brittle fracture increases and the toughness is lowered. Further, in addition to the above-described basic components, further satisfying the conditions of the above formulas (1) and (2) includes Cu: L 〇 〜3· 〇%, or rib: 〇. 〇2~〇·(10), by- Thus, a brake disc having a hardness of HRC 3 〇 or more after tempering treatment can be obtained.

Cu : 1. 0~3. 0% _ Cu If it contains 1.0% or more, it will precipitate fine in the tempering treatment.

Cu' is an element which can be tempered and softened, and can be contained as needed. However, if it contains more than 3.0%, the toughness will deteriorate. 0%的范围内。 Preferably, in the case of the tempering softening resistance for the purpose of Cu, the range of 1. 0~3. 0% is preferred.

Nb : 0.02-0.6%

Nb is used to improve the coffee after the bonfire. When the temperature is about c, the element is precipitated and hardened by the formation of carbonitride (earbQnitride) to suppress the decrease in hardness (i.e., the temper softening resistance) which is maintained at a high temperature, and may be contained as needed. In order to obtain such effects, it is preferable to contain _.〇2% or more, but if Nb is contained in excess of 〇·6%, the toughness is lowered. Therefore, ib is preferably limited to a range of m G2 to 〇·6%. 3%更优选。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。. Further, in the present invention, the ratio of Nb (the amount of Nb precipitated by the precipitate) to the total Nb (the total amount of the ribs) is precipitated (precipitating rib/total rib) to be adjusted to 312XP/invention specification (supplement)/ 95-12/95137108 17 1316966 The following formula (3) is preferred, 〇5<(precipitation/all Nb) ' 〇. 7 . . . (3) (here, Nb is precipitated, and all Nb is mass%) In the steel plate before quenching (annealing), (top, 囍i+ 斫Nb/all Nb) is 〇. 9 or more hunted by quenching treatment to precipitate Nb η, + 4 parts will be solid solution. The solid solution of Nb is precipitated finely in the tempering day, and the ^ f sensation precipitation strengthening effect is exerted. In the case of unsatisfied eight (that is, Nb/all 1 析. 镦丨, 1 Wang Wb) exceeds 0.7, and the amount of solid solution Nb will be less than 4, 'Nb in the tempering phase, N, | reduce. In order to make (precipitating Nb/all Nb) 〇 7 or less, it is preferable to carry out the south temperature quenching treatment on the surface c or more. More than c is better, especially lioot: the above is especially good. On the other hand, if (precipitated Nb/all Nb) is less than 0.5, the amount of solid solution Nb will be "worry, and the amount of Nb which is finely precipitated during tempering will become excessive, and the temper softening resistance will become high, but The precipitate of the cause of the damage will increase excessively, so the toughness will be significantly deteriorated. Further, the measurement of the amount of precipitated Nb was carried out by chemical analysis of a sample obtained from a brake disc by a chemical dross of electrolytic extraction which was subjected to electrolytic treatment to be described later. Further, the total Nb amount is determined by usual chemical analysis. Further, in the present invention, in the range of the above-mentioned basic components or the above-mentioned selected components, if necessary, Mo: 0·0 Bu 2. 0 may be contained under the conditions satisfying the above formulas (1) and (2). % or Ni: 0. 10~2. One or two of 0%. It is selected from Mo ·· 0. 0 Bu 2· 0%, Ni: 0. 10~2. One of the 0% or two kinds of 312XP/Invention Manual (supplement)/95_12/95137108 18 1316966, Ni is improved The element of corrosion resistance can be selected as needed. Further, Ni can be delayed by precipitation of Cr carbide at a high temperature of 6 〇〇 ° C or higher, which can suppress the decrease in the hardness of the granulated iron structure and contribute to the improvement of the temper softening resistance. Mo also suppresses the precipitation of carbonitrides in the same manner as n i , and has an effect of improving the resistance to softening and softening. These effects are effective when they contain Mo: 〇. 01% or more and Nl: 〇. 10% or more. Further, in terms of tempering and softening resistance, it is preferable to contain Mo: 0.02% or more. On the other hand, even if Mo is contained in excess of 2.0% and Ni is more than 2.0%, the effect of improving the temper softening resistance is saturated, and the effect proportional to the content cannot be expected, which is disadvantageous in terms of economic considerations. Therefore, it is preferable to be limited to a range of M〇 : 〇 2 2%, Ni: 〇·1〇~2. 0%. Moreover, even if M〇 is not full, 〇5% can show sufficient temper softening resistance improvement effect. Further, if Ni contains 〇. (10) or more, the temper softening resistance can be further improved. In the present invention, C may be contained as needed in addition to the above-mentioned basic components and selected components. Or one or more selected from the group consisting of Ti, v, Zr, and Ta, and one or two selected from the group consisting of B and Ca.

Co : 0.01-1.0%

Co is an effective element for improving corrosion resistance, and it is preferable to contain 〇 〇% or more as needed. On the other hand, if it contains more than h 〇%, the toughness will fall. Therefore, Co is preferably limited to a range of 1% by weight. The 3% or less is preferred. From Ti: 0. 02~0· 3%, V: 〇. 02~3%, Zr: 〇2~〇.(10),

Ta: 0. 02~0. One or more of 3% or more

Ti, V, Zr, and Ta are all elements which can form carbonitrides and enhance the temper softening resistance by precipitation hardening by 312XP/invention specification (supplement)/95-12/95137108 19 1316966. One or two or more. These effects are remarkably exhibited when Ti: 0.02% or more, V: 0.02% or more, Zr: 0.02% or more, and Ta: 0.02% or more. In particular, the V-tempering softening resistance is more effective, and it is preferably more than 0. 05%, more preferably 0.1% or more. On the other hand, when the content of .Ti : > 〇 · 3%, V : > 0 · 3%, Zr : > 0 · 3%, and Ta : > 0.3%, respectively, the reduction of toughness - Significantly. Therefore, the range is limited to Ti: 0. 02~0. 3%, V: 0. 02~0·3%, Zr: 0. 02~0. 3%, Ta: 0. 02~0_ 3% good. • From B: 0. 0005~0. 0050%, Ca: 0· 0005~0· 0050% of one or two kinds of B and Ca are trace elements containing elements which improve the hardenability of steel, and may be optionally contained. . In order to obtain such effects, it is contained in B: 0.00005% or more, and Ca: 0.0005°/. As described above, when the content exceeds B:0.050% and Ca:0.050%, the corrosion resistance is lowered. Therefore, to be limited to B: 0.0005 to 0.0050 ° /. , Ca: 0.0005~0.0050% range is preferred. The remainder other than the above components are Fe and unavoidable impurities. It is an inevitable impurity, and even if it contains a metal such as Na of 0.05% or less, a test metal such as Mg or Ba, a rare earth element such as Y or La, or a transition element such as Hf, it does not hinder this. The effect of the invention. The method for producing the raw material having the above composition is not particularly limited, and any of the known production methods can be used. For example, the molten steel having the above composition is dissolved in a steel converter, an electric furnace, or the like, and VOD (Vacuum Oxygen Decarburization) and A0D (Argon Oxygen 312XP/Invention Manual) are added to the molten steel. Pieces) /95.12/95137108 20 1316966

Secondary refining (9) (10) (4) refimng), and then known as a casting method. The casting method is preferably a continuous casting method from the viewpoint of productivity and quality. Then, it is preferable to heat the steel material to a preferred thickness of 〇〇 to 125 (rc, and to produce a hot-rolled steel sheet having a predetermined thickness by hot rolling. As a material for the brake disc, the thickness is about 3 to 8 liters. Preferably, the hot-rolled steel sheet is annealed by hot-rolled steel sheet, and descaling is performed by sand blasting, pickling, etc. as a raw material for the brake disc. Further, the hot-rolled sheet is retracted. It is used in batch type box furnaces (batch type b〇x furnac illusion above C ~ 900. (: The temperature is kept for about 10 hours. By annealing the hot rolled sheet, the hardness of the steel sheet is used as a brake disc. The appropriate HRB (Rockwell hardness grade 1) 75~88 of the raw material can be used as a raw material for the brake disc under this hardness. From the raw material, the disc-shaped brake brake disc can be obtained by punching. A predetermined area (friction portion with the brake pad) of the obtained brake disc material is quenched to form a brake disc. The quenching treatment in the present invention is heated to 7 in a region exceeding 1 〇〇〇C after quenching heating temperature The cooling treatment is performed at a cooling rate of a cooling rate of rc/sec or more. The quenching heating temperature is set to a temperature in which the temperature in the γ region exceeds 1. Here, the "7 region" is preferably a Worthian body phase. ) A region of 75% by volume or more is produced. By quenching the heating temperature to a temperature of 1 ° C or higher, an appropriate quenching hardness can be ensured, and an average particle 312XP / invention specification (supplement) / 95- can be obtained. 12/95137108 21 1316966 Diameter: The old 7-grain granulated iron structure above 8 /zm can suppress the above-mentioned hardness reduction after maintaining high temperature, and can significantly improve the temper softening resistance. If the quenching heating temperature is l Below 〇〇〇 ° C, the hardness after being kept at a high temperature is remarkably lowered. Further, from the viewpoint of temper softening resistance, it is preferable that the quenching heating temperature is preferably i 〇 5 〇 ° or more, and more preferably liotrc or more. • In addition, if the quenching heating temperature exceeds 120 (TC, (5 - the amount of ferrite and iron generated will increase, the situation will be increased if the volume of the Vostian body (r) is not more than 75 % by volume). The higher the temperature, the faster the particles grow, and the old 7 tablets are flat. The particle size _ will be 15/zm or more, so it is preferably 1200X: or less. Considering the viewpoint of quenching stability, the quenching heating temperature is set to 115 (TC or less is preferable. Further, the holding time of quenching heating is determined by the fertilizer. The viewpoint of the conversion of granular iron into a Worth field can be fully determined, and it is preferably set to 30 seconds or more. After heating, it is cooled to a Ms point at a cooling rate of 1 ° C/sec or more (martensitic transformation temperature (martensitic transformation) Starting temprature)) The following is better, especially cooling to 20 (TC or less is better. _ If the cooling rate is less than 1 °C / sec, one part of the Wolsfield body phase formed at the quenching heating temperature will be transformed into the ferrite grain iron phase, resulting in a decrease in the amount of iron field produced in the field, and the quenching hardness cannot be Within the appropriate range. Further, it is preferably 5 to 500 ° C / sec. In order to ensure the quenching hardness of stability, it is preferred to cool at a cooling rate of l 〇〇 ° c / sec or more. • The brake disc thus obtained is characterized in that it has the above-mentioned low-carbon 麻田 dispersion iron-based stainless steel, and the friction portion with the brake pad is quenched to have an average particle size of 8 grains of 8 or more and less than 15 ym. The Ma Tian loose iron structure not only has good tempering softening resistance, but also excellent toughness. Further, quenching 312XP/invention specification (supplement)/95-12/9513Ή08 22 1316966 The heating method is not particularly limited, and productive inductive heating is preferred. The point of view is to explain in more detail with high frequency. Hereinafter, the present invention (Example) The molten steel which is not composed of Table 1 is smashed into a steel material by a high-frequency melting furnace aigh-frequency melting iurnace. Then, these steel materials were formed into hot-rolled steel sheets (sheet thickness: 5 mm) by usual hot rolling. Then, the hot-rolled steel sheets are subjected to 8G (rcxM, pure ruthenium (reduced gas) environment, and then slowly cooled after heating. Then, the hot-rolled steel sheets are subjected to pickling treatment to remove surface scale. (seaie), used as a raw material for the brake disc. From this raw material, the test material (size: tx3〇x3〇mm) is heated to the quenching heating temperature shown in Table 2 (hold: 丨 minute), as shown in Table 2 After the quenching, the test piece is used, and the metal structure observation, the measurement of the precipitated Nb 、, the quenching stability test (qUenching stability test), the temper softening resistance test, and the toughness test after the tempering treatment are carried out. (1) After observing the metal structure, the test piece for metal structure observation was used, and the cross section in the thickness direction parallel to the rolling direction of the test piece was ground to obtain the Murakami reagent solution (red Alkaline solution of red prussiate (red blood salt: 10g, caustic hydrate (potassium hydrate): 10g, water: l〇〇cc)) The old 7-grain boundary is presented, and the optical field (optical 312xp/invention specification (supplement)/95-12/95137108 23 1316966 microscope) (400 times) is used for 5 viewing zones (1 viewing zone: 0.2x0. 2mm). Observed, the area of each particle contained in the visual field was measured by an image analysis device, and the diameter of a corresponding circle was calculated, and the average diameter of the circle corresponding to each particle was used as the old T grain of each test piece. (2) Measurement of the amount of precipitated Nb After the quenching treatment, a sample for electrolytic extraction was used, and the electrolyte for the test piece was Φ (electrolyte) · 10 vol/vol% acetonitrile (acetyl acetone)-1 wt/vol% tetramethylammonium chloride-methanol (AA series) is subjected to electrolytic treatment, and the residue is extracted by filtration. Inductively Coupled Plasma emission spectrometry was used to measure the amount of Nb as the amount of precipitated Nb in the precipitate. (3) Quenching stability test* Execution of the test piece after quenching After the surface was removed by acid treatment, the surface hardness HRC at 5 points was measured by a Rockwell hardness tester in accordance with JIS Z 2245, and the average value thereof was used as the quenching hardness. • (4) Temper softening resistance test The test piece after quenching is further subjected to tempering treatment under the conditions shown in Table 2 (air cooling after being kept in a heated state). After the tempered test piece was subjected to pickling for surface descaling, the surface hardness of 5 points was measured by a Rockwell hardness tester in accordance with JIS Z 2245 (surface 312XP / invention specification (supplement) / 95-12/ 95137108 24 广6 [iV—正ai*dness)HRC' is averaged and evaluated as temper softening resistance. (5) Toughness test after tempering treatment After the surface of the quenched and tempered test pieces shown in Table 2 was pickled and subjected to surface descaling, 5 V-cut tests were respectively carried out in accordance with JIS Z 2202. Sheet (width: 5mm small size). Using these test pieces, the Charpy impact test according to the provisions of Jis Z 2242/the Charpy impact value at a test temperature of 25 °C. The average value of the five test pieces was determined, and the value was 50 j/cm 2 or more, and the toughness evaluation # was practically no problem. The results obtained are shown in Table 2. Further, the maximum temperature of the 7 regions shown in Table 2 means the Worth field (the highest temperature at which the phase is generated at a temperature of 75 vol% or more. The ^^ degree on the 5 phase (fertilizer iron phase)) Increased and cannot be guaranteed at 75 vol

95137108 25 1316966

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6Z 000 un s6/tsI-s6/ff}M)_KB ΚΒ ΚΒ ΜΧΠ 16 1316966 All of the examples of the present invention have quenching hardness in the range of HRC32~38, excellent in simmering and high temper softening resistance. Sex and excellent toughness. On the other hand, the comparative example deviating from the scope of the present invention, or the quenching hardness deviates from the range of HRC32 to 38, or the temper softening resistance and the toughness are lowered. In the comparative example in which the average particle diameter of the old γ·particles deviated from the range of the present invention, the hardness after tempering could not satisfy the desired hardness. (Industrial Applicability) φ According to the present invention, temper softening can be easily and inexpensively produced by appropriately setting the particle size of the old Worth field to an appropriate range, that is, by applying an appropriate quenching hardness of HRC 32 to 38. The brake disc with excellent resistance to high tempering softening resistance and excellent toughness can exert excellent effects in the industry. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph showing the effect of the average particle size of the old Worthfield body particles on the temper softening resistance.

312ΧΡ/Invention Manual (supplement)/95-12/95137108

Claims (1)

MAR 2 Ο 2009 Replacement 1316966 X. Patent application scope: μι 3 2 β 1. A brake disc excellent in temper softening resistance and toughness, characterized in that it is composed of the following formula (1) and formula ( 2), C: 0.1% or less, Si: 1. 0% or less, Μη: 2. 0% or less, Cr: 10. 5~15. 0%, N: 0. U or less and Nb: 0· 02~0· 6% (both in mass %), the rest are Fe and unavoidable impurities, and there are Ma Tiantian particles with an average particle size of 8 # m or more and less than 15 # m. For the loose iron structure, the hardness after tempering for 1 hour at 6 于 is above 27 for HRC, and the Charpy impact value is above 50 J/Cm2; 5Cr+10Si+15Mo+30Nb-9Ni -5Mn-3Cu-225N-270C<45...(1) 〇· 03$ {C+N-(13/92)Nb}S 0. 09. . . (2) Here 'Cr, Si, M Niobium, Nb, Ni, Mn, Cu, N, and c are the contents (% by mass) of each element. 2. For the brake disc of the scope of the patent application, in which the ratio of Nb (the amount of Nb precipitated by the precipitate) to the total amount of ribs (the total amount of ribs) is precipitated (precipitated Nb/total) ), satisfying the following formula (3), each of which is as follows: 5Cr+10Si+15Mo+30Nb-9Ni-5Mn-3Cu-225N-270C<45. (1) 0. 03${C+N-(13/92 Nb}S 0.09.·.(2) 0. 5 < (precipitating Nb/all Nb) g〇.7 ·· (3) Here: Cr, Si, Mo, Nb, Ni, Μη, Cu, N C is the content (% by mass) of each element, and Nb and total Nb are precipitated as % by mass. 3: The brake disc of claim 1 or 2, further comprising Cu: 〇.〇1 to 〇·5% (% by mass) in addition to the above composition. 4. The brake disc of claim 1 or 2, wherein the hardness after tempering at 6 〇 0 95137108 31 1316966 ° C for 1 hour is 30 or more in HRC. 5. If the scope of application for patents is 3 j苜: ^ is 丨^. _ brother " member of the car, in which, under 600t", the hardness of the small temple after tempering in the URC is more than 30. For example, in the brake disc of any of the scopes of the second and fifth aspects of the patent application, the above-mentioned composition further includes (4) at least one or more from the bottom (all are mass%): (a) contains the selection From mo mm. or 2; τ i (B) contains Co ··〇. ου. 〇% ; (6) Contains from Ti: 0.02~0.3%, v:o02~o.3%, Zr: 0.02~0.3 %, Ta: one or more of 0.02 sen; (D) 3 is selected from B. 〇. 〇〇〇5~〇· 〇〇5(10), & : 〇 5 5 〇 shoulder (10) And the brake disc of claim 3, wherein the brake disc further contains at least one of the following (A) to (8) in addition to the above composition (all of which are mass V: '(1) contains It is selected from m2.0%, Ni: 〇i〇2 〇%t^4 or 2, (B) contains Co: 〇· 〇1 ～1. 〇%; (6) contains a compound selected from Ti: 〇.〇2 ～0.3 %, v: u2~〇3%, Zr: 0·02~0ϋ 0.02~0.3% of the i type or more; Β: 〇·〇〇 5^〇.0050%.Ca: one or two of 0.0005-0.0050%. 8. The brake disc of claim 4, wherein the composition 95973108 32 1316966 further contains a At least one of (A) to (D) (all of which is of quality « : (A) contains one selected from the group consisting of Mo: 0·0 Bu 2. 0%, Ni: 0. 10~2. 0% Or two types; (B) containing Co: 0·01 〜1. 0%; '(C) containing a compound selected from the group consisting of Ti: 0. 02~0. 3%, V: 0. 02~0· 3%, Zr: 0. 02〜0. 3%, Ta: 0. 02~0. One or more of 3% or more; (D) Containing a selected from B: 0·0005~0. 0050%, Ca: 0. 0005 ~0. 0050% One or two of the appeals. 95137108 33