DE3117539A1 - "WEAR-RESISTANT AUSTENITIC STAINLESS STEEL" - Google Patents

Description

Wear-resistant austenitic stainless steel

The invention relates to an austenitic stainless steel with a relatively low initial cost, which exhibits a very high work hardening rate / excellent wear resistance and a high strength in connection with good ductility and good hot workability. Without being restricted to this ₇ , the steel according to the invention is suitable for transport systems, in particular in mining, body floor assemblies and similar applications that require high wear resistance and abrasion resistance, coupled with adequate corrosion resistance.

The new combination of properties of the steel according to the invention is made more essential by a critical balance of the proportions Elements achieved in order to achieve austenite stability

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to arrive in hot rolled material after a drastic cold reduction a transformation into a controlled amount of deformation martensite with corresponding Hardness, strength and wear resistance. Both the composition ranges of the essential elements as the austenite stability (as defined below) of the steel of the present invention is also critical.

In U.S. Patent 3,940,266, an austenitic stainless steel having a good work hardening rate is disclosed , good cryogenic toughness and good resistance to stress corrosion, essentially from about 0.01 to about 0.06% carbon, about 11 to about 14% manganese, at most 0.06% phosphorus, at most 0.04% sulfur, at most 1% silicon, 15.5 to 20% chromium, 2.50 to 3.75% nickel, 0.20 to 0.38% nitrogen and apart from incidental impurities, consists of iron. This well-known steel has a high Austenite stability and thus withstands transformation into martensite during deformation.

US Pat. No. 3,989,474 describes bars and rods, cold drawn wire and strand-shaped articles made of hot rolled steel consisting essentially of 0.06 to 0.12% carbon, 11 to 14% manganese, up to 0.06% phosphorus , up to 0.04% sulfur, up to 1% silicon / 15.5 to 20% chromium, 1.1 to 2 _r 5% nickel, 0.20 to 0.38% nitrogen and the remainder, apart from incidental impurities made of iron. These objects, too, are almost completely austenitic and have a low magnetic permeability in cold-reduced form.

US Pat. No. 2,778,731 describes an austenitic steel consisting of 0.06 to 0.15% carbon, 14 to 20% Manganese, 0.25 to 1.0% silicon, 17 to 18.5% chromium, 0.05

up to 1.00% nickel, 0.25 to 1.0% nitrogen and the rest made of iron.

British patent specification 995 068 describes an austenitic one stainless steel, consisting of a trace of up to 0.12% carbon, 5 to 8.6% manganese, not more than 2.0% silicon, 15.0 to 17.5% chromium, 3.0 to 6.5% nickel, 0.75 to 2.5% copper, a trace up to 0.10% nitrogen and im the rest of iron, the components are regulated so that the martensite-forming property according to a Formula is less than 10% and that the delta-ferrite-forming Share is less than 10% according to this formula. The copper content depends on the manganese content. This well-known Steel is said to have high austenite stability and a low work hardening rate due to the lack of transformation exhibit in martensite during cold working.

Allegheny Type 211 is an austenitic stainless steel with a low work hardening rate and is used for deep drawing. Its nominal composition is 0.05% carbon, 6.0% manganese, 17.0% chromium, 5.5% nickel, 1.5% copper and the rest iron.

Allegheny Type 205 is an austenitic stainless steel containing 0.12 to 0.25% carbon, 14.0 to 16.0% manganese, 0.2 to 0.7% silicon, 16 to 18% chromium, 1.1 to 2.0% nickel, 0.32 to 0.40% nitrogen and the rest essential iron.

Other austenitic stainless steels with relatively low nickel contents are in the US patents 2,820,725, 3,151,979, 3,192,041 and British patent specification 882,893. ·

As the prior art discussed above shows, listed the desire to control the amount of nickel in austenitic stainless steels and the associated high costs To keep a minimum, the skilled person to use relatively large amounts of manganese, copper, carbon and / or To use nitrogen. Although cheaper than nickel, manganese and copper are inherently relatively expensive alloying elements and result in large quantities of them, in particular when used in combination, create hot working problems. With the exception of US patents 3,940,266 and 3,989,470 of the aforementioned known steels are typically all of low strength and a slow work hardening rate. Aside from cost, the main problem with this is how to get it austenite stability and the maintenance of corrosion resistance.

A main object of the present invention is to provide an austenitic steel with relatively low Contained in expensive alloy components, but at the same time high strength / excellent Wear resistance, good ductility and good hot workability, paired with adequate corrosion resistance.

Another object of the invention is to provide a stainless steel having an austenitic structure Hot rolling temperature with such a stability that only a very small fraction (typically at most 1%), if at all, it transforms into martensite (thermal martensite) during cooling, but that during cold deformation Deformation martensite forms.

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The above objects are in the invention Steel through a critical balance of the percentage ranges of the essential components manganese, chromium, nickel, Copper and nitrogen and by regulating the austenite stability through an instability factor (IF) between 2.5 and 8.5 met, the instability factor according to the following Equation is calculated:

IF = 37.2 - 51.25 (% C) - 2.59 (% Ni)

- 1.02 (% Mn)

- 0.47 (% Cr) - 34.4 (% N) - 3 (% Cu).

In the drawing show:

1 is a state diagram of the composition areas, expressed as nickel equivalent / chromium equivalent and

Figure 2 is a graph showing the relationship between instability factor versus% ferrite and / or martensite.

The present invention provides an austenitic stainless steel having high strength, superior wear resistance, good hot workability, good ductility and a high work hardening rate, which is essentially of 0.015 to 0.10 wt.% carbon, 5.5 to 10.0 % By weight manganese, at most 0.06% by weight phosphorus, at most 0.06% by weight sulfur, at most 2.0% by weight silicon, 12.5 to 20.0% by weight of chromium, 1.0 to 3.5% by weight of nickel, at most 0.85 % By weight copper, 0.15 to 0.30% by weight nitrogen and the remainder essentially consists of iron; this steel has one Instability factor between 2.5 and 8.5 calculated by the equation:

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Instability factor = 37.2 - 51.25 (% C) 2.59 (% Ni) - 1.02 (% Mn) - 0.47 (% Cr) 34.4 (% N) -3 (% Cu).

The percentage ranges and the proportions of the essential elements manganese, chromium, nickel, copper and nitrogen are critical in every respect and deviations therefrom result in losses in one or more of the desired properties.

Although less critical, the carbon and silicon areas are but important to achieve the desired combination of properties .

Manganese is a partial substitute for nickel as an austenite former and austenite stabilizer essential. For this purpose, at least 5.5, preferably 6.0, and more preferably 7.0 % By weight required. A maximum of 10.0, preferably 9.0 and even better 8.5% by weight of manganese should be adhered to, since higher values mean the work hardening rate and thus reduce the strength values. In addition, high manganese levels in combination with relatively high ones result Copper contents to hot working problems.

Chromium is corrosion resistant because of its usual function, steel to confer essential and a minimum of 12.0%, preferably 13.0%, and more preferably 14.75% is to essential for this purpose. A maximum of 20.0%, preferably 17.0% and even better 15.50% must be adhered to in order to the ferrite-forming potential relative to the austenite-forming potential of the elements carbon, manganese, nickel, copper and to keep nitrogen in balance. Also sets

Chromium in an excess over the preferred maximum of 17.0% and determined in excess over the broad maximum of 20.0% the cold curing speed and the im cold machined condition.

Nickel is an essential austenite former and is a broad and preferred minimum of 1.0% and an even better one A minimum of 1.5% is required to fulfill this function. A maximum of 3.5%, preferably less than 3.0%, and more preferably 2.5%, should be considered in view of the adverse influence of higher nickel values the work hardening rate and the strength values are not exceeded. It is also desirable to keep the maximum nickel content at the lowest possible value because of its high cost.

Copper is essential as a partial replacement for nickel and a preferred minimum is 0.5%; should be even better 0.6% must be admitted. However, a maximum of 0.85% must be adhered to, since copper is the work hardening rate greatly reduces and, in combination with high manganese values, results in hot working problems. aside from that It is generally the case that for products used in the dairy industry, the milk has copper contents above about 0.85 contaminate.

Nitrogen is essential and a common and preferred one because of its strong austenite-forming potential A minimum of 0.15% and even better 0.18% is required for this purpose. Also gives a minimum of 0.15% nitrogen improved notch corrosion resistance.

A maximum of 0.30%, preferably 0.25% and even better 0.22% should be maintained in order to achieve equilibrium between the nickel equivalent and the chromium equivalent in terms of the tendency to form austenite and ferrite to maintain.

Carbon is also a strong austenite former and is a minimum of 0.015% and preferably 0.02% desirable for this purpose. A maximum of 0.10%, preferably 0.06% and even better 0.05% must be adhered to because higher carbon values improve corrosion resistance and adversely affect the resistance to corrosion at the grain boundaries.

Silicon is a strong ferrite former and a general maximum of 2.0%, preferably 1.0% and even better 0.75 ' should be adhered to in order to avoid disturbing the austenite-ferrite equilibrium.

Phosphorus and sulfur are common contaminants present and a wide and preferred maximum of 0.06% each and better of 0.04% can be without unfavorable Influences are tolerated.

A preferred steel according to the invention thus consists in essentially of 0.02 to 0.06 wt.% carbon, 6.0 to 9.0 wt.% manganese, at most 0.06 wt.% phosphorus, at most 0.06% by weight sulfur, at most 1.0% by weight silicon, 13.0 to 17.0% by weight chromium, 1.0 to less than 3.0% by weight nickel, 0.5 to 0.85% by weight of copper, 0.15 to 0.25% by weight of nitrogen and the remainder essentially of iron; who owns steel an instability factor between 2.5 and 8.5, calculated from the equation given above for the instability factor .

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An even more preferred steel according to the invention consists essentially of 0.02 to 0.05 wt.% Carbon, 7.0 to 8.5% by weight manganese, at most 0.04% by weight phosphorus, at most 0.04% by weight sulfur, 0.4 to 0.75% by weight *. Silicon, 14.75 to 15.50% by weight chromium, 1.5 to 2.5% by weight nickel, 0.6 to 0.75% by weight copper, 0.18 to 0.22% by weight Nitrogen and the rest essentially of iron; this steel has an instability factor between 2.5 and 8.5, calculated according to the equation given above for the instability factor, with a nickel equivalent between 12 and 15, calculated according to the equation:

Nickel equivalent =% Ni +30 (% C) + 0.5 (% Mn) + 30 (% N) + 0.5 (% Cu),

and a chromium equivalent between 14 and 17, calculated according to the equation:

Chromium equivalent =% Cr +% Mo + 1.5 (% Si) +0.5 (% Cb).

The instability factor is a quantitative calculation, which show the tendency of austenitic microstructures to transform into deformation martensite during cold working indicates. In this regard, it should be noted that a ferritic microstructure does not apply to cold working turns into martensite. As demonstrated by experimental data below, the instability factor must be used to achieve a high work hardening rate are within the range of 2.5 to 8.5. There is a correlation between the instability factor and the amount of ferrite and thermal martensite in the hot rolled and annealed condition; this interaction is referred to here as "Ferrite Number" (FZ). The austenite stability can

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also quantitatively using a modified Schaeffler diagram are reproduced, in which the nickel equivalent is plotted against the chromium equivalent, whereby the existing phases can be predicted at least qualitatively.

1 is a state diagram, specifically a modified Schaeffler diagram. Although the Schaeffler diagram was developed to predict welding microstructures, it has been found that in the steel of the invention there is a good correlation between machined and annealed microstructures. The preferred and the even more preferred compositions of the steels of the invention fall within area ABCD of FIGS thus form either a completely austenitic phase or mixed austenitic-martensitic phases.

Fig. 2 is a graph showing the relationship between instability factor calculated according to the above Equation and ferrite number (ferrite plus thermal martensite) in the machined and annealed condition. It should be noted that the ferrite number with an instability factor of about 8.2 increases sharply, indicating a duplex microstructure of austenite and martensite. It has been found that a proportionate high value for heat martensite does not lead to significantly higher strength values after drastic work hardening leads to reductions of over 50 and up to 60%. A higher number of ferrite in the machined and annealed Condition does not cause the austenite to work faster, but rather the higher proportion of martensite in Annealed condition lowers the ductility of the steel, which creates difficulties in cold working. the end for this reason, an upper limit for the instability factor of 8.5 must be observed. As expected, shows

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a higher number of ferrite in the machined and annealed State a higher strength, but this is only achieved at the expense of ductility. For the best balance of strength and ductility in the machined and annealed condition, the instability factor is preferably between 5.0 and 8.2 and the ferrite number between 1 and 2.

It has been found that an increase in the nickel, chromium, manganese plus nitrogen content or the copper content the Strength values decreased and ductility improved. That is likely due to a low instability factor (and thus ferrite number) with a consequent reduction in the work hardening rate. Nickel and manganese plus nitrogen have the greatest effect in reducing strength. Regarding the work hardening rate The copper content, expressed in percent by weight, has the greatest influence on the reduction this work hardening rate is made up of, followed by nickel, chromium and manganese. An addition of 0.5% by weight of copper is about as effective as 1.5 wt% nickel, 3 wt% chromium, or 4 wt% manganese, reducing the strength values and the level of cold working Deformation martensites concerns.

The above observations are made through a series of experimental melts confirmed that have been manufactured, machined and tested. The influence of changes in the nickel, Chromium, manganese plus nitrogen content and the copper content was both inside and outside of the invention Areas of these elements in the steel are examined. The compositions of these experimental melts are given in Table I. along with calculations of the instability factor, des

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^ hrome equivalents and rJ ^ s nickel equivalents accordingly given the equations given above. Properties of the melts of Table I in cold rolled and Annealed condition are summarized in Table II. For comparison purposes, commercial samples were used at the same time of AISI Type 301 and 304 steels tested in the same condition. The melts were melted and turned into blocks cast, hot rolled at 1260 ° C to a thickness of 2.5 mm and annealed at 1093 ° C. Samples were cold-reduced by 50% to 1.3 mm and annealed at 1093 ° C. The test results in Table II are based on 1.3 mm thick annealed samples. Samples of the hot rolled and annealed 2.5 mm of material were then cold-reduced to different degrees. More specifically, a group was up 50% Rolled down 1.3 mm in thickness, annealed at 1093 ° C, descaled and further cold-reduced by 20% to a thickness of 1.0 mm. Another group of samples was cold-reduced by 30% to a thickness of 1.7 mm, annealed at 1093 ° C., and descaled and cold rolled another 40% to 1.0 mm thickness. A final group of specimens was 60% in rolled down a cold rolling step to a thickness of 1.0 mm.

Samples cold reduced by 20%, 40% and 60% became a Subjected work hardening test, while annealed samples which were cold reduced by 50%, tension tests, Erichsen deep drawing tests (Indentation tests) and GTA weld strength assessments and deformability assessments became. Samples of AISI Type 301 and 304 steels were also strain hardened tests under the same conditions subject for comparison purposes. The work hardening tests are in Table III and the GTA mechanical weld properties are summarized in Table IV.

From the data of Table II show that steels according to the invention with a Ferrite Number of 1, 0 a higher

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Strength showed than 301 and 304 steels and that deformability after the Erichsen deep-drawing test was about the same as that of the 301 and 304 steels. For ferrite numbers about strength increased while ductility and deformability decreased.

The work hardening tests of Table III show that the Work hardening rate of the steels according to the invention is significantly larger than that of 301 and 304 steels. In some cases, steels according to the invention showed after one about 60% cold reduction, a Rockwell C hardness of approximately 50. Steels according to the invention with a ferrite number of 1 strength values achieved in the cold-reduced and annealed condition far above those of conventional alloys, these values being similar to those of hot-treated, approximated precipitation hardened steels when cold reduced by more than 50%.

The autogenous GTA welds given in Table IV concerned ferrite numbers that are well comparable to those of the annealed base metal. Melting with high ferrite numbers showed high strength values and low ductility and deformability. Even some of the melts with low Ferrite numbers showed loss of ductility when the instability factor Exceeded 8.0. With a low ferrite number and an instability factor below 8, there were on according to the invention The strength and deformability of welds carried out on steels are comparable to the values their base metal.

Further melts of steels according to the invention were made and tested for their abrasion or wear resistance. For comparison purposes, samples of carbon steel, AISI type 301 and 304, and one of the ones mentioned

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U.S. Patent 3,940,266 corresponding steel (commercially available under the trademark "NITRONIC 33") passed the same tests subject. The compositions of these steels are given in Table V. Multiple series of wear tests were carried out and the results are given in Tables VJ to IX. In Table VI were those according to the invention Steels in the hot-rolled condition, while in Tables VII to IX the steels according to the invention in the hot-rolled condition and annealed condition.

The test performed on ore chips in Table VI was a severe abrasion test with only slight corrosion effects. The tests in Table VI (Series 3) and Tables VII and VIII performed on phosphate ore pooled Abrasion and corrosion effects. The mixer test performed using a wet phosphate slurry by Table IX simulated operating conditions in a dredging mud line due to the high mud velocity and the open system.

In Table VI, the relative wear resistance of the steels according to the invention was 2.8 to 3.9 times greater than that of carbon steel and much better than that of NITRONIC 33 in the two tests with the pieces of ore. In the test carried out with the phosphate sludge by Table VI, the inventive steels were at least four times better than carbon steel and 78% better than NITRONIC 33.

In the annealed condition considered in Table VII, the relative wear resistance of the steels according to the invention increased compared to carbon steel. Still it was relative wear resistance of the steel according to the invention three times that of carbon steel and was 60% better than NITRONIC 33. It is possible that the new, annealed condition will have a

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suffered process-related wear that was greater than steady-state wear.

In Table VIII, direct comparative tests were performed on stainless steels only. The steel according to the invention showed a slight superiority over type steel and NITRONIC 33. In Table VIII there was also an alloy with high nickel and high copper for comparison purposes tested and used as a comparative number 1.0. At the end of the test, the steel according to the invention was 17% more wear-resistant as the reference alloy with high nickel and high copper content.

In the test of Table IX, the conditions for carbon steel were found in all series with different designs of mixing paddles, at different speeds and with different durations, a great deal more erosive for carbon steel. Although the inventive Steel in two series was worse than NITRONIC and the alloy with high nickel and high copper content, The results of all five series show that the steel according to the invention is superior to the NITRONIC 33 and the High nickel and high copper alloys are about the same. The great superiority of all three stainless steels about carbon steel in Table IX is quite obvious.

As can be seen, the steel according to the invention thus has a relative wear resistance in both hot-rolled and hot-rolled and annealed conditions, which is at least 2.5 times that of carbon steel and the Steel according to the invention shows overall against all tested Steels a superiority.

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For a certain ductility value (measured in% elongation) the steels according to the invention show a much higher hardness in the cold-hardened or work-hardened state as standard steels the 300 series.

The invention thus provides a steel having high strength, superior abrasion resistance, good ductility and one high work hardening rate in the hot-rolled as well as in the hot-rolled and annealed condition and a 0.2% Yield strength of over 200 ksi (1379 MPa) with a cold reduction of more than 50%. Although the invention Steels are suitable for a wide range of applications, as they are particularly suitable for the manufacture of dredging mud pipes by welding a hot-rolled strip made into a cylindrical shape, because of its essential nature better abrasion resistance compared to carbon steel currently used to make such leads.

The steel according to the invention can also be in the form of rods, Rods and wire are provided in both the wide and preferred compositions. The wire drawing Achieved high strength and good ductility results in a new combination of properties, as one in previous Steel not considered achievable, especially when the cross-sectional area is reduced by more than 50%.

% C % Mn XS ZS TABE LLE % Cr % Ni I. % Cu IZ Cr equ. Ni-A 0.025
0.025
0.025 4.01
3.95
3.60 0.020
0.020
0.020 0.018
0.018
0.018 Compositions - 17.26
17.21
16.88 0.96
1.75
3.35 Weight% 0.73
0.71
0.71 +12.8
+10.9
+ 7.3 18.2
18.1
17.7 9.5
10.2
11.6 sample 0.028
0.028 6.92
6.38 0.019
0.018 0.013
0.013 % Si 13.27
16.23 1.71
1.68 % N 0.86
0.85 + 8.2
+ 7.5 14.0
16.9 12.7
12.4 1
2
3 0.043
0.043
, 0.028
0.028 4.70
8.89
4.56
8.75 0.020
0.020
0.018
0.018 0.015
0.015
0.015
0.015 0.51
0.48
0.42 15.35
14.92
14.79
14.32 1.71
1.72
1.72
1.72 0.18
0.18
0.18 0.76
0.71
0.75
0.72 + 9.7
+ 5.'4
+12.0
+ 8.0 16.2
15.6
15.5
15.0 11.7
13.8
10.0
12.1 4th
5 * 0.030
0.030 7.10
7:00 0.019
0.021 0.014
0.014 0.36
0.30 15.24
14.90 1.73
1.92 0.21
0.21 0.21
2.20 + 9.0
+ 5.0 16.1
15.7 12.6
13.7 6th
η-k
8th
G* 0.39
0.35
0.31
0.28 0.20
0.20
0.16
0.16 10
11 0.40
0.39 0.21
0.21

* steels according to the invention

TABLE II

F.Z. Properties in (444)
(390)
(352) Tensile strength
ksi (MPa) (1210)
(1131)
(965) hot rolled and equal Bottom condition (5.4)
(6.8)
(11.2) sample 28
7.5
1.0 0.2% stretch
strength
ksi (RPa) (330)
(339) 175.5
164.0
140.0 (945)
(896) % Elongation
2 inch (50.8mm) hardness
RB / C Erichsen-
Dent test
Ht-inch (mm) (8.8)
(11.8) 1
2
3 2.5
1.0 64.5
56.5
51.0 (745)
(348)
(529)
(308) 137.0
130.0 (1300)
(824)
(1286)
(876) 16.0
20.0
34.0 C27.5
C21.0
B91.5 0.210
0.270
0.440 (6.3)
(12.3)
(7.Γ)
(12.3) 4th
5 * 26th
1.0
> 30
1.0 47.9
49.2 (365)
(345) 188.5
119.5
186.5
127.0 (1052)
(745) 35.0
45.5 B94.5
B92.0 0.345
0.465 (11.7)
(11.7) 6th
7 *
8th
9 * 1.0
1.0 108.0
50.5
76.7
44.6 (276)
(241) 152.5
108.0 (758)
(586) 14.0
57.0
10.0
52.0 C42.5
B93.5
C41.0
B88.5 0.250
0.485
0.280
0.485 (12.2)
(12.1) IO
11 53.0
50.0 110.0
85.0 49.5
55.5 B96.5
B89.5 0.460
0.460 T-301
T-304 40.0
35.0 60
55 B85
B80 0.480
0.475

steels according to the invention

TABLE I. 0.2% stretch
strength tensile strength
ksi (MPa) ksi (MPa) 175.5 (1210)
210.5 (1452)
235.5 (1624)
256.0 (1765) II State ferrite
number \
JO
7 ° Mechanical properties in 64.5 (444)
172.5 (1189)
230.5 (1589)
253.5 (1748) 164.0 (1131)
204.0 (1407)
227.0 (1565)
249.5 (1720) cold machined hardness
RB / C 28
T »30
> 30
> 30 \ sample %
Cold
working 56.5 (390)
121.5 (838)
215.5 (1486)
247.0 (1703) 140.0 (965)
182.5 (1258)
204.5 (14,1O)
221.0 (1524) % Strain
2 inch (50.8mm) C27.5
C48.0
C49.0
C49.0 7.5
> 30
> 30
> 30 1 0
19.2
40.3
56.9 51.0 (352)
107.0 (738)
180.0 (1241)
216.5 (1492) 137.0 (945)
179.0 (1234)
216.0 (1489)
233.0 (1641) 16.0
9.5
4.0
3.0 C21.0
C47.0
C49.5
C50.5 1.0
16.5
> 30
> 30 2 0
19.2
38.9
56.6 47.9 (330)
111.0 (765)
198.0 (1365)
234.0 (1613) 130.0 (896)
173.0 (1192)
198.5 (1369)
229.0 (1579) 20.0
12.0
5.5
2.5 B91.5
C43.0
C48.5
C50.5 2.5
16
> 30
> 30 3 0
17.6
39.7
55.9 49.2 (339)
110.0 (758)
185.5 (1279)
213 (1468) 34.0
17.0
13.5
7.0 B94.5
C40.0
C47.0
C48.5 1.0
11.5
> 30
> 30 4th 0
19.2
40.3
59.1 35.0
18.0
9.0
3.5 B92.0
C39.5
C47.0
C48.0 5 * 0
18.8
40.6
56.5 45.5
20.0
14.0
4.0

steels according to the invention

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• TABLE III (page 2)

Mechanical properties in the quay 0.2% stretch
strength
ksi (MPa) (745)
(1290)
(1686)
(1858) Tensile strength
ksi (MPa) 2 tworked State ferrite
number sample Cold
working 108.0
187.5
244.5
269.5 (348)
(882)
(.1116)
(1524) 188.5 (1300)
217.5 (1500)
248.0 (1710)
273.0 (1382) % Elongation
Inch (50.8mm) hardness
RB / C 26th
> 30
> 30
> 30 6th 0
20.2
40.0
58.8 50.5
128.0
162.0
221.0 (529)
(1448)
(1590)
(1700) 119.5 (BIh)
172.5 (.1190)
189.0 (1303)
229.0 (1579) 14.0
12.0
5.0
7.0 C42.5
C49.5
C52.5
C53.0 1.0
7.5
12.5
19.5 7 * 0
22.9
35.9
58.4 76.7
210.0
230.5
.246.5 (308)
(758)
(1217)
(1451) 186.5 (1286)
218.0 (1503)
234.0 (1613)
250.5 (1727) 57.0
23.0
17.0
4.0 B93.5
C43.0
C47.5
C51.0 > 30
> 30
> 30
> 30 8th 0
17.6
39.8
57.9 44.6
110.0
176.5
210.5 (365)
(772)
(1441)
(1754) 127.0 (876)
164.5 (1134)
193.5 (1334)
221.0 (1524) 10.0
3.5
3.0
2.5 C41.0
C45.0
C48.0
C48.0 1.0
12.5
29.5
> 30 9 * 0
19.2
40.0
56.6 53.0
112.0
209.0
254.5 152.5 (1052)
192.0 (1324)
221.5 (1528)
261.0 (1800) 52.0
22.0
13.0
3.5 B88.5
C38.5
C46.0
C47.0 1.0
12.5
> 30
> 30 10 0
16.3
39.5
58.4 49.5
21.5
13.0
3.5 B96.5
C44.5
C51.5
C53.5

steels according to the invention

sample
11

τ-301

Τ-304

Kaitbe work.

20.8
34.8
56.8

20th
40
60

18.5
40.3
59.5

0.2% yield strength
ksi (MPa)

50.0 (345)

120.0 (828)

158.5 (1092)

194.5 (1341)

44.0 (303)

115.6 (797)
182.6 (1259)

29.2 (201)
• 91.0 (627)
131.0 (903)
156.4 (1078)

Tensile strength ksi (MPa)

108.0 (745)

153.5 (1058)

170.5 (1176)

203.5 (1403)

117.4 (809)

165.4 (1140)

196.0 (1351)

203.1 (1400)

83.4 (575)

106.2 (732) 145.2 (1001) 169.2 (1167)

% Elongation
2ZoII (50, amm)

55.5

25.0

20.0

5.0

63.0
30.0

10
4th

68.0

32.0

9.0

5.0

Hardness RB / C

B89.5 C38.0 C44.O C48.0

B88.0 C37.5 C45.O C44.5

B70.0 C23.0 C34.5 C38.0

Ferrite number

1.0

4.0

8.0

11.0

* steels according to the invention

sample Mechanical (448)
(404)
(362) TABLE IV (744)
(738)
(862) Welds Erichsen-
Dent test
Ht-inch (mm) (3.4)
(4.5)
(10.0) ι ferrite
number 1
2
3 0.2% stretch
strength
ksi (MPa) (.326)
(350) properties of (455)
(890) strain
2 inches
(50.8mm) 0.135
0.175
0.390 (7.4)
(10.2) 26.5
6.5
1.0 IZ 4th
5 * 65.0
58: 5
52.5 (734)
(348)
(533)
(302) %
Tensile strength
ksi (MPa) (1076)
(827)
(1089)
(858) 4.0
8.5
21.0 0.290
0.400 (4.0)
(11.9)
(4.4)
(11.9) 1.5
1.0 12.8
10.9
7.3 6th
7 *
8th
9 * 47.2
50.8 (372)
(348) 108.0
107.0
125.0 (1017)
(768) 7.0
43.5 0.160
0.470
0.170
Ο.47Ό (9.2)
(12.0) > 30
1.0
> 30
1.0 8.2
7.5 10
11 106.5
50.5
77.3
43.8 66.Ό
129.0 7.0
54.5
3.0
46.0 0.360
0.475 1.0
1.0 .9.7
5.4
12.0
8.0 54.0
50.5 156.0
120.0
158.0
124.5 37.0
53.0 9.0
5.0 147.5
111.5

* steels according to the invention

C. TABEL V Si Cr Weight% N Cu 56 0.34 Compositions - 0.17 - Ni - - 55 sample 0.053 Mn 0.67 17.47 - 0.28 - 56 Carbon steel
(AISI 1030) 0.068 1.14 0.48 18.45 3.45 0.01 - 48 NITRONIC 33 0.058 12.93 0.40 14.99 8.9 0.18 0. Type 304 0.059 1.66 0.38 14.95 0.99 0.18 0. 12 * 0.056 7.36 0.35 14.93 1.50 0.18 0. 13 * 0.035 7.34 0.45 05/17 1.96 0.14 2. 14 * 7.18. 4.56 15 (Much Ni ₇
a lot of Cu) 1.76

* steels according to the invention

TABLE VI Abrasion tests performed on wet sludge in the ball mill

Conditions: 2000 ml water + 200 ml ore pieces + 100 ml SiO ₂
42.38 m / min., 1 hour, counter samples, room temperature

Relative wear life (carbon steel as reference value 1.0)
Series 1

cycle Carbon steel Sample 12 Sample 13 Sample 12 Sample 14 Sample 14 1 1.0 5.4 3.8 4.8 3.9 2.9 2 1.0 2.9 3.0 4.0 3.0 cumulative 1.0 3.9 3.4 4.3 3.5 Sample 14 Series 2 4.7 cycle Carbon steel Nitronic 33 Sample 12 Sample 13 3.5 1 1.0 2.1 3.1 2.8 4.0 Series 3 1800 ml of water + 1000 ml of phosphate ore - 2 hours cycle Carbon steel Nitronic 33 Sample 13 1 1.0 2.4 4.8 2 1.0 2.1 3.6 cumulative 1.0 2.3 4.1

Conditions:

TABLE VII Abrasion tests performed on wet sludge in the ball mill

ml water + 1000 ml phosphate ore, 42.38 m / min.,
Hours, counter samples, room temperature

Relative wear life (carbon steel as reference value 1.0)

Series 1

cycle Carbon steel Nitronic 33 Sample 12 Sample 13 Sample 14 1 1.0 1.9 3.0 2.7 2.8 2 1.0 1.8 2.6 2.5 2.6 cumulative 1.0 1.8 2.8 2.6 2.7 Series 2 cycle Carbon steel Nitronic 33 Sample 12 Sample 13 Sample 14 1 1.0 2.2 3.7 3.5 3.4 2 1.0 1.8 3.1 3.0 3.2 3 1.0 1.6 2.5 2.5 2.5 cumulative 1.0 1.86 3.00 2.93 2.91

Ol CaJ CD

TABLE VIII

Abrasion tests performed on wet sludge in the ball mill

Conditions:

1800 ml water + 1000 ml phosphate ore, 42.38 m / min., 2 hours, counter samples, room temperature

Relative wear life (sample 15 as reference value 1.0)

Series 1

cycle Type 304 Nitronic 33 Sample 15 Sample 13 1 1.4 1.4 1.0 1.2 2 1.2. 1.3 1.0 1.3 3 1.2 1.0 1.0 1.3 cumulative 1.25 1.23 1.0 1.25 Series 2 Cycle new mud - 6 hours 1 1.08 1.05 1.0 1.17

If »

CO

-—Τ O

TABLE IX Mixer Test - By Wet Phosphate Slurry

Conditions: 1000 ml of phosphate ore diluted to 3000 ml,

Cross-checks, room temperature

Relative wear time (carbon steel as reference value 1.0) Series 1 - 18 hours

Carbon steel Nitronic 33 sample 12 sample 15 1.0 47.6 37.9 31.4

Series 2 - 2 hours - same slurry + 300 ml SiO ₂

1.0 20.5 10.1 14.3

Series 3 - 23 hours

1.0 62.3 63.9 117.7

Series 4 - 5 hours - new slurry - 1500 ml phosphate ore, no SiO ₂ 1.0 30.1 x 35.9 46.1

Series 5 - 20 hours - 1500 ml phosphate ore + 300 ml SiO ₂

1.0 26.0 61.0 50.3

cumulative 1.0 34.6 44.5 45.5

CO

CO UD

L e ~ e r s e i t e

Claims (11)

ü 1 I / ^ j ο patent attorneys Dipl.-Ing. Dipl.-Chem. Dipl.-Ing. E. Prince - Dr. G. Hauser - G. Leiser Ernsbergerstrasse 19 8 Munich 60 ARMCO INC. ^{May 4 , 1981} 703 Curtis Street Middletown, Ohio 45043 /V.St.A. Our reference: A 1857 Claims . Austenitic stainless steel with high strength, superior wear resistance, good hot workability, good ductility and high work hardening rate, consisting essentially of 0.015 to 0.10 wt.% Carbon, 5.5 to 10.0 wt.% Manganese, at most 0.06 wt.% Phosphorus, at most 0.06 wt.% Sulfur, at most 2.0% by weight silicon, 12.5 to 20.0% by weight chromium, 1.0 to 3.5% by weight nickel, at most 0.85% by weight copper, 0.15 to 0.30% by weight nitrogen and the rest of iron, with an instability factor of 2.5 to 8.5, calculated according to the equation: Instability factor = 37.2 - 51.25 (% C) 2.59 (% Ni) - 1.02 (% | Mn) - 0.47 (% Cr) 34.4 (% N) -3 (% Cu). 2. Steel according to claim 1, consisting essentially of 0.02 to 0.06 wt.% Carbon, 6.0 to 9.0 wt.% Manganese, at most 0.06 wt.% Phosphorus, at most 0.06 wt.% Sulfur, not more than 1.0% by weight silicon, 13.0 to 17.0% by weight chromium, 1.0 to less than 3.0 wt.% Nickel, 0.5 to 0.85 wt.% Copper, 0.15 to 0.25 wt.% Nitrogen and the rest of Iron. Dr. Ha / Gl 3. The steel of claim 1 consisting essentially of 0.02 up to 0.05 wt.% carbon, 7.0 to 8.5 wt.% manganese, at most 0.04 wt.% phosphorus, at most 0.04 wt.% sulfur, 0.4 to 0.75% by weight silicon, 14.75 to 15.50% by weight chromium, 1.5 to 2.5% by weight of nickel, 0.6 to 0.75% by weight of copper, 0.18 to 0.22% by weight of nitrogen and the rest of iron, with this steel is calculated to have a nickel equivalent between 12 and 15 according to the equation: Nickel equivalent. =% Ni + 30 (% C) + 0.5 (% Mn) +30 (% N) +0.5 (% Cu) and a chromium equivalent between 14 and 17, calculated from the equation: Chromium equivalent =% Cr +% Mo + 1.5 (% Si) +0.5 (% Cb). 4. Steel according to claim 2 or 3, characterized by a relative wear duration in the hot-rolled and in the hot-rolled and annealed state, which is at least 2.5 times that of carbon steel. 5. Steel according to claim 2 in the form of hot-rolled and annealed strip with an austenitic microstructure, high strength, superior wear resistance, good ductility and high work hardening rate. 6. Steel according to claim 2 in the form of cold-reduced and annealed Sheet metal and strips with a 0.2% yield strength of over 200 ksi with over 50% cold reduction and with superior wear resistance. 7. The steel of claim 1 in the form of a finished product having high strength, superior wear resistance and good ductility. 3117533 8. The steel of claim 2 in the form of a finished product having high strength, superior wear resistance and good ductility. 9. By welding a hot rolled and shaped austenitic stainless steel strip according to claim 2 manufactured mud pipe with better wear resistance than that of carbon steel. 10. The steel of claim 1 in the form of bars, rods and wire having high strength, superior wear resistance and good ductility. 11. The steel of claim 2 in the form of bars, rods and wire having high strength, superior wear resistance and good ductility.