CN1039267A

CN1039267A - Wear-resistant high chromium cast iron

Info

Publication number: CN1039267A
Application number: CN 89104726
Authority: CN
Inventors: 何俊; 彭治龙; 张清; 钱永芳; 王雄; 王永恒; 曹永菁
Original assignee: China Iron and Steel Research Institute Group
Current assignee: China Iron and Steel Research Institute Group
Priority date: 1989-07-17
Filing date: 1989-07-17
Publication date: 1990-01-31
Also published as: CN1011985B

Abstract

The invention belongs to casting iron field.Be particularly suitable for being produced in the field such as metallurgy the anti abrasive component that Working environment is very harsh.

The present invention mainly is not nickeliferous in the composition, and vanadium and molybdenum adopt thermal treatment process of the present invention can obtain high-wearing feature cast iron all than other material height in the prior art.This cast iron has wear-resistant compared with prior art, good mechanical property, the thermal treatment process advantage that simply is easy to grasp and cuts down the consumption of energy etc.

Description

Antiwear high-chromium cast iron

The invention belongs to casting iron field.Be particularly suitable for making the low-stress erosion resistance and the anti abrasive component of working in the severe rugged environments such as metallurgical mine, building materials, water power, chemical industry.

The domestic flow passage part material that is used to make pump often adopts the 320 * 20H grade of steel of the ZG35 steel and the Soviet Union and the Ni-hard series cast iron of American I NCO company at present.Adopt the made component of above-mentioned materials all to be operated in the medium easy to wear.Therefore it is poor that the former has wear resisting property.Shortcomings the such as then latter is low because of mechanical property, and fragility is big, wear resistance is relatively poor, and the high and energy consumption of thermal treatment scrap rate is big and be difficult to promote, the while is all contained nickel in these materials, the use of material is restricted.Also introduced a patent (SU-1047986-A) in addition abroad, though it is not nickeliferous in the composition of this material, but vanadium and molybdenum content are all lower in the composition, so the wear resistance of material and mechanical property are all relatively poor, also have shortcomings such as the complicated and energy consumption height of thermal treatment process.

The objective of the invention is to propose a kind of not nickeliferous antiwear high-chromium cast iron, and have good mechanical property and wear resistance, and can reach the qualification rate of a large amount of saving energy and raising product by the brief heat treating method.

According to above-mentioned purpose of the present invention, the present invention proposes a kind of antiwear high-chromium cast iron material.Its concrete chemical ingredients (weight %) is C 2.9～3.2%; Si 0.4～0.8%; Mn 0.4～1.0%; Mo 1.2～2.0%; Cr 18.0～20.0%; V 4.0～5.0%; Cu 0.8～1.2%; Re 0.05～0.5%; P＜0.08; S≤0.05%, all the other are Fe.

In the ordinary course of things, the cast iron eutectic carbon amount that contains Cr15% is 3.6%, and the cast iron eutectic carbon amount that contains Cr18% and Cr20% is respectively 3.4% and 3.2%, and high chromium cast iron contains the Cr amount should be more than 10%, and the factor that determines its hardening capacity is mainly the Cr/C ratio, requires between 4～11.The carbide type is by Me like this ₃C(HV840～1100) type changes Me into ₇C ₃Type (HV1500～1800).Because Me ₃C type carbide is an external phase, and metallic matrix is isolated phase.But Me ₇C ₃The type carbide is just in time opposite, and the successive metallic matrix gives carbide strong " support " effect, and therefore very high resistance to abrasion and suitable toughness are arranged.To low temperature wash away wear-resistant Cr/C than between being controlled at 6.0～7.5 for good.Be lower than 18% as Cr content, Cr/C influences hardening capacity than reducing, and Cr content is higher than 20%, though the wear resistance and corrosion resistance of material is identical with the former, thermotolerance increases.So adopt thermal treatment process of the present invention, Cr content is advisable between being controlled at 18%～20%.

V is a kind of utmost point intensive carbide forming element in material of the present invention.Under the cooling conditions of as cast condition, it can make austenite separate out proeutectoid carbide, reduces the content of carbon and chromium, can improve the Ms point again.Thereby be beneficial to martensitic transformation, improve the wear resistance of material.Its as-cast structure and ordinary white cast iron are more or less the same when V content is low, though carbide is broken into interrupted shape, still see to ledeburite eutectic attitude.The ledeburite eutectic disappears substantially when V increases to 2.14%, all is austenite on the matrix, but has needle type martensite to separate out on matrix and carbide interface.Occur white bright high V carbide particle when V content increases to 3.7%, the matrix disperse goes out proeutectoid carbide, has obviously reduced austenitic stability, makes the part matrix be transformed into martensite.When V content increased to 4%, the proeutectoid carbide quantity of high V carbide particle and disperse obviously increased, and the matrix fundamental transformation becomes martensite, so V content is controlled at 4～5%.V mainly is distributed in the V that is isolated strip and block or bone shape ₄O ₃Among/the VC, in the abrasive wear process, it neither breaks also indeformable, also has crystal grain thinning simultaneously, strengthens the effect of the resistance to abrasion of matrix.

Mo can improve wear-resistant and mechanical property in material of the present invention.Because Mo generates the tiny dispersive carbide of infusible Mo in cast iron ₂C, it is included in Me ₇C ₃In the type double carbide, the unusual effect that suppresses perlitic transformation and improve hardening capacity is arranged.Though Mo dissolves in austenite sosoloid, it does not have the effect of stable austenite, can not hinder martensitic transformation yet.Mo is lower than under the requirement in limited time, tissue is formed inoperative, but surpass the upper limit brittle carbides amount is increased, and has also improved the cost of cast iron.Therefore Mo requirement content is 1.2%～2.0%.Add 0.8%～1.2% Cu and be in order to increase hardening capacity, to avoid matrix pearlitic structure to occur, the particularly compound adding of Mo, Cu significantly makes " vanadium " curve move to right.Improved the form of carbide and the flowability of distribution and molten steel, but Cu also can play the effect of stable austenite phase,, limit the quantity of below 1.2% so excessive Cu can cause molten iron " pollution ".Mn has raising hardening capacity, stable austenite, the effect that the Ms point is reduced.So Mn content limit is 0.4～1.0%.Si uses as deoxidation during for melting, and too high Si can cause fragility, so content should be less than 0.8%.Adding a spot of Re is for processing that molten steel is gone bad.It can crystal grain thinning, purifies crystal boundary, and toughness, bending strength, hardness are all benefited.It is a kind of element that improves over-all properties.DeGrain then when add-on is less than 0.05% can cause the pollution of too much non-metallic inclusion but surpass at 0.5% o'clock, thereby be directed at the embrittlement of material.

High-chromium abrasion-proof cast iron of the present invention can adopt high frequency, intermediate frequency, line frequency induction furnace or electric arc furnace smelting.

The heat treating regime of cast iron of the present invention is: foundry goods through 500 ℃ the insulation 4～6 hours after air cooling to room temperature.Mechanical property and wear resisting property all can meet or exceed the effect that adopts conventional heat treatment process foundry goods.Particularly eliminate the scrap rate that produces by thermal treatment.Because of the conventional thermal treatment thermal treatment scrap rate height that (4 hours air coolings of 960 ℃～1040 ℃ insulations are to room temperature, again through 260 ℃ of insulations air cooling after 4-6 hour) caused when the heat.

Antiwear high-chromium cast iron of the present invention compared with prior art (SU-10479 86-A) to have wear resistance good, the product percent of pass height.It is simple also to have thermal treatment process simultaneously, is easy to grasp, and saves a large amount of energy.Because of not nickeliferous in the cast iron composition of the present invention, so be a kind of economic and practical wear-resistant cast iron material.

Embodiment

The concrete chemical ingredients of antiwear high-chromium cast iron designed according to this invention has been smelted three stove cast irons in the 500kg line frequency induction furnace, in order to contrast, smelted each stove of the similar cast iron with the U.S. of the Soviet Union simultaneously, and concrete composition sees Table 1.Cast iron of the present invention through 5 hours air coolings of 500 ℃ of insulations to the room temperature thermal treatment with similar contrast cast iron make a service test relatively see Table 2 and mechanical property and wear resisting property relatively see Table 3.Wear test is carried out on ML-10 abrasive test machine, with 150#SiC silicon carbide paper, load 2.36kg, 14.4 meters of tracks.

Chemical component table 1

Alloy number	Chemical ingredients (weight percent)
										C	Si	Mn	Mo	Cr	V	Cu	Ni	Re
	The present invention	1 2 3	2.9 3.0 3.12	0.55 0.65 0.87	0.84 0.75 1.04	1.3 1.5 1.96	17.9 19.5 20.25	3.96 4.23 4.16	0.73 0.95 1.23										0.08 0.35 0.51
The universal Ni-hard cast iron of 320 20H										3.12 3.2	0.95 0.41	1.06 0.54	0.18	25.72 2.32			3.2 4.0

The residual % amount of the present invention and universal high chromium cast iron:

Table 2

Alloy number	Residual %, as cast condition	Residual %, conventional processing	Residual %, subcritical processing
				The present invention	43.8	9.6	6.0
Universal	59.9	21.0	41.3

Claims

1, a kind of antiwear high-chromium cast iron is characterized in that the concrete chemical ingredients (weight %) of this cast iron is C2.9～3.2%; Si0.4～0.8%; Mn0.4～1.0%; Mo1.2～2.0%; Cr18.0～20.0%; V4.0～5.0%; Cu0.8～1.2%; Re0.05～0.5%; P＜0.08; S≤0.05; All the other are iron.

2, a kind of heat treating method of antiwear high-chromium cast iron is characterized in that foundry goods is heated to 500 ℃, is incubated after 4～6 hours, and air cooling is to room temperature.