CN100392140C

CN100392140C - Tungsten aluminium containing bainite forged steel special for railroad frog

Info

Publication number: CN100392140C
Application number: CNB2006100481098A
Authority: CN
Inventors: 张福成; 郑炀曾; 吕博
Original assignee: Yanshan University
Current assignee: Yanshan University
Priority date: 2006-08-03
Filing date: 2006-08-03
Publication date: 2008-06-04
Anticipated expiration: 2026-08-03
Also published as: CN1904121A

Abstract

A type of steel used for railroad crossing which contains wolfram and aluminium bainite. It belongs to MnCrWAlNi series low-alloy steel. The chemical composition(wt%) is : C 0.25-0.40,Mn 1.0-3.0,Al 0.7-2.0, Ni 0.1-1.0,Cr 0.5-2.0,W 0.4-2.0,Si 0.3-0.8,S<0.03,P<0.03, and the rest is Fe. Use electric furnace to smelt, then cast, anneal the ingot to room temperature. Twice heat treatment after forging: heat treatment after forging, and heat treatment at last. The last tissue is no-carbide bainite and small amounts retained austenite. The last feature: sigma b>=1250MPa,sigma s>=1100MPa, delta 5>=10%,aKU>=80J/cm2,aKU(-40DEG C)>=35J/cm2,HRC 38-45. It can boost the lifetime of railroad above 60% compare with ZGMn13 railroad, the overloading capacity can beyond 300,000,000 tons.

Description

Tungsten aluminium containing bainite forged steel special for railroad frog and manufacture method thereof

Technical field

The present invention relates to a kind of railroad frog dedicated tungsten-containing bainite steel, it need use through forging the back.

Background technology

The ZGMn13 Hadfield Steel is that Britain slip-stick artist Hadfield invented in September, 1882, its first purposes is exactly the railway frog that was used to make tramway in 1892, from then on, nearly all in the world railroad frog all is to be made by this material over more than 100 year.The chemical ingredients of the ZGMn13 that initial Hadfield announces is: C1.35%, Si0.69%, Mn12.76%, at present.The chemical ingredients scope of the ZGMn13 steel of generally acknowledging is C1.0-1.4, Mn11-14, and all the other are iron and small amount of impurities such as Si, S, P etc.The average overload quantity (work-ing life) of the ZGMn13 steel railway frog that China produces is 1.5 hundred million tons, and can reach more than 200,000,000 tons the mean life of the ZGMn13 steel railway frog that the U.S. and some developed countries of Europe produce.Along with the raising of social development and transportation by railroad speed, people are to the higher requirement of railroad frog proposition in work-ing life.Therefore people many new achievements in research occurred from the former ZGMn13 steel of further raising railway frog work-ing life with seek new aspects such as railway frog material and launched extensive studies.As world patent WO0136698, Canadian Patent CA2159358, United States Patent (USP) 4514235, Chinese patent CN02157927.X and 98124899.3 or the like.Make a general survey of these achievements in research and practical effect, we can say at present and mainly contain two major sects about railroad frog selection aspect in the world, first Hadfield Steel promptly utilizes processing methodes such as metallurgy, casting, thermal treatment and mechanical enhancer further to improve its work-ing life on the basis of original high mangaenese steel; It two is the middle low-carbon low-alloy steels that mainly are organized as bainite.

Bainitic steel is because of it has high intensity, suitable toughness and hardness makes it show good anti-contact fatigue and wear resisting property, and especially it has excellent welding processing properties, it is become make novel high speed railway one of ideal material of railway frog.Therefore, it is having application more and more widely aspect the making railroad frog at present, and the impetus that replaces traditional High Manganese Steel Frog is gradually arranged.Chinese patent CN02157927.X has announced the compound central body of frog of a kind of bainitic steel electroslag casting, and the technical process of its making is: get the raw materials ready → electroslag casting is compound → machining → thermal treatment → flaw detection → finished product; Its structure is formed for being that brached rail is compound by non-carbide bainitic steel central body of frog and common rail; Heart rail main alloy element is Si, Mn, Cr, Mo, Ni, and is attached with micro-V and Nb, and all the other are Fe.Chinese patent 98124899.3 is announced a kind of railroad frog proprietary material, the inventor is the tough weldable air-cooled great health bainitic steel of the special-purpose superelevation of its called after railroad frog, this invention is a main alloy element with Mn, Si, be aided with elements such as Cr, Ni, Mo, air cooling can arrive the bainite/martensite heterogeneous structure behind austenitizing; Its Essential Chemistry composition is that (Wt%): C0.10～0.65, Si≤2.65, Mn0.50～3.20, Cr0.20～2.80, Ni≤3.50, Mo≤2.00, remainder are Fe.Another achievement in research of our country has been reported " high-performance novel alloy steel novel material of new generation ", it is to be main alloy element with Si and Mn, Cr, Mo, Ni are auxilliary, be aided with Re, V, the rotten railway switch heart rail of Ti, concrete chemical ingredients is: 0.25～0.4%C, 1.0～2.5%Si, 1.0～2.5%Mn, 1.0～2.0%Cr, 0.3～0.8%Mo, 0.3～1.0%Ni, and Re, B, V, the Ti of trace.The forging method moulding of this steel, normalizing or annealed state obtain bainite structure.The mechanical performance index of steel is under the user mode: tensile strength sigma _b1240～1360MPa, yield strength σ _s〉=1100MPa, unit elongation δ ₅〉=8%, room temperature impelling strength 〉=75J/cm ², low-temperature impact toughness 〉=40J/cm ²(40 ℃), hardness HRC37～42.

Chemical ingredients from the special-purpose bainitic steel of the present railroad frog of announcing wherein all exists alloying element Si and Mo and contains microalloy element V, Nb, Ti or B etc.Yet the Mo resource is deficient day by day in the world, and especially in recent years, the western developed country utilization contains the fertilizer of Mo and plants the grass that stock cattle eats, and makes the Mo resource nervous more.Therefore, a large amount of research at present concentrates on and utilizes W to replace Mo.Because, studies show that W has very big influence to the perlite and the bainitic transformation of steel, and can significantly hinder separating out of austenite grain boundary carbide, its effect is similar to Mo, from the temper brittleness and the obstruction perlitic transformation angle that reduce steel, the viewpoint of generally acknowledging is that the effect of W is equivalent to half of Mo.China is one of richly endowed country of W resource in the world, and therefore research contains the W steel and has practical significance.Yet W is less relatively as the use of alloy element in the steel bainite.The present invention proposes the aluminiferous again bainite forged steel of a kind of tungstenic, through Overheating Treatment, obtains the material of comprehensive mechanical property excellence, is used to make safety in utilization and higher railroad frog of life-span.

Summary of the invention

The present invention in systematic study W and Al content and thermal treatment process, especially forge on the basis of postheat treatment technology to bainitic steel tissue and conventional mechanical property, a kind of novel wear resistant antifatigue railroad frog dedicated tungsten-containing aluminium bainitic steel and manufacture method thereof are provided, and this steel uses through forging the back.Benly be, bainitic steel hydrogen embrittlement susceptibility of the present invention is little, and therefore, its unit elongation as one of plasticity index is greatly improved, thereby the security of railroad frog is improved, and this relevant bainite steel frog patent of also announcing is not at present just fully taken into account.

The technical solution adopted in the present invention is: this novel wear resistant that provides, antifatigue railroad frog dedicated tungsten-containing bainite steel, its chemical ingredients (wt%) is: C0.25～0.40, Mn1.0～3.0, Al0.7～2.0, Ni0.1～1.0, Cr0.5～2.0, W0.4～2.0, Si0.3～0.8, S＜0.03, P＜0.03, all the other are Fe.The conventional mechanical property of steel user mode is: σ b 〉=1250MPa, σ s 〉=1100MPa, δ 5 〉=10%, a _KU〉=80J/cm ², a _{KU (40 ℃)}〉=35J/cm ², HRC38-45.The manufacturing process of steel is: electrosmelting, and its smelting technology is: tapping temperature is identical with general medium carbon low alloy steel with teeming temperature; When smelting, alloying element (corresponding iron alloy) by the addition sequence after arriving first is: ferrotungsten, ferronickel, ferrosilicon, ferrochrome, ferromanganese pour into steel ingot then.Forging process is: the rate of heating of steel ingot≤120 ℃/h, Heating temperature 1150-1250 ℃, initial forging temperature 1150-1220 ℃, final forging temperature 〉=850 ℃.Final thermal treatment process is: at first forging is heated to 850 ℃～950 ℃ and carries out normalizing treatment, and then be heated to 300 ℃～400 ℃ and carry out temper.

The invention has the beneficial effects as follows: steel is organized as carbide-free Bainite and small portion of residual austenite after the final thermal treatment.Improve 60% or more than the common ZGMn13 steel railway frog that uses at present the work-ing life of this bainite forged steel railway frog, and overload quantity can reach more than 300,000,000 tons.

Embodiment

Embodiment 1

The chemical ingredients of steel billet (wt%) is: C0.32, and Mn1.55, Al1.50, Ni0.32, Cr1.58, W1.35, Si0.45, S0.025, P0.028, all the other are Fe.Forging process is: the 100 ℃/h of rate of heating of steel ingot, 1220 ℃ of Heating temperatures, 1200 ℃ of initial forging temperatures, 950 ℃ of final forging temperatures.Final thermal treatment process is: steel is heated to 920 ℃ carries out normalizing treatment, and then be heated to 350 ℃ and carry out temper.Forging ' s block dimension is 120 * 200 * 1000mm, 30mm place sampling under the forging surface, and mechanical property is: σ _b=1325MPa, σ _0.2=1106MPa, δ ₅=15%, a _K=122J/cm ², HRC42.

Embodiment 2

The chemical ingredients of steel billet (wt%) is: C0.35, and Mn1.77, Al1.48, Ni0.33, Cr1.66, W1.21, Si0.50, S0.024, P0.021, all the other are Fe.Forging process and thermal treatment process are with example 1.Forging ' s block dimension is 120 * 200 * 1000mm, 30mm place sampling under the forging surface, and mechanical property is: σ _b=1389MPa, σ _0.2=1115MPa, δ ₅=16%, a _K=135J/cm ², HRC42.

Embodiment 3

The chemical ingredients of steel billet (wt%) is: C0.26, and Mn2.17, Al0.98, Ni0.63, Cr1.11, W1.61, Si0.52, S0.025, P0.020, all the other are Fe.Forging process and thermal treatment process are with example 1.Forging ' s block dimension is 120 * 200 * 1000mm, 30mm place sampling under the forging surface, and mechanical property is: σ _b=1257MPa, σ _0.2=1111MPa, δ ₅=17%, a _K=146J/cm ², HRC40.

Embodiment 4

The chemical ingredients of steel billet (wt%) is: C0.38, and Mn2.43, Al1.23, Ni0.23, Cr1.81, W0.82, Si0.64, S0.011, P0.008, all the other are Fe.Forging process and thermal treatment process are with example 1.Forging ' s block dimension is 120 * 200 * 1000mm, 30mm place sampling under the forging surface, and mechanical property is: σ _b=1417MPa, σ _0.2=1189MPa, δ ₅=15%, a _K=109J/cm ², HRC45.

Embodiment 5

The chemical ingredients of steel billet (wt%) is: C0.31, and Mn1.86, Al1.01, Ni0.31, Cr0.89, W1.10, Si0.55, S0.016, P0.018, all the other are Fe.Forging process and thermal treatment process are with example 1.Forging ' s block dimension is 120 * 200 * 1000mm, 30mm place sampling under the forging surface, and mechanical property is: σ _b=1322MPa, σ _0.2=1117MPa, δ ₅=18%, a _K=142J/cm ², HRC41.Be used to make a collection of railroad frog, the average overload quantity of every railway frog reaches 2.1 hundred million tons at present, and frog centre portion has only the trace wearing and tearing.

Claims

1. tungsten aluminium containing bainite forged steel special for railroad frog, it is characterized in that: its chemical ingredients is wt%:C0.25～0.40, Mn1.0～3.0, Al0.7～2.0, Ni0.1～1.0, Cr0.5～2.0, W0.4～2.0, Si0.3～0.8, S＜0.03, P＜0.03, all the other are Fe; The conventional mechanical property of user mode steel is: σ b 〉=1250MPa, and σ s 〉=1100MPa, δ 5 〉=10%, a _K〉=80J/cm ², a _{K (40 ℃)}〉=35J/cm ², HRC38-45.

2. technology of making the described tungsten aluminium containing bainite forged steel special for railroad frog of claim 1 is characterized in that:

A. smelting manufacturing process is:

Electrosmelting, its smelting technology is: tapping temperature is identical with general medium carbon low alloy steel with teeming temperature;

When smelting, alloying element by the addition sequence after arriving first is: ferrotungsten, ferronickel, ferrochrome, ferromanganese, commercial-purity aluminium pour into steel ingot then; Steel ingot need be in ingot mould slowly cool to room temperature depanning;

B. forging process is:

The rate of heating of steel ingot≤120 ℃/h, Heating temperature 1150-1250 ℃, initial forging temperature 1150-1220 ℃, final forging temperature 〉=850 ℃;

C. final thermal treatment process is:

At first forging is heated to 850 ℃～950 ℃ and carries out normalizing treatment, and then be heated to 300 ℃～400 ℃ and carry out temper, obtain carbide-free Bainite and small portion of residual austenite structure.