CN1865482A

CN1865482A - Dedicated aluminum-containing bainite forged steel for railway frog crossing

Info

Publication number: CN1865482A
Application number: CN 200610012825
Authority: CN
Inventors: 张福成; 郑炀曾; 吕博
Original assignee: Yanshan University
Current assignee: Yanshan University
Priority date: 2006-06-09
Filing date: 2006-06-09
Publication date: 2006-11-22

Abstract

The invention discloses a specific bainite hammered steel with aluminum of rail frog in the low alloy steel of MnAlCrMoNi system, which comprises the following parts: 0.24-0.40 wt percent C, 1.0-3.0 wt percent Mn, 0.7-2.0 wt percent Al, 0.5-2.0 wt percent Cr, 0.2-1.0 wt percent Mo, 0.1-1.0 wt percent Ni, 0.3-0.8 wt percent Si, less than 0.03 wt percent S, less than 0.03 wt percent P and Fe. The smelting method comprises the following steps: smelting in the electric stove; cooling the cast ingot to indoor temperature in the mould; forging to proceed heat disposal and final heat disposal as non-carbide bainite and residual austenite; possessing the following final disposal property: sigmab>=1250MPa,sigmas>=1100 MPa,delta5>=10%,aKU>=80J/cm2,aKU(-40 deg.c )>=35J/cm2,HRC 38-45. The invention lengthens the utility lifetime than present ZGMn13 by over 60 percent, whose overload quantity can reach over 0.3 billion ton.

Description

Dedicated aluminum-containing bainite forged steel for railway frog crossing

Technical field

The present invention relates to a kind of railroad frog dedicated aluminum-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%): C 0.10～0.65, Si≤2.65, Mn 0.50～3.20, Cr 0.20～2.80, 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 there are alloying element Si and Mo and contain microalloy element V, Nb, Ti or B etc., also not with the bibliographical information of Si as the bainitic steel of alloy element, the content of Si is all higher in the existing document.The present invention proposes the bainite forged steel of a kind of Al of containing, and replaces most of Si with Al.Through Overheating Treatment, obtain the material of comprehensive mechanical property excellence, be used to make safety in utilization and higher railroad frog of life-span.

Summary of the invention

The present invention in systematic study Al content and thermal treatment process, especially forge on the basis of postheat treatment technology to bainitic steel tissue and conventional mechanical property, provide the special use of a kind of novel wear resistant antifatigue railroad frog to contain the Al bainitic steel, 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: a kind of novel wear resistant, antifatigue dedicated aluminum-containing bainite forged steel for railway frog crossing are provided, its chemical ingredients (wt%) is: C 0.24～0.40, Mn 1.0～3.0, and Al 0.7～2.0, and Cr 0.5～2.0, Mo 0.2-1.0, Ni 0.1～1.0, and Si 0.3～0.8, S＜0.03, P＜0.03, all the other are Fe.The smelting process for making 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: molybdenum-iron, ferronickel, ferrochrome, ferromanganese and commercial-purity aluminium 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.The conventional mechanical property of steel user mode is: σ b 〉=1250MPa, σ s 〉=1100MPa, δ 5 〉=10%, a _KU〉=80J/cm ², a _{(40 ℃ of KU}) 〉=35J/cm ², HRC 38-45.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

In embodiment 1, the chemical ingredients of dedicated aluminum-containing bainite forged steel for railway frog crossing (wt%) is: C 0.28, and Mn 1.56, and Al 1.34, and Ni 0.32, and Cr 1.62, and Mo 0.43, and Si 0.33, and S 0.032, P0.028, and all the other are Fe.Its forging process is: the 100 ℃/h of rate of heating of steel ingot, 1220 ℃ of Heating temperatures, 1200 ℃ of initial forging temperatures, 920 ℃ 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=1261MPa, σ _0.2=1098MPa, δ ₅=16%, a _KU=112J/cm ²

Embodiment 2

In embodiment 2, the chemical ingredients of dedicated aluminum-containing bainite forged steel for railway frog crossing (wt%) is: C 0.30, and Mn 1.58, and Al 1.38, and Ni 0.41, and Cr 1.45, and Mo 0.50, and S 0.028, and P 0.027, and all the other are Fe.Its forging process and thermal treatment process are with embodiment 1.Forging ' s block dimension is 120 * 200 * 1000mm, 30mm place sampling under the forging surface, and mechanical property is: σ _b=1289MPa, σ _0.2=1156MPa, δ ₅=18%, a _KU=95J/cm ²

Claims

1. dedicated aluminum-containing bainite forged steel for railway frog crossing is characterized in that:

(1) chemical ingredients of dedicated aluminum-containing bainite forged steel for railway frog crossing (wt%) is: C 0.24～0.40, and Mn 1.0～3.0, and Al 0.7～2.0, and Cr 0.5～2.0, Mo 0.2-1.0, Ni 0.1～1.0, and Si 0.3～0.8, S＜0.03, P＜0.03, all the other are Fe; Use The state steelConventional mechanical property be: σ b 〉=1250MPa, σ s 〉=1100MPa, δ 5 〉=10%, aKU 〉=80J/cm ², aKU (40 ℃) 〉=35J/cm ², HRC38-45.

(2) manufacturing process of dedicated aluminum-containing bainite forged steel for railway frog crossing is:

A. electrosmelting, 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: molybdenum-iron, ferronickel, ferrochrome, ferromanganese, commercial-purity aluminium, pour into steel ingot then, and steel ingot need slowly cool to room temperature depanning in ingot mould;

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.