CN101701325A - E-grade steel with low cost - Google Patents

Abstract

The invention relates to new material E-grade steel with low cost. Because the content of alloying elements of C, Mn, Cr, Ni and Mo of the components of the new material E-grade steel with low cost is regulated, i.e. the content of the C is slightly increased, the contents of the Mn and the Cr are slightly decreased, and the contents of precious alloys of the Ni and the Mo are increased as little as possible or not increased; and a necessary means is adopted on heat treatment, thus the mechanical property of a new material cast is ensured to achieve the requirement of an original technique. The new material cast is obtained by using the same casting technique as an original cast except for preparation proportion and has stable quality after the heat treatment adopts a measure of eliminating temper brittleness, high primary qualification rate of the heat treatment and good repair welding property.

Description

E-grade steel with low cost

Technical field

The invention belongs to steel, particularly a kind of E-grade steel with low cost.

Technical background

E level steel is as a kind of casting low-carbon (LC), low alloy steel, is widely used in various draft gear housing, hook tail frame, coupler hook body, hook tongue of rail vehicles accessory etc.This casting E level composition of steel of technical qualification regulation is: 0.22%-0.28%C, 0.20%-0.40%Si, 1.20%-1.50%Mn, 0.40%-0.6%Cr, 0.35%-0.55%Ni, 0.20%-0.30%Mo, S, P≤0.040%, Cu≤0.30%, it will reach with stove coupon mechanical property foundry goods after modifier treatment: tensile strength sigma b 〉=830MPa, yield strength σ s 〉=690MPa, 6 〉=14%, ψ 〉=30%,-40 ℃ of low-temperature impact AKv 〉=27J (are not less than under the prerequisite of 27J three average A Kv values of impacting test block, it is qualified to allow the AKv value of one of them test block to reach promptly to judge more than the 18J to impact), hardness: 241HBW-302HBW.From 2005.Casting E level steel rises with the price of important raw and processed materials (containing 60%Mo) Mo iron is anxious on the market, is once reaching 460,000 yuan/ton, and the price of 2006 another important raw and processed materials Ni plates also soars, and the cost of casting E level steel significantly increases, and the price of foundry goods is constant.In addition, in long term production, we have also found some problems that now exist with E level steel, as: (1). carbon containing is low, and when C contained quantity not sufficient 0.25%, 60% casting strength was low, hardness is low, need thermal treatment processings of doing over again, or even dissect casing reduction standard of performance in kind and could let pass.(2) .Mn, Cr, Ni content are more, the carbon equivalent value is bigger, carbon equivalent ce=C%+Mn%/6+ (Cr%+Mo%)/5+ (Ni%+Cu%)/15 calculation formula that provides by MES1.16F, calculating its minimum carbon equivalent is 0.6, maximum carbon equivalent is 0.77, cause foundry goods easily to crack, and be unfavorable for the foundry goods repair welding.

With reference to for many years, our production U.S. MIENER draft gear housing experience, this foundry goods technical qualification of U.S.'s casing predetermined component scope is: 0.27%-0.33%C, 0.70%-1.00%Mn, 0.30%-0.50%Mo, 0.03%-0.08%Al ,≤0.20%Cu ,≤0.25%Cr ,≤0.25%Ni, S, P, Si content are identical with E level steel casting regulation with China railways, and the regulation carbon equivalent can not surpass 0.68.Mechanical property will reach: tensile strength sigma b 〉=830MPa, yield strength σ s 〉=690MPa, δ 〉=14%, ψ 〉=30% ,-40 ℃ of low-temperature impact AKv 〉=20J (three AKv values of impacting test block all will reach more than the 20J), hardness: 255HBW-321HBW.As seen U.S.'s casing mechanical property requires with China railways also basic identical with E level steel casting.But U.S.'s casing becomes in the sub specification C content big with E level steel casting than China railways, and alloying element all is lower than China E level steel casting except that Mo, and Cr, Ni exist as residual element especially, and the Al of 0.03%-0.08% can improve the low temperature impact properties of material.Calculate the cost of production with Mo content 0.35% (in the actual production general Mo content at 0.30%-0.33%), still be lower than China E level steel casting (Mo content is in 0.25%), and during carbon equivalent 0.53-0.68, its thermal treatment first-time qualification rate height, the foundry goods repair welding is good.

Metallic substance knowledge in conjunction with above-mentioned two kinds of casting composition standards and we grasp when C content is low, increases with C content, and the intensity of steel, hardness increase obviously after the thermal treatment, should suitably increase C content in the novel material prescription; Si content increases, and increases casting and heat treatment crack tendency, and Si content should not increase; Though belonging to, Mn and Cr improve the strength of materials, hardness alloy, but consumption is abundant in existing E level composition of steel standard, and this two element is obvious to increasing the effect of material carbon equivalent, Mn also increases the responsive tendency of material heat treatment oxidation and decarbonization in addition, this two element should not increase in the novel material prescription, even Mn content will fall slightly; Nitrogen in Al and the foundry goods can form AlN, eliminates the deleterious effect of nitrogen to brittle transition temperature on the one hand, controls the grain fineness number of steel on the one hand, should require an amount of Al in the novel material prescription; S, P, Cu as harmful element, be controlled in steel≤0.04%S ,≤0.04%P ,≤0.25%Cu gets final product; The Mo and the Ni prices of raw and semifnished materials are more expensive, can reach by thermal treatment at novel material under the prerequisite of its mechanical property requirement, should add less as far as possible, even do not add, thereby reduce casting cost.

Summary of the invention

The purpose of this invention is to provide a kind of E-grade steel with low cost.That is: adjust each alloying element prescription in the E level steel, reduce valuable Alloy Elements Mo, Ni content in the material, and the improvement by corresponding thermal treatment process, under the prerequisite that guarantees new E level steel mechanical property, the cost of manufacture of reduction E level steel components.

The content of this E-grade steel with low cost novel material prescription is:

The E-grade steel with low cost prescription:

0.27%-0.32%C, 0.20%-0.40%Si, 1.10%-1.40%Mn, 0.30%-0.50%Cr, 0.15%-0.25%Ni or 0.10%-0.20%Mo (only there be a kind of getting final product in these two kinds of noble metals of Ni and Mo), 0.03%-0.08%Al, S, P≤0.040%, Cu≤0.25%.

The advantage characteristics of invention:

The technical program is a kind of E-grade steel with low cost novel material prescription, is that a kind of little Ni does not have the E-grade steel with low cost novel material component prescription that Mo or little Mo do not have Ni.

This novel material is applicable to foundry goods such as the various draft gear housing of passenger train from goods train and hook tail frame, hook tongue.

Table 1 is test E-grade steel with low cost chemical ingredients and mechanical property synopsis

The characteristics of this E-grade steel with low cost novel material:

1.. material C content newly developed has increase slightly, and intensity, hardness increase obviously after the material heat treatment, after the temper brittleness measure is eliminated in employing, thermal treatment first-time qualification rate height.

2.. material carbon equivalent newly developed is controlled at 0.53-0.68, and repair welding is good.

3.. material cost reduction newly developed obviously sees Table 2.Table 2 is to add the influence to steel cost per ton of Mn iron, Cr iron, Ni plate, Mo iron when consider smelting E level steel, the price of Mn iron, Cr iron, Ni plate, Mo iron be by current market value (that is: the price that the price of Ni plate that contains 11 yuan/Kg of price, the ni content 99% of the Mn iron of Mn amount 70% is 149 yuan/middle Kg, the price that contains the Cr iron of Cr amount 64% is 9.9 yuan/Kg, contain the Mo iron of Mo amount 60% be 133 yuan/Kg) calculate, its add-on all is with lower limit add-on (in the actual production, also with the lower limit add-on as first-selection) calculating.

Table 2 material newly developed and China railways rolling stock are now used E level steel economic comparison

	Add Mn iron cost (unit/ton steel)	Add Cr iron cost (unit/ton steel)	Add Mo iron cost (unit/ton steel)	Add Ni plate cost (unit/ton steel)	Add up to cost (unit/ton steel)
						Now use E level steel	Minimum 188.6	Minimum 61.9	Minimum 443.3	Minimum 526.8	??1220.6
The Ni novel material is arranged	Minimum 172.8	Minimum 46.4	??0	Minimum 225.8	??445.0
						The Mo novel material is arranged	Minimum 172.8	Minimum 46.4	Minimum 221.7	??0	??440.9

As seen from the above table, the about 775.6-779.7 of E-grade steel with low cost newly developed saving cost per ton unit.

4.. E-grade steel with low cost newly developed is with now China railways used for rolling stock E level steel is except that batching, and smelting technology is basic identical.

Embodiment

Be by steel scrap, Mn iron, Cr iron and Ni plate or Mo iron through charge calculation, drop into electric arc furnace or intermediate frequency furnace by a certain percentage and smelt again that cast forms, its smelting and pouring technology are except that the proportion scale adjustment, fully with to show E level steel identical.

Testing sequence and method:

Plan with intermediate frequency furnace, the new material formula composition range of initial setting is, 0.27%-0.32%C, 0.20%-0.40%Si, ≤ 1.40%Mn, 0.30%-0.50%Cr≤0.25%Ni, ≤ 0.20%Mo, 0.03%-0.08%Al, S, P≤0.040%, Cu≤0.25% cast Kiel coupon (China railways used for rolling stock E level steel casting requires the coupon type with the stove cast), about 10 coupons of every stove, during thermal treatment every stove coupon is further divided into two groups and heat-treats technological test, wherein about 3/5 coupon is done tension test after the thermal treatment, 2/5 coupon is done low temperature impact test, after each cast heat coupon technology and performance test are finished, the analysis of summarizing, adjust and test concrete scheme next time, reach technical requirements fully until test-results.By seven cast heats, nearly 70 coupon technologies and performance test are found: after the conventional thermal treatment, its drawn test-results is qualified, but Ni content is in the 0.15%-0.25% scope in composition, and when Mo contained quantity not sufficient 0.10%, cold impact value had only 6-10J, can not reach technical requirements, we think relevant with material temper brittleness, and after thermal treatment taked to eliminate the temper brittleness measure, all mechanical propertys can reach technical requirements; Ni contains quantity not sufficient 0.15% in composition, and when Mo contained quantity not sufficient 0.10%, although after thermal treatment takes to eliminate the temper brittleness measure, cold impact value can only reach more than the 18J, can not guarantee all to reach more than the 27J.We have formulated the E-grade steel with low cost component prescription that (1) provides for this reason, and this prescription after repetition test result (table 1) is stable, carries out exemplar in kind and short run full scale test again again.

On the basis of above coupon technology and performance test, the component prescription (not adding Mo in the batching) that we adopt (1) to provide, with 2 U.S. MINER of intermediate frequency furnace cast (U.S. MINER casing allows under the prerequisite that guarantees mechanical property and carbon equivalent≤0.68, but adjusting tank body composition; But China's draft gear housing does not allow the composition adjustment) casing, take during thermal treatment to eliminate that it all reaches technical requirements with stove coupon, the casing mechanical property of dissecting in kind after the temper brittleness measure.Thereafter the prescription (not adding Mo in the batching) of using (1) to provide, pour into a mould stove 30 U.S. MINER casing with electric arc furnace, it is qualified with stove coupon mechanical property after taking to eliminate the temper brittleness measure during thermal treatment, after 12 exemplars mail to the U.S., after U.S. MINER company dissects casing, its metallographic structure, mechanical property, hardness are all checked, thought to meet the requirements; Its impact test in kind also reaches requirement.U.S. MINER company has agreed that we press the component prescription that (1) provide and produce its casing for this reason, and we have supplied over thousands of of its this E-grade steel with low cost casing.

Claims (1)

1. E-grade steel with low cost is characterized in that:

In Fe, contain:

C：0.27％-0.32％、

Si：0.20％-0.40％、

Mn：1.10％-1.40％、

Cr：0.30％-0.50％、

Ni 0.15%-0.25% or Mo 0.10%-0.20% wherein a kind of,

Al?0.03％-0.08％、

S、P≤0.040％、

Cu≤0.25％。