CN103243269A

CN103243269A - Novel low-cost, wear-resistant and high-strength Q420A/B steel plate and production method thereof

Info

Publication number: CN103243269A
Application number: CN2012105850056A
Authority: CN
Inventors: 朱书成; 许少普; 刘庆波; 崔冠军; 袁少威; 郭艳芳; 康文举; 雷文慧; 陈景雪; 庞百鸣
Original assignee: Nanyang Hanye Special Steel Co Ltd
Current assignee: Nanyang Hanye Special Steel Co Ltd
Priority date: 2012-12-30
Filing date: 2012-12-30
Publication date: 2013-08-14

Abstract

The invention discloses a novel low-cost, wear-resistant and high-strength Q420A/B steel plate and a production method thereof. The steel plate comprises the following elements: 0.12-0.20% of C, 0.15-0.35% of Si, 1.20-1.40% of Mn, not more than 0.020% of P, not more than 0.015% of S, 0.005-0.060% of Als, 0.025-0.070% of Ti, 0.20-0.30% of Cr and the balance of Fe and inevitable impurities. The production method comprises the steps of: converter smelting, LF (ladle furnace) refining, VD (vacuum degas) treatment (optional), continuous casting, casting blank slow cooling, heating, TMCP (thermomechanical control process) rolling and slow cooling. Through the above novel composite micro-alloying component design idea and simple and effective process flow design, the indexes such as mechanical property and ultrasonic flaw detection of the steel plate are ensured and the wear resistance and high-temperature strength of the steel plate are improved. The steel plate has uniform properties, excellent flaw detection quality and certain wear resistance, can be widely used in engineering machinery, the coal machine industry, machine manufacturing and the like and has good popularization significance.

Description

A kind of novel low-cost wear-resisting high-strength steel Q420A/B steel plate and production method thereof

Technical field

The present invention relates to continuous casting and produce the plate of moderate thickness field, be specifically related to a kind of novel low-cost wear-resisting high-strength steel Q420A/B steel plate and production method thereof.

Background technology

Specification 10～80mm Q420A/B is a kind of High Strength Structural Steel steel plate, and it has higher intensity, good cold deformation ability, and plasticity and toughness can be widely used in projects such as all kinds of engineering machinery, bridge, building, large-sized workshop, stadium preferably.But along with the continuous progress of machine industry, the index request of mechanical means and engineering machinery is improved constantly, existing High Strength Structural Steel Q420A/B steel plate is difficult to meet the demands fully, and this new departure of ad hoc meter for this reason is to satisfy user's design requirement.

Summary of the invention

At the problems referred to above, the inventor has obtained a kind of specification 10～80mm guaranteed cost, has protected the novel low-cost wear-resisting high-strength steel Q420A/B steel plate of flaw detection, thereby finished the present invention through groping.

Therefore, the object of the present invention is to provide the high-strength steel Q420A/B steel plate of the low-cost guaranteed cost of a kind of specification 10～80mm, guarantor's flaw detection.

Another object of the present invention is to provide the production method of the novel low-cost wear-resisting high-strength steel Q420A/B steel plate with certain wear resisting property.

For reaching above-mentioned first purpose, in the national standard scope, alloying elements such as the Nb that price in the steel is high, V reduce, to reduce production costs;

The reduction of alloying element content such as Nb, V, can cause plate property to descend, bad stability, for guaranteeing the performance of steel plate, change under the little situation at process cost, utilize the lower Cr alloying element of price to replace alloying elements such as NB, V, under situation about reducing cost, reach the stability, uniformity of requirement performance index and performance, guarantee the overall quality index of steel plate.

For achieving the above object, novel low-cost wear-resisting high-strength steel Q420A/B steel plate of the present invention is by following elementary composition: C 0.12～0.20%, Si0.15～0.35%, Mn1.20～1.40%, P≤0.020%, S≤0.015%, Als0.005～0.060%, Ti 0.025～0.070%, Cr0.20～0.30%, all the other are Fe and unavoidable impurities.

The function analysis of above-mentioned chemical element is as follows:

C: be most basic strengthening element in the steel, improve intensity, but C influences the welding property of steel and influences toughness.Si: be the solution strengthening element, favourable to the intensity that improves steel plate.Mn: be the solution strengthening element, all favourable to intensity and the toughness that improves steel plate, but segregation causes detecting a flaw defective easily.P: unfavorable to welding, and have certain cold shortness, and in this steel grade, belong to harmful element, that should control is low as far as possible.S: easily form the MnS type impurity, have certain red brittleness, belong to harmful element in this steel grade, that should control is low as far as possible.Al: can play the crystal grain thinning strengthening effect.Nb, Ti: crystal grain thinning, the intensity of raising steel plate.Cr: chromium and iron form continuous solid solution, dwindle the austenite region, significantly improve intensity and hardening capacity, and have good abrasion resistance.

For achieving the above object, the production method that the present invention takes comprises: converter smelting, LF refining, VD vacuum-treat (optional), continuous casting, strand slow cooling, heating, rolling, the slow cooling of TMCP.

1, in described converter smelting, tapping carbon≤0.06%, tapping P≤0.018%, S≤0.020%; Point blows number of times and must not avoid slag under the tapping process greater than 2 times; The argon station adds the aluminum steel deoxidation.

2, in described LF refining, take the big quantity of slag to carry out slag making, guarantee that white slag hold-time control more than 15min, blew by force after ferro-niobium, ferrotianium, the ferrochromeization 3-5 minute, again more than the soft blow 8min.

3, in described casting process, adopt the whole process protection cast, the control of cast superheating temperature is at 5～20 ℃, and permanent pulling rate cast was gone into the burial pit slow cooling 24 hours after the continuously cast bloom cutting.

4, pine in described adding, heat-up time 0.8-1.4min/mm, the control of the holding temperature of soaking zone is at 1200 ℃～1280 ℃.

5, in described TMCP, 1000 ℃～1100 ℃ of start rolling temperatures; One stage finishing temperature is at 880～980 ℃, and the two-stage start rolling temperature is at 800～900 ℃, steel thickness 〉=1.5 times of drying in the air, and the two-stage takes to depress for a short time rolling, finish rolling accumulative total draft＞40%, finishing temperature≤880 ℃; Return red temperature＜650 ℃, cooling rate is controlled at 5～25 ℃/s.

6, in described slow cooling, go into burial pit temperature 〉=150 ℃; Cooling in heap time 〉=6 hour.

By combined microalloying composition mentality of designing and the brief effective process design of above novelty, guaranteed the index such as mechanical property, UT (Ultrasonic Testing) of steel plate; And wear resisting property and the hot strength of steel plate have been improved.This plate property is even, the flaw detection good quality, and has certain wear resisting property, can be widely used in aspects such as engineering machinery, coal machine industry, machinofacture, is with the promotion of good sense.

Embodiment

Novel low-cost wear-resisting high-strength steel Q420A/B steel plate of the present invention is by following elementary composition: C 0.12～0.20%, Si0.15～0.35%, Mn1.20～1.40%, P≤0.020%, S≤0.015%, Als0.005～0.060%, Ti 0.025～0.070%, Cr0.20～0.30%, all the other are Fe and unavoidable impurities.

The composition design that the present invention takes such as following table 1:

Table 1 novel components (unit, wt%)

Element

C

Si

Mn

P

S

Als

Ti

Cr

Company standard

≤0.20

≤0.60

≤1.80

≤0.030

≥0.010

≤0.20

≤0.30

Novel components

0.12～0.20

0.15～0.35

1.20～1.40

≤0.020

≤0.015

0.005～0.060

0.025～0.07

0.20～0.30

The production method that the present invention takes comprises: converter smelting, LF refining, VD vacuum-treat (optional), continuous casting, strand slow cooling, heating, rolling, the slow cooling of TMCP.

Claims

1. novel low-cost wear-resisting high-strength steel Q420A/B steel plate, it is by following elementary composition: C 0.12～0.20%, Si0.15～0.35%, Mn1.20～1.40%, P≤0.020%, S≤0.015%, Als0.005～0.060%, Ti 0.025～0.070%, Cr0.20～0.30%, all the other are Fe and unavoidable impurities.

2. production method of novel low-cost wear-resisting high-strength steel Q420A/B steel plate according to claim 1, it comprises: converter smelting, LF refining, VD vacuum-treat (optional), continuous casting, strand slow cooling, heating, rolling, the slow cooling of TMCP; It is characterized in that:

(1), in described converter smelting, the tapping carbon≤0.06%, the tapping P≤0.018%, S≤0.020%; Point blows number of times and must not avoid slag under the tapping process greater than 2 times; The argon station adds the aluminum steel deoxidation;

(2), in described LF refining, take the big quantity of slag to carry out slag making, guarantee that white slag hold-time control more than 15min, blew by force after ferro-niobium, ferrotianium, the ferrochromeization 3-5 minute, again more than the soft blow 8min;

(3), in described casting process, adopt the whole process protection cast, the control of cast superheating temperature is at 5～20 ℃, permanent pulling rate cast was gone into the burial pit slow cooling 24 hours after the continuously cast bloom cutting;

(4), pine in described adding, heat-up time 0.8-1.4min/mm, the holding temperature control of soaking zone is at 1200 ℃～1280 ℃;

(5), in described TMCP, 1000 ℃～1100 ℃ of start rolling temperatures; One stage finishing temperature is at 880～980 ℃, and the two-stage start rolling temperature is at 800～900 ℃, steel thickness 〉=1.5 times of drying in the air, and the two-stage takes to depress for a short time rolling, finish rolling accumulative total draft＞40%, finishing temperature≤880 ℃; Return red temperature＜650 ℃, cooling rate is controlled at 5～25 ℃/s;

(6), in described slow cooling, go into burial pit temperature 〉=150 ℃; Cooling in heap time 〉=6 hour.