CN103205637A

CN103205637A - Novel and low-cost Q345A/B/C low-alloy steel plate and production method thereof

Info

Publication number: CN103205637A
Application number: CN2012105867413A
Authority: CN
Inventors: 朱书成; 许少普; 袁少威; 刘庆波; 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: 2013-07-17
Anticipated expiration: 2032-12-30
Also published as: CN103205637B

Abstract

The invention discloses a low-cost Q345A/B/C low-alloy steel plate which is composed of the following elements: 0.13-0.18 % of C, 0.20-0.40 % of Si, 0.90-1.10 % of Mn, less than or equal to 0.020 % of P, less than or equal to 0.020 % of S, 0.010-0.040 % of Als, 0.010-0.030 % of Ti and the balance being Fe and unavoidable impurities. A production method comprises converter smelting, continuous casting, slow cooling of casting blank, heating, TMCP and slow cooling. Through the above novel ideas of composite micro-alloying composition design and simple and effective process design, mechanical properties, ultrasonic testing and other indicators of steel plates can be ensured, and cost per ton of steel is saved by 60-70 yuan/ton, thereby being with good promotion meaning.

Description

A kind of novel low-cost Q345A/B/C Low Alloy Steel Plate and production method thereof

Technical field

The present invention relates to continuous casting and produce the technical field of plate of moderate thickness, be specifically related to a kind of novel low-cost Q345A/B/C Low Alloy Steel Plate and production method thereof.

Background technology

Specification 16～100mm Q345A/B/C is a kind of low-alloy high-strength steel plate commonly used, it has higher intensity, good cold deformation ability, plasticity and toughness preferably, be widely used in all kinds of welding structural elements and the mechanical component, related data shows that Q345A/B/C series steel plate output accounts for 20～35% of plate of moderate thickness total amount at present.Along with the continuous reduction of steel industry profit, Iron And Steel Company taps the latent power inside and reduces ton steel cost and put on agenda.

Summary of the invention

At the problems referred to above, the inventor has obtained a kind of specification 16～100mm guaranteed cost of low cost production, the Q345A/B/C Low Alloy Steel Plate of guarantor's flaw detection, thereby has finished the present invention through groping.

Therefore, the object of the present invention is to provide the Q345A/B/C Low Alloy Steel Plate of a kind of low-cost specification 16～100mm guaranteed cost, guarantor's flaw detection.

Another object of the present invention is to provide the production method of this low cost steel plate.

For reaching above-mentioned first purpose, in the national standard scope, and do not influence under the situation of end product quality, utilize Ti alloying element with low cost to replace the higher Mn alloying element of a part of cost, significantly reduce ton steel cost, enlarge the product profit space.

For achieving the above object, low-cost Q345A/B/C Low Alloy Steel Plate of the present invention is by following elementary composition: C 0.13～0.18%, Si0.20～0.40%, Mn0.90～1.10%, P≤0.020%, S≤0.020%, Als0.010～0.040%, Ti 0.010～0.030%.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.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.Ti: in steel, can be combined with C, N, form fine carbide or carbonitride, can play crystal grain thinning and dispersion-strengthened action, thereby reach the effect of the intensity of effective raising steel, Ti/C≤4 because of composition design of the present invention, can not form the nitride of carbon and sulfide and cause and the embrittlement of steel cause the impelling strength of steel plate to descend at crystal boundary.

For achieving the above object, the production method that the present invention takes comprises: converter smelting, continuous casting, strand slow cooling, heating, TMCP, slow cooling.

1, in described converter smelting, tapping carbon 〉=0.06%, tapping P≤0.015%, S≤0.010%; Point blows number of times and must not avoid slag under the tapping process greater than 2 times;

2, behind the converter tapping during alloying, ferro-titanium added before aluminum steel, fix N element in advance, minimizing may cause the AlN of crackle to form, leaving from station before strong Argon 3 minutes, soft blow argon 〉=8 minute;

3, adopt continuous casting 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 0.9min/mm, the control of the holding temperature of soaking zone is at 1220 ℃～1240 ℃;

5, in described TMCP, 1050 ℃～1120 ℃ of start rolling temperatures; One stage finishing temperature is at 950 ℃～1000 ℃, and the two-stage start rolling temperature is at 830～850 ℃, 1.5～2 times of the steel thickness of drying in the air, and the two-stage takes to depress for a short time rolling, finish rolling accumulative total draft＞45%, finishing temperature≤820 ℃; Return red temperature＜760 ℃, cooling rate is controlled at 3～8 ℃/s;

6, in described slow cooling, go into burial pit temperature 〉=450 ℃; Cooling in heap time 〉=24 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; The ton steel is saved cost at 60～70 yuan/ton, is with the promotion of good sense.

Description of drawings

Below in conjunction with accompanying drawing, the present invention is further elaborated.

Fig. 1 is process flow sheet of the present invention.

Fig. 2 is the typical gold phase constitution figure (100X) of TMCP of the present invention after rolling.

Fig. 3 is the typical gold phase constitution figure (100X) of TMCP of the present invention after rolling.

Embodiment

Low-cost Q345A/B/C Low Alloy Steel Plate of the present invention is by following elementary composition: C 0.13～0.18%, Si0.20～0.40%, Mn0.90～1.10%, P≤0.020%, S≤0.020%, Als0.010～0.040%, Ti 0.010～0.030%, all the other are Fe and unavoidable impurities.

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

The traditional composition of table 1 and novel components contrast (unit, wt%)

Element

C

Si

Mn

P

S

Als

Ti

National standard

≤0.20

≤0.50

≤1.70

≤0.035

～

≤0.20

The tradition composition

0.13～0.18

0.20～0.40

1.40～1.60

≤0.020

0.010～0.040

～

Novel components

0.13～0.18

0.20～0.40

0.90～1.10

≤0.020

0.010～0.040

0.010～0.030

The production method that the present invention takes comprises: converter smelting, continuous casting, strand slow cooling, heating, TMCP, slow cooling.

Claims

1. low-cost Q345A/B/C Low Alloy Steel Plate, it is by following elementary composition: C 0.13～0.18%, Si0.20～0.40%, Mn0.90～1.10%, P≤0.020%, S≤0.020%, Als0.010～0.040%, Ti 0.010～0.030%, all the other are Fe and unavoidable impurities.

2. production method such as low-cost Q345A/B/C Low Alloy Steel Plate according to claim 1, this production method comprises: converter smelting, continuous casting, strand slow cooling, heating, TMCP, slow cooling is characterized in that:

(1), in described converter smelting, the tapping carbon 〉=0.06%, the tapping P≤0.015%, S≤0.010%; Point blows number of times and must not avoid slag under the tapping process greater than 2 times;

(2), behind the converter tapping during alloying, ferro-titanium added before aluminum steel, fix N element in advance, minimizing may cause the AlN of crackle to form, leaving from station before strong Argon 3 minutes, soft blow argon 〉=8 minute;

(3), adopt continuous casting 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 0.9min/mm, the holding temperature control of soaking zone is at 1220 ℃～1240 ℃;

(5), in described TMCP, 1050 ℃～1120 ℃ of start rolling temperatures; One stage finishing temperature is at 950 ℃～1000 ℃, and the two-stage start rolling temperature is at 830～850 ℃, 1.5～2 times of the steel thickness of drying in the air, and the two-stage takes to depress for a short time rolling, finish rolling accumulative total draft＞45%, finishing temperature≤820 ℃; Return red temperature＜760 ℃, cooling rate is controlled at 3～8 ℃/s;

(6), in described slow cooling, go into burial pit temperature 〉=450 ℃; Cooling in heap time 〉=24 hour.