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Double-phase steel and production method thereof

A production method and dual-phase steel technology, applied in the field of iron and steel manufacturing, can solve the problems of yellowing of the surface of the steel strip, serious surface oxidation, and surface oxidation of the steel strip, and achieve cooling rate reduction, strong reduction ability, and lighten the cooling load Effect

Inactive Publication Date: 2013-05-15
MAANSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the production method of cold-rolled dual-phase steel mainly adopts continuous annealing. During the rapid cooling process, in order to ensure the cooling rate required for hardenability, the capacity of most equipment reaches full-load operation, and air can easily infiltrate it, thereby Oxidize the surface of the steel strip, causing the surface of the steel strip to turn yellow or even black; for cold-rolled dual-phase steel with high Si content, the surface oxidation is more serious

Method used

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Embodiment example

[0012] Chemical composition (mass percentage): C0.08%, Mn1.7%, Si0.5%, P0.010%, S0.008%, Nb0.025%, the balance is iron and unavoidable impurities.

[0013] A production method of dual-phase steel, the technological process of which is: molten iron pretreatment→converter smelting→alloy fine-tuning station→LF→continuous casting→hot continuous rolling→pickling and cold rolling→continuous annealing;

[0014] In the continuous annealing process step: the continuous annealing temperature is 780°C, slow cooling to 650°C and then rapid cooling at a cooling rate of 30°C / s or above, and then overaging treatment at 320°C. In the fast cooling section, the volume percentage of hydrogen containing gas is 35% N 2 -H 2 The mixed gas is used as a protective gas, and the surface of the obtained dual-phase steel is bright silvery white.

Embodiment 2

[0016] 1.0mm 600MPa grade cold-rolled dual-phase steel implementation case:

[0017] Chemical composition (mass percentage): C0.08%, Mn1.7%, Si0.5%, P0.007%, S0.005%, Nb0.014%, the balance is iron and unavoidable impurities.

[0018] A production method of dual-phase steel, the technological process is: molten iron pretreatment→converter smelting→alloy fine-tuning station→LF→continuous casting→hot continuous rolling→pickling and cold rolling→continuous annealing

[0019] In the continuous annealing process step: the continuous annealing temperature is the heating temperature of 780°C, slow cooling to 670°C and rapid cooling at a cooling rate of 30°C / s or above, and then overaging treatment at 300°C. In the fast cooling section, the volume percentage of hydrogen containing gas is 5% N 2 -H 2 The mixed gas is used as a protective gas, and the surface of the obtained dual-phase steel is bright silvery white.

Embodiment 3

[0021] 1.5mm 600MPa grade cold-rolled dual-phase steel implementation case:

[0022] Chemical composition (mass percentage): C0.095%, Mn1.55%, Si0.4%, P0.015%, S0.008%, Nb0.020%, the balance is iron and unavoidable impurities.

[0023] A production method of dual-phase steel, the technological process of which is: molten iron pretreatment→converter smelting→alloy fine-tuning station→LF→continuous casting→hot continuous rolling→pickling and cold rolling→continuous annealing;

[0024] In the continuous annealing process step: the continuous annealing temperature is 800°C, slow cooling to 660°C and then rapid cooling at a cooling rate of 30°C / s or above, and then overaging treatment at 320°C. In the fast cooling section, the volume percentage of hydrogen containing gas is 20% N 2 -H 2 The mixed gas is used as a protective gas, and the surface of the obtained dual-phase steel is bright silvery white.

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Abstract

The invention discloses double-phase steel and a production method thereof. The double-phase steel comprises the following components in percentage by mass: not more than 0.12 percent of C, not less than 0.40 percent of Si, not more than 2.50 percent of Mn, not more than 0.020 percent of P, not more than 0.010 percent of S and not more than 0.030 percent of Nb. The production method comprises the following steps of: pretreatment of molten iron, smelting in a converter, fine adjustment of alloys, treatment in an LF (ladle furnace), continuous casting, hot continuous rolling, acid-washing and cold-rolling, and continuous annealing, wherein in the continuous annealing step, an N2-H2 mixed gas in which H2 accounts for 5-35 percent is used for cooling, the heating temperature T1 is 760-840 DEG C, the slow cooling temperature T2 is 640-670 DEG C and the overaging temperature T3 is 300-320 DEG C. The double-phase steel disclosed by the invention is good in surface quality.

Description

technical field [0001] The invention relates to the technical field of iron and steel manufacturing, in particular to a dual-phase steel and a production method thereof. Background technique [0002] Dual-phase steel has high strength and high toughness, that is, it has a good combination of strength and toughness. In addition, dual-phase steel has a low yield ratio (Rp0.2 / Rm), high elongation and high work hardening Rate, and no discontinuous yield phenomenon. The yield strength is low, and the low yield strength makes the stamping member easy to form, with small springback and small wear of the stamping die. There is no yield point elongation, and the stress-strain curve is smooth arched, which avoids wrinkling of the surface of the formed part without additional smoothing or other additional operations. High strength, high tensile strength can make the component have high hat-shaped mechanism crush resistance, impact energy absorption and fatigue strength. A large numbe...

Claims

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Application Information

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IPC IPC(8): C22C38/12C22C38/04C22C38/02C21D1/26
Inventor 刘永刚张建潘红波杨兴亮詹华杨少华胡学文谷海容
Owner MAANSHAN IRON & STEEL CO LTD
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