Ultralow yield ratio 980 MPa-grade cold rolling two-phase steel and manufacturing method thereof

Abstract

The invention discloses ultralow yield ratio 980 MPa-grade cold rolling two-phase steel and a manufacturing method of the ultralow yield ratio 980 MPa-grade cold rolling two-phase steel, and belongs to the technical field of two-phase steel. Chemical components of the steel comprise, by weight, 0.13-0.18% of C, 0.3-0.6% of Si, 1.7-2.4% of Mn, 0.03-0.06% of Als, 0-0.05% of Nb, 0.3-0.5% of Cr and the balance Fe and inevitable impurities. In composition design, the composite strengthening way mainly comprising phase transformation strengthening and combining solid solution strengthening, refined crystalline strengthening, phase change strengthening and precipitation strengthening is adopted, the cold rolling two-phase steel plate can be used as an automobile anti-collision part, a structural part and an inner plate material. The steel has the advantages that DP980 has the ultralow yield ratio YS / TS which is smaller than 0.50, good ductility A50 which is larger than or equal to 14%, the high n value, the small mechanical property fluctuation range, the low process sensitivity and other property characteristics, can reduce springback after stamping and is beneficial to follow-up deep processing of the automobile industry.

Description

technical field

[0001] The invention belongs to the technical field of dual-phase steel, and in particular provides a cold-rolled dual-phase steel with an ultra-low yield ratio of 980 MPa and a manufacturing method thereof. Background technique

[0002] In recent years, with the increasing global energy and environmental crisis, body weight reduction has become an important issue faced by contemporary automobile design and manufacturing. Due to its high strength, good elongation and formability, and strong absorption of collision energy, dual phase steel has become the most widely used and most mature high-strength steel in the lightweight trend of car bodies. steel material. At the same time, the lightweight of automobiles puts forward higher requirements for dual-phase steels, mainly including excellent formability, high-strength plasticity, high geometric accuracy, high surface quality, good homogeneity, and serialization of new product development. However, as the tens...

Examples

Embodiment 1

[0019] A 980MPa low process sensitivity, low yield ratio cold-rolled dual-phase steel, its components and weight percentage content: C: 0.17%, Mn: 1.76%, Als: 0.04%, Si: 0.5%, P: 0.010 %, S: 0.005%, Cr: 0.4, and the balance is Fe and unavoidable impurities. The manufacturing process is as follows:

[0020] 1) Smelting and continuous casting into billets;

[0021] 2) Heat the cast slab to 1250°C, keep it warm for 2.5 hours, then carry out hot rolling, start rolling at 1150°C, and control the final rolling temperature at 900°C:

[0022] 3) Carry out coiling, control coiling temperature at 650 ℃;

[0023] 4) Carry out conventional pickling;

[0024] 5) Carry out cold rolling, and control the cumulative reduction rate of cold rolling to 66.7%;

[0025] 6) Carry out continuous annealing, control the annealing temperature at 780°C, and annealing time 120s;

[0026] 7) Cool to 720°C at a slow cooling rate of 3°C / s;

[0027] 8) Perform rapid cooling, the cooling rate is controll...

Embodiment 2

[0030] 980MPa low process sensitivity, low yield ratio cold-rolled dual-phase steel, its components and weight percentage content: C: 0.17%, Mn: 1.76%, Als: 0.04%, Si: 0.5%, P: 0.010%, S: 0.005%, Cr: 0.4, and the balance is Fe and unavoidable impurities. The manufacturing process is as follows:

[0031] 1) Smelting and continuous casting into billets;

[0032] 2) Heat the cast slab to 1250°C, keep it warm for 2.5 hours, then carry out hot rolling, start rolling at 1150°C, and control the final rolling temperature at 900°C:

[0033] 3) Carry out coiling, control coiling temperature at 650 ℃;

[0034] 4) Carry out conventional pickling;

[0035] 5) Carry out cold rolling, and control the cumulative reduction rate of cold rolling to 66.7%;

[0036] 6) Carry out continuous annealing, control the annealing temperature at 800°C, and annealing time 120s;

[0037] 7) Cool to 710°C at a slow cooling rate of 3°C / s;

[0038] 8) Perform rapid cooling, the cooling rate is controlled ...

Embodiment 3

[0041] 980MPa low process sensitivity, low yield ratio cold-rolled dual-phase steel, its components and weight percentage content: C: 0.14%, Mn: 2.0%, Als: 0.04%, Si: 0.5%, P: 0.010%, S: 0.005%, Nb: 0.03%, Cr: 0.3%, and the balance is Fe and unavoidable impurities. The manufacturing process is as follows:

[0042] 1) Smelting and continuous casting into billets;

[0043] 2) Heat the cast slab to 1250°C, keep it warm for 2.5 hours, then carry out hot rolling, start rolling at 1150°C, and control the final rolling temperature at 920°C:

[0044] 3) Carry out coiling, control coiling temperature at 680 ℃;

[0045] 4) Carry out conventional pickling;

[0046] 5) Carry out cold rolling, and control the cumulative reduction rate of cold rolling to 66.7%;

[0047] 6) Carry out continuous annealing, control the annealing temperature at 790°C, and annealing time 120s;

[0048] 7) Cool to 700°C at a slow cooling rate of 3°C / s;

[0049] 8) Perform rapid cooling, the cooling speed is...

technical field

[0001] The invention belongs to the technical field of dual-phase steel, and in particular provides a cold-rolled dual-phase steel with an ultra-low yield ratio of 980 MPa and a manufacturing method thereof. Background technique

[0002] In recent years, with the increasing global energy and environmental crisis, body weight reduction has become an important issue faced by contemporary automobile design and manufacturing. Due to its high strength, good elongation and formability, and strong absorption of collision energy, dual phase steel has become the most widely used and most mature high-strength steel in the lightweight trend of car bodies. steel material. At the same time, the lightweight of automobiles puts forward higher requirements for dual-phase steels, mainly including excellent formability, high-strength plasticity, high geometric accuracy, high surface quality, good homogeneity, and serialization of new product development. However, as the tens...

Examples

Embodiment 1

[0019] A 980MPa low process sensitivity, low yield ratio cold-rolled dual-phase steel, its components and weight percentage content: C: 0.17%, Mn: 1.76%, Als: 0.04%, Si: 0.5%, P: 0.010 %, S: 0.005%, Cr: 0.4, and the balance is Fe and unavoidable impurities. The manufacturing process is as follows:

[0020] 1) Smelting and continuous casting into billets;

[0021] 2) Heat the cast slab to 1250°C, keep it warm for 2.5 hours, then carry out hot rolling, start rolling at 1150°C, and control the final rolling temperature at 900°C:

[0022] 3) Carry out coiling, control coiling temperature at 650 ℃;

[0023] 4) Carry out conventional pickling;

[0024] 5) Carry out cold rolling, and control the cumulative reduction rate of cold rolling to 66.7%;

[0025] 6) Carry out continuous annealing, control the annealing temperature at 780°C, and annealing time 120s;

[0026] 7) Cool to 720°C at a slow cooling rate of 3°C / s;

[0027] 8) Perform rapid cooling, the cooling rate is controll...

Embodiment 2

[0030] 980MPa low process sensitivity, low yield ratio cold-rolled dual-phase steel, its components and weight percentage content: C: 0.17%, Mn: 1.76%, Als: 0.04%, Si: 0.5%, P: 0.010%, S: 0.005%, Cr: 0.4, and the balance is Fe and unavoidable impurities. The manufacturing process is as follows:

[0031] 1) Smelting and continuous casting into billets;

[0032] 2) Heat the cast slab to 1250°C, keep it warm for 2.5 hours, then carry out hot rolling, start rolling at 1150°C, and control the final rolling temperature at 900°C:

[0033] 3) Carry out coiling, control coiling temperature at 650 ℃;

[0034] 4) Carry out conventional pickling;

[0035] 5) Carry out cold rolling, and control the cumulative reduction rate of cold rolling to 66.7%;

[0036] 6) Carry out continuous annealing, control the annealing temperature at 800°C, and annealing time 120s;

[0037] 7) Cool to 710°C at a slow cooling rate of 3°C / s;

[0038] 8) Perform rapid cooling, the cooling rate is controlled ...

Embodiment 3

[0041] 980MPa low process sensitivity, low yield ratio cold-rolled dual-phase steel, its components and weight percentage content: C: 0.14%, Mn: 2.0%, Als: 0.04%, Si: 0.5%, P: 0.010%, S: 0.005%, Nb: 0.03%, Cr: 0.3%, and the balance is Fe and unavoidable impurities. The manufacturing process is as follows:

[0042] 1) Smelting and continuous casting into billets;

[0043] 2) Heat the cast slab to 1250°C, keep it warm for 2.5 hours, then carry out hot rolling, start rolling at 1150°C, and control the final rolling temperature at 920°C:

[0044] 3) Carry out coiling, control coiling temperature at 680 ℃;

[0045] 4) Carry out conventional pickling;

[0046] 5) Carry out cold rolling, and control the cumulative reduction rate of cold rolling to 66.7%;

[0047] 6) Carry out continuous annealing, control the annealing temperature at 790°C, and annealing time 120s;

[0048] 7) Cool to 700°C at a slow cooling rate of 3°C / s;

[0049] 8) Perform rapid cooling, the cooling speed is...

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