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Production method of hot rolling on-line heat treatment 1200mpa grade complex phase steel coil

A production method and technology of complex phase steel, applied in the field of metallurgy, can solve the problems of complex production process, large environmental pollution and high energy consumption, and achieve the effects of improving formability, weight reduction and safety improvement

Active Publication Date: 2021-09-10
HEBEI IRON AND STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existing advanced high-strength steel production process all adopts the process route of cooling to room temperature after hot rolling, and then heat treatment after reheating to achieve the target performance. The production process is complicated, and there are problems of high energy consumption and large environmental pollution.

Method used

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  • Production method of hot rolling on-line heat treatment 1200mpa grade complex phase steel coil
  • Production method of hot rolling on-line heat treatment 1200mpa grade complex phase steel coil
  • Production method of hot rolling on-line heat treatment 1200mpa grade complex phase steel coil

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] The thickness of the 1200MPa grade hot-rolled multiphase steel coil in this embodiment is 6mm, and its chemical composition and mass percentage are shown in Table 1. Manufacturing, on-line heat treatment, coiling and slow cooling process, the specific process steps are as follows:

[0026] (1) Slab heating process: the slab heating temperature is 1200°C;

[0027] (2) Controlled rolling process: the final rolling temperature is 860°C;

[0028] (3) On-line heat treatment process: laminar flow cooling adopts centralized cooling in the front section, the cooling rate is 25°C / s, and the coiling temperature is 460°C;

[0029] (4) Coiling and slow cooling process: enter the slow cooling pit 0.8h after coiling, and exit the pit for inspection after slow cooling for 75h.

[0030] The 1200MPa grade hot-rolled multiphase steel coil in this example is strengthened by ferrite, retained austenite, martensite, and bainite, and the microstructure is shown in figure 1 ; Performance i...

Embodiment 2

[0032] The thickness of the 1200MPa grade hot-rolled multiphase steel coil in this embodiment is 5mm, and its chemical composition and mass percentage are shown in Table 1. Manufacturing, on-line heat treatment, coiling and slow cooling process, the specific process steps are as follows:

[0033] (1) Slab heating process: the slab heating temperature is 1220°C;

[0034] (2) Controlled rolling process: the final rolling temperature is 850°C;

[0035] (3) On-line heat treatment process: laminar flow cooling adopts centralized cooling in the front section, the cooling rate is 27°C / s, and the coiling temperature is 450°C;

[0036] (4) Coiling and slow cooling process: enter the slow cooling pit 0.9h after coiling, and exit the pit for inspection after slow cooling for 72h.

[0037] The 1200MPa grade hot-rolled multiphase steel coil in this example is strengthened by ferrite, retained austenite, martensite, and bainite, and the microstructure is shown in figure 2 ; Performance ...

Embodiment 3

[0039] The thickness of the 1200MPa grade hot-rolled multiphase steel coil in this embodiment is 4mm, and its chemical composition and mass percentage are shown in Table 1. Manufacturing, on-line heat treatment, coiling and slow cooling process, the specific process steps are as follows:

[0040] (1) Slab heating process: the slab heating temperature is 1240°C;

[0041] (2) Controlled rolling process: the final rolling temperature is 870°C;

[0042] (3) On-line heat treatment process: laminar flow cooling adopts centralized cooling in the front section, the cooling rate is 35°C / s, and the coiling temperature is 455°C;

[0043] (4) Coiling and slow cooling process: 0.95h after coiling, enter the slow cooling pit, slow cooling 74h and leave the pit for inspection.

[0044] The 1200MPa grade hot-rolled multiphase steel coil in this example is strengthened by ferrite, retained austenite, martensite, and bainite, and the microstructure is shown in image 3 ; Performance indicato...

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Abstract

The invention discloses a production method for hot-rolled on-line heat treatment of 1200MPa-grade multiphase steel coils. The production method includes slab heating, controlled rolling, on-line heat treatment, coiling and slow cooling; the on-line heat treatment process, layer Flow cooling adopts centralized cooling in the front section, the cooling speed is 20-40°C / s, and the coiling temperature is 440-480°C; in the coiling and slow cooling process, the time for entering the slow cooling pit after coiling is ≤1h, and the slow cooling is ≥72h for exiting the pit test. Through online heat treatment and post-rolling slow cooling pit slow cooling annealing technology, the present invention realizes the stable control of residual austenite of 1200MPa multiphase steel coils, effectively regulates the yield ratio of the steel plate, and the yield strength of the product is ≥750MPa, and the tensile strength is ≥750MPa. Strength ≥ 1200MPa, elongation ≥ 12%, yield ratio ≤ 0.8, which improves the formability of high-strength and complex parts, and realizes structural weight reduction and safety improvement for construction machinery and heavy-duty vehicles.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a production method of hot-rolled on-line heat-treated 1200MPa-grade multiphase steel coils. Background technique [0002] As an important steel species, ultra-high-strength steel plays an important role in structural lightweight, large-deformation impact strength and improving product life. Its products are widely used in the market, including construction machinery, bridges and automobile manufacturing. With the continuous improvement of structural weight reduction and safety requirements, the strength of steel is gradually increased to 1200MPa level. At this time, the yield strength is close to the tensile strength, and the elongation is difficult to guarantee, so the safety of steel structures is difficult to guarantee. [0003] The Advanced High Strength Steel (AHSS) developed in recent years can increase the strength without reducing the elongation. These pro...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D8/02C22C38/02C22C38/34C22C38/38C22C38/06C22C38/22C22C38/28
CPCC21D8/0205C21D8/0247C22C38/02C22C38/06C22C38/22C22C38/28C22C38/34C22C38/38
Inventor 陆凤慧杜林秀刘伟邢俊芳陈国涛郝占全
Owner HEBEI IRON AND STEEL