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Method for producing Q890 high-strength steel intermediate-thickness plate through online quenching

A production method and high-strength steel technology, which is applied in the field of production of high-strength steel Q890 medium-thick plates with a thickness of 16-50mm by on-line quenching, which can solve the problems of large surplus

Inactive Publication Date: 2016-11-23
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is how to obtain a dual-phase structure steel with high strength, high toughness, low carbon lath bainite plus lath bainite through process control, and the yield margin is above 20Mpa, and the tensile margin is in More than 30Mpa, the margin of elongation is 2%-3%, the impact performance is uniform, and the margin is large

Method used

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  • Method for producing Q890 high-strength steel intermediate-thickness plate through online quenching
  • Method for producing Q890 high-strength steel intermediate-thickness plate through online quenching
  • Method for producing Q890 high-strength steel intermediate-thickness plate through online quenching

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Embodiment 1--4

[0015] The chemical composition that present embodiment mentions is as shown in table 1 below:

[0016] Table 1: Chemical Composition (%) of Examples

[0017]

Embodiment 1

[0021] Rolling: Heating furnace heating temperature 1150°C, total heating time 1.0 hour; adopt two-stage rolling, rough rolling descaling 2 passes, finish rolling descaling 2 passes, rough rolling start rolling temperature 1050°C, intermediate billet thickness ≥ 80mm, the second-stage rolling temperature is 860°C, and the final rolling temperature is 830°C;

[0022] Cooling: Water-cooled on-line quenching is adopted, the water inlet temperature is 770°C, the redness temperature is 250°C, the cooling speed is 15°C / s, and the cooling strength is enhanced by 2-3 swings during the water cooling process;

[0023] Heat treatment: Tempering temperature is 490°C, heating rate is 1.8min / mm, holding time is 20min, and then air-cooled to room temperature to obtain a dual-phase structure of lath martensite plus lath bainite.

Embodiment 2

[0025] Rolling: The heating temperature of the heating furnace is 1180°C, and the total heating time is 1.1 hours; Two-stage rolling is adopted, with 2 passes of rough rolling and descaling, 2 passes of finishing rolling and descaling, the starting temperature of rough rolling is 1100°C, and the thickness of the intermediate billet is ≥ 80mm, the second-stage rolling temperature is 850°C, and the final rolling temperature is 800°C;

[0026] Cooling: Water-cooled on-line quenching is adopted, the water inlet temperature is 780°C, the red return temperature is 240°C, the cooling speed is 20°C / s, and the cooling strength is enhanced by 2-3 swings during the water-cooling process;

[0027] Heat treatment: Tempering temperature is 500°C, heating rate is 1.6min / mm, holding time is 25min, and then air-cooled to room temperature to obtain a duplex structure of lath martensite plus lath bainite.

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Abstract

The invention provides a method for producing a Q890 high-strength steel intermediate-thickness plate through online quenching. The method comprises the steps that rolling is carried out, wherein the heating temperature of a heating furnace is 1180+ / -30 DEG C, the total heating time is 1.0-1.2 hour, two-stage rolling is adopted, rough rolling and scale removing are conducted for two passes, finish rolling and scale removing are conducted for two passes, the temperature at the beginning of the rough rolling is 1050-1150 DEG C, the thickness of an intermediate slab is larger than or equal to 80 mm, the temperature at the beginning of the second-stage rolling is lower than or equal to 860 DEG C, and the finishing rolling temperature is lower than or equal to 830 DEG C; cooling is conducted, wherein water cooling online quenching is adopted, the temperature of the intermediate slab is 780+ / -10 DEG C when entering water, the self-tempering temperature is lower than or equal to 250 DEG C, and the cooling speed is higher than 15 DEG C per second; and heat treatment is conducted, wherein the tempering temperature is 500+ / -10 DEG C, the heating rate is 1.8+ / -0.2 min / mm, the heat preservation time is 20-30 min, the temperature is lowered to the indoor temperature through air cooling, and then a double-phase structure of a lath martensite and a lath bainite is obtained. Online quenching shortens the technological process and reduces cost.

Description

technical field [0001] The invention relates to a production method of a medium-thick plate, in particular to a production method for producing a high-strength steel Q890 medium-thick plate with a thickness of 16-50 mm by on-line quenching. Background technique [0002] At present, the production of high-strength high-strength steel plates of Q890 grades is mostly delivered in a quenched and tempered (offline quenching+tempering) state; The online quenching method is used to produce steel plates with a thickness range of 20mm-50mm, and the final rolling temperature and water entry temperature are relatively high. After quenching, the steel plates are tempered at high temperatures, and the strength level is not high; Quenching production process method (CN200810013604.4) and an online quenching production method of low-cost high-strength wear-resistant steel plate (CN201310127995.3) and a method of online quenching production of high-toughness 5Ni steel plate (CN201510815584....

Claims

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Application Information

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IPC IPC(8): C22C38/04C22C38/02C22C38/18C22C38/12C22C38/08C22C38/14C21D8/02C21D1/18
CPCC22C38/04C21D1/18C21D8/0226C21D8/0247C21D2211/002C21D2211/008C22C38/02C22C38/08C22C38/12C22C38/14C22C38/18
Inventor 秦玉荣唐春霞
Owner NANJING IRON & STEEL CO LTD
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