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Method for producing high-hole-expansion-rate steel 420L for automotive frame

A technology for an automobile beam and a production method, which is applied in the field of automobile structural steel plates, can solve the problems of difficult to meet the requirements of high stamping and forming performance of automobile beams, etc., and achieves the effects of less difficulty in production control, good forming, and great economic benefits.

Inactive Publication Date: 2015-10-21
TANGSHAN IRON & STEEL GROUP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the main hole expansion rate of domestic automobile frame steel 420L is about 80%, which is difficult to meet the high stamping performance requirements of automobile frame

Method used

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  • Method for producing high-hole-expansion-rate steel 420L for automotive frame

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Embodiment 1: The specific process of the production method of the steel 420L for automobile frame with high hole expansion rate is as follows.

[0022] (1) Steelmaking step: The weight percent of the chemical composition of the molten steel is: C 0.07, Mn 1.15, S 0.005, P 0.010, Si 0.08, Als 0.025, N 0.0040, and the rest is iron and unavoidable impurities.

[0023] (2) Hot rolling step: A. Heating process: the slab heating temperature is 1180-1200°C;

[0024] B. Rolling process: control the starting temperature of the rough rolling of the slab at 1080-1100°C; the starting temperature of the finish rolling is 1030±10°C, the final rolling temperature is 850±10°C, and the thickness of the rolled steel plate is 3.0mm;

[0025] C. Laminar cooling adopts a two-stage cooling process. The cooling process is: the strip enters the first group of laminar cooling at 835±10°C, and is rapidly cooled to 680-700°C at a speed of 60°C / s; then air-cooled in this temperature range 2.5s; ...

Embodiment 2

[0027] Embodiment 2: The specific process of the production method of the steel 420L for automobile frame with high hole expansion rate is as follows.

[0028] (1) Steelmaking step: The weight percentage of the chemical composition of the molten steel is: C 0.06, Mn 1.10, S 0.006, P 0.015, Si 0.05, Als 0.030, N 0.0045, and the rest is iron and unavoidable impurities.

[0029] (2) Hot rolling step: A. Heating process: the heating temperature of the slab is 1210-1230°C;

[0030] B. Rolling process: control the starting temperature of the rough rolling of the slab at 1100±10°C; the starting temperature of the finish rolling is 1040±10°C, and the final rolling temperature is 845~865°C; the thickness of the rolled steel plate is 2.0mm;

[0031] C. Laminar cooling adopts a two-stage cooling process. The cooling process is: the strip enters the first layer of laminar cooling at 840±10°C, and is rapidly cooled to 680-700°C at a speed of 80°C / s; then air-cooled in this temperature rang...

Embodiment 3

[0033] Embodiment 3: The specific process of the production method of the steel 420L for automobile frame with high hole expansion rate is as follows.

[0034] (1) Steelmaking step: The weight percent of the chemical composition of the molten steel is: C 0.08, Mn 1.20, S 0.008, P 0.020, Si 0.1, Als 0.030, N 0.0050, and the rest is iron and unavoidable impurities.

[0035] (2) Hot rolling step: A. Heating process: the slab heating temperature is 1200-1210°C;

[0036] B. Rolling process: control the starting temperature of the rough rolling of the slab at 1090±10°C; the starting temperature of the finish rolling is 1040±10°C, and the final rolling temperature is 850±15°C; the thickness of the rolled steel plate is 4.0mm;

[0037] C. Laminar cooling adopts a two-stage cooling process. The cooling process is: the strip enters the first group of laminar cooling at 820-840°C, and is rapidly cooled to 680-700°C at a speed of 50°C / s; then air-cooled in this temperature range 2.3s; fi...

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Abstract

The invention discloses a method for producing high-hole-expansion-rate steel 420L for an automotive frame. The method includes the steel-making step and the hot rolling step; the steel-making step is characterized in that produced molten steel comprises, by weight, 0.06%-0.08% of C, 1.10%-1.20% of Mn, not larger than 0.008% of S, not larger than 0.020% of P, not larger than 0.10% of Si, 0.015%-0.035% of Als, not larger than 0.0050% of N and the balanced iron and inevitable impurities; and the hot rolling step includes the heating working procedure, the rolling working procedure and the cooling working procedure. The cooling working procedure includes the steps that strip steel enters a first set laminar cooling area at the temperature of 835+ / -15 DEG C, and the strip steel is rapidly cooled at the speed ranging from 50 DEG C / s to 80 DEG C / s to the temperature of 690+ / -20 DEG C; then air cooling within the temperature range is carried out for 2.3 s to 2.8 s; and finally the strip steel enters a second set laminar cooling area, and is cooled at the speed ranging from 20 DEG C / s to 40 DEG C / s to the coiling temperature of 460+ / -20 DEG C. By means of the method, ingredient elements such as the C, the Mn and the Si are adopted, the steel 420L for the automotive frame in needed thickness and specification is produced through the subsection cooling process, and the metallographic structure of the 420L is shown in an attached map; and the development requirement for high-molding performance is met, a small alloy adding amount is added, and a huge economic benefit can be generated.

Description

technical field [0001] The invention relates to an automobile structural steel plate, in particular to a production method of steel 420L for automobile frame with high hole expansion rate. Background technique [0002] Auto frame steel is mainly used to manufacture beams and longitudinal beams of pickup trucks and trucks, and is one of the materials with the most stringent quality requirements in automotive structural parts. The quality of the girder affects the service life and driving safety of the vehicle. Therefore, in addition to the conventional structural strength performance requirements, the automotive girder steel must also have good formability, dent resistance, sufficient structural rigidity and welding performance. Since the beginning of the 21st century, the rapid economic growth has accelerated the development of the automobile industry. With the rapid development of my country's automobile industry, the amount of steel used in automobiles is also increasing. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/06C21D8/02
Inventor 王健乔治明于世川张玉文李梦英杨杰李毅挺师可新田秀刚刘丽萍马光宗武冠华宋晓娟张春花王春平
Owner TANGSHAN IRON & STEEL GROUP
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