355MPa-grade low-alloy high-fatigue-strength steel and manufacturing method thereof

A manufacturing method and low-alloy technology, applied in the field of iron and steel smelting, can solve the problems of lack of strict control of large particle inclusions, affecting structure and mechanical fatigue life, and insufficient secondary smelting, so as to achieve favorable fatigue performance and fuel saving. Consumption and materials, the effect of low cost

Inactive Publication Date: 2020-08-21
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The steel mill does not carry out vacuum treatment for general 235MPa grade materials or the secondary smelting of the ladle is not deep enough, lacks strict control over large grain inclusions, and grain control is not fine enough. These technical quality problems seriously affect the fatigue life of the structure and machinery. Improvement, limiting the life improvement of construction machinery

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] A 355MPa grade low-alloy high-fatigue steel provided in this example, 60mm specification Q355B steel plate, its chemical composition and mass percentage are as follows: C: 0.17%, Si: 0.27%, Mn: 1.53%, P: 0.011%, S: 0.002%, Nb: 0.021%, V: 0.035%, Al: 0.019%.

[0030] The manufacturing method includes hot metal pretreatment-converter steelmaking-deoxidation alloying-LF ladle refining-RH ladle refining vacuum degassing-CCM continuous casting-slab heating-two-stage rolling-cooling-straightening-sampling inspection marking-finished product: Hot metal pretreatment, hot metal pretreatment, S: 0.002% in hot metal; converter BOF smelting, post-furnace deoxidation alloying; LF refining outside the furnace for 25 minutes, fine-tuning the alloy composition, so that the temperature of molten steel reached 1588 °C; RH vacuum degassing treatment for 30 minutes, bottom Argon blowing, stirring and floating to remove non-metallic inclusions, reducing nitrogen, hydrogen and oxygen content...

Embodiment 2

[0033] A 355MPa grade low-alloy high-fatigue steel provided in this example, 50mm specification Q355B steel plate, its chemical composition and mass percentage are as follows: C: 0.17%, Si: 0.26%, Mn: 1.55%, P: 0.012%, S: 0.002%, Nb: 0.026%, V: 0.032%, Ti: 0.023%, Al: 0.022%.

[0034] The manufacturing method includes hot metal pretreatment-converter steelmaking-deoxidation alloying-LF ladle refining-RH ladle refining vacuum degassing-CCM continuous casting-slab heating-two-stage rolling-cooling-straightening-sampling inspection marking-finished product: Hot metal pretreatment, hot metal pretreatment, S: 0.001% in hot metal; converter BOF smelting, post-furnace deoxidation alloying; LF refining outside the furnace for 25 minutes, fine-tuning the alloy composition, so that the temperature of molten steel reached 1582 °C; RH vacuum degassing treatment for 30 minutes, bottom Argon blowing, stirring and floating to remove non-metallic inclusions, reducing nitrogen, hydrogen and ox...

Embodiment 3

[0037] A 355MPa grade low-alloy high-fatigue steel provided in this example, a 40mm specification Q355B steel plate, has the following chemical composition and mass percentages: C: 0.16%, Si: 0.29%, Mn: 1.56%, P: 0.011%, S: 0.001%, Nb: 0.027%, V: 0.034%, Ti: 0.029%, Al: 0.025%.

[0038] The manufacturing method includes hot metal pretreatment-converter steelmaking-deoxidation alloying-LF ladle refining-RH ladle refining vacuum degassing-CCM continuous casting-slab heating-two-stage rolling-cooling-straightening-sampling inspection marking-finished product: Hot metal pretreatment, hot metal pretreatment, S: 0.002% in hot metal; converter BOF smelting, post-furnace deoxidation alloying; LF refining outside the furnace for 26 minutes, fine-tuning the alloy composition, so that the temperature of molten steel reached 1586 °C; RH vacuum degassing treatment for 30 minutes, bottom Argon blowing, stirring and floating to remove non-metallic inclusions, reducing nitrogen, hydrogen and ...

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Abstract

The invention discloses 355MPa-grade low-alloy high-fatigue-strength steel and relates to the technical field of steel smelting. The thickness of a steel plate is 6-60 mm. The chemical ingredients ofthe 355MPa-grade low-alloy high-fatigue-strength steel comprise, by mass percentage, 0.12%-0.23% of C, 0.10%-0.60% of Si, 0.80%-1.90% of Mn, smaller than 0.018% of P, smaller than 0.008% of S, 0-0.060% of Nb, 0-0.15% of V, 0-0.12% of Ti and 0.010%-0.050% of Al. The adopted alloy ingredient design is to conduct controlled rolling and controlled cooling to obtain uniform and fine ferrite+pearlite structure, and then good mechanical performance and anti-fatigue performance are obtained.

Description

technical field [0001] The invention relates to the technical field of iron and steel smelting, in particular to a 355MPa grade low-alloy high-fatigue steel and a manufacturing method thereof. Background technique [0002] In recent years, my country has vigorously developed infrastructure construction, which has greatly promoted the vigorous development of construction machinery technology and manufacturing. Engineering construction machinery is subjected to complex and variable alternating stress during use, and some parts or components will form fatigue damage in advance under the action of alternating stress, resulting in a decrease in the service life of the entire machine, which is very uneconomical and causes a waste of social resources. In order to achieve high-quality development, prolong mechanical fatigue life, improve social resource utilization, and reduce costs, it is urgent to improve the inherent quality and technical parameters of steel. [0003] The common...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/12C22C38/14B21C37/04C21C7/00C21C7/06C21C7/072C21C7/10C21D8/02C22C33/04
CPCB21C37/04C21C7/0006C21C7/0056C21C7/06C21C7/072C21C7/10C21D8/0205C21D8/0226C21D2211/005C21D2211/009C22C33/04C22C38/02C22C38/04C22C38/06C22C38/12C22C38/14
Inventor 冯勇吴俊平谯明亮李明潘中德霍松波李伟刘继宏
Owner NANJING IRON & STEEL CO LTD
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