Method for improving elongation rate and strain hardening index n value of cold-rolled deep-drawing steel

A technology of strain hardening index and elongation, applied in the field of metallurgical technology, can solve the problems of product scrap, unstable fracture, low production qualification rate, etc., and achieve the effect of low cost, reduction of tensile fracture, and reduction of the probability of fracture

Pending Publication Date: 2019-11-12
BAOTOU IRON & STEEL GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The existing public cold-rolled deep-drawing steel material standards require that the n value is greater than 0.18 and the elongation is 34% to 40%. Cold-rolled deep-drawing steel with a lower n value and elongation often suffers from instability when processing parts Fracture, causing the product to be scrapped, and the defect of low production pass rate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056] Embodiment 1, the preparation of cold-rolled deep-drawing steel

[0057] The preparation of the cold-rolled deep-drawing steel of this embodiment adopts the following steps:

[0058] Desulfurization pretreated molten iron is smelted in a converter to decarburize the molten iron, followed by RH refining to obtain molten steel; the molten steel is subjected to continuous casting to obtain a slab, and the slab is subjected to a hot rolling process to obtain a hot-rolled steel coil. The rolling temperature is 927°C, the coiling temperature is 722°C, and the thickness of the hot coil is 4.5mm; the hot-rolled steel coil is pickled to remove scale and then cold-rolled. The thickness of the coil is 1.8mm, and the cold-rolled steel coil is obtained; the cold-rolled steel coil is subjected to bell annealing, the annealing temperature is 730°C, the annealing time is 15h, the slow cooling time is 6h, and the furnace temperature is 78°C; finally, after the smoothing process, the fla...

Embodiment 2

[0060] The preparation of the cold-rolled deep-drawing steel of this embodiment adopts the following steps:

[0061] Desulfurization pretreated molten iron is decarburized by converter smelting, followed by RH refining to obtain molten steel; the molten steel is subjected to continuous casting to obtain slabs, and the slabs are subjected to hot rolling processes to obtain hot-rolled steel coils. The rolling temperature is 915°C, the coiling temperature is 718°C, and the thickness of the hot coil is 3.0mm. The thickness of the coil is 0.7mm, and the cold-rolled steel coil is obtained; the cold-rolled steel coil is subjected to bell annealing, the annealing temperature is 720°C, the annealing time is 13h, the slow cooling time is 6h, and the furnace temperature is 75°C; finally, after the smoothing process, the flattening elongation is 0.5% obtains the cold-rolled deep-drawing steel described in the present invention;

Embodiment 3

[0063] The preparation of the cold-rolled deep-drawing steel of this embodiment adopts the following steps:

[0064] Desulfurization pretreated molten iron is smelted in a converter to decarburize the molten iron, followed by RH refining to obtain molten steel; the molten steel is subjected to continuous casting to obtain a slab, and the slab is subjected to a hot rolling process to obtain a hot-rolled steel coil. The rolling temperature is 930°C, the coiling temperature is 726°C, and the thickness of the hot coil is 6.0mm; the hot-rolled steel coil is pickled to remove scale and then cold-rolled. The thickness of the coil is 2.5mm, and the cold-rolled steel coil is obtained; the cold-rolled steel coil is subjected to bell annealing, the annealing temperature is 730°C, the annealing time is 15h, the slow cooling time is 6h, and the furnace temperature is 80°C; finally, after the smoothing process, the smoothing elongation is 0.6% obtains the cold-rolled deep-drawing steel desc...

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Abstract

The invention discloses a method for improving elongation rate and strain hardening index n value of cold-rolled deep-drawing steel. The method comprises the steps of carrying out cold rolling by adopting a cold rolling reduction rate of 58%-77%, then carrying out cover annealing, and flattening to obtain the cold-rolled deep-drawing steel. The elongation rate of the cold-rolled deep-drawing steelis more than 40%, and the strain hardening index n value is 0.22-0.25. According to the method for improving the elongation rate and the strain hardening index n value of the cold-rolled deep-drawingsteel, through optimizing the production process method, the obtained cold-rolled deep-drawing steel has higher elongation rate and strain hardening index n value, the expansion and ductility performance of a steel plate material is improved, and the probability of fracture of the steel material in the expansion process is reduced; the production qualified rate is improved; and the method for improving the elongation rate and the strain hardening index n value of the cold-rolled deep-drawing steel is improved on the basis of an original steel production line, process parameter control is optimized, and industrial production improvement is facilitated.

Description

technical field [0001] The invention relates to the technical field of metallurgical technology, in particular to a method for increasing the elongation and strain hardening exponent n value of cold-rolled deep-drawing steel. Background technique [0002] At present, with the continuous upgrading of cold-rolled deep-drawn steel products used in automobile manufacturing and home appliance industries, the design appearance and internal structure of products are becoming more and more complex, with large deformation, complex deformation, high stamping efficiency, and fast stamping speed. The stamping performance requirements of stamping steel are getting higher and higher. The American ASTM-E26 standard committee has conducted 1,000 actual punching tests on 18 groups of steel under strict rolling, strict auxetic and complex combination of the two conditions. The results show that: components mainly auxetic require cold rolling and deep drawing Steel materials have a high n val...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D8/02C21D1/26C22C38/02C22C38/04C22C38/06C22C38/14
CPCC21D1/26C21D8/0226C21D8/0236C21D8/0273C22C38/002C22C38/004C22C38/02C22C38/04C22C38/06C22C38/14
Inventor 陆斌尚秀廷韩玉龙华国龙张秀青
Owner BAOTOU IRON & STEEL GRP
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