High-strength hot-dip galvanized steel sheet reduced in burr formation and process for producing same

Abstract

Provided are a high-strength hot-dip galvanized steel sheet which is reduced in burr formation, i.e., low in the height of burrs, and a process for producing the steel sheet. The high-strength hot-dip galvanized steel sheet reduced in burr formation is characterized by having a composition which contains, in terms of mass%, 0.04-0.13% C, 1.0-2.3% Si, 0.8-2.0% Mn, up to 0.05% P, 0.0010-0.01% S, up to 0.1% Al, and up to 0.008% N, with the remainder comprising Fe and incidental impurities, and by having a structure which comprises, in terms of areal proportion, at least 75% ferrite phase, at least 1% bainitic ferrite phase, and 1-10% pearlite phase, has a martensite phase content less than 5% in terms of areal proportion, and satisfies (areal proportion of martensite) / ((areal proportion of bainitic ferrite)+(areal proportion of pearlite))<=0.5.

Description

technical field [0001] The present invention relates to a steel sheet excellent in burr resistance during processing, which is used after punching, shearing, etc., for automobiles, home appliances, etc., and a method for producing the same. Background technique [0002] Thin steel sheets are widely used for automobiles, home appliances, furniture, etc., but generally, they are finished into desired products or parts in the order of blank processing-forming-assembly. In recent years, against the background of the complexity and high functionality of products, the requirements for machining accuracy have become increasingly strict. In terms of raw materials, what degrades machining accuracy is the burr that occurs on the end surface during punching. If the burr is large, it will cause fatal accuracy degradation in the final assembly stage. Furthermore, in the case of automobiles, there is a possibility that a gap may be generated in a superimposed portion between steel sheets...

AI Technical Summary

Problems solved by technology

In terms of raw materials, what degrades machining accuracy is the burr that occurs on the end surface during punching. If the burr is large, it will cause fatal accuracy degradation in the final assembly stage.

In addition, in the case of automobiles, there may be serious effects on functions such as the occurrence of gaps in the superimposed part of the steel plates and the deterioration of corrosion resistance.

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