430不锈钢1.8 mm冷轧退火酸洗板折弯开裂的原因分析及工艺改进

430不锈钢冷轧酸洗板在折弯加工过程中出现了开裂现象,为了找出裂纹成因,对所使用的430不锈钢冷轧酸洗板进行了化学成分分析、力学性能测试和金相检验,并对样品折弯开裂处的裂纹进行了形貌观察。结果表明,430不锈钢酸洗板折弯开裂的主要原因为基体组织中晶粒大小不均匀,存在异常长大的情况,且晶界处存在大量碳化物析出聚集,促使开裂裂纹沿着晶界由外向内迅速地扩展,导致产品的折弯开裂。通过分析可知,430不锈钢冷轧板材在退火过程中的加热时间过长、材温偏高导致基体内部组织异常。通过控制430不锈钢冷轧板的退火工艺参数:1区加热段温度840～850℃,2区加热段温度870～900℃,在炉时间130～140 S,从而避免了折弯开裂的发牛。

Analysis and Process Improvement on Bending Cracking of 430 Stainless Steel 1.8 mm Cold Rolling-Annealing Pickling Plate

The cracking is appeared at bending 430 stainless steel pickling plate. In order to find out the cause o£ cracking, chemical composition analysis, mechanical properties test, metallographic analysis and crack analysis on the specimen have been carried out. The results show that the bending cracking of 430 stainless steel pickling plate is caused by the heterogeneity of grain size in matrix and the aggregation of precipitated corbide on grain boundary, which accelerated crack propagation along the grain boundary and led to bending cracking of products. It is proved that the abnormal microstructure is introduced by the longer annealing period of 430 stainless steel pickling plate at higher temperature. With control of annealing parameters of 430 stainless cold-rolling plate: annealing of 1^# heating section at 840 〜850 ℃ and 2^# heating section at 870 ~900 ℃. for 130 ~ 140 s in annealing process,the bending cracks of plate is avoided