小压下率冷轧过程中低碳钢氧化铁皮断裂行为研究

Study on fracture behavior of oxide scale of low carbon steel during small reduction cold rolling

针对免酸洗新工艺中采用小压下率冷轧或平整工艺,试验研究了不同压下率冷轧前后SPHC带钢操作侧(OS侧),中间部位,驱动侧(DS侧)3个位置表面和截面的氧化铁皮形貌和厚度,以及氧化铁皮在冷轧过程中的断裂行为。结果表明,试验钢热轧后冷却过程中的热应力使其表面氧化铁皮产生裂纹,且卷取后的冷却速率会对表面氧化铁皮结构产生较大影响;采用10%冷轧压下率时,带钢表面出现较多氧化铁皮块状脱落和粉化脱落现象,表面质量破环严重;采用5%冷轧压下率时,带钢表面仅出现少量氧化铁皮块状脱落,大部分氧化铁皮达到只开裂不剥落状态;氧化铁皮在常温下塑性较差,在冷轧后氧化铁皮厚度未发生随钢基体明显变薄的协同变形。

Aiming at the cold rolling or temper rolling with a small reduction in the new pickling-free process,the morphology and thickness of the scale on the surface and cross section of the operating side(OS side),middle part,and driving side(DS side)of SPHC strip before and after cold rolling with different reduction rates were tested studied as well as the fracture behavior of the scale during cold rolling.The results show that the thermal stress in the cooling process after hot rolling of the test steel caused cracks of the scale on the strip surface,and the cooling rate after coiling will have a large effect on the structure of the scale on the strip surface.When using a 10%cold rolling reduction,there are more lumps of scale and pulverization,and the surface quality is severely broken.When using a 5%cold rolling reduction,only a small amount of scale on the surface of the strip is shed,and most of the scale is only cracks and does not peel off.the scale is poor in plasticity at room temperature,it does not undergo a coordinated deformation with the steel substrate becoming significantly thinner after cold rolling.