应变硬化对冷轧301L不锈钢点焊接头疲劳强度的影响

将应变硬化程度不同、厚度均为1.5 mm的国产和进口301L不锈钢冷轧板采用相同的焊接工艺分别制成标准电阻点焊试样,进行了疲劳试验和微观结构分析.结果表明:应变硬化程度较高的国产板点焊试样疲劳极限低于应变硬化程度较低的进口板点焊试样;国产板点焊试样焊点边缘产生了折叠变形,该部位同时存在再结晶组织和应变硬化组织,所以不但有结构应力集中而且出现了组织性能不均匀所造成的应力集中,折叠变形和应力集中是造成疲劳极限降低的主要原因.

Effects of Strain Hardening on the Fatigue Strength of Cold Rolling 301L Stainless Steel Resistance Spot Welding Joint

Two kinds of standard resistance spot welding fatigue specimens were respectively prepared from 1.5 mm thick domestic and imported commercial grades of cold rolled 301L stainless steel with different strain hardening degrees, by adopting the same resistance spot welding procedure parameters. Fatigue test and microstructure analysis on the two kinds of spot welding specimens were performed. The fatigue limit of the higher strain hardening domestic specimen was lower. There was folding deformation on the edge of spot welding joint of domestic specimen. Recrystallized microstructure and strain hardening microstructure were simultaneously found in the same area, which resulted in not only structural stress concentration but also the one resulting from non-uniform texture. Therefore, folding deformation and stress concentration are the main reasons of fatigue limit decrease.