P355NL1低合金钢焊补后力学性能研究

Research on mechanical properties of P355NL1 low alloy steel after welding repair

P355NL1低合金钢是转向架构架常用材料,对P355NL1低合金钢的焊接件和一次焊补件进行拉伸、冲击、弯曲和疲劳试验。结果表明,焊接修补对于接头显微组织无有害影响,并且可细化保留的下层焊缝的晶粒。经一次焊补后,焊缝硬度无明显下降。两种构件拉伸断裂均发生在母材,焊补对焊接接头的静载强度没有影响。与原始焊接件相比,由于焊补对上一次残余的焊接接头部分起到了热处理作用,细化了晶粒,改善了组织分布,一次焊补件冲击韧性和疲劳强度略有提高。

P355NL1 low alloy steel is a commonly used material for bogie frame. In this paper,the tensile,impact,flexural and fatigue tests of the welded parts of P355NL1 low alloy steel and its repairing part are carried out. The result shows that it＇s not bad for microstructure of welding repair and the grain size of the retained lower welding layer can be refined. There is no obvious decrease in the welding hardness after single pass welding. The tensile failures of the two parts happened on the base metal ,the welding repairs have no effect on the static load strength. Comparing with original welding part,due to the welding of the last remaining welding joints parts played a role in heat treatment,grain refined,improved tissue distribution,the impact toughness and fatigue strength of repairing part is improved.