微合金元素镍和铌对金属粉芯焊丝焊接接头性能的影响

在自行研制的高强钢金属粉芯焊丝的基础上,通过拉伸试验、冲击试验等方法分别研究了微合金元素镍和铌对高强钢焊接接头力学性能的影响,并结合金相分析、扫描电镜分析、化学成分分析等方法从组织和成分的角度对两种微量合金元素的影响机理进行了合理的解释。结果表明,微合金元素镍具有增加焊缝组织中贝氏体和马氏体组织含量从而提高焊接接头强度的作用,并能促进针状铁素体形成而改善接头低温冲击韧性;微合金元素铌同样具有促进焊缝组织形成针状铁素体作用,同时通过细化晶粒和沉淀强化提高接头的抗拉强度。

Effect of micro-alloying nickel and niobium elements on mechanical properties of welded joint with metal powder-cored wire

On the basis of high strength low alloy steel flux cored wire which was designed by authors, the effects of micro-alloying elements nickel and niobium on mechanical properties of welded joint were researched by tensile test, charpy V-notch test, et al. Combined with metallographic observation and scanning electron microscopy analysis and chemical analysis, the mechanism about the effect of micro-alloying nickel and niobium elements on mechanical properties of welded joint was reasonable explained from the microstructure and chemical composition. The results show that the micro-alloying nickel element in the flux cored wire plays the role of increasing strength of welded joint by increasing the contents of bainite and martensite in the weld metal, and improve impact toughness of welded joint at low temperature through promoting the nucleation and growth of acicular ferrite. The micro-alloying niobium elements in the flux cored wire has the same effect with the micro-alloying nickel element that is beneficial to promote the nucleation and growth of acicular ferrite, meanwhile it can enhance the tensile strength of welded joint by refining grain and precipitation strengthening.