Ar-N2混合气体对奥氏体不锈钢焊缝化学成分的影响

为了验证Ar-N2混合气体对焊缝中各元素含量和焊缝铁素体数(FN值)的影响，对SS304L奥氏体不锈钢进行了4种比例的Ar-N2混合气体GTAW多层多道焊接试验，研究了4种Ar-N2比例对焊缝金属中各元素含量的影响，以及每条焊缝中各元素含量随着焊道层数的变化趋势。结果表明，不同保护气体类型的11种焊缝化学元素中，只有N元素随着保护气体中氮气比例的升高而明显增加，其它元素则没有明显的影响；经过汇总分析，认为由于稀释率的原因，导致各元素含量在同一保护气体焊缝中的规律为：C元素含量随着层数的增加而下降；Si，P，S和Nb元素含量随着层数的增加无明显上升或下降趋势；Mn，Ni，Cr，Mo和Cu元素含量随着层数的增加而上升；而N元素在纯氩气保护SG-A时的含量随着层数的增加而稍微下降，在SG-AN-0.5，SG-AN-1，SG-AN-1.5 3种保护气体中N元素含量随着层数的增加而上升；分析结果也表明,Creq/Nieq值和FN值有相同的变化趋势，都与氮气含量呈现反比关系。 创新点： 采用了阶梯式的多层多道焊，保留了各层焊缝的原始信息，验证了GTAW焊接方法在保护气体中添加氮气对奥氏体不锈钢焊缝各种化学元素成分的影响，为Ar-N2混合气体GTAW焊接奥氏体不锈钢在工程中的应用提供了可参考的试验数据。

Effect of Ar-N2 mixture on chemical composition of austenitic stainless steel welds

In order to verify the effect of argon-nitrogen mixture on the content of each element and FN value in the weld, the author carried out four ratios of argon-nitrogen mixture GTAW multi-layer multi-pass welding test on austenitic stainless steel SS304L, and the effects of four argon-nitrogen ratios on the content of each element in the weld metal and the changing trend of the content of each element in each weld with the number of bead layers were studied.The results show that among the 11 chemical elements of welds with different types of shielding gas, only N element increases significantly with the increase of nitrogen ratio in shielding gas, and other elements have no obvious effect; After a summary analysis, the author believes that the dilution rate induce the regularity of the content of each element in the weld of the same shielding gas: The C content decreases with the increase of the number of layers; The content of Si, P, S and Nb does not increase or decrease significantly with the increase of the number of layers; The content of Mn, Ni, Cr, Mo and Cu increase with the increase of the number of layers; The content of N element in pure argon protection SG-A decreased slightly with the increase of the number of layers, while in SG-AN-0.5, SG-AN-1, SG-AN-1.5, the N content in the three shielding gases increases with the increase of the number of layers; The analysis results also show that the Creq/Nieq value and the FN value of the weld ferrite have the same trend of change , are inversely proportional to the nitrogen content. Highlights: Due to step-by-step multi-pass welding is adopted, the original information of each layer of welds is retained, so a large amount of data so succeed to obtained to verify the effect of adding nitrogen to the shielding gas in GTAW welding process on various chemical compositions of austenitic stainless steel welds, which provides indispensable test data for the further engineering application of argon-nitrogen mixed gas GTAW welding of austenitic stainless steel.