焊接熱裂敏感性
(北京有色金屬研究總院 國(guó)家有色金屬?gòu)?fù)合材料工程技術(shù)研究中心，北京 100088)
摘 要: 采用魚(yú)骨狀試樣裂紋試驗(yàn)、SEM和DSC等分析方法研究Sc、Zr和Er的復(fù)合添加對(duì)新型Al-5.6Mg-1.0Zn-0.6Mn基填充合金焊接熱裂敏感性的影響。結(jié)果表明：Sc、Zr和Er(含Ti)參與形核核心Al3(Sc，X)的生成，Er(Ti)元素在晶界處形成富Er相，這對(duì)試驗(yàn)合金焊道熔池區(qū)域的晶粒度和晶間相富集狀態(tài)影響顯著；優(yōu)化的Sc、Zr和Er成分配比能獲得優(yōu)異的晶粒細(xì)化效果，并抑制含Er相對(duì)晶界結(jié)合的惡化作用，使合金獲得較高的焊接熱裂抗力；焊接熱裂敏感性降低的機(jī)理為合金偏析程度的降低、凝固終了溫度的相對(duì)提高、細(xì)小晶粒的轉(zhuǎn)動(dòng)滑移和細(xì)晶晶界應(yīng)力的分散。
關(guān)鍵字: Al-Mg合金；填充合金；微合金化；熔焊；熱裂敏感性
Al-5Mg filler metals
（National Engineering and Technology Research Center for Non-ferrous Metal Matrix Composites,
General Research Institute for Non-ferrous Metals, Beijing 100088, China）
Abstract:The influence of Sc, Zr and Er additions on the welding hot-cracking susceptibility of Al-5.6Mg-1.0Zn-0.6Mn alloys was investigated by fishbone specimen hot-cracking test, SEM and DSC. The results show that Sc, Zr and Er including Ti participate from the melts in the Al3(Sc, X) nucleus, and Er (Ti) subsequently generates Er-riched phases at the grain boundaries. This significantly affects the grain size and phase enrichment state at the grain boundaries of the specimen molten pools. Optimized composition match of Sc, Zr and Er gives excellent grain-refining effect and suppresses the worsening effects of Er-bearing phases on the grain boundary binding, which endues the alloy with high hot-cracking resistance. The mechanism of lowering hot-cracking susceptibility is reduction of solute segregation, rise of finishing temperature, rotation and intergranular movement of refined grains and stress dispersion effect of large amounts of grains.
Key words: Al-Mg alloy; filler metal; microalloying; fusion welding; hot-cracking susceptibility
