Author(s): SHEN Yan-jin, College of Materials Science and Engineering, Hunan University, Hunan Automotive Engineering Vocational College
Pages: 415-420
Year: 2016 Issue:  3
Journal: Journal of Donghua University(English Edition)
Keyword:  AZ91 magnesium alloy; fracture model; liquefied crack; stress crack;
Abstract: The characteristics of the welding molten pool of AZ91 magnesium alloy were studied and the welding interface model was built using metallographic observation and scanning electorn microscope(SEM) composition analysis.The welding area was divided into heat affected zone(HAZ),liquefaction zone(LZ),rich poly zone(RPZ),sparse zone(SZ) and weld zone(WZ).The analyses of the microstructure and composition of each region show that optimizing the welding process can improve mechanical properties of weld zone.While for LZ,its tensile properties can be strengthened only by improving the composition of the parent metal and the second phase distribution.And the way to improve the tensile properties of LZ,RPZ,and SZ is to give priority to improve the parent metal composition and the second phase distribution,improving welding technology as the complementary method.Furthermore,based on the results above and the analyses of the microstructure and composition of welding cracks,it is found that the tensile fracture is mainly caused by the stress cracking rather than composition crack.