摘要
Abstract
The 45 steel composite billet was sealed and fabricated by vacuum electron beam welding method.The micro-structure and mechanical properties of the electron beam joint at different positions(1#arc,2#middle and 3#arc closure)were analyzed by means of metallography microscope(OM),scanning electron microscope(SEM),Vickers hardness tester and impact testing machine.The results show that:When the welding position changes from the arc starting point to the arc retracting point,the joint penetration depth is almost constant,and the heat affected area decreases gradually.After welding,the cooling rate of the 1#joint is relatively slow,no crack occurs at the root of the weld,the structure is a mixture of acicular martensite and clumpy trotensite,the hardness(HV)is 588,the impact energy of the weld root is 25.7J,and the fracture is ductile.After welding,the cooling rate of the 2#and 3#samples is high,and obvious transgranular cracks appear at the root of the weld,and the microstructure is acicular martensite.With the acceleration of the cooling rate after welding,the number of martensite increases and the size becomes finer.The hardness(HV)increased to 674 and 729,respectively,and the impact property decreased to 18J and 13.7J,respectively,and showed a brittle fracture.关键词
45钢复合坯/真空电子束焊接/接头组织/硬度/裂纹Key words
45 steel composite billet/electron beam welding/joint organization/hardness/crack分类
矿业与冶金
