The characteristics of weld shape,microstructure,mechanical properties and defects of 5A90 Al-Li alloy joint by laser welding(LBW)and laser welding with filler wire(LWFW)were studied and analyzed.The results indicated...The characteristics of weld shape,microstructure,mechanical properties and defects of 5A90 Al-Li alloy joint by laser welding(LBW)and laser welding with filler wire(LWFW)were studied and analyzed.The results indicated that the microstructure of joint by LWFW was fine-grained layer and the equiaxed grain in most of seams,which were similar to the joint by LBW.Compared with the joint by LBW,the microstructure of joint by LWFW tended to fine,and the range of the columnar crystals zone was prone to decrease.The Microhardness of the joint by LWFW(92.57HV0.2)was lower than that by LBW(95.65HV0.2),but the uniformity was better.The ultimate tensile strength of the joint by LWFW was lower than that by LBW slightly,which reached to 73.03%and 79.22%of the base metal respectively.However,the elongation of the LWFW joint was higher than that of the LBW joint significantly,which reached to 38.65%and 20.38%of the base metal respectively.The microstructure and mechanical properties of 5A90 Al-Li alloy by LWFW were better than that by LBW.The defects of joint were mainly forming defects which were caused by improper parameters and porosity inside the joint,which was caused by uncleaned surface and incomplete penetration.展开更多
INTRODUCTIONRadiology has been greatly advanced in China sinceits founding in 1949 and has been developed fasterand further more since China adopted the policy ofsocioeconomic reform in 1978.It plays anincreasingly im...INTRODUCTIONRadiology has been greatly advanced in China sinceits founding in 1949 and has been developed fasterand further more since China adopted the policy ofsocioeconomic reform in 1978.It plays anincreasingly important role in the medical healthcare and treatment in the country and has reachedthe world’s advanced level in certain fields.We nowbriefly review the history of China’s radiology so asto give a clear picture of its development.展开更多
文摘The characteristics of weld shape,microstructure,mechanical properties and defects of 5A90 Al-Li alloy joint by laser welding(LBW)and laser welding with filler wire(LWFW)were studied and analyzed.The results indicated that the microstructure of joint by LWFW was fine-grained layer and the equiaxed grain in most of seams,which were similar to the joint by LBW.Compared with the joint by LBW,the microstructure of joint by LWFW tended to fine,and the range of the columnar crystals zone was prone to decrease.The Microhardness of the joint by LWFW(92.57HV0.2)was lower than that by LBW(95.65HV0.2),but the uniformity was better.The ultimate tensile strength of the joint by LWFW was lower than that by LBW slightly,which reached to 73.03%and 79.22%of the base metal respectively.However,the elongation of the LWFW joint was higher than that of the LBW joint significantly,which reached to 38.65%and 20.38%of the base metal respectively.The microstructure and mechanical properties of 5A90 Al-Li alloy by LWFW were better than that by LBW.The defects of joint were mainly forming defects which were caused by improper parameters and porosity inside the joint,which was caused by uncleaned surface and incomplete penetration.
文摘INTRODUCTIONRadiology has been greatly advanced in China sinceits founding in 1949 and has been developed fasterand further more since China adopted the policy ofsocioeconomic reform in 1978.It plays anincreasingly important role in the medical healthcare and treatment in the country and has reachedthe world’s advanced level in certain fields.We nowbriefly review the history of China’s radiology so asto give a clear picture of its development.
