The quasi-static and dynamic tensile behaviors in electron beam welded(EBW) Ti-6Al-4V alloy were investigated at strain rates of 10-3 and 103 s-1,respectively,by materials test system(MTS) and reconstructive Hopki...The quasi-static and dynamic tensile behaviors in electron beam welded(EBW) Ti-6Al-4V alloy were investigated at strain rates of 10-3 and 103 s-1,respectively,by materials test system(MTS) and reconstructive Hopkinson bars apparatus.The microstructures of the base metal(BM) and the welded metal(WM) were observed with optical microscope.The fracture characteristics of the BM and WM were characterized with scanning electronic microscope.In Ti-6Al-4V alloy joint,the flow stress of WM is higher than that of BM,while the fracture strain of WM is less than that of BM at strain rates of 103 and 10-3 s-1,respectively.The fracture strain of WM has apparent improvement when the strain rate rises from 10-3 to 103 s-1,while the fracture strain of BM almost has no change.At the same time,the fracture mode of WM alters from brittle to ductile fracture,which causes improvement of the fracture strain of WM.展开更多
The effect of cryogenic temperatures on the mechanical properties and fracture mechanism of SnAgCu−SnPb mixed solder joints was investigated.The results showed that the tensile strength of mixed solder joints first in...The effect of cryogenic temperatures on the mechanical properties and fracture mechanism of SnAgCu−SnPb mixed solder joints was investigated.The results showed that the tensile strength of mixed solder joints first increased with the increase of Pb content and reached its maximum at 22.46 wt.%Pb;subsequently,it decreased as Pb content increased.However,cryogenic temperatures improved the tensile strength of the solder joints.Both Pb content and cryogenic temperature caused the fracture mode of the mixed solder joints to change;however,temperature remained the main influencing factor.As the temperature fell from 298 to 123 K,the failure pattern in the solder joints transformed from ductile fracture to quasi-ductile fracture to quasi-brittle fracture and finally,to brittle fracture.展开更多
文摘The quasi-static and dynamic tensile behaviors in electron beam welded(EBW) Ti-6Al-4V alloy were investigated at strain rates of 10-3 and 103 s-1,respectively,by materials test system(MTS) and reconstructive Hopkinson bars apparatus.The microstructures of the base metal(BM) and the welded metal(WM) were observed with optical microscope.The fracture characteristics of the BM and WM were characterized with scanning electronic microscope.In Ti-6Al-4V alloy joint,the flow stress of WM is higher than that of BM,while the fracture strain of WM is less than that of BM at strain rates of 103 and 10-3 s-1,respectively.The fracture strain of WM has apparent improvement when the strain rate rises from 10-3 to 103 s-1,while the fracture strain of BM almost has no change.At the same time,the fracture mode of WM alters from brittle to ductile fracture,which causes improvement of the fracture strain of WM.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.51965044)the Aeronautical Science Foundation of China(No.20185456005).
文摘The effect of cryogenic temperatures on the mechanical properties and fracture mechanism of SnAgCu−SnPb mixed solder joints was investigated.The results showed that the tensile strength of mixed solder joints first increased with the increase of Pb content and reached its maximum at 22.46 wt.%Pb;subsequently,it decreased as Pb content increased.However,cryogenic temperatures improved the tensile strength of the solder joints.Both Pb content and cryogenic temperature caused the fracture mode of the mixed solder joints to change;however,temperature remained the main influencing factor.As the temperature fell from 298 to 123 K,the failure pattern in the solder joints transformed from ductile fracture to quasi-ductile fracture to quasi-brittle fracture and finally,to brittle fracture.