The effects of two post-weld heat treatment processes on the microstructure and fatigue properties of the electron beam welded joints of 30CrMnSiNi2A steel were studied. Electron beam local post-weld heat treatment (E...The effects of two post-weld heat treatment processes on the microstructure and fatigue properties of the electron beam welded joints of 30CrMnSiNi2A steel were studied. Electron beam local post-weld heat treatment (EBLPWHT), in a vacuum chamber, immediately after welding and a traditional furnace whole post-weld heat treatment (FWPWHT) were accepted. The experimental results show that, after EBLPWHT, the main microstructure of weld is changed from coarse acicular martensite into lath martensite, and base metal is changed from ferrite and perlite into upper bainite and residual austenite, however the microstructures of different zones of joints in FWPWHT conditions are tempered sorbite. The fatigue crack growth rate da/dN of welds and base metal are not obviously changed among EBLPWHT, FWPWHT test and as-welded (AW) test, as the mechanical properties of materials have a certain but not large effect on the da/dN of welded joints. The resistance to near threshold fatigue crack growth data of welded joints can be largely improved by EBLPWHT and it is related to microstructure and crack closure effect.展开更多
Based on thermal-elasto-plastic finite element theory, a two-dimensional finite element model for calculating electron beam brazing temperature and residual stress fields of stainless steel radiator are presented. The...Based on thermal-elasto-plastic finite element theory, a two-dimensional finite element model for calculating electron beam brazing temperature and residual stress fields of stainless steel radiator are presented. The distributions of temperature and residual stress are studied. The resuhs showed that temperature distribution on brazing surface is rather uniform, ranging from 1 026 ℃ to 1 090 ℃. The residual stresses are varied from initial compressive to tensile , and the variation of residual stress is very little in total zone of brazing surface.展开更多
基金thefoundationoftheNationalDefenseTechnologyKeyLaboratory (No .99JS5 0 .3 .2JW14 0 2 )
文摘The effects of two post-weld heat treatment processes on the microstructure and fatigue properties of the electron beam welded joints of 30CrMnSiNi2A steel were studied. Electron beam local post-weld heat treatment (EBLPWHT), in a vacuum chamber, immediately after welding and a traditional furnace whole post-weld heat treatment (FWPWHT) were accepted. The experimental results show that, after EBLPWHT, the main microstructure of weld is changed from coarse acicular martensite into lath martensite, and base metal is changed from ferrite and perlite into upper bainite and residual austenite, however the microstructures of different zones of joints in FWPWHT conditions are tempered sorbite. The fatigue crack growth rate da/dN of welds and base metal are not obviously changed among EBLPWHT, FWPWHT test and as-welded (AW) test, as the mechanical properties of materials have a certain but not large effect on the da/dN of welded joints. The resistance to near threshold fatigue crack growth data of welded joints can be largely improved by EBLPWHT and it is related to microstructure and crack closure effect.
文摘Based on thermal-elasto-plastic finite element theory, a two-dimensional finite element model for calculating electron beam brazing temperature and residual stress fields of stainless steel radiator are presented. The distributions of temperature and residual stress are studied. The resuhs showed that temperature distribution on brazing surface is rather uniform, ranging from 1 026 ℃ to 1 090 ℃. The residual stresses are varied from initial compressive to tensile , and the variation of residual stress is very little in total zone of brazing surface.
