The present work was undertaken to improve superplastic ductility of friction-stir welded joints of ultrafine-grained(UFG)Al-Mg-Sc-Zr alloy.In order to suppress the undesirable abnormal grain growth,which typically oc...The present work was undertaken to improve superplastic ductility of friction-stir welded joints of ultrafine-grained(UFG)Al-Mg-Sc-Zr alloy.In order to suppress the undesirable abnormal grain growth,which typically occurs in the heavily deformed base material,the UFG material was produced at elevated temperature.It was suggested that the new processing route could reduce dislocation density in the UFG structure and thus enhance its thermal stability.It was found,however,that the new approach resulted in a relatively high fraction of low-angle boundaries which,in turn,retarded grain-boundary sliding during subsequent superplastic tests.Therefore,despite the successful inhibition of the abnormal grain growth in the base-material zone,the superplastic deformation was still preferentially concentrated in the fully-recrystallized stir zone of the material.As a result,the maximal elongation-to-failure did not exceed 700%.展开更多
In this work, the current understanding and development of fliction-stir welding and processing of Ti- 6Al-4V alloy are briefly reviewed. The critical issues of these processes are addressed, including welding tool ma...In this work, the current understanding and development of fliction-stir welding and processing of Ti- 6Al-4V alloy are briefly reviewed. The critical issues of these processes are addressed, including welding tool materials and design, tool wea,, processing temperature, material flow, processing window and residual stresses. A particular emphasis is given to microstructural aspects and microstructure-properties relationship. Potential engineering applications are highlighted.展开更多
This work was undertaken to evaluate the applicability of the Ashby grain-boundary hardening model for a high strain range.To this end,Al Mg alloy with distinctly different grain sizes(~100μm vs^1μm)was cold-rolled ...This work was undertaken to evaluate the applicability of the Ashby grain-boundary hardening model for a high strain range.To this end,Al Mg alloy with distinctly different grain sizes(~100μm vs^1μm)was cold-rolled to a true strain of^1.6 and the resulting dislocation densities were compared by using transmission electron microscopy.A minor difference revealed by the measurements suggested a violation of the Ashby’s model.This effect was attributed to a partial relaxation of strain constraints due to significant change of grain shape,development of texture and formation of pronounced substructure.展开更多
基金financially supported by the Russian Science Foundation(No.18-79-10174)。
文摘The present work was undertaken to improve superplastic ductility of friction-stir welded joints of ultrafine-grained(UFG)Al-Mg-Sc-Zr alloy.In order to suppress the undesirable abnormal grain growth,which typically occurs in the heavily deformed base material,the UFG material was produced at elevated temperature.It was suggested that the new processing route could reduce dislocation density in the UFG structure and thus enhance its thermal stability.It was found,however,that the new approach resulted in a relatively high fraction of low-angle boundaries which,in turn,retarded grain-boundary sliding during subsequent superplastic tests.Therefore,despite the successful inhibition of the abnormal grain growth in the base-material zone,the superplastic deformation was still preferentially concentrated in the fully-recrystallized stir zone of the material.As a result,the maximal elongation-to-failure did not exceed 700%.
文摘In this work, the current understanding and development of fliction-stir welding and processing of Ti- 6Al-4V alloy are briefly reviewed. The critical issues of these processes are addressed, including welding tool materials and design, tool wea,, processing temperature, material flow, processing window and residual stresses. A particular emphasis is given to microstructural aspects and microstructure-properties relationship. Potential engineering applications are highlighted.
基金financially supported by the Russian Science Foundation, grant No.18-79-10174
文摘This work was undertaken to evaluate the applicability of the Ashby grain-boundary hardening model for a high strain range.To this end,Al Mg alloy with distinctly different grain sizes(~100μm vs^1μm)was cold-rolled to a true strain of^1.6 and the resulting dislocation densities were compared by using transmission electron microscopy.A minor difference revealed by the measurements suggested a violation of the Ashby’s model.This effect was attributed to a partial relaxation of strain constraints due to significant change of grain shape,development of texture and formation of pronounced substructure.
