The influence of quenching rate on microstructure and stress corrosion cracking （SCC） of 7085 aluminum alloy was investigated by tensile test, slow strain rate test （SSRT）, combined with scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and electrochemical test. The results show that with decreasing the quenching rate, the size and inter-particle distance of the grain boundary precipitates as well as precipitation free zone width increase, but the copper content of grain boundary precipitates decreases. The SCC resistance of the samples increases first and then decreases, which is attributed to the copper content, size and distribution of grain boundary precipitates.
The role of subtransus hot working on microstructure morphology of TA15 titanium alloy plate with elongatedαphases was studied by quantitative metallography on different sections. The results show that the microstructure morphology is mainly affected by loading direction. When the sample is compressed along normal direction, microstructure on the section vertical to normal direction has equiaxed primaryαphase but microstructure on the section vertical to rolling direction has strip primaryαphase with long axis along tangential direction. When the sample is compressed along rolling direction, microstructure on the section vertical to normal direction has strip primaryαphase elongated along tangential direction but microstructure on the section vertical to rolling direction consists of strip and irregular broad-band primaryαphase. The strip primaryαphase aspect ratio is smaller at lower temperature due to the dynamic break-down ofαphase. The difference on primaryαphase aspect ratio between different sections decreases after compression along distinct directions in two loading passes, suggesting the improvement of equiaxity of primaryαphase.
Using simple unequal-thickness billet combining isothermal local loading can control the metal flow and improve the cavity fill in manufacturing process of large-scale rib-web titanium alloy component with low cost and short cycle. The beveling transition pattern is well used for variable-thickness region of billet （VTRB） due to its simple and ample range of transition condition. The transition condition development in the local loading process has a significant influence on dynamic boundary of unrestricted portion of VTRB. With the help of reasonable assumptions, a mathematical model of transition condition development was established by theoretical analysis. The predicted results for local loading process of rib-web component using the established model were compared with the numerical and experimental ones, and the results indicated that the model of transition condition development is reasonable. Using the established model could deal with the dynamic boundary of unrestricted portion of VTRB well, and the model is suitable for the analysis of metal flow and cavity fill in local loading process of multi-ribs component.
