氢对Ti-6Al-4V合金组织及超塑变形行为的影响
摘要
The effect induced by hydrogen on the microstructure of Ti-6Al-4V alloy had been investigated by optical microscopy and superplastic tensile tests were performed at 800℃~860℃ with initial strain rate 10^(-1) s^(-1). Experimental results indicate that the volume fraction of β phase in hydrogenated Ti-6Al-4V increases with the increase of the content of hydrogen and the equiaxed microstructure transforms to duplex microstructure. With the further increase of hydrogen, the hydride precipitated in a phase. The peak stress can be decreased significantly by adding in appropriate content of hydrogen, while the peak stress is reduced by 55% at 0.32wt% H. The temperature of superplastic deformation of Ti-6Al-4V alloy can be decreased significantly by adding in appropriate content of hydrogen while the optimum temperatures of superplastic deformation of hydrogenated Ti-6Al-4V alloy can be reduced by 60℃~90℃ in comparing to the as-received materials. The sample charged with 0.11wt% H exhibites an elongation of 1190% which is higher by 75% than the as-received materials at the same conditions. The results provide reference for optimization of superplastic forming and superplastic forming/diffusion bonding processes.