Effect of pre-sintered structure on sintering rate in the final stage of HIP process for pure titanium

摘要

The sintering rate in the final stage during HIP has been investigated by measurement of relative density of compacts which were preliminary sintered in vacuum. The activation energy of the final stage HIP-sintering rate Q_h of 218 kJ/mol and the stress exponent n_h of 4.5 are obtained for the pure titanium compact with an equiaxed structure and Q_h of 213 kJ/mol and n_h of 4.7 are obtained for that with a non-equiaxed structure. These values are approximately equal to the creep parameters, Q_c and n_c, obtained from creep experiments. The sintering rate of the pure titanium with the equiaxed structure is larger than that with the non-equiaxed structure under the same condition of temperature and pressure in the HIP process, which is influenced by the structure of compacts pre-sintered in vacuum. This is mainly due to the variation of A value in the equation of power-law creep influenced by the microstructure. The control of presintered structure is important for the followed HIP process.