Optimisation of the heat treatment for increasing the creep resistance of heat-resistant titanium alloys

摘要

The invention relates to a heat treatment process for the reliable setting of a total plastic strain /= 0.1% in a 100 hour creep test at 510@C and 210 MPa loading in semifinished parts and components of the titanium alloy Ti6Al2Sn4Zr2Mo with and without addition of silicon. The material, which has an alpha + beta microstructure, is solution-annealed at from 10 to 40@C below the beta transformation temperature for longer than 0.5 hour and is then cooled in such a way that, after being additionally maintained for 10-4 h at 570-600@C with air cooling, there is present an alpha + beta microstructure having a primary alpha content of 10-50% with relatively broad alpha needles or plates having a small length/thickness ratio in the alpha / beta grains and with at least a partial coating of the grain boundaries by alpha phase in accordance with the representative microstructure of Figure 1.