GB883027A - Titanium alloys - Google Patents

Abstract

A titanium alloy contains 1-40% of one or more alpha promoting elements, namely at least 1% of Zr with or without Al up to 12% Sn up to 23%, Sb up to 19%, one or more of the beta eutectoid promoting elements Cu, Ni and Co in amounts of from more than 5% and up to 20% of Cu and/or from more than 5% and up to 12% of Co and/or Ni, 0-3% of Si, 0-2% of Be, 0-0,5% of C, O and N but not exceeding 0,4% O and 0,25% N, the balance being Ti in amount at least 50% by weight of the alloy. There may be substituted on a proportionate basis for up to one-half the maximum permissible content of the beta eutectoid promoting elements present in the alloys other beta stabilisers selected from Mo, V, Ta, Nb, Cr, Mn, Fe and W in the following amounts, up to 20% in total of one or more of Mo, V, Nb and Ta, up to 5% of Mn, up to 3,5% of Fe, up to 12% of Cr and/or W, and proportionally lesser amounts of these other beta stabilisers for lesser amounts of the said beta eutectoid promoters. Alloys containing one or more of the beta eutectoid promoters Cu, Co, Ni, Si, and Be in total amount in the range 0,25-20%, and each subject to the maximum amount specified for it above, the said alloys otherwise having the composition specified above, may be heat treated above the eutectoid temperature until transformation to the beta phase is substantially complete and then cooled rapidly through the eutectoid temperature at a rate sufficient to produce martensite or a fine eutectoid structure. The alloys may then be aged at a temperature below the eutectoid temperature. Examples of the heat treatments are a) heating for 7 hours at 1400 DEG F., furnace cooling to 1100 DEG F., holding for 16 hours at 1100 DEG F. and then air cooling; b) heating for 24 hours at 1250 DEG F., furnace cooling to 1100 DEG F., holding for 16 hours at 1100 DEG F. and air cooling; c) heating for one hour at 1550 DEG F. and then air cooling.