Abstract: An alloy for heat transfer pipes excellent in an alkali stress corrosion cracking resistance which is obtained by heating and retaining said alloy at a temperature within the range of a temperature (T.degree.C.), at which a carbide in said alloy is thoroughly solubilized, to T+100.degree. C. for 1 minute or more; cooling it once to a level of 200.degree. C. or less; and carrying out a thermal treatment under conditions within a hatched range Z in FIG. 2, said alloy comprising: in terms of % by weight, 0.15% or less of C; 1.0% or less of Si; 1.0% or less of Mn; 25 to 35% of Cr; 40 to 70% of Ni; 0.5% or less of Al; 0.01 to 1.0% of Ti; 0.5 to 5.0%, in all, of one or more of Mo, W and V; 0.30% or less of P; 0.020% or less of S; and the residue of Fe and impurities.