Influence of precipitation hardening and reversible martensite reactions on recrystallization textures of 17%Ni–8%Co–4%Mo steel

The respective rôles of precipitation hardening and reversible martensite reactions have been analysed in relation to development of textures in 17 %Ni-8 %Co-4 %Mo steel. Cold-rolling textures after 90 % reduction are independent of the heat treatment prior to rolling, and are described as mainly {001}〈10〉_α′, and {557}〈10〉_α′, components, with a {111}〈2〉_α′, component of lower intensity. The corresponding recrystallization textures produced by annealing in the austenite region vary according to prior heat treatment: solution-treated material exhibits a recrystallization texture consisting mainly of {557}〈10〉_α′, and ~{510}〈50〉_α′, components, whereas when precipitation of Ni₃Mo takes place before the recrystallization anneal, the texture is more diffuse and contains, in addition to these components, a more even distribution of orientations which fie within a 〈111〉 fibre texture normal to the rolling plane. It is considered that the {557}〈10〉_α′ + ~{510}〈50〉_α′, recrystallization texture could be accounted for by a double shear transformation α′ → γ → α′, combined with texture sharpening during recrystallization in the austenite. It is necessary to invoke variant selectivity during the shear transformation in order to explain the absence of certain groups of orientations in the final α′ texture. The effect of Ni₃Mo is attributed to restriction of grain boundary mobility in the austenite, so preventing sharpening of the texture at this stage by recrystallization.