On the strain-free lattice constants in residual stress evaluation by diffraction

Any discussion of methodical problems in residual stress evaluation by diff raction (X-rays or neutrons) is based on the so-called 'general transformat ion equation'. The problem of the unknown strain-free lattice constants has to be treated by an appropriate use of the transformation equation. We out line several solutions known from the literature for this problem. In the m ost general case, we include the lattice constants and the strain/stress te nsor components as unkowns into the evaluation the general transformation e quation. This results in a nonlinear equation system for the unknowns which can be solved numerically. (C) 2000 Elsevier Science Ltd. All rights reser ved.