EFFECT OF DEFORMATION AND TEMPERATURE ON ANISOTROPHY AND RESIDUAL STRESS OF IF STEEL
Abstract
The article deals with the effect of deformation and temperature on anisotrophy and residual stress of IF steel. Two models of microstructural parameters were used: isotropic and anisotropic. Values of anisotrophy and residual stresses were measured using by X-ray diffraction apparatus and then processed in the MAUD software. The MAUD software allows microdeformation calculation from a diffraction lines profile by Rietvield method, thereby allowing an accurate determination of the structure. The values of lattice parameter a0 [nm], crystallite size DL [nm] and lattice distorsion ?z [-] were measured as the diffraction lines profile in the MAUD software. The lattice parameter a0 [nm] increased from 0.2866 nm to 0.2867 nm as well the crystallite size DL [nm] decrease from 220 nm to 53 nm, with increase in deformation value for both models. The change of lattice distorsion ?z [-] in dependence on deformation is not significant. The residual stresses across sample thickness with 90% deformation of IF steel were measured using sin2? method by X-ray diffraction apparatus. The measurement was realized on both sides of sample after double-size etching in rolling direction, in cross direction and in 45° direction. Results show that residual stresse distribution was symmetric in cross direction and unsymmetric in rolling direction. The coefficient of normal anisotrophy for IF steel was calculated using by model „pencil“ in popLA software. The popLA software for texture analysis and modeling software provides a comprehensive treatment of material texture analysis by reducing texture data and using these data to predict the normal anisotrophy coefficient. The absolute value of r increases to about 1.6 and with deformation increasing.
Keywords: IF steels|RTG|MAUD|diffraction|residual stress|
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