Effect of cutting-edge geometry and workpiece hardness on surface residualstresses in finish hard turning of AISI 52100 steel

An experimental investigation was conducted to determine the effects of too l cutting-edge geometry (edge preparation) and workpiece hardness on surfac e residual stresses far finish hard turning of through-hardened AISI 52100 steel. Polycrystalline cubic boron nitride (PCBN) inserts with representati ve types of edge geometry including ''ug-sharp'' edges, edge hones, and cha mfers were used as the cutting tools in this study. This study shows that t ool edge geometry is highly influential with respect to surface residual st resses, which were measured using x-ray diffraction. In general, compressiv e surface residual stresses in the axial and circumferential directions wer e generated by large edge hone tools in longitudinal turning operations. Re sidual stresses in the axial and circumferential directions generated by la rge edge hone tools are typically more compressive than stresses produced b y small edge hone tools. Microstructural analysis shows that thermally-indu ced phase transformation effects are present at all feeds and workpiece har dness values with the large edge hone tools, and only at high feeds and har dness values with the small edge hone tools. In general, continuous while l ayers on the workpiece surface correlate with compressive residual stresses , while over-tempered regions correlate with tensile or compressive residua l stresses depending on the workpiece hardness. [S1087-1357(00)00304-X].