METHOD FOR EVALUATING PHYSICAL-MECHANICAL PROPERTIES OF HIGH-VISCOSITY SHEET STRUCTURAL STEELS Russian patent published in 2016 - IPC G01N3/30 

FIELD: metallurgy.

SUBSTANCE: invention relates to material science, particularly to methods for integrated assessment of physical and mechanical properties of high-viscosity structural steels, and can be applied to rapid analysis of crack resistance status of material, and to prediction of crack resistance of steel material. Subject: two specimens of type 15 are prepared for tests, according to GOST 9454-78, side V-shaped cuts are applied on both specimens, specimens are quenched and tempered. Tempering of first specimen is carried out at lower values of tested temperatures from preset temperature interval of analysis, and of second specimen, at higher values. Fatigue crack-concentrator is applied upon both specimens, wherein fatigue crack-concentrator is applied upon both specimens of one relative length - λ. Specimens are destructed by single impact action to produce two parts of each sample. After destruction, dynamic crack resistance KST * of both specimens is determined, and degree of viscosity is visually determined on test material specimens. Plastic deformation zone is examined on two newly formed surfaces of each specimen in start segment of crack development, and the micro-hardness HV_max are determined, HV in deformed and non-deformed parts of tested surfaces, and depth of plastic zone - r_PZ in starting segments of tested surfaces. By results of tests on specimens, curves are plotted of dynamic crack resistance of KST*, depth of plastic zone r_PZ, microhardness HV, HV_max at lower and upper values of tested tempering temperatures - t_temp, approximate them with inclined straight lines, wherein relationships are built in form of nomographs: on one coordinate field, or in form of nomograph column, complex of analyzed interconnected values KST * - r_PZ is obtained therein; r_PZ - HV_max; KST* - r_PZ - HV_max at all tempering temperatures t_temp in preset interval, whereupon studied values are evaluated, and properties of high-viscosity sheet structural steels in entire tempering temperature range are predicted.

EFFECT: technical result is increased predicting accuracy of crack resistance of steel, and quality assessment of parametric relationships responsible for crack resistance, and also simplified procedure.

1 cl, 3 dwg