16KhSN high-strength steel in various structural conditions and with various deformation conditions

Conclusions

• 1. Drawing and reducing of 16KhSN steel with degrees of 0–60% leads to an increase in yield strength σ_y from 300 to 680 MPA and in tensile strength σ_t from 500 to 860 MPa and a reduction in the reduction of area ψ from 72 to 57%, in the elongation δ from 30 to 9%, in the work for limiting deformation A_f from 1020 to 940 MJ/m³, and in the strain-hardening factor from 0.177 to 0.080.

• 2. The influence of hardening heat treatment (harden from 930°C and temper at 350°C) on the mechanical properties of 16KhSN steel is similar to the influence of work hardening, but the strength properties of this steel after heat treatment increase to a greater degree than after deformation, σ_y to 1080 MPa, σ_t to 1280 MPa, and A_f to 1660 MJ/m³.

• 3. As a result of cold plastic deformation of 16KhSN steel by drawing or reducing, the density decreases (by 0.41% with degrees of deformation of ε=60%). The increase in specific volume is an indication of the "loosening" of the material in work hardening and is caused by the occurrence of submicro- and microscopic cracks and microdistortions.

• 4. The intense decrease in plasticity of the steel in the work-hardened condition with an increase in the index of the stressed state (i.e., in the volume of the path of tension) and the increase in the notch sensitivity π_ψ from 0.160 to 0.575 are related to the presence of discontinuities in the structure of the material.