The structure, phase composition, and residual stresses of diffusion boride layers formed by thermal-chemical treatment on the die steel surface

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 23 No. 2 2021 a b Fig. 6. Microstructures of steel 3Kh2V8F after TCT at temperature: а – 950 °С; б – 1050 °С Fig. 7. Depth distribution of microhardness after TCT at temperature: а – 950 °С; б – 1050 °С a b Figure 10 shows the strip samples as a result of electrochemical etching (anodic dissolution) after the RS determination on the UDION-2 installation. Figures 11, 12 show the RS epures based on the experiment result. As it is seen on the diagrams, the normal component of the RS appears due to the diffusion processes occurring throughout the entire base metal and forms a plane stress-strain state of one type. That means any direction is a main one, therefore, it is necessary and sufficient to measure only one normal (main) component of the RS [18]. The obtained data proved that die steel (0.3 % C, 2 % Cr, 8 % W, 0.2 % V) boriding at 950 °C led to compressive RS (Fig. 11). The minimum values of ​-180 MPa were observed at a distance from the sur- face of 25...55 μm in transition zone. The active part of the RS epure was estimated at 0.18 mm thickness