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 Fig. 1. Parts packing scheme for saturation from powder mixtures accelerating voltage of 10 keV in SE mode at the Research Center “Progress”, ESSUTM. EDS analysis results were presented with an accuracy of tenths of a percent. In this case, the error probability was 1–5 % by weight. Phase analysis was carried out on a D8 ADVANCE Bruker X-ray diffractometer in copper radiation with an interval of 10–70° at the Research Center of BINM SB RAS. RS in boride layers after TCT were measured using a UDION-2 installation for RS testing by a mechanical method, which was developed at INITU (Fig. 2) [13, 14]. The research focuses on the subsurfaceRSmeasurement as the main source of the mechanical components’ destruction. The RS examination was carried out on flat samples such as plates. This mechanical method for RS determining upon this particular shape is also known as a strip method. The method is a procedure of the samples’ deformations recording during continuous removal of stressed zones depending on the thickness of the removed layer. Strain gauges with a data collection system were used to register the samples’ deformation and electrochemical etching or anodic dissolution was used to remove layer from the samples. Elementary strip samples were prepared to determine the RS after TCT, (Fig. 3). Dimension parameters of the sample strips (thick­ ness  h and width b ) were measured, as well as its initial deformations (deflection arrow f 0 ) (Fig. 5) necessary for the subsequent RS calculation. Then the samples were dipped into protective rubber enamel and dried. After drying, the protective enamel was removed from the investigated surface by a blade in a rectangular shape of 30 mm long and with the same width as the strip. A two-armed lever was mounted to one end of the sample strip to transmit deformations to strain gauges, while the other end of the sample was fixed to the bracket of the metrological frame of the UDION-2 installation (Fig. 4). Fig. 2. Installation UDION-2/УДИОН-2 for mea - suring residual stresses by mechanical method: 1 – scrubber; 2 – device for sample fixing (met - rological frames); 3 – bracket; 4 – fume hood; 5 – bath with electrolyte solution; 6 – thermostatic bath; 7 – bath lifting device; 8 – personal com- puter; 9 – strain gauge modules of the data collec- tion system; 10 – electrochemical circuit power supply