The analysis of phase transformation of undercooled austenite and selected mechanical properties of low-alloy steel with boron addition

The paper presents continuous cooling transformation (CCT) diagram of selected low-alloy boron steel with high resistance to abrasion. Tests were performed on samples with dimensions of Ø 3 mm × 10 mm. Samples were prepared from examined material in as – delivery conditions, then were austenitized at 930 °C for 20 min, and then cooled with the rates of V800-500 = 0.17, 0.33, 1, 5, 10, 25 and 47 °C/s. During the dilatometric research, the critical temperatures were defined as well as the critical points specified for different cooling rates were designated. In addition, metallographic documentation of received microstructures after dilatometric investigations was prepared and hardness measurement was performed. Moreover, examinations of the basic parameters of strength, impact test and abrasion resistance test were performed and a tendency to brittle fracture was analyzed. The studies show big differences of the analyzed parameters depending on the applied heat treatment, which should provide guidance to users to specific applications of this type of steel.