فهرست نشریات علمی دسترسی آزاد ایران

Present study investigates the effect of low-temperature tempering duration (200 °C, 1 – 14 h) and short-duration low- and high-temperature tempering regimes on crack resistance development in various alloyed tool and structural steels: 5Kh2SMF, KhVG, 12KhNVA and 38KhN3MFA. The experiments revealed that the dependence of crack resistance on tempering duration for each steel grade mentioned above exhibits a non-monotonic character. For KhVG steel, maximum crack resistance is achieved after tempering for 5 h; for 5Kh2SMF steel – after 3 and 5 h; for 12KhNVA – after 3, 5, and 7 h; for 38KhN3MFA – after 3 h. Application of short (minute-scale) tempering regimes enables achieving equal or greater crack resistance values at a comparable hardness level in comparison to standard (hour-long) tempering. For 5Kh2SMF steel, short-term low-temperature tempering (265 °C, 10 min and 660 °C, 15 min) improves resistance to brittle fracture compared to standard tempering regimes at 200 and 600 °C for 2 h. For KhVG steel, the optimal short tempering regime of 255 °C, 6 min ensures enhanced crack resistance with only a minor reduction in hardness, which is probably due to the preservation of a higher amount of retained austenite. For 12KhNVA steel, short tempering at 255 °C, 6 min and 270 °C, 7 min results in a substantial increase in crack resistance – 500 and 340 kgf, respectively, compared to brief standard tempering, with only insignificant loss of hardness. For 38KhN3MFA steel, short tempering regimes allow achieving similar or higher crack resistance values without any decrease in hardness.