PROSPECTS FOR USE AS SUBSTITUTES OF HEAT-RESISTANT DIE STEELS, HIGH-NITROGEN AUSTENITIC CHROMIUM-MANGANESE STEELS WITH VANADIUM AND MOLYBDENUM

Abstract

Purpose. To study the effectiveness of additional (along with vanadium) alloying of high-nitrogen austenitic chromium-manganese steels with molybdenum to determine the prospects for their use instead of high-temperature resistant serial martensitic stamped steels. Research methods. Metallographic, durometric, tensile and impact strength tests at room and high temperatures.. Results. The peculiarities of dispersion hardening and microstructures of the investigated high-nitrogen austenitic chromium-manganese steels alloyed with vanadium and molybdenum were determined. The mechanical properties of the selected steels were determined depending on the content of strengthening alloying elements. Significant advantages in the high-temperature (750 and 850 °C) strength of high-nitrogen austenitic chromium-manganese steels alloyed with vanadium and molybdenum were found compared to the serial high-temperature stamping steel 5Х3В3МФС (ДИ23). The highest hardness and strength values correspond to the research steel 60Х11Г16АФ2М2, which allows us to recommend it as an effective substitute for die steels when required to provide increased resistance to high-temperature dehardening of hot-die tools. Scientific novelty. An abnormal presence of a minimum on the dispersion hardening curves of high-nitrogen austenitic chromium-manganese steels with molybdenum and its shift towards a shorter aging duration with increasing aging temperature have been determined. The formation of large particles of primary excess phases with increasing vanadium and molybdenum content in steels was revealed. The dependence of strength and ductility characteristics on the total alloying of the studied austenitic chromium-manganese steels with nitrogen and carbon was established. Practical value. The effectiveness of molybdenum alloying along with vanadium in high-nitrogen austenitic chromium-manganese steels has been established to provide significant (1.5...2.5 times) advantages in high-temperature strength compared to heat-resistant commerciall stamped steels.. The research steel 60Х11Г16АФ2М2 may be the most promising substitute for die steels under high force loads at operating temperatures of 750 °C and above.