关键词: Cr-Ti-B系微碳钢, 加热速率, 淬火温度, 马氏体, 奥氏体形核, 织构

Abstract: Cr-Ti-B micro-carbon steel was intercritically quenched at different temperatures under heating rates of 10 ℃/s and 100 ℃/s, respectively, after reaching the temperature, held for 90 s. The effects of heating rate and quenching temperature on microstructure were analyzed, and the effect mechanism of phase transformation on matrix texture was also discussed. The results show that martensite exhibits island distribution at low intercritical quenching temperature (780 ℃) when heated at 10 ℃/s. With the increase of quenching temperature, the composite structure of martensite and bainite is observed. When heated at 100 ℃/s, martensite shows chain distribution at low intercritical quenching temperature (780 ℃), and martensite with network distribution appears with the increase of quenching temperature. The nucleation of austenite is obviously affected by heating rate. Nucleation occurs on the grain boundary of ferrite during slow heating, while nucleation occurs inside pearlite during rapid heating. The specimen heated at 10 ℃/s has strong γ texture and weak Goss texture when quenched at 830 ℃, while the specimen heated at 100 ℃/s has strong Goss texture and weak γ texture when quenched at 830 ℃. The selective phase transformation of {110} oriented grains during quenching is beneficial to weaken Goss texture.

Key words: Cr-Ti-B micro-carbon steel, heating rate, quenching temperature, martensite, nucleation of austenite, texture