Effect and mechanism of heat treatment temperature on microstructure and mechanical properties of 0Cr16Ni5Mo martensitic stainless steel

摘要

The quenching treatment (QT) condition and tempering precipitation of low carbon martensitic stainless steel 0Cr16Ni5 Mo are characterized by optical microscope, scanning electron microscope, transmission electron microscope and X-ray diffraction.The results show that the QT condition is identified as 950 °C for 1h to make sure the carbides completely dissolve into martensitic matrix and prevent the grains coarsening too much.After quenching followed by tempering below 500 °C, reversed austenite grows up along martenite lathes;Tempering above 550 °C, massive lumps of retained austenite appear at grain and martenite boundaries, and M23C6 carbides precipitate on austenite.Lumps of retained austenite cannot improve impact energy but destroy tensile strength.Tempering at 600 °C, the content of retained austenite 29％ is the maximum.Tempering above 600 °C, secondary quenching happens and grain sizes are refined, which leads to strength increase and toughness decrease.