Effect of quenching temperature on Microstructure and hardness of 2Cr13

The temperature node is taken between AC1 and AC3 of 2Crl3. Since the austenitizing of 2Crl3 begins at 820 ° C and is basically completed at 950 ° C, the temperature is taken at about 820 ° C and 950 ° C to analyze the change of structure and hardness value. 2Cr13 is a normal martensitic stainless steel, At 950 ° C, carbides will not exist in large amount in the structure, and the austenitizing is uniform. On the premise that the cooling mode is rapid oil cooling, take a more typical microstructure between 780 ° C and 1040 ° C, as shown in Fig. 1. Generally, with the increase of temperature, the martensite structure becomes more and more obvious, and the large crystal nucleus and coarsening of the structure appear around 100ctc, indicating that with the increase of temperature, the austenitization is gradually obvious and the carbides are gradually dissolved in the structure, Too high temperature also makes the crystal nucleus grow and coarse. At 780 °C-860 ° C, the martensite in the structure is not obvious, and ferrite also accounts for a part. At about 920 ° C, the structure is basically martensite phase. At 960 ° C, the martensite phase in the structure is more and more obvious, and residual austenite appears. Since residual austenite appears more or less after quenching, the amount and stability are determined by the amount of alloying elements dissolved in austenitizing. 980 ° C – 1040 ° C with the increase of temperature, the martensite lamellae becomes more and more obvious and coarsened. At this time, ferrite can hardly be found.

With the increase of carbon content α- There are more and more supersaturated solid solutions in Fe, which will increase the hardness value of the material in terms of mechanical properties. The picture shows that the dislocation density of martensite structure is enhanced, which is also an important reason for the increase in hardness. The temperature hardness curve is shown in Fig. 2. At 840 ° C, the hardness suddenly rises, and at 950 ° C, it begins to rise slowly and gradually, generally speaking, it has a rising trend, which is basically consistent with the appearance of metallographic diagrams at different temperatures.