Li Yupeng and others found that under the same quenching and tempering process, the tensile strength of 2Cr13 Steel after isothermal annealing can be more than 850mpa, and the impact energy aku2 value can also be increased by 21.8%, reaching 75.5j. Under the process of 1000 ° C + 4H air cooling to 660 ° C + 8h air cooling, Moreover, it can achieve balance quickly, and all properties are better than those under ordinary annealing process. See Table 1 for the comparison of mechanical properties.
|Test items:||Rp0.2／MPa||Elongation at break /%||Reduction of area /%||Tensile strength ／ MPa||Aku2|
|2Crl3 quenching after conventional annealing||615.598||18.56||67.845||790.658||62.0|
|2Crl3 quenching after isothermal annealing||682.658||21.35||71.325||852.968||75.5|
When discussing the best quenching conditions of lcrl2, lCrl3, 2Crl3 and lcrllmov, Su Xin and others found that when the quenching temperature is below 980 ° C, the mechanical properties and grain size requirements of the materials can reach more than 5.5. Table 2 shows the mechanical properties of various materials at 980 ° C, which are tempered according to different strength levels. In order to reduce the grain size of 12% Cr Martensitic stainless steel and avoid the phenomenon of unqualified impact energy, the quenching tests at various temperatures were carried out on lcrl2mo. As shown in the figure below, it can be seen that the structure grain changes with the temperature.
Zhou Lianzhao found that after two or three times of quenching in 2Crl3, the material has obvious low-temperature impact toughness enhancement after high-temperature tempering (700 ° C, 2h, oil cooling), which solves the mechanical property problem of ship parts under low-temperature operation. The heat treatment process of 980-1000 ° C, LH, oil cooling + 880 ° C, LH, oil cooling + 650 ° C, 2h and water cooling is finally adopted in this test, which meets the mechanical property requirements.
|Material grade||Rp0.2 N/mm2||Rm N/mm2||A %||Z %||KAV J||Grain|
The test shows that the low-temperature toughness of the three critical zone quenching is better than that of the two critical zone quenching. Since the strength and hardness requirements cannot be met at the beginning, the first quenching temperature is changed to 1000 ° C, and the high-temperature tempering is about 650 ° C. the mechanical properties meet the requirements that the hardness after tempering is about 100hrb, The tensile strength and yield strength are 700n / mm2 and 500N / mm2, respectively. At this time, the plastic toughness is improved, – 40 ° C, and the low-temperature impact value is > 27j.
Qin Shangwu et al. Studied the relationship between five elements in Crl3 stainless steel and its quenching transformation temperature, simulated the metallographic structure of lcr3 with jmat Pro software, and then established the relationship between the five alloy elements of lcr3 and the quenching temperature range by multivariate linear fitting with MATLAB.