Effect of quenching temperature on microstructure and mechanical properties of Fe-Cr-Ni-Mo steel for gas cylinder
In order to optimize the quenching process of Fe-Cr-Ni-Mo steel for gas cylinders,the influence of quenching temperature on the microstructure and mechanical properties of a Fe-Cr-Ni-Mo steel for gas cylinders was studied by using SEM,TEM,EBSD,tensile and impact testing.The results show that the alloy steel quenched at different temperatures exhibit lath martensite and its carbide precipitation and lath substructure remain basically unchanged.Whereas with the increase of quenching temperature,the prior austenite grain(PAG)shows obvious coarsening,growing from 4.3 μm at 800℃ to 29.6 μm and 371.1 μm at 930℃ and 1 200℃,respectively.Meanwhile the effective grain size(EGS)also gradually increases,from 0.60 μm at 800℃ to 1.20 and 3.22 μm at 930℃ and 1 200℃,respectively.The quenching temperature has little effect on the tensile strength,yield strength and elongation at room temperature of Fe-Cr-Ni-Mo steel.However,with the increase of quenching temperature,the impact energy shows a significant decrease,from 119 J at 800℃ to 68 J and 38 J at 930℃ and 1 200℃,respectively.Increasing EGS leads to partial cleavage fracture during impact process,which is the main cause for decrease of impact energy of the alloy steel quenched at higher temperature.When the quenching temperature is 800～860℃,the Fe-Cr-Ni-Mo steel has excellent combination of strength and impact toughness.The research results have guiding significance for the industrial production of Fe-Cr-Ni-Mo steel gas cylinders.
gas cylinderFe-Cr-Ni-Mo steelquenching temperatureeffective grain size(EGS)mechanical properties
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