Research On Microstructure And Properties Of Carburizing Alloy Steel Treated By Intensive Quenching Process

As a new promising heat-treatment technology,intensive quenching process, for its energy-saving,high-efficiency,environmental protection and low-cost in comparison with the conventional process,attracts wide attention in the world.In this work,the cement steel 18Cr2Ni4WA and 20CrMnTi were treated by quenching process.After measuring the microstructure and mechanical properties, the optimum treatment process was obtained by analyzing the relation among the microstructure,properties and process.Experimental results indicated the super-fine grains can be derived from the steels selected by intensive quenching process with calcium bichloride with different concentration,liquid nitrogen or combining the calcium bichloride with liquid nitrogen,moreover,the cement steels showed super-high intensity and excellent toughness.The investigation implied that the microstructure obtained by intensive quenching were mainly composed by lath martensite and residual austenite and surface residual compressive stress was between 75～310MPa.In comparison with the conventional heat-treatment process,the mechanical properties of low-carbon alloy steel,such as tensile strength,impact toughness,can be improve 10～30%by the intensive quenching process and can meet the requirement of carburizing alloy steel properties.Analysis showed the residual compressive stress on the intensive quenching surface was responsible for the higher fatigue properties resistance of the low-carbon alloy steel.