| In this work, an innovative solid-phase carburizing method was used to improve the surface of stainless steel. The(Fe,Cr)7C3 particle-reinforced composite layer was produced in-situ on the surface of 2Cr13 and 316 stainless steel with the carbon source of HT300. The thermodynamics, kinetics, phase constitution, microstructure,microhardness, two-body abrasive performance and mechanism and corrosion resistance of the surface composites has been studied.The results showed that:(1)The Gibbs free energy of the formation of Cr3C2, Cr23C6 and Cr7C3 were negative, these carbides can be stable in Fe-Cr-C system in the temperature range of25-1120℃. The Gibbs free energy of carbide will decrease with the increase of temperature, The stability of carbides can be showed in the order: Cr3C2 > Cr23C6 >Cr7C3. Based on the isothermal section of Fe-Cr-C system at 950℃, it can be deduced that the major carbide in the composite layer of two kinds of stainless steels.(2)The microstructure of 2Cr13 stainless steel and 316 stainless steel composite layers after solid-phase carburizing in different holding time and temperature are basically the same. The(Fe,Cr)7C3 carbides were dispersively distributed as particle at the interior of the grains and continuously distributed at the grain boundary at high temperatures. The microstructure of the sample under the hold temperature of 850℃ is the most uniform, and the size of(Fe,Cr)7C3 particles is 3-5 μm. A 40-60 μm thick layer reinforced by dispersively distributed(Fe,Cr)7C3 particles was formed on the surface of2Cr13 steel and 316 stainless steel at low temperature, the size of(Fe,Cr)7C3 particles is0.5-2 μm.(3)The michardness of stainless steel was gradient from surface to matrix aftersolid-phase carburizing. The microhardness of 2Cr13 stainless steel can reach 1082 HV and 316 stainless steel 980 HV after high-temperature carburizing. The microhardness of 2Cr13 stainless steel can reach 590 HV and 316 stainless steel 640 HV after low-temperature carburizing.(4)Two-body abrasive wear texts were carried out on the surface of carburized stainless steel. The relative wear resistance of 2Cr13 and 316 stainless steels was increased as the increase of load. The relative wear resistance of high-temperature carburized 2Cr13 stainless was 2.59 times of traditional 2Cr13 stainless steel and high-temperature carburized 316 stainless steel was 2.61 times of traditional 316 stainless steel. The relative wear resistance of low-temperature carburized 2Cr13 stainless was 1.75 times of traditional 2Cr13 stainless steel and high-temperature carburized 316 stainless steel was 2.18 times of traditional 316 stainless steel. The wear mechanism of 2Cr13 stainless steel and 316 stainless steel under abrasive wear condition was micro-cutting and micro-ploughing, leading to a well toughness and ductility.(5)The corrosion resistance of composite surface was tested. There was a decrease on the corrosion resistance of samples after solid-phase carburizing. The corrosion resistance decrease of high-temperature carburized samples was serious and low-temperature carburized samples slight. At the same time, the corrosion resistance of carburized 316 stainless steel was better than that of carburized 2Cr13 stainless steel. |
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