Effect of Heat Treatment on Microstructure and Properties of Fe-Nb-C Alloying Layer

304 stainless steel has a series of excellent properties, such as high temperature resistance, corrosion resistance and so on, which is superior to other iron-based alloys, and now it has become a widely used material. However, the grain boundary corrosion and hot crack will appear when it works in high temperature environment, which makes the corrosion resistance of the alloy decrease seriously during service. Therefore, in order to make 304 stainless steel have higher strength, wear resistance and corrosion resistance, this paper used laser alloying technology to modify 304 stainless steel surface. The effect of heat treatment on the phase, microstructure and element distribution of Fe-Nb-C alloyed layer were investigated. At the same time, the effect of heat treatment on wear resistance and corrosion resistance of Fe-Nb-C alloy layer was also studied. In order to investigate the effect of heat treatment on the properties and microstructure of Fe-Nb-C alloying layer, the phase, carbide crystal structure, microstructure, wear resistance and corrosion resistance of the coating were tested and analyzed by X-ray diffractometer, field emission scanning electron microscope, friction and wear tester and CS electrochemical workstation. The results show that the main phases are gamma-Fe, (Fe, Nb) and NbC after heat treatment at different temperatures, and the peaks of NbC and gamma-Fe increase with the increase of heat treatment temperature. The surface of laser alloying specimen is mainly a compact NbC ceramic layer, which is metallurgical bonded with the substrate. There is a layer of heat-affected zone between the NbC layer and the substrate, after heat treatment at different temperatures, the microstructure of each region is more compact and the grain size is smaller, but the thickness of alloying layer has no obvious change. After heat treatment at 1000 degrees C, the wear resistance of the sample is improved greatly, and the wear weight loss of the sample is about 0.0015 g less than that of the sample without heat treatment, the self-corrosion potential of the samples all moved about 0.2 V in a negative direction after heat treatment. After heat treatment at 1050 degrees C, the corrosion resistance of the samples was the best. The self-corrosion current density of the samples decreased by 4.137 x 10 - 5 A/cm2. The capacitive arc resistance radius of the Nyquist images was the largest, and the impedance of Bode image was the largest at low frequency.