Research On Technology And Wear Resistance Of The Fe-Mn-Si Shape Memory Alloy Prepared By Laser Cladding

γâ†'ε martensite phase transformation in Fe-Mn-Si shape memory alloy was used to to release the residual stress and improve wear resistance of coating in this paper. Fe, Mn, Si, Ni, Cr mixed elemental powders were used to in situ generated Fe-Mn-Si shape memory alloy laser cladding coating on surface of304stainless steel by using a CO2laser device. Micro hardness, sliding and rolling wear resistance were detected by using a microhardness tester, reciprocating friction tester and BC6063shaper equipped with rolling friction pressure head. The friction mechanism was analysed by XRD and SEM..Laser Cladding experiment shows that the height and width of cladding coating is smaller, and the width and height of heat affected zone is greater when the scanning speed is greater. The suitable laser spot diameter is3mm, and when the light spot diameter far from3mm, the surface of the coating is easy to appear nodules, cracks and bubbles. When the lap rate is at a rate of50%, the quality of the cladding layer is great.Laser cladding Fe-Mn-Si shape memory alloy coating test shows that burning loss rate of Mn and Si elements of are big in the cladding process, the substrate contents a lot of Fe and Cr elements, parts of the alloy elements melt into the coating making the levels of of Cr and Ni element increased. Thus Mn and Si element decrease, and Cr and Ni element increased in the cladding layer. The Fe-17Mn-5Si-10Cr-5Ni shape memory alloy coating can be successfully prepared on the surface of stainless steel at the technics parameters of Fe:Mn:Si:Cr:Ni=52:32:9:4:3(wt%) ratio of mixed powder composition, presetting powder thickness of1mm, laser spot diameter of3mm, laser power of2kW, scanning speed of600mm/min, and overlapping rate of50%.Metallographic microscopic analysis shows that the coating is composed of martensitic and y austenite phases containing transition from planar crystal, to cellular crystal, dendretic crystal, equiaxed crystal and the oxide with an increase in distance from the surface of the substrate, and the tempering coating is composed of coarse austenite.Microhardness analysis shows that the hardness of Fe-Mn-Si alloy coating is bigger than taht of the stainless steel substrate. Reciprocating sliding friction test analysis that the Fe-Mn-Si memory alloy coating has better sliding wear resistance than304stainless steel substrate. Reciprocating rolling friction test shows that compared with the304stainless steel base material, the rolling wear resistance of Fe-Mn-Si shape memory alloy coatings have obvious improvement. The wear stress induced γâ†'ε phase transformation and its transformation deformation can inhibit the slip deformation and the formation and extension of the dislocation, this is main reason why the coating shows better wear resistance and contact fatigue strength compared with the304stainless steel substrate.