Residual stress simulation and measurement of Fe-Mn-Si shape memory alloy coating

To prepare a low-residual-stress laser cladding coating, Fe-Mn-Si shape memory alloy(SMA) coating was prepared on the surface of the AISI 304 stainless steel. And the ANSYS finite element software was used to simulate its stress field, meanwhile the residual stress distribution of the cladding specimens was measured by the mechanical hole-drilling method under the same process to verify the correctness of simulation. What's more, the mechanism of low residual stress inside Fe-Mn-Si SMA coating was analyzed by XRD. The results show that the stress caused by laser cladding induces the γ→ε martensite phase transition inside the coating to get a low residual stress coating. And the coating alternately bears the thermal stress of tensile-pressure-tensile during laser spot getting closer and further to the coating center. And the thermal stress was inversely proportional to the distance between the simulating nodes and the center of laser heat source. When the specimen was completely cooled to the room temperature, the residual stress inside coating presented tensile stress, and its maximum value happened at the junction between the substrate and the coating. In the directions of parallel and vertical to the laser scanning, stress value was relatively small in the middle region, but large in two sides. And from the coating peak to the fusion line in the thickness direction, the residual stress was tensile stress and the extreme value of stress was locating at the center of the coating. Far away from the fusion line, the substrate bore pressure stress and levels off to zero-stress state. © 2017, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.