Influence Of Ni Content On Microstructure And Properties Of Specimens By Laser Rapid Forming

The alloy elements contained in the stainless steel are much more than those in the ordinary steel. The microstructure and properties of stainless steel will be changed by adding different kinds of alloying elements, Ni is the element that promotes the formation of austenite and the expansion of the gamma region. Adding proper amount of Ni element in stainless steel alloy powder, and through a certain heat treatment process can improve the performance of laser rapid prototyping of stainless steel specimens. This paper mainly research the organization and performance of different Ni content stainless steel specimens of Laser rapid prototyping. Adopt Olympus microscope, X-ray diffraction, Luo's micro hardness tester, tensile fatigue tester and electrochemical workstation to test the surface quality, section morphology,microstructure and mechanical properties of laser rapid prototyping specimens, and calculate the residual stress of the laser rapid prototyping specimens, and obtain the following conclusions:(1) With the increase of Ni content, the diffraction peak intensity of martensite decreases gradually, and the austenite increases continuously.The content of martensite is decreased, and the austenite is just theopposite.(2) With the increase of Ni content, The hardness and tensile strength of the laser rapid prototyping specimens shows downtrend, the residual stress changed from compressive stress to tensile stress.(3) When the Ni content are 2.08%, 3.70% and 5.87%, tensile specimens fracture shows brittle failure, and the residual stress is compressive stress, When the Ni content are 8.46%, 10.28% and 13.77%,the fracture of the tensile specimens is plastic fracture, residual stress of forming specimen is tensile stress, When the Ni content is between 5.87%and 8.46%, there is a critical point of the transition from compressive stress to tensile stress.Researching the macrostructure morphology, microstructure,mechanical properties and residual stress, to master the principle of microstructure and properties of different Ni content molding specimens,optimize the Ni content of the alloy element to adapt different industrial requirement, and provide theoretical basis for adding Ni content of stainless steel forming specimens in the industrial production.