| 316 stainless steel is widely used in aerospace,pressure pipelines,automobiles,ships and military industries due to its good corrosion resistance and excellent high-temperature mechanical properties.The traditional processing method of 316 stainless steel is prone to waste of materials and complicated procedures.Compared with the traditional subtractive manufacturing process,316 stainless steel additive manufacturing greatly shortens the working hours and saves raw materials to the greatest extent.However,due to the low thermal conductivity and strong fluidity of 316 stainless steel,the formation of 316 stainless steel additive manufacturing components is more difficult.Low-power pulsed laser-induced arc is a new type of heat source with arc as the main energy.Low-power laser is used as an auxiliary to induce and enhance the arc.It can stabilize the additive process and improve the forming quality and efficiency.It has a strong Forward-looking and practical.Therefore,it is of great significance to study it.Using TIG arc and low-power pulsed laser-induced arc as heat sources,1 to 8 layers of single-channel walls were added.The macroscopic appearance shows that after adding the laser,the width of the wall decreases and the width of the wall increases.The microstructure results show that the addition of pulsed laser does not generate new phases and does not change the solidification mode of the wall,but the enhanced stirring effect of pulsed laser will improve the uniformity of the structure and increase the number of grain boundaries.The addition of pulsed laser increases the heat input,accelerates the process of transforming austenite to ferrite,and increases the recrystallization rate.The microhardness test shows that the addition of low-power pulsed laser will uniform the organization,thereby improving the microhardness.Low-power pulsed laser-induced arc-coupled heat sources are used to manufacture single-channel walls with 1 to 8 layers respectively,and the microstructure of the bottom,middle and top layers of each wall is inspected.The bottom structure is composed of cellular crystals and cellular dendrites,and the solidification mode is A mode.Under the action of the post-layer heat treatment,the grains of the bottom layer grow by an average of 5 μm.The middle layer of the wall is composed of dendrites,the primary dendritic spacing is about16μm,and the solidification mode is FA mode.The top layer structure of each wall is composed of equiaxed dendrites,and the solidification mode is still FA mode.The microhardness value of the low-power pulsed laser-induced arc 8-layer additive wall generally shows a trend of first decreasing and then slowly increasing.The hardness value is floating between 187HV-233 HV,and δ ferrite precipitates at the grain boundary or in the grain.Play a strengthening role.Finally,low-power pulsed laser-induced arc deposition of a single wall is used to explore the tensile properties of the wall under different solidification conditions and the tensile properties of different sampling directions.Studies have shown that the top tensile strength of the wall with the solidification condition of FA mode is 583.3Mpa,and the elongation rate is42%.The tensile strength of the middle part of the wall with the solidification condition of FA mode is slightly lower,566.7Mpa,and the elongation rate can reach 45%.The tensile strength of the bottom of the wall is higher,578.3Mpa,but the elongation is poor,38%.The mechanical properties of tensile specimens in different directions are anisotropic.The elongation rate of specimens at an angle of 45° can reach 60%,but the tensile strength is low,516.7Mpa.The tensile strength of the vertical tensile specimen is 528.3Mpa,and the elongation is 43%. |
