Joining of 316L stainless steel by using spark plasma sintering method

Spark plasma sintering equipment was used to join 316L stainless steel rods with or without a powder interlayer. The powder layer with high electrical resistance was assumed to act as an effective local heat source. Resistance measurements of powders at room temperature showed that the resistance increased by orders of magnitude compared to the bulk material. The parameters influencing the joining process including current (heating power), heating time, pressure, pulse sequence, particle size and powder amount have been investigated. Results showed that especially by rightly adjusting current and heating time, high strength joint can be obtained. By applying only small pressure, deformation of the joint could be avoided. With a thicker powder interlayer, the distortion of the sample could be reduced, and powders with small particle size can produce higher strength samples. By adjusting all these parameters, samples with high strength can be obtained within seconds, so that the heat-affected zone can be markedly reduced.