Shear Strength Optimization of Laser-Joined Polyphenylene Sulfide-Based CFRTP and Stainless Steel

Abstract

A thermosetting plastic and stainless steel were joined by the fiber laser with and without polyphenylene sulfide (PPS) additive. Its microstructure, interface morphology, and shear strength were investigated. The laser joining is shown to change the microstructure of the stainless steel and result in the heat-affected zone and fusion zone, which contains the lathy ferrite and skeletal ferrite, respectively. Without the PPS interlayer, the additive in the plastic can be overheated and decomposed during laser joining, which is detrimental to the interface bonding. The additive can contribute to the plastic and stainless steel interpenetration, but its amount should be controlled. Insufficient additive quantities cannot fill the gap between stainless steel and plastic, but its higher quantities can cause excessive melting, which would prevent from gaining the joint with optimum shear strength. The appropriate interlayer thickness is 300 μm, which improves the shear strength of the stainless steel and plastic joint to 15.1 MPa.