The Influence Of Local Heat Treatment On The Strength Of SPR And Clinch Joints

With the development of the automotive light weighting design, light steel, magnesium alloy, titanium alloy and other new lightweight materials has been widely applied. It has been developed in our country in recent years, a sheet material connection techno logy--self-piercing riveting and clinching. Clinching connection by connecting device for extrusion deformation plate to connect two or more layers of sheet material, that is difficult to connect with traditional connection method for the new lightweight materials. It’s forming a self-locking mechanism with a certain strength and achieve the material connection; Self-piercing rivet is that plates and rivets of plastic deformation and resilient are used by the special connection equipment, the mechanical interlocking is formed to completed the connection of plates.The paper was based on 410 stainless steel, titanium alloy no rivets self-piercing rivets and rivets self-piercing rivet joints before and after heat treatment for the study, based on experimental study on tensile and fatigue properties of joints before and after local quenching heat treatment, SEM microscopic fracture. Comparative analysis the performance of static strength and fatigue life for the joints before and after heat treatment on this paper, completed a certain amount of research work and obtained some study results. This paper studies mainly from the following aspects:1. The connection research of 410 stainless steel, titanium alloy no rivets self-piercing rivets and rivets self-piercing rivetResearch showed the connection technology of 410 stainless steel, titanium alloy thin plate self-piercing rivet and clinching, acquired the optimum riveting process parameters of 1.0mm+1.0mm 410, 1.0mm+1.0mm TAl joints. Static mechanical properties and fatigue test specimen preparation, the specimens are prepared of static test and fatigue test.2. Study on static performance of 1.0mm+1.0mm 410, 1.0mm+1.0mm TAl without rivets self-piercing rivet and rivets self-piercing rivet joints with heat treatment or notLocal quenching heat treatment was carried on the joints of 1.0mm+1.0mm 410, 1.0mm+1.0mm TA1 without rivets self-piercing rivet and rivets self-piercing rivet joints and quasi-static mechanical properties test was used on the eight groups of joints, obtained the joint load-displacement curves, static failure process and failure mode, analysis energy absorption capacity of the joints.3. Based on the fatigue test of 1.0mm+1.0mm 410 without rivets self-piercing rivet and rivets self-piercing rivet joints with heat treatment or not, study on fatigue performanceThe fatigue test was carried on four groups of joints of 1.0mm+1.0mm410 stainless steel without rivets self-piercing rivets and rivet self-piercing rivets with heat treatment or not, won the S-N curves and fatigue failure process and failure modes of the joints.4. Analysis of fatigue fracture based on SEM testSEM test was carried on the typical of fatigue failure modes of 1.0mm+1.0mm410 self-piercing rivet joints and clinched joints with heat treatment or not, the micro-fracture was described and analyzed.