Study of joining mechanism of ABS polymer and steel/aluminum by resistance spot welding

The joining of metal and polymer is an increasingly important method to get lightweight components in the development of manufacturing industry- nowadays. In this artiele, metal and polymer lap joint was achieved by means of resistance spot welding （RSW） and ultrasonic assistance welding （UAW）. The joining mechanism of lap joint was analyzed by OM, TEM on microstructure at the interface of lap joints and XPS and IR spectra was discussed based on the following different ones： mechanical-interlocking, diffusion bond and coordination bond. The results showed that it was the combined action that played an important role in the effective joining work. Besides, ultrasonic assistance was used in the study to aid welding process based on its high-frequency ultrasonic vibration, which made joints shaping better and improved tensile strength visibly contrast to joints with the same lower heat input parameters.

Kinematics Analysis and Optimization of the Fast Shearing-extrusion Joining Mechanism for Solid-state Metal

Dynamical Joining of the solid-state metal is the key technology to realize endless hot rolling. The heating and laser welding method both require long joining time. Based on super deformation method, a 7-bar and 2-slider mechanism was developed in Japan, and the joining time is less than 0.5 s, however the length of each bar are not reported and this mechanism is complex. A relatively simple 6-bar and 1-slider mechanism is put forward, which can realize the shearing and extrusion motion of the top and bottom blades with a speed approximately equal to the speed of the metal plates. In order to study the kinematics property of the double blades, based on complex vector method, the multi-rigid-body model is built, and the displacement and speed functions of the double blades, the joining time and joining thickness are deduced, the kinematics analysis shows that the initial parameters can＇t satisfy the joining process. Hence, optimization of this mechanism is employed using genetic algorithm（GA） and the optimization parameters of this mechanism are obtained, the kinematics analysis show that the joining time is less than 0.1 s, the joining thickness is more than 80% of the thickness of the solid-state metal, and the horizontal speeds of the blades are improved. A new mechanism is provided for the joining of the solid-state metal and a foundation is laid for the design of the device.

An Overview of Self-piercing Riveting Process with Focus on Joint Failures, Corrosion Issues and Optimisation Techniques

Self-piercing riveting(SPR)is a cold forming technique used to fasten together two or more sheets of materials with a rivet without the need to predrill a hole.The application of SPR in the automotive sector has become increasingly popular mainly due to the growing use of lightweight materials in transportation applications.However,SPR joining of these advanced light materials remains a challenge as these materials often lack a good combination of high strength and ductility to resist the large plastic deformation induced by the SPR process.In this paper,SPR joints of advanced materials and their corresponding failure mechanisms are discussed,aiming to provide the foundation for future improvement of SPR joint quality.This paper is divided into three major sections:1)joint failures focusing on joint defects originated from the SPR process and joint failure modes under different mechanical loading conditions,2)joint corrosion issues,and 3)joint optimisation via process parameters and advanced techniques.

Friction self-piercing riveting(F-SPR)of aluminum alloy to magnesium alloy using a flat die

Friction self-piercing riveting(F-SPR)process based on a pip die has been invented to solve the cracking problems in riveting high-strength and low-ductility light metals,such as magnesium alloys,cast aluminum,and 7 series aluminum alloys.In this paper,in order to solve quality issues caused by the misalignment between rivet and pip-die in F-SPR,a flat-die based F-SPR process was proposed and employed to join 1.27 mm-thick AA6061-T6 to 3 mm-thick AZ31B.The results indicate that a 1.0 mm die distance is effective to avoid rivet upset and insufficient flaring.As the feed rate increases,the heat input in the whole process decreases,resulting in a larger riveting force,which in turn increases both the bottom thickness and interlock amount.Besides,solid-state bonding,including Al-Mg intermetallic compounds(IMCs),Al-Mg mechanical mixture,and Al-Fe atom interdiffusion was observed at the joint interfaces.The upper Al layer was softened,but the lower Mg layer was hardened,and both sheets exhibited a narrowed affected region with the increase of feed rate,while the rivet hardness shows no obvious change.Three fracture modes appeared accompanying the variations in lap-shear strength and energy absorption as the feed rate increased from 2 mm/s to 8 mm/s.Finally,the F-SPR process using a flat die was compared to those using a pip die and a flat bottom die to show the advantage of flat die on coping with the misalignment problem.

A Comparative Study of Friction Self-Piercing Riveting and Self-Piercing Riveting of Aluminum Alloy AA5182-O

In this paper,self-piercing riveting(SPR)and friction self-piercing riveting(F-SPR)processes were employed to join aluminum alloy AA5182-O sheets.Parallel studies were carried out to compare the two processes in terms of joint macrogeometry,tooling force,microhardness,quasi-static mechanical performance,and fatigue behavior.The results indicate that the F-SPR process formed both rivet–sheet interlocking and sheet–sheet solid-state bonding,whereas the SPR process only contained rivet–sheet interlocking.For the same rivet flaring,the F-SPR process required 63%less tooling force than the SPR process because of the softening effect of frictional heat and the lower rivet hardness of F-SPR.The decrease in the switch depth of the F-SPR resulted in more hardening of the aluminum alloy surrounding the rivet.The higher hardness of aluminum and formation of solid-state bonding enhanced the F-SPR joint stiffness under lap-shear loading,which contributed to the higher quasi-static lap-shear strength and longer fatigue life compared to those of the SPR joints.

Lightweight Design:Friction‑Based Welding between Metal and Polymer

The heterojunctions between metal and polymer have become the effective ways to produce the lighter,safer and more environmental friendly vehicles for the manufacturing fields of automotive and aerospace.The state-of-the-art frictionbased welding techniques are characterized by low peak temperature,severe plastic deformation,energy efficiency and nonpollution,which can simultaneously realize the mechanical and chemical bonding,improving mechanical performances.In this review,the current progress about friction-based welding techniques is summarized,containing technical development,welding tool design,microstructural characteristic,process optimization,surface modification and joining mechanism.The conclusions and prospects are presented,which focus on the practical implications for the manufacturing sectors and recommendations for further research and development.The purpose of this review is to elucidate the benefits of friction-based welding techniques so that these methods may be better exploited and industrialized.