Process Optimization and Formation Analysis of Friction Plug Welding of 6082 Aluminum Alloy

The response surface analysis method was used to systematically study the effect of various parameters on the tensile strength of 6082 aluminum alloy friction plug welding (FPW) joints in this work. The fluidity of the joint and microstructure were observed with a metallurgical microscope. Combined with the temperature field and force analysis, the reason why the root of the joint appears as a weak zone was explained. The results showed that the degree of influence on the tensile strength of FPW joints was rotational speed > upsetting speed > welding time. The optimal FPW joint was obtained when the rotational speed was 2254 rpm, the upsetting speed was 2 mm/s, and the welding time was 25 s, so the tensile strength could reach 262.34 MPa. The microstructure of the FPW joint appeared heterogeneous. According to the different plastic metal fluidities of the joint, it could be divided into four areas. The interaction force at the friction interface was not strong at the root of the FPW joint, so the root often becomes the weak area of the FPW joint.

Mathematical Modeling of Friction Plug Welding with Preheating Effect

Friction plug welding, a recent variation of friction welding is a process of joining of two similar or dissimilar materials. The joint efficiency can be enhanced by applying external heat source or pre-heating at the work piece surfaces. Heat flux generation at intermediate surface is computed due to friction between the materials considering the co-efficient of friction. The land width is varied by varying the diameter of the plug to find its effect on the temperature profile. Analytical modeling is carried out with and without the effect of pre-heating. Temperature distribution in the work piece was calculated for different plug diameter with different values of pre-heating temperature ranging from 300oC-600oC. It is observed that while decreasing the land width there is a linear fall in temperature profile. With preheating, higher peak temperature is achieved at less friction time. High quality weld could be achieved with less processing time.

A Microstructure and Microhardness Characterization of a Friction Plug Weld in Friction Stir Welded 2195 Al-Li

In this study, extruded 2195-T8 plugs that were friction welded into the friction stir weld of 2195-T8 base metal plates were examined. This study characterizes the resulting microstructure and microhardness of the plug weld interfaces with the friction stir welded material and base metal in an effort to identify the extent of the thermal, thermomechanical, and mechanical effects introduced by the friction plug welding process. A zone of recrystallized material was observed around the plug weld circumference. The thickness of the recrystallized layer was measured to be 30–122 μm. The hardness measured near the plug weld interface was found to be 110–130 HK100g, or approximately 35% less than the base metal hardness. By characterizing the hardness of these zones, insight can be gathered into the transformation of material from the friction plug welding process around the fusion zone, and areas that may control the fatigue behavior of the joint.