Friction Stir Welding and Processing XI: Derivative Technologies for Dissimilar
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Shaping and Forming Committee
Program Organizers: Yuri Hovanski, Brigham Young University; Piyush Upadhyay, Pacific Northwest National Laboratory; Yutaka Sato, Tohoku University; Nilesh Kumar, University of Alabama, Tuscaloosa; Anton Naumov, Peter The Great St. Petersburg Polytechnic University
Wednesday 2:00 PM
March 17, 2021
Room: RM 39
Location: TMS2021 Virtual
2:00 PM
An Analysis of Joint between AZ31 and DP590 Steel Created Using Friction-stir Assisted Scribe Technique: Metallurgical vs Mechanical Bonding: Shank Kulkarni1; Hrishikesh Das1; Daniel Tamayo1; Piyush Upadhyay1; Kyoo Sil Choi1; Ayoub Soulami1; 1Pacific Northwest National Laboratory
One important aspect to achieve significant use of lightweight metals in the automobile industry is the development of a robust technique for joining dissimilar metals. Friction-stir Assisted Scribe Technique (FAST) is one of the viable methods to do so. In this work, FAST was used to join AZ31 magnesium alloy to DP590 steel. The main aim of this study is to understand the mechanical properties and performance of a FAST joint. Tensile tests were performed by cutting dogbone samples in the direction perpendicular and parallel to the weld. Finite element method based computational model was introduced to understand the effect of mechanical interlocking between two materials on the joint performance. The interfacial bonding was modeled using a cohesive zone model. The geometry of the hook feature was adapted in the FEM model using SEM images. Finally, correlating the contribution from mechanical and metallurgical bonding to understand the basic joining phenomenon.
2:20 PM
Oscillation Behavior of Dissimilar Aluminum/Steel Joints Realized by Ultrasound Enhanced Friction Stir Welding (USE-FSW): Marco Thomä1; Andreas Gester1; Guntram Wagner1; 1Chemnitz University of Technology
Ultrasound enhanced friction stir welding, where power ultrasound is transmitted in one of the metal sheets, was verified to be beneficial compared to conventional friction stir welding. The most mentionable verified influences are the reduction of welding forces, the improvement of the stirring of the nugget and the breakup of oxide layers for dissimilar joints. The additional power ultrasound results in a stronger mechanical stimulation of the stirring zone. Regarding this USE-FSW process the oscillation behaviour of the metal sheets is an important effect which has not been investigated in detail so far. The current work is under progress and is investigating the oscillation behaviour from a qualitative and quantitative point of view on the metal sheets during USE-FSW on dissimilar aluminium/steel joints using different laser vibrometers. Special attention is also given to the resulting microstructure and mechanical properties of the joints to investigate possible correlations with the oscillation behavior.
2:40 PM
Process Robustness of Friction Stir Dovetailing of AA7099 to Steel with In Situ AA6061 Interlayer Linking: Md Reza-E-Rabby1; Timothy Roosendaal1; Piyush Upadhyay1; Nicole Overman1; Joshua Silverstein1; Martin McDonnell1; Scott Whalen1; 1Pacific Northwest National Laboratory
Rolled homogeneous armor (RHA) steel was joined to aluminum alloy AA7099-T7451 with an interlayer of AA6061-T651 by single-pass friction stir dovetailing (FSD). The evolution of the AA7099/AA6061 and AA6061/Steel interfacial microstructure and mechanical properties of the joints were examined. The AA6061 interlayer prevented Zn from migrating from the AA7099 to the steel during FSD and forming brittle, Zn-rich, Fe-Al intermetallic compounds within the joint. The flow of the dissimilar aluminum alloys at the interface was controlled with a partially threaded friction stir welding pin and a dovetail geometric configuration optimized in previous work. The process robustness was explored to establish parameter windows by elucidating parametric effects on the relationship between process conditions and the joint’s microstructure and mechanical properties. Ranges of process forge force (50–70 kN) and interface temperature (475°C–520°C) consistently yielded joints with adequate performance. The load-carrying capacity in lap shear tensile tests was 2100±100 N/mm.