Friction Stir Welding and Processing IX: Poster Session
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Shaping and Forming Committee
Program Organizers: Yuri Hovanski, Brigham Young University; Rajiv Mishra, University of North Texas; Yutaka Sato, Tohoku University; Piyush Upadhyay, Pacific Northwest National Laboratory; David Yan, San Josť State University

Monday 6:00 PM
February 27, 2017
Room: Hall B1
Location: San Diego Convention Ctr

Session Chair: Yuri Hovanski, Brigham Young University

A-84: Effect of Morphological Characteristics of Intermetallic Compounds on Mechanical and Metallurgical Properties of Aluminium A6061- 304 Steel Joint: Jhonathan Alfonso Salazar1; Edward A Torres Lopez1; Henry A Colorado1; 1University of Antioquia
    Friction welding process was investigated in dissimilar joins A6061-AISI 304.The effect of the parameters is analyzed: upset pressure, rotation speed, friction time, and heat input in the intermetallic compound formation. Joints were characterized by tensile test, microhardness mapping, optical, and scanning electron microscopy. Morphology effect in the mechanical properties was analyzed.

A-86: Effect of Tool Shoulder Feature on Heat Generation and Material Flow of Friction Stir Welded Al-Mg-Si Alloy: Krishna Mugada1; Adepu Kumar1; 1NIT Warangal
     The contribution of shoulder friction heat in FSW is ~80%, which benefits the material to plasticize and weld formation. In this paper, Different recessed tool shoulder features such as scrolls, ridges, concentric circles, knurling, grooves and spiral are considered, the equal volume of recess is maintained to design different features, Initially to understand the material flow a Copper strip (of 0.5 mm thick) is inserted with the configurations of parallel to weld line (Center, Advancing side(AS) Tangent to pin, Retreating side(RS) Tangent to pin) & perpendicular to weld line (AS, RS, both) which are performed with best tool pin and varied tool shoulders. The results reveal that because of shoulder and pin driven flows the copper strip is completely sheared off and formed a particle track in the weld zone. Shoulder features improved the heat generation. Joints with Knurling tool and Ridges tool shoulder features, resulted with better mechanical properties.

A-87: Fabrication and Characterization of Al/Al2O3-SiC Hybrid Surface Nano Composite by Friction Stir Process: Parumandla Naresh1; Adepu Kumar1; 1National Institute of Technology
    In this investigation, a new technique is used to produce a hybrid surface nano composite by friction stir processing (FSP). Nano Al2O3 and SiC reinforcement were added into the AA 6061 –T6 matrix material and fabricated a hybrid surface nano composite by FSP. A large surface region was produced as surface composite by applying this unique technique. Single pass FSP is applied to fabricate the Al/Al2O3-SiC composite. Distribution of the nano reinforcement particles in the processed region was analyzed by using optical microscope, SEM-EDX and phase volume fraction analysis. A superior microstructural, microhardness and wear resistance properties were achieved.

A-88: Fatigue-Strength Increase by Friction Stir Processing between Different Strength Grades of Butt-Welded High-Tensile Steels: Hajime Yamamoto1; Kazuhiro Ito1; Makoto Takahashi1; Kazuyuki Kohama1; Hidetoshi Fujii1; 1Joining and Welding Research Institute, Osaka University
    Fatigue strength of the high-tensile steels increases with increasing their yield stress, but that of their welds does not. It is caused mainly by tensile residual stress and microstructure-related issues in heat-affected zone (HAZ) due to fusion welding. In this study, friction stir processing (FSP) was conducted on HAZ surfaces of the butt-welded joints for 490 MPa and 780 MPa grade high-tensile steels (hereafter HT490 and HT780, respectively) to investigate whether or not FSP is an effective microstructural modification technique to increase their fatigue strength. FSP for the both grade welded joints was able to increase their fatigue strength due to grain refinements. The effect on increase in fatigue strength was higher in the butt-welded joints of HT490 than that of HT780. This can be explained by increase of high angle boundary and a hard cementite layer wrapping an ultrafine ferrite grain observed in the butt-welded HT490 joints with FSP.

A-89: Friction Stir Welding of Dissimilar Metals: Xiangbin Wang1; Yi Pan1; Diana Lados1; 1Worcester Polytechnic Institute, Integrative Materials Design Center
    Friction stir welding (FSW) is a solid-state welding process that has demonstrated the ability to join both similar and dissimilar alloys, as well as materials unweldable by traditional fusion welding techniques. To develop a fundamental understanding of the process, it is imperative to establish relationships between welding parameters and weld quality, resulting microstructures, and mechanical properties. Dissimilar welds using multiple rotation and traverse speed combinations were produced using three heat treated wrought aluminum alloys (Al6061-T651, Al2024-T351, and Al7075-T735), located systematically on both advancing and retreating sides of the weld. Similar welds were also produced and characterized for comparison. Weld quality was first evaluated to assess and optimize the processing conditions. Further, microstructural changes were systematically evaluated and correlated with micro-hardness and tensile properties of the welds. FSW of Al6061-T651 to steel was also performed successfully, and the resulting microstructures and mechanical properties will also be presented and discussed.

A-90: Effect of Heat Treatment on Friction-stir-processed Nanodispersed AA7075 and 2024 Al Alloys: Iman El-Mahallawi1; Mohamed Ahmed2; Amir Mahdy3; Abdelrahman Abdelmotagaly4; Wael Hoziefa5; Mohamed Refat6; 1Cairo University; 2Suez and Sinai Metallurgical and Materials Research Center of Scientific Excellence (SSMMR-CSE); 3Al-Azhar University; 4Centre for Advanced Materials; 5Al-Azhar University ; 6The British University in Egypt
    Friction stir processing (FSP) is gaining wide recognition in producing surfaces with high hardness and enhanced properties for light weight transportation application and armored vehicles. This work compares the effect of T6 peak-aging heat treatment on the toughness properties and the aging precipitation behavior of friction stir processed and nanodispersed AA 2024 and AA7075 alloys. Plates of aluminum alloy AA7075-O with and without the addition of alumina nano-particles (Al2O3) of average size ~40nm were FSP. The AA2024 nanodispersed alloys were prepared by casting, then were FSP. Combining nanodispersion and friction stir processing with peak-aged condition has shown to be an effective route in enhancing the elongation% of AA2024 alloy to double that of the T6 peak aged condition, and improving the impact toughness of AA7075 by 35% compared to the peak aged condition. The presence of nanodispersions affects the precipitation behavior of both AA2024 and AA7075 in peak aged condition.

A-91: Circumferential Tool Path Control for Friction Stir Spot Welding of Thin Al/Fe Dissimilar Metal Joint: JinYoung Yoon1; Cheolhee Kim2; Sehun Rhee1; 1Hanyang University; 2KITECH
    Joining Al/Fe dissimilar metals is becoming a subject of special interest in the assembly of automotive parts as a trade-off between the weight lightening and the cost reduction. As a solid state welding, friction stir welding has been preferred to fusion welding processes in the dissimilar metal joints. This study investigated friction stir spot welding (FSSW) of Al alloy to the thin steel sheet with a thickness of 0.65 mm. The conventional FSSW is a stationary spot welding process but new approach adopted an additional circumferential movement in company with high speed tool rotation. A full factorial experimental design was implemented, and the main and interaction effects of parameters were analysed on the failure load in the tensile shear test. The direction and radius of rotation were statistically significant parameters and these two parameters affected the joint width and the shape of the hook.

A-92: Numerical Analysis of FSW Employing Discrete Element Method: Kenta Mitsufuji1; Masahito Nambu1; Fumikazu Miyasaka1; 1Osaka University
    The Friction Stir Welding (FSW) is known as the non-melting joining technique. Numerical analysis methods employing grid methods for FSW process have been developed. However, the FSW includes the complex phenomena as plastic flow of the substances, temperature flow and a phase transformation. Some complex processes are required to analyze the substances of different physical properties on the bonded interface and the dissimilar joining. This paper proposes the analysis technique for the FSW employing the Discrete Element Method (DEM). The DEM is the analysis technique that analyze the powders behavior. In This report, a proposal analysis model of plasticity body for FSW simulation is described. Finally, the usefulness is discussed through the analysis result of FSW process.