Purveyors of Processing Science and ICME: A SMD Symposium to Honor the Many Contributions of Taylan Altan, Wei Tsu Wu, Soo-Ik Oh, and Lee Semiatin: Enhanced Properties via Thermomechanical Processing
Sponsored by: TMS Structural Materials Division, TMS: Shaping and Forming Committee, TMS: Titanium Committee
Program Organizers: Adam Pilchak, Pratt & Whitney; Ayman Salem, MRL Materials Resources LLC; Viola Acoff, University of Mississippi; Nathan Levkulich, UES; Michael Glavicic, Rolls-Royce; Yufeng Zheng, University of North Texas; John Joyce-Rotella, Air Force Research Laboratory
Wednesday 8:30 AM
February 26, 2020
Room: 30E
Location: San Diego Convention Ctr
Session Chair: Rongpei Shi, Lawrence Livermore National Laboratory; Nathan Levkulich, UES
8:30 AM Invited
Engineered Residual Stress Optimization and Utilization: David Furrer1; Robert Goetz1; Jean Philippe Thomas1; Vasisht Venkatesh1; 1Pratt & Whitney
Residual stresses are a complicated feature of nearly all materials and processes. The impact of residual stresses is non-trivial and must be contended with for modern component and system design. Efforts have been conducted by many to develop methods to eliminate or minimize these stresses. Other efforts have aimed to generate residual stresses for local component benefit. As the technology of residual stress measurement has matured, and modeling and simulation capabilities are following, these capabilities are being targeted toward further optimization and utilization of residual stresses for advanced component design. Steps forward are possible, but challenges still remain. Current capabilities of applying engineered residual stresses will be presented along with open issues related to material property understanding, process controls, representation and portability of residual stress data, and overall need for life-cycle digital thread capabilities.
9:00 AM Invited
Heterogeneous Deformation during Forming of Pure Niobium and its Influence on Superconducting Radio Frequency Cavity Performance: Thomas Bieler1; Mingmin Wang1; Di Kang1; Mengge Zhao1; Kaige Zheng1; Maria Terol; Ricardo Rodriguez2; Eureka Pai1; Philip Eisenlohr2; 1Michigan State University; 2Universidad Polytechnica Madrid
Superconducting Radio Frequency niobium cavities are the core structure of particle accelerators. These cavities are assembled from deep drawn parts welded together. Though the cavities are structural in that they support the pressure of liquid helium, they are primarily a functional material to provide the oscillating currents that accelerate particles. The fabricated cavity must have as few defects as possible, as defects such as impurities, grain boundaries, and dislocation substructure can trap magnetic flux and cause local heating that degrades cavity performance. Primary processing starting with ingots with large (10-1000 mm) grains are used to form sheet metal, resulting in highly variable microstructures. There is a need to understand why the microstructure is so variable, and if this is the source of unpredictable cavity performance. Heterogeneous deformation resulting from tensile and rolling deformation of single and multicrystals, and the effect of original crystal orientation on recovery and recrystallization is examined.
9:30 AM
Austenite Transformation Behavior during Tensile Deformation of Quenched and Partitioned Steels: Christopher Finfrock1; Chandler Becker1; Trevor Ballard1; Grant Thomas2; Amy Clarke1; Kester Clarke1; 1Colorado School of Mines; 2AK Steel
Metastable austenite has been shown to significantly enhance strength and ductility combinations in advanced high strength steels by delaying the onset of strain localization. Processes such as Quenching & Partitioning have been developed to both increase retained austenite fraction and stability. Designing steels with higher initial retained austenite fractions and increased total austenite transformation during deformation is pursued to achieve a greater strain hardening rate, which leads to greater resistance to localization and increased strength and ductility. Steels with similar compositions and varying initial austenite fractions were examined to evaluate the correlation between austenite transformation and effective instantaneous strain hardening rate during deformation, and results suggest that neither retained austenite fraction or total austenite transformation during tensile testing correlate with increased strength and ductility combinations. In addition, the effects of strain rate on the uniform and total elongation was investigated for the same steels.
9:50 AM Invited
Pushing the Performance Limits of Metallic Alloys through Severe Plastic Deformation Processing: Rajiv Mishra1; 1University of North Texas
Thermo-mechanical processing is the most common way of enhancing structural performance of metallic alloys. Friction stir processing (FSP) is a unique high temperature severe plastic deformation technique that can push the structural efficiency of an alloy. In this overview, examples of exceptional strength-ductility combination obtained using FSP will be highlighted. The examples will cover magnesium alloys, aluminum alloys, titanium alloys and steels. Hierarchical microstructure in a FSP Ti-6Al-2Sn-4Zr-6Mo alloy leads to strength of 2 GPa. FSP results in a unique modulated microstructure comprised of fine acicular α"-laths with nano precipitation within the laths. The specific strength attained in one of the conditions is close to 450 MPa m3/mg, which is about 22% to 85% greater than any commercially available metallic material. Future potential of such microstructural approach will be discussed in the context of advanced manufacturing.
10:20 AM Break
10:40 AM Invited
Processing Heterostructured Materials for Superior Mechanical Properties: Yuntian Zhu1; Hao Zhou2; Yusheng Li2; Xiaolei Wu; Xiaolei Wu3; 1North Carolina State University; 2Nanjing University of Science and Technology; 3Institute of Mechanics, CAS
Heterostructured materials have been reported to possess superior combinations of strength and ductility that are not accessible to their homogeneous counterparts. Strong and tough materials are desired for light-weight applications such as electric cars. Heterostructured (HS) materials consist of domains with dramatic strength differences, which causes hetero-deformation, and consequently hetero-deformation induced (HDI) hardening to improve strength and ductility. HS materials have been reported produced by several processing methods, some of which are conducive to industrial scale productions at low costs. In this talk I’ll present the current advances in the processing of HS materials and various processing approaches as well as future challenges and issues in this emerging field.
11:10 AM
On the Mechanical Behavior of Keyhole-free Friction Stir Welded Copper-Aluminum Spot Joints: Isam Jabbar Ibrahim1; Guney Yapici1; 1Ozyegin University
Intermediate layer friction stir spot welding (IL-FSSW) is a recently developed solid-state joining method appropriate for making spot joints free of keyhole formation, which is a problem associated with conventional techniques. Utilizing a welding tool consisting of a non-consumable flat rotating pin, sound lap joints are fabricated including an intermediate layer. This study investigates the effect of IL-FSSW parameters on the lap shear strength of dissimilar copper-aluminum joints. Effects of processing parameters (tool rotational speed, tool descending depth, welding feed rate) on the joint strength are delineated with a comparative analysis with conventional FSSW Results are elaborated with support from microstructural and fracture surface observations concentrated at the weld region.