Greater Than the Sum of Its Parts — Concurrent Alloy Design and Processing Science: An LMD Symposium Honoring Raymond Decker: Session II
Sponsored by: TMS Light Metals Division, TMS: Magnesium Committee
Program Organizers: Victoria Miller, University of Florida; Eric Nyberg, Kaiser Aluminum Trentwood; J. Brian Jordon, Baylor University; Wilhelmus Sillekens, European Space Agency; Neale Neelameggham, IND LLC; Vineet Joshi, Pacific Northwest National Laboratory
Tuesday 8:30 AM
March 16, 2021
Room: RM 31
Location: TMS2021 Virtual
Session Chair: Victoria Miller, University of Florida
8:30 AM Invited
Thixomolded Magnesium: Quick, Light, and Mighty: Tracy Berman1; 1University of Michigan
Thixomolding is a semi-solid inject process that takes advantage of thixotropy, also known as shear thinning. Combining the lowered viscosity due to shearing with the relatively low melting point of magnesium alloys allows for cast metallic components that cool in seconds. This rapid solidification creates fine grain sizes and limits solute segregation. The Thixomolding process also leads to less porosity than is usually seen in die casting. This talk covers the history of Thixomolding with special emphasis given to Ray Decker’s contributions to the technology. Current and future applications of Thixomolded magnesium alloy components will also be discussed.
9:00 AM Invited
Magnesium Sheet Alloy Development for Room Temperature Forming: Alan Luo1; Renhai Shi1; Jiashi Miao1; Thomas Avey1; 1Ohio State University
The majority of the forming processes used to convert sheet metal into automobile components occur at room temperature (RT), including stamping, flanging, bending, hemming and trimming. Unfortunately, the limited RT formability of magnesium due to its hexagonal close packed (HCP) structure makes the use of these processes very difficult. However, the formability of magnesium can be improved via fine grain structure and random texture to enable some RT forming operations. This talk presents the latest magnesium alloy development at The Ohio State University supported by the United States Automotive Materials Partnership (USAMP). Our alloy design and thermomechanical process development are based on CALPHAD (CALculation of PHAse Diagram) and kinetic modeling as well as experimental validation. The new sheet alloy offers excellent ductility (31% tensile elongation) and RT formability (7.8 mm Erichsen Index) at solution-treated condition (T4), and a high yield strength (270 MPa) upon post-forming aging treatment (T6).
9:30 AM
Impacts of Grain Boundary Particle Characteristics on Twin Transmission: Benjamin Anthony1; Brandon Leu2; Irene Beyerlein2; Victoria Miller1; 1University Of Florida; 2University of California Santa Barbara
Deformation twinning is a mechanism of critical interest in magnesium as it allows for the accommodation of strain, but can also create preferential fracture pathways. This issue is amplified by instances of twin transmission, where a twin impinges on a grain boundary and nucleates a new twin in the neighboring grain due to the stresses associated with the intense local shear. Most commercial Mg alloys are multi-phase, featuring micron-scale particles located along the grain boundaries that can create potential barriers for the stresses generated by impingement of the twin tip. A combined computational and experimental approach is utilized to examine how the characteristics of these grain boundary particles can modify twin transmission behavior in commercial Mg alloys.
9:50 AM Keynote
Evolution of Alloy Design, It’s Science/Instruments Base, Tech Transfer
Routes and Market Pull, 1921-2021
: Raymond Decker1; 1University of Michigan
The art and science of alloy and process design have flourished over the last century. This evolution will be demonstrated by case histories, from 1921 to 2021. The original hypotheses, target properties and target markets will be contrasted with the ultimate properties and uses, while recording the time to market. Most striking is the advance in the science base available for the discoverers – both in microstructure/processing/property theory; but, also, in scientific instruments to confirm the theories. Time of reduction to commercial use of the discoveries has varied from weeks to decades, depending on market pull. Over the century, the support base for alloy discovery and application has evolved from largely industrial based to a base enhanced by Universities, Government Agencies, National Laboratories and entrepreneurs – all playing a role in discovery and tech transfer.
10:35 AM Break
10:55 AM Panel Discussion