GOALI: Shear Texture and Microstructure Control in Sheet Metal for Enhanced Deformation Processing and Properties

Purdue University, West Lafayette IN

Investigators

Abstract

Metal sheet and foil are widely used or under consideration for use in advanced structural and magnetic product applications. Currently, sheet and foil are produced by multi-stage rolling processes. Rolling processes, while mature and large-scale, offer only limited control of sheet attributes. Furthermore, they are quite energy intensive and encumbered by high capital costs. In collaboration with three industrial partners, this Grant Opportunity for Academic Liaison with Indstry (GOALI) research will develop the processing science of a class of extrusion-cutting processes to produce sheet and foil in a single step. Simultaneously, the extrusion-cutting can tailor specific attributes of the sheet, via control of texture and microstructure, in ways not possible by the conventional rolling processes. Successful development and implementation of the extrusion-cutting will provide efficient routes for production of high-performance sheet metals of light-weight magnesium and titanium alloys, and magnetic silicon-iron. This will be a key enabling step for use of these alloys in automotive, bio-medical, aerospace and power systems applications. Complementing the research is an education and training program that includes industry internships, fostering of entrepreneurship in graduate study and undergraduate research internships, including a new dimension to training involving physically challenged students from the National Technical Institute for the Deaf. The large-strain, extrusion-cutting processes can overcome some key barriers that limit the scope of rolling for producing sheet and foil from advanced alloys. Specifically, the extrusion-cutting can effect development of strong shear textures and fine-grained microstructures in sheet metals. Prior work has shown scalability of the extrusion-cutting, even for alloys of poor workability such as magnesium and titanium. These observations suggest a paradigm for creating new sheet metals with interesting structural, magnetic and formability properties. The project team will build on the preliminary findings with four coordinated thrusts. First, a deformation science initiative will measure, directly, the process strain, strain rate and temperature fields using in situ high-speed imaging. It will establish how special deformation paths can be exploited to control texture and microstructure. Second, structure development will be analyzed through texture analysis and electron microscopy. New shear-based textures, combined with fine-grained structures, and their effects on formability are of particular interest. Correlations will be established between deformation, texture and microstructure. Third, microstructure-property relationships will be assessed by characterizing orientation-dependent properties such as strength, formability and magnetic permeability. Lastly, by integrating the results, process design for producing sheet with optimal properties will be assessed in collaboration with the industry partners.