Deformation processing of an aluminum alloy containing particles: Studies on AI-5 pct Si alloy 4043
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I.
INTRODUCTION
IN recent
years, deformation processing of materials has assumed considerable importance since a knowledge of the interrelation between process parameters, microstructure, and the product property will help in achieving products giving longer service with reliability. In a generalized deformation processing system as defined by Backofen, Lthe success of mechanical processing depends critically on the microstructure of the starting material, deformation zone geometry, the temperature and the strain rate employed, and the frictional conditions. From this viewpoint, the development of a processing map 2'3 defining a "safe" window in the strain rate-temperature field is of great significance. The third dimension of this map is the microstructure of the material being processed which decides the extent of microstructural damage likely to be caused by mechanisms like cavity formation at hard particles, wedge cracking at grain boundary triple junctions, and flow localization due to adiabatic heating. It is relevant to note that the processing map referred to above is based on the nucleation thresholds for the damage mechanisms mentioned. The properties of the product will be greatly affected by these damage mechanisms inasmuch as the microstructure of the product will retain the damage caused in the processing stage. The aim of the present investigation is to study the deformation processing of an aluminum alloy with a view to establishing an interrelation between the process parameters (temperature and strain rate), the microstructure, and the product properties. The A1-5 wt pct Si alloy (4043) has been chosen for this purpose since its microstructure offers an interesting possibility of having silicon particles in the matrix as well as at the grain boundaries. It is well known that K. P. RAO is Research Scholar, Metal Forming Laboratory, Department of Metallurgy, Indian Institute of Technology, Madras 600036, India. S. M. DORAIVELU, formerly Assistant Professor, Indian Institute of Technology, Madras, is now Visiting Scientist (AFWAL Materials Laboratory), Universal Energy Systems Inc., Dayton, OH 45432. H. Md. ROSHAN, Professor, Indian Instirate of Technology, Madras, is now Chief Executive, Tamil Nadu Alloy Foundry Company Ltd., Hosur, India. Y. V. R. K. PRASAD, Associate Professor, Department of Metallurgy, Indian Institute of Science, Bangalore 560012, India, is now at AFWAL (MLLM), Wright-Patterson Air Force Base, Dayton, OH 45433. Manuscript submitted December 15, 1982. METALLURGICALTRANSACTIONS A
cavity formation is influenced by the matrix particles while wedge cracking is affected by the particles at the grain boundary. Moreover, the 4043 alloy is classified as a wrought aluminum alloy and hence the results will have practical significance. In this investigation, the material is processed by upset forging, and the transverse tensile properties of the forged product have been evaluated. The transverse tensile ductility, for example, is sensitively dependent on the microstructural damage in th
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