Accession Number : AD0699598

Title :   DEFORMATION PROCESSING OF ANISOTROPIC METALS.

Descriptive Note : Final rept. 1 Jul 68-30 Jun 69,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE METALS PROCESSING LAB

Personal Author(s) : Backofen,Walter A. ; Holt,David L.

Report Date : DEC 1969

Pagination or Media Count : 54

Abstract : An account is given of the development of a process for using superplasticity in forming. Its focus is necessarily specific, but there is general value in its findings. The actual parts were examples of hollow ware that had once been produced by conventional methods. The material was the Zn-Al eutectoid alloy, which can be made highly superplastic and should give adequate service behavior for a variety of applications, including this one. The development proceeded by first separating the total process into two largely dissimilar components: stretching, to establish general shape (macroforming), and another, more related to coining, to generate surface detail (microforming). The results of the separate studies were finally combined to allow predictions of the outcome of practical forming. These, in turn, were tested experimentally with good success. Of the two components, microforming is more often likely to be pressure- and rate-controlling. An analysis is presented for the bulging by lateral pressure of superplastic alloy sheet that has a flow equation in uniaxial tension or compression. Two cases are dealt with: (1) the bulging of a flat circular sheet clamped at its perimeter and (2) the bulging of a sheet into 90 degree-V grooves. The latter process is pertinent to the problem of molding a sheet to a die contour so as to achieve detail. Bulge profile and sheet-thickness distribution are predicted as a function of the variables, pressure, geometry, time, K and m. (Author)

Descriptors :   (*MATERIAL FORMING, PLASTIC PROPERTIES), SHEETS, DEFORMATION, ZINC ALLOYS, ALUMINUM ALLOYS

Subject Categories : Fabrication Metallurgy

Distribution Statement : APPROVED FOR PUBLIC RELEASE