Accession Number : AD0624257

Title :   INVESTIGATION OF THE NATURE OF STRUCTURAL DAMAGE IN METAL-FORMING PROCESSES.

Descriptive Note : Final rept. 18 Oct 64-18 Nov 65,

Corporate Author : GENERAL ELECTRIC CO SCHENECTADY N Y RESEARCH AND DEVELOPMENT CENTER

Personal Author(s) : Rogers,H. C. ; Leech,R. C. ; Coffin,L. F. ,Jr.

Report Date : NOV 1965

Pagination or Media Count : 76

Abstract : An experimental investigation of the structural damage in sheet drawing of tough-pitch copper, aluminum alloy 6061-T6, and 60-40 brass was undertaken with regard to the role of the stress state, particularly the hydrostatic component of stress, during deformation. Sheet drawing was carried out at ambient atmosphere and at high external fluid pressure. For the latter case, a novel high-pressure facility was employed that permits manipulation inside a 5-inch ID vessel at pressures up to 100,000 psi. Stresses within the deforming zone were determined from the Hill-Tupper slip-line field solution, the conditions of the experiments being made to match as closely as possible the assumptions of the theory regarding plane strain, constancy of yield stress, die geometry, and the absence of die friction. Although friction was indeed present, use of a Teflon spray lubricant satisfactorily lowered the coefficient of friction such that, with little error, the drawing operation could be considered frictionless. This was verified from an analysis made of the slip-line field and resulting stress state in which die friction was included. An important result from the analysis is that, depending on the die angle and reduction per pass, severe hydrostatic tension can develop at the center line of the strip, while hydrostatic compression occurs at the surfaces for the case where the external pressure is ambient.

Descriptors :   (*METALS, DRAWING(FORMING)), (*DRAWING(FORMING), METALS), SHEETS, COPPER, ALUMINUM ALLOYS, BRASS, STRESSES, DENSITY, LUBRICATION, DIES, FRICTION, FRACTURE(MECHANICS), DEFORMATION, HYDROSTATIC PRESSURE, MICROSTRUCTURE, DAMAGE

Subject Categories : Properties of Metals and Alloys
      Fabrication Metallurgy

Distribution Statement : APPROVED FOR PUBLIC RELEASE