Effect of Cold Forming on the Strain-Controlled Fatigue Properties of HSLA Steel Sheets
Abstract:
The effect of cold forming under different strain states on the strain-controlled fatigue properties of three hot-rolled sheet steels, ranging in thickness from 2.4 to 3.3 nun, was investigated. The steels were: a Dual Phase 80 steel (AISI 80DF), a 50-ksi minimum yield strength HSLA steel (AISI 50XF), and, as a reference, a drawing-quality low-carbon aluminum killed steel (AISI 1006), These steels were deformed to various strain levels (effective strains ranging from Eeff = 0.04 to 0,6) using different modes of deformation to produce strain states similar to those· found in formed parts: uniaxial tension, plane-strain deformation (cold rolling), and in-plane balanced biaxial stretching. Monotonic tension tests and strain controlled fatigue tests were performed after deformation and also in the as-received, undeformed condition. At long lives (longer than 104 to 1 o5 reversals), the fatigue life was increased by prior deformation, whereas, at short lives, the fatigue life either remained the same or was reduced, depending on the mode of prior deformation and on the steel. The cyclic yield strength increased with the amount of prior deformation but less rapidly than the monotonic yield strength, reflecting the increased cyclic softening associated with the cold-worked microstructures.
Author:
J. M. Holt (1) and P. L. Charpentier (2)
Affiiation
(1) United States Steel Corporation, Research Laboratory, Monroeville, PA
(2) Wright State University, Dayton, Ohio, formerly with U.S. Steel Research
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Source:
Vanadium Structural Steels - Reprint of papers on vanadium steel from the proceedings of “ASM HSLA Steels Technology and Applications Conference, Philadelphia, USA, Oct., 1983, pp.139-152
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