MECHANICAL BEHAVIOR OF HEAT-TREATED AISI 4340 STEEL UNDER BIAXIAL STRESS AND RAPID HEATING,

This report presents the results of biaxial stress tests under rapid heating conditions on AISI 4340 steel tubular test specimens heat-treated to a tensile yield strength of 228,000 psi. The test specimens were subjected to uniaxial tension and to tension-tension biaxial stress ratios of 21, 11, and 12 at effective biaxial stress levels of 150,000, 170,000, and 190,000 psi and heating rates of 50, 100, and 500 Fsec. In general, increasing the heating rate delays specific amounts of plastic deformation to higher temperatures for all stress levels and biaxial stress ratios. For engineering purposes, the biaxial deformation behavior of this material could be predicted from uniaxial tests at plastic strains up to 2 percent for a heating rate of 50 Fsec for stress levels of 170,000 and 190,000 psi. The biaxial plastic flow of this material could also be predicted from uniaxial data for the 11 and 12 biaxial stress ratios for all three stress levels for strains of less than 0.5. Author