BIAXIAL STRESS AND STRAIN DATA ON HIGH STRENGTH ALLOYS FOR DESIGN OF PRESSURIZED COMPONENTS
Abstract:
A cross shaped specimen was developed for generating complete biaxial stress-strain curves under 11 and 21 biaxial tension stress ratio loading. Tests showed the specimen has good reliability. The influence of strength level on the behavior of the 5CrMoV steel under biaxial loading was investigated. Tests showed that by lowering the uniaxial strength level from 280 ksi, the shattering type failure observed at the 280 ksi level ceased to exist. However, the biaxial failure strains did not increase as the strength level was decreased. Pressure vessel tests which were conducted showed that the shattering type behavior obtained from the biaxial specimens is in indicative of poor resistance to crack-like flaws. Good correlation was obtained between the failure stresses from the pressure vessels and the biaxial specimens. Notch toughness tests were conducted to obtain a correlation between these tests and the biaxial specimen tests. No correlation could be shown between the notch toughness values and the biaxial failure strains. However, the notch toughness tests corroborated the conclusion that the shattering type failure in the biaxial test is indicative of poor resistance to crack-like flaws in the material. The biaxial stress and strain data is presented in a form which can be used directly in the design of biaxially loaded components. In addition, the test materials are ranked according to the efficiency parameters biaxial ductility rating, resistance to crack-like flaws and biaxial strengthweight.