Development of a Constitutive Equation for HSLA (High-Strength Low- Alloy)-100 at Cryogenic Temperatures
Abstract
HSLA-100 is a 100ksi nominal yield strength steel being developed by the Navy for Naval shipbuilding applications. To assist in ductile and brittle failure modelling of this low carbon steel, tensile tests were conducted at temperatures ranging from 37 C(99 F)to liquid nitrogen(-196 C/-321 F)to determine a constituitive equation for this alloy at low temperature. The Hollomon Power Equation and the Voce Equation are used to describe the true stress/true strain behavior to failure of individual tests. The Bridgman correction is applied to the true stress to compensate for the triaxial stress state that exists at and beyond the necking (maximum load) point. The power and Voce equations are then fit to the Bridgman corrected true stress versus true plastic strain. Relative comparisons are made between the two equations resulting in the conclusion that the Voce equation describes the stress-strain characteristics of this alloy better than the Holloman equation. The temperature dependence of the material constants So, Si, and A, in the Voce equation were determined producing a constitutive equation for the tensile behavior of HSLA- 100 as a function of strain and temperature, at a strain rate of about .001 in/ in sec. The Bridgman correction factor was investigated in detail, mapping its change as a function of strain past the necking point. The Bridgman correction produced a discontinuity in the stress-strain curve at strains in the vicinity of the necking strain. This is not believed to be the true material behavior and thus, indicates that the Bridgman correction methodology is suspect. Keywords: Voce equation, Power equation, Temperature dependence.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1987
- Accession Number
- ADA189243
Entities
People
- David M. Bissot
Organizations
- Naval Postgraduate School