The principal aim of the research is to determine the
stress/strain characteristics of stainless steels at high
rates of strain (> 100sec-1), and so to investigate the
effects of changing strain rate on yield point and plastic
flow stress. The material properties obtained in this work are
intended for use in the analysis of explosive tests on
model fast breeder reactor containment vessels. The
experimental technique used is the split Hopkinson pressure
bar method in which stress pulses are used to produce
high rates of loading in the sample.
Practical problems with pulse measurement and sample
preparation are discussed, and recommendations are made to
improve the reliability and accuracy of tests. New
techniques described include the use of a transient recorder
and micro-computer for improving pulse recording and analysis,
pulse-shaping to control the strain rate of tests and a
modification of the basic Hopkinson bar to enable a simple
conversion to be made from compressive to tensile testing.
The results of extensive testing of samples from 321
stainless steel bar in compression and tension over a wide
range of strain rates (static and 100 to 2000sec-1), testing
temperatures (20 to 6000C); and different annealing temperatures
are reported. Results of tests on 304,316,321 and 325 stainless
steel rod are also presented. Comparison with previous empirical
and theoretical material constitutive equations is discussed.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.