STRESS-STRAIN RESPONSE OF AUSTENITIC STEE L-316L IN CYCLIC STRAINING

Cylindrical specimens of austenitic stainless steel 316L were cycled i n a computer controlled electrohydraulic testing machine. Plastic stra in amplitude was kept constant and stress amplitude and the shape of t he hysteresis loop was measured. Loop shape parameter was also evaluat ed. Fatigue hardening-softening curves depend on the plastic strain am plitude. Three regimes were observed and are also reflected on the sha pe of the cyclic stress-strain curve. In regime I (epsilon(ap) < 2 x 1 0(-4)) either saturation or slight hardening is observed and cyclic st ress-strain curve has low fatigue hardening exponent. In regime II (2 x 10(-4) < epsilon(ap) < 1.5 x 10(-3)) original hardening is followed by softening and there is a plateau on the cyclic stress-strain curve. In regime III (epsilon(ap) > 1.5 x 10(-3)) continuous hardening was f ound and cyclic stress-strain curve exhibit high hardening exponent.Fa tigue-life curves were measured and appropriate numerical parameters c haracterising the cyclic plastic stress-strain response and fatigue li fe were evaluated.