BAUSCHINGER EFFECT IN HAYNES-230-ALLOY - INFLUENCE OF STRAIN-RATE ANDTEMPERATURE

Quasistatic and dynamic Bauschinger behavior in HAYNES 230 alloy is ex amined. At low strain rate (10(-3)/s), the as-received 230 alloy does not show a drop in flow stress, i.e., no Bauschinger effect is display ed. At high strain rate (10(3)/s), a drop in flow stress of 240 MPa wa s observed upon stress reversal. In contrast, the precipitation-streng thened condition exhibited a Bauschinger effect in both low and high s train rate stress-reversal experiments. The magnitude of the Bausching er effect was found to increase with increasing strain rate, forward s train, and decreasing temperature. The substructure evolution accompan ying the forward loading cycles was investigated by transmission elect ron microscopy and is related to the back stresses that developed. The increased Bauschinger stress drop observed at high strain rate and/or low temperature was correlated to an increased degree of planar slip under these conditions.