Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr 지르코늄 합금 압연 판재의 동적 변형시효 거동

Abstract

The behavior of dynamic strain aging (DSA) in a Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr alloy strip was investigated at temperature ranges of 25-600 degrees C via a tensile test. The tensile test was performed at two different strain rates 8.33 x 10(-5) and 1.67 x 10(-2) s(-1). The shear stress of the alloy strip revealed a linear dependency on the test temperature when the specimens were tested under a higher strain rate (1.67 x 10(-2) s(-1)). However, the linear relationship was broken due to DSA when the samples were deformed under a lower strain rate (8.33 x 10(-5) s(-1)). The discrepancy was most significant at 400 degrees C. The trend in DSA behavior was similar irrespective of the orientation of the samples, i.e., rolling direction (RD) or transverse direction (TD). However, the effect of DSA was larger in the TD samples than the RD samples. The phenomena were interpreted to the variation in work hardening exponents and strain rate sensitivity. The value of the exponent decreased from 0.14 to 0.08 along a RD and from 0.1 to 0.07 along a TD, respectively. However, the smallest value was observed at 400-500 degrees C irrespective of the specimen orientation, which is consistent with the DSA behavior. It is suggested that the DSA was caused by an interaction of moving dislocations with solute atoms typically oxygen.