THE EFFECT OF COLDWORK ON THE LOW CYCLE FATIGUE AND CREEP-FATIGUE INTERACTION PROPERTIES OF ALLOY D9

摘要

Alloy D9, a 15Cr-15Ni, Ti modified stainless steel is a candidate material for fast reactor core components due to its excellent resistance to void swelling. The alloy with Ti/C ratio of 4 has been investigated for its Low Cycle Fatigue (LCF) and Creep-Fatigue Interaction (CFI) properties in solution annealed and 20 percent cold worked condition. LCF tests have been conducted in air at 823K and 923K, while CFI tests were performed at 923K using holds at peak tensile strain. Under continuous cylcing LCF conditions, solution annealed material exhibited superior LCF resistance than cold worked material at both 823 and 923K, except at low strain ranges at 923K. The solution annealed material underwent cyclic hardening while cold worked material displayed cyclic softening. Under CFI conditions, solution annealed material exhibited a recovery in life at longer hold times, while coldworked material exhibited a continuous decrease in life with increasing hold time. The LCF and CFI properties have been correlated with the substructural recovery and precipitation at these temperatures.