Effect of test temperature and load ratio on hydride cracking rate of Zr-2.5Nb alloy

Abstract

Delayed hydride cracking (DHC) rate in Zr-2.5Nb pressure tube material was determined under different temperature and loading conditions. Test specimens con-taining hydrogen were manufactured from RBMK (TMT-1) and CANDU pressure tube materials, depositing hydride layer and homogenizing it at elevated temperatures to the required hydrogen concentration.
Delayed hydride cracking rates at constant load-ing were measured at 144, 250 and 283°C.
Cycle loading tests were done at 250°C. Loading frequency was 1 cycle/min with different mini-mum/maximum load ratio R, changing from 0.13 to 1. It was determined that with the decrease of load ratio R, DHC rate increases up to 7 times, from 3.2·10-8 m/s to 4.8·10-9 m/s.