Pressure tube spools fabricated from Zr-2.5%Nb alloy, were subjected to gaseous hydrogen charging and stress reorientation treatment to form radial hydrides in a specially designed fixture. Curved Compact Tension specimens of 17 mm width containing 100 wppm of hydrogen were made using electro discharge machining. Some of the samples were annealed at 300, 325 and 350 °C followed by furnace cooling. Metallographic examination of the samples revealed 100% radial hydride in the samples to which stress reorientation treatment was imparted. The radial hydride fraction decreased with increase in the temperature of annealing that followed stress reorientation. Fracture toughness of samples with variable radial hydride fraction was evaluated as per ASTM E1820-13 procedure between 25 and 300 °C. All the samples exhibited a sharp ductile to brittle transition behavior and the transition temperature was observed to increase with increase in the radial hydride fraction.

由Zr-2.5％Nb合金制成的压力管线轴经过气态氢填充和应力重新定向处理，以在专门设计的固定装置中形成放射状氢化物。使用放电加工制得宽度为17 mm的弯曲压缩张力样品，其中包含100 wppm的氢气。一些样品在300、325和350°C退火，然后进行炉冷。样品的金相检查表明，在样品中进行了应力重新定向处理的径向氢化物为100％。径向氢化物分数随应力重新定向后退火温度的升高而降低。根据ASTM E1820-13程序在25至300°C之间评估了径向氢化物分数可变的样品的断裂韧性。