BARC/PUB/2018/0618

 
 

Effect of radial hydride fraction on fracture toughness of CWSR Zr-2.5% Nb pressure tube material between ambient and 300 C temperatures

 
     
 
Author(s)

Sharma, R. K.; Bind, A. K.; Avinash, G.; Singh, R. N.; and others
(MMD)

Source

Journal of Nuclear Materials, 2018. Vol. 508: pp. 546-555

ABSTRACT

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 17mm width containing 100 wppm of hydrogen were made using electro discharge machining. Some of the samples were annealed at 300, 325 and    350 oC 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 oC. 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.

 
 
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