Plastic Straining of Iridium Alloy DOP-26 During Cup Sizing Operations

Ohriner, Evan Keith ; Ulrich, George B ; Sabau, Adrian S

Oak Ridge National Laboratory

关键词: Iridium Alloys;    Plastics;    Grain Growth;    Dimensions;    Geometry;   

DOI  :  10.2172/931049
RP-ID  :  ORNL/TM-2007/169
RP-ID  :  DE-AC05-00OR22725
RP-ID  :  931049

美国|英语

来源: UNT Digital Library

【 摘 要 】

DOP-26 iridium alloy cups are used for fuel cladding for radioisotope power systems. The cups are deep drawn and recrystallized prior to final fabrication operations. This study characterizes the plastic deformation of cups during a sizing operation following the recrystallization heat treatment. The purpose of the sizing operation is to achieve the specified roundness, diameter, and radius dimensions of the cup. The operation introduces various levels of plastic strain in the cup. Plastic strain can be a cause of inhomogeneous or abnormal grain growth during subsequent exposure to elevated temperature during the service life of the fueled clad. This is particularly true in the case of cups which have irregularities in the cup walls from the deep drawing operations. Diameter and roundness measurements were made on two cups both before and after sizing. Plastic strain levels were calculated using the ABAQUSTM finite element software. The calculated plastic strain levels in both cups were below 0.025, a value shown to be below the critical strain for abnormal grain growth during a simulated service exposure. The calculated maximum plastic strain was found to increase with increased applied sizing load and was not sensitive to the input value for the clearance between the cup and the sizing die. The calculated geometry of the sized cups was in good agreement with the measurements on the finished cups.