Development of thermomechanical processing method to enhance twinning in commercially pure Zr

Zirconium is widely used as fuel cladding material in nuclear power reactors. Here, a thermomechanical processing technique has been developed and implemented to improve the mechanical properties of commercially pure Zr-702. In the process the twin density increased to 45 areal%. The twins were identified to be mostly of {101-bar 2}<101-bar 1-bar > tensile twins or {101-bar 1}<101-bar 2> compression twins. The significant increase in hardness was analyzed for its contributing factors and was attributed to the microstructural refinement caused by twin boundaries.