Effect of Calcium Treatments and Strain Rate on Reheat Cracking of Vanadium-Modified 2.25Cr-1Mo Steel

Vanadium-modified (V-Mod) 2.25Cr-1Mo steel has been studied to determine the effect of calcium treatments and strain rate on susceptibility to reheat cracking of the heat-affected zone in low-alloy steels for reactor applications. The susceptibility to reheat cracking was determined by tensile tests in the strain-rate range of 1 × 10−4/s to 3 × 10−6/s in the temperature region of 293K to 1023K. The grain size of tensile specimens was about 200μm. For the low-sulfur V-Mod steel, calcium treatment dramatically increased the total elongation and reduction of area at 923K at high strain rates. However, the beneficial effect on the ductility decreased as the strain rate decreased. For the V-Mod steel with commercial sulfur-content level, the addition of calcium was not very effective in decreasing the susceptibility to reheat cracking, independent of the strain rates investigated. The results are described and discussed.