Split Heat Mechanical Property Comparison of ESR (Electroslag Remelting) and VAR (Vacuum Arc Remelting) 4340 Steel

摘要

This report addresses a mechanical property characterization of a split argon-oxygen decarburized (AOD) heat of 4340 steel which was further processed by vacuum arc remelting (VAR) and electroslag remelting (ESR) into 5-inch-square forgings. Properties examined were hardness, tensile, Charpy V-notch impact, and fracture toughness as a function of tempering temperature over the range of 325 F to 1200 F for both the longitudinal and transverse orientations. Microstructural aspects are also addressed. Results indicate nearly identical tensile properties for the ESR and VAR processed material. These properties exceed the required specification in the HRC 54-57 range. Ductility measurements were anisotropic for both remelting techniques. Charpy impact values were consistently higher for VAR scatter in impact data was observed at tempers from 325 F to 400 F. Fracture toughness, KQ, was higher for VAR material in both the LT and TL orientations for tempering temperatures up to 800 F. The lower values observed in the ESR heat examined are attributed to calcium aluminate inclusions which can be introduced by electroslag remelting.