A Study of the Weld Heat-Affected Zone of Centrifugally Cast Five Percent Chromium Steel

摘要

The weldability of centrifugally cast 5% chromium steel was investigated by using a hot ductility and synthetic heataffected zone technique. Ductility of the specimen was greatly reduced above 2400F for the on-heating test. However, after heating to a detrimental temperature of 2500F and cooling to 2400F, ductility almost recovered its original value. Therefore, hot-cracking is not considered likely. The microstructure in the heat-affected zone at various locations was reproduced in Charpy impact test specimens which were later tested at various temperatures ranging from -60 to +212F. The result showed that a specimen thermally cycled at an 1800F peak temperature gave the lowest impact strength. X-ray diffraction and electron micrography revealed the existence of retained austenite which decomposed during tempering treatment. It is believed that the retained austenite is responsible for the lowering of impact strength in the specimens which experienced an 1800F peak thermal cycle. (Author)