Behavioural Investigation of Hardness Profile for Dissimilar TIG-Weldment between P22 and P91 Steels
Bikram Jit Singh, Srihari Palli, Parmod Kumar, Shashi Bahl
Abstract
The Gas Tungsten Arc Welding (GTAW) is now commonly being used to join condenser pipes of railway locomotives, beside boiler and super heater tubes, generally made from dissimilar steel-alloys like P22 (2.25Cr-1Mo) and P91 (9Cr-1Mo). After welding, excessive hardness values of the Heat Affected Zones (HAZs) of those dissimilar weld joints are certainly obtained due to uneven and uncontrolled cooling rates, which resulted in an eruption of abrupt martensitic transformations. This ultimately leads to cracking and failure while operating at elevated temperatures. Therefore, there is a dire need to establish an appropriately optimized post-weld heat treatment process to eliminate this hazardous nuisance. The present work statistically studies the hardness profile of these critical material zones, before and after GTAW.