Effect of Preweld Heat Treatment on the Microstructure of Heat-Affected Zone (HAZ) and Weldability of Inconel 939 Superalloy

摘要

The effect of two preweld heat treatments on the final microstructure of a heat-affected zone (HAZ) and its effect on the weldability of the superalloy Inconel 939 have been analyzed. The HAZ cracking related to the mechanical driving force criteria during the cooling cycle was directly influenced by the strain state at this zone. Heat treatments result in the formation of (1) irregular γ' precipitates (more negative misfits) which showed higher strain (high density of interfacial dislocations) and (2) spherical precipitates (near-zero misfits) which as a result of their structure improve weldability by reducing weld HAZ cracking considerably.