Investigation on the Microstructure and Mechanical Properties of Dissimilar Weld Joint for Inconel 617 Alloy and 12Cr Steel

The Inconel 617 nickel base alloy and 12Cr steel were welded by auto-TIG welding method, the microstructure and mechanical properties of dissimilar weld joint were investigated. The results showed that the optimized TIG welding process could obtain no defect dissimilar weld joint. Characterization on the microstructure of the weld joint showed that the weld metal was the coarsed columnar crystal with the secondary precipitation phase distribution in interdendritic which was growth with each other and through the weld layers. HAZ of 12Cr consisted of coarse grain zone, fine grain zone, and carbides near the fusion line of Inconel 617 change obviously. The hardness distribution of welded joint showed that HAZ near 12 Cr steel existed tempered soften zone, the minimum hardness is 240 HV; hardness of weld was fluctuant, and the average hardness is about 330 HV because of the coarsed columnar crystal and the secondary precipitation phase distribution in interdendritic in weld; hardness of 617 side gradually reduced from the fusion line to the parent metal. Tensile test of the weld joint fractured at HAZ near 12Cr; the lowest value of impact energy test occurred at HAZ near 617. Mechanical properties test result showed that the performance can satisfy the requirements.