Rolled Homogeneous Armour (RHA) steels are preferred for Armed vehicles over other armour materials because of their low price, availability and high formability.

The presence of tempered martensite and high hardness makes the welded joints of RHA steel susceptible to hydrogen induced cracking and HAZ softening. With less heat input and high deposition rate, the Rotating Arc Welding technique is an emerging GMAW method.

In this work, 18mm thickness RHA plate was welded with three passes using multiple filler wires Austenitic Stainless Steel (ASS), Low Hydrogen Ferrite (LHF) and Duplex Stainless Steel (DSS) to examine the microstructure and microhardness behaviour of the weld on the RHA steel beneath a Rotating Arc GMAW process.

The microhardness of each weldment is observed in the weld metal region and HAZ region as per the ASTM standard. Then, microstructural characterization was carried out in the weld metal region and HAZ region by using an optical microscope.

Due to variation in the weld thermal cycle during fabrication, the joints made using DSS filler wire showed less degree of softening than other joints, however, the joints fabricated using ASS filler wire exhibited more degree of softening of the HAZ.

The microstructural analysis of FGHAZ invariably indicates a hardened region of untempered martensite in all the joints. In CGHAZ all the joints reveal tempered martensite.

The microstructure of CGHAZ of DSS joint shows fine tempered martensite when compared with other joints.

This article is shared by R. Rajpradeep, S. Malarvizhi, V. Balasubramanian, Hafeezur Rahman and V. Balaguru