Study of effect of nitrogen on the corrosion behaviour of AISI 316LN austenitic stainless steel weldment.

In this study an attempt is made to study the effect of nitrogen on the corrosion of weld metal in 316LN base plate made with different filler wires having different concentration of molybdenum. This weld metal was tested for critical pitting temperature (CPT), pitting corrosion, and stress corrosion cracking (SCC). The behaviour were determined by observing the pit at 100X under optical microscope, cyclic electrochemical polarisation at slow scan and slow strain rate test (SSRT). The media used were 10% FeCl2 for CPT, 3.5% NaCl for pitting and, air, 1 N HCL & 25% boiling NaCl respectively. The nitrogen content of weld metal was varied by change of welding parameters like speed of welding, arc gap, welding current, volume fraction of nitrogen in shielding gas mixture of Ar+N2 electrode tip angle. Molybdenum content in the weld metal was varied by use of different types of filler wires. To find a correlation of nitrogen in the weld metal and the welding parameters, all the welding parameters were changed simultaneously and they were correlated by ANOVA approach. More Info

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