Studies on microstructure, mechanical and corrosion properties of high nitrogen stainless steel shielded metal arc welds

[摘要] The present work is aimed at studying the microstructure, mechanical and corrosion properties of high nitrogen stainless steel shielded metal arc (SMA) welds made with Cromang-N electrode. Basis for selecting this electrode is to increase the solubility of nitrogen in weld metal due to high chromium and manganese content. Microstructures of the welds were characterized using optical microscopy (OM), field emission scanning electron microscopy (FESEM) and electron back scattered diffraction (EBSD) mainly to determine the morphology, phase analysis, grain size and orientation image mapping. Hardness, tensile and ductility bend tests were carried out to determine mechanical properties. Potentio-dynamic polarization testing was carried out to study the pitting corrosion resistance using a GillAC basic electrochemical system. Constant load type testing was carried out to study stress corrosion cracking (SCC) behaviour of welds. The investigation results shown that the selected Cr-Mn-N type electrode resulted in favourable microstructure and completely solidified as single phase coarse austenite. Mechanical properties of SMA welds are found to be inferior when compared to that of base metal and is due to coarse and dendritic structure.

[发布机构] Department of Metallurgical and Materials Engineering, NIT, Andhra Pradesh, India^1;Department of Metallurgical Engineering, Andhra University, Visakhapatnam, India^2;Defence Metallurgical Research Laboratory, Hyderabad, India^3

[效力级别] 机械制造

[关键词] Dendritic structures;Electrochemical systems;Electron back-scattered diffraction;Field emission scanning electron microscopy;High nitrogen stainless steel;Manganese content;Mechanical and corrosion properties;Shielded-metal-arc welds