Microstructural Aspects of TIG and A-TIG Welding Process of Dissimilar Steel Grades and Correlation to Mechanical Behavior

作者：Badheka Vishvesh J^*; Basu Ritwik; Omale Joseph; Szpunar Jerzy

来源：Transactions of the Indian Institute of Metals, 2016, 69(9): 1765-1773.

DOI：10.1007/s12666-016-0836-5

• Tungsten inert gas (TIG) welding
• Activated flux-TIG (A-TIG) welding
• Electron backscattered diffraction (EBSD)
• Local average misorientation
• Orientation relationship
• Grain boundary characteristics

The present study reports microstructural characteristics of two grades of steels, stainless steel (SS 304) and carbon steel welded using tungsten inert gas (TIG) and activated flux-TIG (A-TIG) processes. Activated fluxes such as TiO2, ZnO and MnO2 are effective for A-TIG welding of dissimilar weld between carbon steel to stainless steel. Mechanical properties, joint efficiency of A-TIG welds are found to be higher than normal TIG Welds. This study attempts to establish a correlation between observed mechanical behavior (hardness and strength) and the microstructural characteristics of the weld samples. Significant differences in microstructures are recorded in terms of grain size, local misorientation, grain and phase boundary characteristics in distinct regions of the welded samples. The microstructural observations exhibit: (1) the presence of Widmanstatten ferrite structure at the heat affected zone of the carbon steel part in the A-TIG welded specimen and (2) differences in structure at the interface of stainless steel and weld metal region under the two conditions of welding. These structures are morphologically different and shows differences in the number fraction of 45A degrees < 114 > phase boundary orientation relationship. The microstructure also displays significant heterogeneity in grain size and grain misorientation.

• 出版日期2016-11
• 单位Saskatchewan; 中国石油大学（北京）; Saskatoon