Investigation of Microstructure and Mechanic Properties of Petroleum and Natural Gas Pipeline Weldment by Submerged Welding Processes

In this study, roll sheet materials that were produced for natural gas and oil pipelines by different steel producers, have the same carbon equivalent, x52 and x65 quality were turned into pipe. these materials were combined with submerged arc welding method. microstructure and mechanical properties of weld samples which taken from combined pipes were investigated. in experimental studies, chemical analysis, hardness tensile, notch-impact tests were performed. the macro-microstructure and mechanical test investigations for the samples taken from welded joints showed that tensile strength and weld metal hardness of x65 material produced for oil pipeline and have fine-grained structure were higher than that of x52 material produced for gas pipeline and have coarser-grain structure. on the other hand, the toughness values of x65 material were lower than that of x52 material.