Evaluation of mechanical strength of ۳۰۴L austenitic stainless steel pipe welds at of -۱۹۰ ° C for operation in steel making oxygen unit

This study evaluated the mechanical strength of ۳۰۴L austenitic stainless steel welds at minus ۱۹۰ ° C for GTAW welding steel unit, which was in fact a case study. To introduce the oxygen unit, it should be said that the best and cheapest way to achieve pure oxygen is to use ambient air, which first takes the ambient air with high-power compressors and then this compressed air enters the turbine. This turbine cools the air to a temperature of minus ۱۹۰ degrees Celsius and enters the separator to be stored in separate tanks after separating the liquids. ۳۰۴L austenitic stainless steel pipe is one of the most widely used steels in the industry. In this study, the oven, ion and welding instructions of ۳۰۴L pipes were evaluated by GTAW welding method, and then all nondestructive tests, including radiography, were performed to ensure that the welds did not oxidize and did not have any defects. Then, the necessary mechanical tests wereperformed to ensure the connection of ۳۰۴L steel pipes at very low temperatures. The results of welding samples showed that the specimens were stretched in the appropriate range and failed in the standard range, as well as no cracks in the specimens. Weld surface and root bending test was not observed and finally the most important test that was performed in three areas of base metal, heat affected area and welding Charpi impact test, although at this temperature the impact energy was very low but showed soft failure results. Finally, these connections were approved for operation for the steelmaking oxygen unit.

Keywords:

Welding , Mechanical tests , ۳۰۴L , Oxygen unit , Fracture.