Evaluation of Mechanical Properties for Bi-Metallic Welds

Abstract

Bi-metallic welds (BMW) plays crucial and essential role in Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR), where heavy section alloys are connected to stainless steel piping systems. In Pressurized Boiling Reactor (PWR) and Boiling Water Reactor (BWR) are usually used where heavy steam flow is generated i.e. nozzles of Reactor Pressure Vessel (RPV), steam generators and pressurizers. Bi-metallic welds are often used to connect ferritic piping with austenitic piping. Recent study and experiments have shown that there are several cracking problems, fabrication induced defects, corrosion, ageing and thermal fatigue caused due to temperature changes during the whole process. Thus, here we are going to experiment with the mechanical properties and try to resolve all the above problems. The material used in present study is austenitic stainless steel 304L and carbon steel SA516 Gr.70. We welded these both materials through GTAW at different elevated currents i.e. 180 Amp, 200 Amp and 210 Amp. Filler rod used during GTAW was 309L.We made a butt joint on the plates. Hardness, Tensile and Impact test was conducted in the different parameters samples. From all the test result, it was concluded that highest heat absorption capacity was found in the sample that was welded at 200 Amp. The heat absorption capacity of the plate was 140.50 Joules. Also, lowest hardness observed was 198.33 HV 10 in the sample welded at 200 Amp. Thus, 200 Amp samples were most reliable and could reduce the above mentioned problems.