Indian Journal of Science and Technology

Abstract

Objectives: Present work investigates the effects of base metal dilution and the thermal aging treatments on corrosion performance and strength of stainless steel claddings, fabricated by gas metal arc welding process. Methods/Statistical Analysis: Austenitic stainless steel AISI SS 316L was selected as the cladding material and low carbon steel as substrate for the present study. Experimental conditions were selected to achieve a varying degree of base metal dilution of the deposit. Thermal aging treatment were given to specimens at 700°C, for 2 hours, 4 hours and 20 hours. The specimens were subjected to Double Loop Electrochemical Potentio Kinetic Reactivation (DLEPR), boiling nitric acid, and microhardness testing. Findings: Microhardness results of the clad deposits showed a continuous decrease in values from top of clad deposit to the base metal. However almost constant values of microhardness were observed when it was measured along the clad deposit. Moreover the deposits with high dilution showed low microhardness values than that of low dilution clad beads. The low dilution clad deposits also performed better under corrosion testing and sensitization measurement conditions as compared to high dilution deposits. Corrosion rate measured from boiling nitric acid test showed a significant growth with increase of thermal aging time due to carbide precipitation. The corrosion rate of specimens in the as cladded condition was as low as 0.19 mm/month which increased to 3.64 mm/month when sensitized for 20 hours at 700°C. Degree of sensitization (DOS) found to be more significantly affected by the thermal aging treatment. The DOS values varied from as low as 2.47 % to high as 31% for the as cladded and sensitized conditions respectively. Application/Improvements: The present study can beneficially be adopted for weld overlay fabrications as it suggests the processing conditions to forecast the adequate strength and corrosion performance of components in similar service conditions.
Keywords: Corrosion Rate, Dilution, Degree of Sensitization, Microhardness, Thermal Aging