J. S. Gill ¹, A. S. Shahi ¹

Affiliations
1 Department of Mechanical Engineering, SLIET Longowal, Sangrur - 148106, Punjab, IN

Abstract

Objectives: Present work investigates the effects of base metal dilution and the thermal aging treatment 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 dilution of the deposit. Thermal aging treatment was given to specimens at 700ºC 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 there is almost constant values of microhardness 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 on testing the corrosion rate and degree of sensitization 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 clad condition was as low as 0.19 mm/month which increased to 3.64 mm/month when sensitized for 20 hours at 700ºC. Degree of sensitization (DOS) calculated by DLEPR test is more significantly affected by the thermal aging treatment. The DOS values varied from as low as 2.47 % to high as 31% for as clad 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.

Full Text

   

Mohd. Majid ¹, A. S. Shahi ¹

Affiliations
1 Department of Mechanical Engineering, Sant Longowal Institute of Engineering and Technology, Longowal - 148106, Punjab, IN

Abstract

Objectives: The aim of the present work was to investigate the influence of welding process variation as well as post weld thermal aging treatment on the metallurgical properties of Duplex Stainless Steel (DSS) 2205 welds. Method: Butt welded joints were fabricated using 10 mm thick plates of DSS 2205 by two different welding processes namely, Gas Tungsten Arc Welding (GTAW) process and Flux Cored Arc Welding (FCAW) process. These welded specimens were further subjected to thermal aging treatment at 800°C for 40 minutes to study the precipitation tendencies in the welds. Findings: Ferrite content was found to increase more in case of thermally aged FCAW joints as compared to the thermally aged GTAW joints. Also, GTAW weld metal showed a softening effect while FCAW weld metal underwent hardening after thermal aging treatment. Aging resulted into variation of ferrite content indicating that the process change can affect the important metallurgical ratio of austenite to ferrite in these welds. Ferrite phase was the predominating phase that showed dissolution which led to different inter-metallic phase formations like carbides, oxides as well as sigma phase formation. Application/Improvements: The present study is beneficial from the industrial view point, as the data generated through this piece of research can be directly used for DSS fabrications.

Keywords

DSS, FCAW Process, GTAW Process, Metallurgical Properties, Welded Point

Full Text