MIAB welding of alloy steel tubes in pressure parts: Metallurgical characterization and non destructive testing

Abstract

In this research, a pivotal attempt is being made to determine the feasibility of welding alloy steel tubes in pressure parts by employing Magnetically Impelled Arc Butt (MIAB) welding process. In view of this, a specially made state of art MIAB welding unit (MD1) available at WRI, BHEL, Trichy has been employed and adequate number of welding trials are conducted to weld alloy steel tubes of 6–7mm thickness for boiler applications. This paper presents a brief description of various non destructive tests carried out on the MIAB welded joints. Radiography test is performed on the welded specimen under the non destructive tests. Further, metallographic examinations [micrograph, macrograph and SEM] were carried out on the welded specimens. Finally, X-rd examination is performed on the MIAB welded specimens to observe the strain developed at the welded joint and the chemical composition of the weld and the base metal. There are no test standards available for carrying out tests specifically on MIAB welded joints. Hence, the test standards specified for welded tube specimens with solid state welding process (flash butt welding) are adopted for the tests on MIAB welded specimens to assess the quality and strength. It is observed that MIAB has several advantages in terms of its metallurgical integrity, quality and strength.