Microstructure Evaluation of Heterogeneous Electron Beam Weld between Stabilised Austenitic and ODS Ferritic Steel

The weldability of advanced heat resistant ODS metallic materials in combination with conventional materials is a prior requirement for their wider use in energy production. The microstructure of ODS steels is composed of alpha iron based matrix with dispersed oxide particles. Due to heating during conventional welding, the microstructure and properties of the resulting weld joints are affected and the joints often become the weakest point of the structure. The electron beam welding with its reduced heat affected zone size may be an answer in this. The presented article is focused on thorough metallographic evaluation of the structure of heterogeneous electron beam welds which combine stabilized austenitic stainless steel with the MA956 ferritic ODS steel. EB welded joints were evaluated by light and analytical electron microscopy including EDS and phase EBSD analyses in the as-welded state and after post-weld heat treatment. Mechanical properties of the weld were evaluated from the results of micro hardness profiles. Achieving an appropriate structure of such welds and correct welding parameters are crucial aspects for future successful application of similar joints in energy industry

Phased Array Ultrasonic Testing of Thin DP Steel Electron Beam Weld Joints

Duplex steels are an important group of materials which are generally used for applications where resistance to corrosion, or high strength and creep resistance at elevated temperatures, are required. They are used extensively in nuclear plant. Although ultrasonic inspection methods have been routinely used in industry for some three decades, it is well known that cast or welded austenitic components can be difficult, or even impossible, to examine ultrasonically. Development of ultrasonic techniques is therefore in progress in several countries to provide improvements which are being sought on safety and economic grounds.The aim of this paper is a brief description of the relevant metallurgical characteristics given before a consideration of the physical properties of the weld metal and the current theoretical models used to describe ultrasound propagation in it. The paper deals with the steps taken to improve the capabilities of ultrasonic inspection and includes a discussion of the problems of flaw location and sizing.