Structural Integrity of Welded Joint between Steel Grades X10CrMoVNb9-1 and 12X18H12T

Abstract

The two heterogeneous materials, austenitic stainless steel 12X18H12T and modified martensitic steel X10CrMoVNb9-1 (W.Nr.1.4903) are part of this experimental research. Both materials are used in boiler applications as structural materials and joints behaviour in service life is essential for structural integrity. The welds are made with nickel base electrode, NiCr20Mn3Nb according to EN ISO 18274 (Thermanit Nicro 82), first performing buttering layer of the martensitic steel, post weld heat treatment at 760 °C and welding with TIG process with austenitic steel. Mechanical testing was performed on the welds, tensile test, hardness measurement and microstructural analysis on base materials, heat affected zone, buttering layer, and weld metal. Tensile test showed that failure of the samples is on the austenitic side, on base material, indicating integrity of the weld joints. Microstructural analysis shows no cracks on critical regions, both the heat affected zone and fusion line region of martensitic steel and the weld metal.

Keywords

• austenitic steel
• dissimilar welded joints
• martensitic steel
• pressure parts
• X10CrMoVNb9-1
• 12X18H12T