The paper describes the weldability and fracture toughness of three low carbon martensitic stainless steel grades with 13%Cr investigated for a group sponsored research project initiated by the Belgian Welding Institute.

The weldability of the different steel grades has been studied through weld simulation testing followed by metallographic examinations and notch impact testing carried out on the 20 mm thick as delivered or as simulated post weld heat treated base metals (heat treatments typical for induction heating of pipes). Moreover, extensive mechanical and fracture toughness testing has been performed to characterise these low cost test materials offering high strength, good toughness and weldability and adequate corrosion resistance for mild sour conditions.

Conventional submerged arc welding with newly developed matching consumables has been realised in the lean alloy, while high power laser weldments have been made in the medium alloy. These welded joints have been investigated by means of metallographic examinations, hardness measurements, transverse full-thickness tensile tests, notch impact tests, CTOD fracture toughness tests and realistic wide plate tensile tests at temperatures below zero (mainly at -20 °C and -40 °C).