Examination of mechanical properties of welds of docol 1200M toward application in components of special vehicles

Summary. The paper focuses on modern martensitic steel (Docol 1200M) and its joint manufactured by means of welding process supported by micro-jet cooling for special vehicles’ structures. Docol 1200M is a type of material denoted as AHSS (A- advanced; H - high; S – strength; S - steel) with important material characteristics, which allows the potential to reduce the weight of the construction of transport means. The paper verifies if the use of micro-jet cooling after MAG welding process could help to maintain initial mechanical parameters of special vehicles’ components. The quality of the joining process was checked by nondestructive and destructive tests. Results from tensile tests have enabled capturing the stress-strain curve as well as mechanical parameters and comparison with data of the parent material. Fatigue properties of the weld are described in terms of the fatigue limit and fatigue diagram, presenting fatigue limit as a key mechanical parameter with respect to the application of the joint examined. Testing the fatigue strength of a new steel grade for special vehicles’ structures in the innovative MAG process at micro-jet cooling was treated as the main goal of the study.