WELDING OF PINS TO MOBILE PLATFORMS ARMS

There is an increasing demand for mixed joints made of hard-weldable steels used in the construction of transport means. An illustration of this is the welding of movable platform elements such as a pin to arm joints. The pin is made of high-strength structural steel S690 QL (1.8928) while the arm of the movable platform is made of DOCOL 1200M steel from the AHSS group (Advanced High-Strength Steel). Such a joint is not easy to make due to the different chemical composition of both steels. The difference in thickness of welded elements creates an additional difficulty. The thickness of the cylindrical pin is 40 mm, whereas the thickness of the sheet metal used for the platform arm is much smaller and amounts to 2 mm. Joints of varying thickness and chemical composition tend to produce cracks in the heat-affected zone as well as in the weld. The purpose of this article is to determine the most appropriate welding parameters and the selection of additional materials to obtain correct joint with good mechanical properties, free of welding defects and incompatibilities.