Thread Content
In the weld and fusion zone of heterogenous steel welding joints, a transition zone exists due to factors such as the dilution of alloying elements and carbon migration. In this transition zone, not only are the chemical composition and microstructure uneven, but there are also significant differences in physical and mechanical properties. If the welding electrode is not selected appropriately, it may lead to welding defects such as cracks, thereby reducing the performance of the joint. The electrodes used for welding dissimilar steels should be selected based on the chemical composition, mechanical properties, application requirements, and type of joint. Generally, the following factors should be taken into consideration: (1) As long as no welding defects such as cracks occur in the weld joint, if it is not possible to achieve both strength and toughness in the weld metal, then electrodes with better plasticity and toughness should be chosen; (2) As long as the properties of the weld metal meet those of one of the two base materials, it can be considered to satisfy the technical requirements for use; (3) For structural steels of the same strength grade, low-hydrogen electrodes with good crack resistance should be selected; (4) Subject to meeting the performance requirements, electrodes that have good processability, low cost, and are easy to obtain should be chosen; (5) For pipes that require preheating before welding but where such preheating cannot be carried out at the construction site, austenitic stainless steel electrodes can be used, as this improves the plasticity and toughness of the weld metal, prevents the formation of cold cracks, and also meets the mechanical property requirements.