Characteristics and key points of welding dissimilar metal materials

Consider the complexity of the collective shape of the weldment, the stiffness, the preparation of the welding fracture and the welding position.

1. For weldments with complex shapes or large thicknesses, the weld metal will have large shrinkage stress during cooling and is prone to cracks. Welding rods with strong crack resistance must be selected, such as low-hydrogen welding rods, high-toughness welding rods or iron oxide welding rods.

2. For welding parts that cannot be turned over due to conditions, welding rods that can be welded in all positions must be selected.

3. For welding parts that are difficult to clean, choose welding rods that are highly oxidizing and insensitive to scale and oil to avoid defects such as pores.

Consider improving welding processes and protecting workers’ health

1. Where both acidic and alkaline electrodes can meet the requirements, acidic electrodes should be used as much as possible.

2. Consider labor productivity and economic rationality

Selection principle: Consider the physical, mechanical properties and chemical composition of the weldment.

1. From the perspective of equal strength, choose welding rods that meet the mechanical properties of the base metal, or combine the weldability of the base metal and switch to welding rods with non-equal strength but good weldability, but consider the structural form of the weld to meet the equal strength , and other stiffness requirements.

2. Make its alloy composition consistent with or close to the base material.

3. When the base material contains high levels of C, S, and P harmful impurities, welding rods with better crack resistance and porosity resistance should be selected. It is recommended to use calcium titanium oxide electrode. If it still cannot be solved, low hydrogen sodium type welding rod can be used.