Low-alloy steel welding rods include low-alloy high-strength steel welding rods, heat-resistant steel welding rods and low-temperature steel welding rods with a tensile strength of 500MPa or higher. In line with the international low-alloy steel electrode, its performance is evaluated in accordance with the national standard GB/T5118-1995 or GB/T 983-1995.
Instructions for use:
To do a good job of welding, you must have an understanding of the material of the welding workpiece, the performance of the welding equipment and the performance of the welding materials used, and make appropriate choices and cooperation in order to ensure the quality of the welded products.
Usually according to the chemical composition, mechanical properties, crack resistance and other requirements of the steel plate, comprehensive consideration is also given to the shape of the welded structure, working conditions, stress conditions and welding equipment. If necessary, weldability tests are required to determine Welding rod and take necessary process measures.
A: Welding of low alloy steel. Generally, the corresponding welding rod is selected according to the strength grade of the steel. At the same time, comprehensive consideration should be made according to the weldability of the steel, the transition of the base metal composition, the size, shape, groove, and force of the welded structure. In the unfavorable situation that the welding seam has a higher cooling rate, which increases the strength, and the weld joint is prone to cracks, the welding rod with the first level of strength than the base metal can often be selected. In case of multi-layer welding of thick plates or normalizing treatment after welding, it is necessary to prevent the phenomenon of low weld strength.
B: Selection of acid electrode or alkaline electrode of the same strength level. Mainly depends on the structural shape of the weldment (simple or complex), the thickness of the steel plate (large or small rigidity), working conditions (static load or dynamic load) and the crack resistance of the steel. Generally, when it requires good plasticity, high impact toughness, good low temperature performance, and strong crack resistance, alkaline electrodes are used. If the DC power supply is difficult, you can choose AC and DC alkaline electrodes.
C: For carbon steel and low-alloy steel, or dissimilar steel welded joints between low-alloy steel and low-alloy steel, welding materials corresponding to steels with lower strength grades are generally selected.
D: Welding of medium carbon steel. Due to the high carbon content of steel, the tendency of welding cracks is increased. Low-hydrogen welding rods or welding rods with good plasticity and high toughness of deposited metal can be selected, and the weldments should be preheated and slowly cooled.
E: Welding of cast steel. Cast steel generally has a high carbon content, a large thickness and a complex shape, and it is easy to produce welding cracks. Especially when the content of alloying elements in cast iron is more, it is more prominent. Therefore, special attention should be paid in welding. Generally, low-hydrogen electrode can be used, and measures such as preheating and suitable welding process should be taken.
F: For steel grades and welded structures with special use conditions, special electrodes can be used.
G: Current range reference: If the workpiece is preheated, it can be reduced by 5%-15% compared to the normal current; when DC is used, it is about 10% less than AC; the current for vertical welding and overhead welding is 10%-15% less than that of flat welding