Low alloy high-strength steel can be divided into hot-rolled steel, normalized steel, low-carbon quenched and tempered steel, and medium carbon quenched and tempered steel according to its strength level and heat treatment state. When welding low alloy high-strength steel, the selected welding rod has a very important impact on the performance of the weld metal.

Selection of Low Alloy High Strength Steel Welding Rods.

Low alloy high-strength steel welding rods are also selected based on the strength grade of the steel, and factors such as the weldability of the base material, welding structure size, groove shape, and stress conditions are comprehensively considered to select welding rods.

In situations where the ambient temperature is low, the cooling speed is fast, and the welded joint is prone to cracking, welding rods with a strength one level lower than the base material should be selected.

① Selection of welding rods for hot-rolled and normalized steel

The main basis is to ensure that the mechanical properties such as strength, plasticity, and impact toughness of the welded metal match the base metal, without requiring the chemical composition of the weld metal to be consistent with the base metal.

To prevent welding cold cracks in thick and large parts, the principle of "low strength matching" can be adopted, and welding rods with weld metal strength lower than the base material strength can be selected.

Select welding rods such as J606, J607, J707, etc.

② Welding rod selection for low-carbon quenched and tempered steel welding

Low carbon quenched and tempered steel tends to produce cold cracks during welding, so strict control of hydrogen in the weld metal is particularly important. So low hydrogen or ultra-low hydrogen welding rods should be used for welding low-carbon quenched and tempered steel.

For example: JXXXH, JXXXRH

③ Welding rod selection for medium carbon quenched and tempered steel welding

Medium carbon quenched and tempered steel has a high carbon content. To ensure the plasticity, impact toughness, and strength of the weld metal, and improve its crack resistance, low-carbon alloy welding rods should be selected to minimize the sulfur and phosphorus impurities in the weld metal.

For components that require heat treatment after welding, it is also necessary to consider that the chemical composition of the weld metal should be similar to that of the base metal.