Arc welders, MIG welders, TIG welders, and Stick welders have to perform different welds with high-strength steels in their professional life. In the second part of this theme we will cover the welding of medium-alloy harden steels. Multiprocess welders know that these steels are used mainly in the aircraft industry to secure the formation of structural applications that are of ultra-high-strength.

The commercial welders are aware that these welds have low to medium carbon levels and good fracture toughness. Further to that, these steels are hardened with air, which reduces the distortion with quenching methods. The steels that belong to this group are called hot work die steels and one of them has been also named 5Cr-Mo-V aircraft quality steel. MIG welders, Arc welders, Stick welders, and TIG welders know that these steels are available in the bars and sheets, in the plates and strip, as well as in the forging billets.

Among the medium-alloy harden steels also belong the tempered steel high-yield or HY 130/150, which is used by the MIG welders, Arc welders, Stick welders, and TIG welders when they make aerospace applications, submarines applications and pressure vessels. Offered as plate, this steel has excellent toughness properties at 0°C and below these temperatures. These steels have much lower carbon levels as well.

Multiprocess welders know well that they must always do preheating of  316°C when they are performing flame cutting or when they are welding aircraft steels, as the steels are hardening through air. The preheating is done by the commercial welders before the flame cutting and then they are annealed after the flame cutting operation to avoid brittleness of the layer.

The medium-alloy harden steels are high-yield strength tempered steels that are welded by the Arc welders, Stick welders, MIG welders, and TIG welders with the help of gas metal arc, shielded metal arc, or the submerged arc welding. The filler wire here provides deposited metal similar in strength level as the base material. Heat-treating afterwards is usually not required.