Welding “difficult to weld steels”
There are many steels in the repair and maintenance field which can be regarded as difficult to weld due to their high hardenability.
These steels include:
- high carbon steels
- high strength steels
- tool steels
- spring steels
- heat-treated steels
- wear-resistant steels
- steels of unknown composition
Steels of unknown composition must be treated as having limited weldability
in order to avoid failure when welding.
In principle, all these steels can be welded with matching ferritic consumables with the aid of preheating and postweld heat treatment to avoid hydrogen cracking in the heat affected zone (HAZ).
In the case of repair welding, it is, however, often not possible to preheat or to perform any postweld heat treatment.
So, in this case, welding with austenitic stainless or nickel-based consumables is considered to be one of the best methods. The risk of cracking is reduced by the higher solubility of hydrogen and the greater ductility of the weld metal.
OK 68.81/OK 68.82/OK Autrod 16.75
Have a great capacity for dilution and are chosen when high strength is needed. The ferrite level in undiluted weld metal is often >40%, which may promote embrittlement when used for applications at elevated temperatures.
These types are the best choice when the material to be welded is of unknown composition