Weldability of A588 Grade C Weathering Steel

The weldability of A588 Grade C steel is a subject of much debate among welders and structural engineers because it is an alloyed structural steel containing copper and chromium, which is known to react with oxygen to form moisture that can cause welds to crack.

The most common weldability issue with A588 Grade C weathering steel is the potential for joint cracking due to hydrogen-induced cold cracks, especially when the steel is exposed to water and the surrounding environment. This is directly related to the higher copper content which can form hydrogen embrittlement and subsequent hydrogen cracking. The higher copper content of the A588 grade C steel can cause hydriding when the steel is exposed to water and the surrounding environment. This hydriding weakens the metal resulting in the formation of hydrogen embrittlement and subsequent hydrogen cracking in the weld joint.

Another weldability concern for A588 Grade C weathering steel is the fact that it can readily form surface oxides due to its high copper content. This surface oxide can impede the penetration of the weld and its ability to properly bond with parent material, which can cause cracking of the weld. It is therefore recommended that surface oxides be removed through chemical or mechanical means prior to welding.

In general however, most welding professionals find that A588 Grade C weathering steel can be welded without issue when proper precautions are taken. It is advised that low amperage and low penetration welding techniques be used at all times to avoid the formation of embrittlement and hydrogen cracking. Preheating and postheating the parent material is also highly recommended. In the case of cold-weather welding, the use of a backing bar or pre-welding of a crack sensitive material should also be employed to avoid any potential embrittlement.

A588 Grade C weathering steel is considered weldable with proper precautions. However, normal welding practice should be used to ensure that any potential weld cracking is prevented. It is strongly recommended that any welding of this material should be performed by a qualified welding engineer who fully understands the risks associated with welding A588 Grade C weathering steel. With their experience and knowledge, welders should be able to produce high-strength welds that are strong and have excellent corrosion resistance.