Relationship between post weld heat and post weld heat treatment of submerged arc welding wire
First of all, post heating refers to the process measures of heating or insulating all or part of the weldment to slow down the cooling after submerged arc welding wire welding. The purpose of post heating is to reduce the content of diffusible hydrogen in the welded joint, especially in the heat affected zone. It is also called dehydrogenation treatment, which is an important process measure to prevent delayed cracking in welding some low alloy structural steels. Generally speaking, the afterheat effect is very significant in submerged arc welding, which can effectively ensure that the weldment will not crack.
In addition, post weld heat treatment is used to improve the structure and properties of welded joints or eliminate residual stress. It should be known that during electroslag welding, because of the large heat input, the heating and cooling speed is relatively slow, and the high temperature residence time is very long, the primary crystalline grain of the weld is large, and the impact toughness is low, so heat treatment is required after welding.
Relationship between post heating and post welding heat treatment of submerged arc welding wire:
Post heat in welding is not equal to post weld heat treatment. The purpose of post heat is to remove hydrogen and prevent delayed cracking, while the purpose of post weld heat treatment is to improve joint microstructure and properties and eliminate welding residual stress. Moreover, the heating temperature of post weld heat treatment is much higher than that of post heat treatment. Of course, if the post weld heat treatment can be carried out in time, it can also be dispensed with.
In this way, post welding heat and post welding heat treatment have a certain connection, and also have a great difference. We must understand this clearly to ensure the welding quality of submerged arc welding wire.
It is believed that many people who have been exposed to submerged arc welding will know that there are two major links in the process of submerged arc welding: post heating and post welding heat treatment.