Although there are some obstacles that make the industry are reluctant to use this welding technique, in fact there are several businesses that improvements have been made, both in technique and quality welding electrodes, ie
Hydrogen cracking and hardness in the HAZ area can be minimized or avoided by the application of multiple techniques temper bead (MTB). The concept of this technique is to control the ratio of thermal (heat input) between the layers of weld bead. Control of this heat, weld bead size on the first layer should be adjusted so that the minimum penetration into the material can be obtained. Likewise for the second layer and so on. There are three parameters that affect the quality of welding in the implementation of MTB, ie the distance between the bead tempering, welding time span, and the heat input.
- Buttering technique can also be used, especially for materials with CE more than 0.4%. Electrodes used butter can have oxidizing agent electrode or electrodes Thermit.
- Usage of electrodes with oxidizing agent. This agent will reabsorb hydrogen or oxygen gas is absorbed in the HAZ.
- Use Thermit electrodes can also be used. Electrodes of this type will produce high heat and providing material welding (weld metal) a bit to reduce the rate of cooling of the welding results by surrounding temperature resulting in a kind of post-welding heat treatment process.
- Nickel-based electrode could not resist hydrogen to diffuse into the HAZ area. Unfortunately hardness in the HAZ area is still high and the quality of welding is only good for up to 10 meters depth.
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Tagged @ Underwater Welding
