Internal characteristic of droplet and its influence on the underwater wet welding process stability

2021

Materials

The paper presents the effects of waterproof coatings use to cover electrodes on the weldability of high-strength, low-alloy (HSLA) steel in water. With the aim of improving the weldability of S460N HSLA steel in water, modifications of welding filler material were chosen. The surfaces of electrodes were covered by different hydrophobic substances. The aim of the controlled thermal severity (CTS) test was to check the influence of these substances on the HSLA steel weldability in the wet welding conditions. The visual test, metallographic tests, and hardness Vickers HV10 measurements were performed during investigations. The results proved that hydrophobic coatings can reduce the hardness of welded joints in the heat-affected zone by 40–50 HV10. Additionally, the number of cold cracks can be significantly reduced by application of waterproof coatings on the filler material. The obtained results showed that electrode hydrophobic coatings can be used to improve the weldability of HSLA steel in underwater conditions.

Section: Resultssupporting

confidence: 80%

“…Moreover, it was stated that the welding arc stability was much lower than during welding in air. The instability of the welding arc in underwater conditions resulted from gas bubbles being created in the water, which was proven by Xu et al [ 15 ]. Such bubbles are filled with hydrogen, which can also penetrate into welded joints.…”

Section: Introductionmentioning

confidence: 99%

Weldability of Underwater Wet-Welded HSLA Steel: Effects of Electrode Hydrophobic Coatings

2021

Materials

“…Water causes instability of welding arc and reduction of the quality of the welded joints [8,9]. Zhang et al [10] proved that unstable welding arc generates problem with droplet transition, which may cause geometric shape imperfections.…”

Section: Introductionmentioning

confidence: 99%

Effect of Electrode Waterproof Coating on Quality of Underwater Wet Welded Joints

Fydrych

Wilk³

2020

Materials

In this paper, the effects of different hydrophobic coatings on the surface of covered electrodes on the quality of wet welded carbon steel joints were discussed. Commonly available hydrophobic substances used in industrial applications were selected for the research. The aim of using waterproof coatings was to check the possibility to decreasing the susceptibility of high-strength low-alloy S460N steel to cold cracking. During experiments diffusible hydrogen content in deposited metal determination by mercury method, metallographic macro- and microscopic testing and hardness measurements were performed. Investigations showed that waterproof coatings laid on covered electrodes can improve the quality of wet welded joints, by decreasing the Vickers HV10 hardness in heat-affected zone and decreasing the diffusible hydrogen content in deposited metal, which minimalize possibility of cold cracking.

“…It was proved that water generates much more diffusible hydrogen than during air welding [35]. An additional factor increasing the risk of cracking is the local stress concentration due to imperfections resulting from the instability of the welding arc [36][37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Dissimilar underwater wet welding of HSLA steels

Int J Adv Manuf Technol

Fydrych

2020

The high-strength low-alloy S460ML and S460N steels were chosen for underwater wet welding of dissimilar T-joints using covered electrodes. For improving the quality of joints, the temper bead welding (TBW) method was used. The application of TBW in pad welding conditions has been investigated earlier but the possibility of usage of this technique in welded joints was not analyzed. The main aim of the study was to check the influence of TBW on the hardness and structures of the heat-affected zone (HAZ) of dissimilar T-joints made in the underwater conditions. The experiments conducted showed that the technique used can reduce the susceptibility to cold cracking by decreasing the hardness in HAZ, which is a result of changes in its structure. The TBW technique reduced the hardness in the HAZ of the S460N steel by 40-50 HV10 and in S460ML by 80-100 HV10. It was also found that the changes in S460ML and S460N were much different, and therefore, the investigated technique can provide better results in the steel characterized by lower carbon equivalent Ce IIW .