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

Jacek Tomków

doi:10.3390/ma14061364

Abstract

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.

Highlights

Each year the usage of high-strength, low-alloy (HSLA) steels increases
The highest number of gas bubbles was observed during welding of this specimen. This proved the connection between a high number of gas bubbles and instability of the welding arc, which had been previously stated in the literature [15]
It was proven that paraffin wax as a coating on covered electrodes provides significantly decreases the hardness in the heat-affected zone (HAZ)

Summary

Introduction

Each year the usage of high-strength, low-alloy (HSLA) steels increases These materials are characterized by their mechanical properties, which allow the weight of structures to be reduced [1]. 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 penetrate into welded joints. The diffusible hydrogen content in the deposited metal lowers the quality of underwater wet-welded joints [16]. Increasing the depth of welding decreases the corrosion rate, as shown by Surojo et al [21]

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