A Recent Progress in Performance and Property Improvement in Underwater Welding

Underwater welding is the process of connecting materials underwater in the presence of water. It is used to maintain and improve the structure in marine and offshore applications. It's utilized for underwater pipeline maintenance, submerged offshore oil drilling, and ship repairs. It can also be found in nuclear power plants and deep-sea mining. Underwater welding is divided into two categories dry welding and wet welding. Dry welding entails enclosing the weld zone in a hyperbaric tank filled with a gas mixture and welding at the prevailing pressure. Wet welding is a type of welding that uses waterproof electrodes and is done directly on the component to be welded. The major benefit of this welding is its simplicity and cost effectiveness, but we can't obtain high weld quality as easily as we can with dry welding. Dry welding, on the other hand, may provide high weld quality, but it is a time-consuming procedure that needs the welder to secure the region with the hyperbaric vessel, and it is also a costly method. Underwater welding has a number of issues, including bubble arc generation, cold cracking, microstructural deformation, and more. We attempted to bring together the most recent developments in the field of underwater welding. We've outlined several techniques that were used to improve welding characteristics as well as important issues that must be addressed. This review article may be used to figure out what measures need to be taken to enhance the underwater weld joint quality. Keywords: Underwater welding, underwater wet welding, underwater dry welding, hyperbaric vessel, underwater welding development

Development of physical models for calculating thermal fields in wet underwater welding

В статье рассматривается влияние на развитие технологии мокрой подводной сварки использование методов математического моделирования значительно облегчает исследование тепловых потоков, что позволяет рассчитать скорость охлаждения металла в опасном диапазоне температур (800-500оС) и определить свойства металла сварного соединения. Определяющую роль в сварке играет теплообмен, который формирует протекание физико-химических, диффузионных, гидродинамических процессов. Форма сварочной ванны, а значит, объем и теплосодержание характеризуется ее длиной, шириной, толщиной и глубиной проплавления основного металла. Сварочная ванна ограничивается изотермической поверхностью, имеющей температуру плавления основного металла. Предполагается, что на свойства сварного соединения влияет только энергия, поступающая в основной металл. В известных физических образах и математических моделях теплового процесса сварки и наплавки не рассматривается, какое влияние на околошовную зону оказывают потоки теплоты от объема (массы) металла сварочной ванны, хотя в некоторых моделях изучается влияние скрытой теплоты плавления на тепловое состояние основного металла. The article discusses the impact on the development of wet underwater welding technology the use of mathematical modeling methods significantly facilitates the study of heat flows, which allows us to calculate the cooling rate of the metal in the dangerous temperature range (800-500oC) and determine the properties of the metal of the welded joint. The decisive role in welding is played by heat transfer, which forms the flow of physico-chemical, diffusion, and hydrodynamic processes. The shape of the weld pool, and hence the volume and heat content, is characterized by its length, width, thickness, and depth of penetration of the base metal. The welding bath is limited to an isothermal surface having a melting point of the base metal. It is assumed that the properties of the welded joint are affected only by the energy entering the base metal. In the known physical images and mathematical models of the thermal process of welding and surfacing, it is not considered what effect the heat fluxes from the volume (mass) have on the near-seam zone) the effect of the latent heat of melting on the thermal state of the base metal is studied in some models.

Analytical Evaluation of Strengthening, Local Internal Stresses and Microderformations in Welded Joint Metal during Wet Underwater Welding

Analysis of structural factor influence on local internal stresses and zones of deformation localization in upper and lower bainite structures in welded joints of low-alloy steel at wet underwater welding was performed. It is established that when welding joints under the water and applying an external electromagnetic field in the metal of the heat-affected zone (HAZ), a finer-grained substructure is formed with a general decrease in the dislocations density and with their uniform distribution. Estimates of the local internal stresses level considering the dislocation density distribution in the structural zones of their localization show that their maximum level is formed in the metal of the HAZ overheating region at welding without the external electromagnetic field along the upper bainite laths boundaries. The upper bainite structure is characterized by forming localized deformation zones, where the most significant dislocation density gradients are observed. This can lower the crack resistance of welded joints. Low values of local internal stresses are characteristic of welded joints obtained in the modes applying an external electromagnetic field. This is facilitated by the overall decrease in the dislocation density and their uniform distribution in the lower bainite structural components, which provides high crack resistance of welded joints.

Analysis of underwater welding in Indonesian warship using low hydrogen electrodes

As a security unit for the territorial waters of the Republic of Indonesia, the Indonesian Navy is required for combat readiness to carry out security operations quickly and precisely. It is very important to the readiness of the Indonesian Navy's ABK Soldiers and the Republic of Indonesia's defense equipment for warships in carrying out security activities in the territorial waters of the Republic of Indonesia. This study discusses underwater wet welding in anticipating an emergency if the ship's hull is hit by a collision so that the hull has cracks or holes. This research method uses AH36 steel plate metal. Then, underwater wet welding was carried out on the AH36 plate using a low hydrogen type electrode. Before welding, the electrodes were subjected to a drying process to a temperature of 900C. Wet welding underwater is carried out at a depth of 5 meters in seawater. The results of underwater wet welding are NDT testing; penetrant test, radiography test, then also DT test; hardness test, tensile test, and test according to ASTM standard. Analysis of underwater wet welding results compared to atmospheric welding results as quality control, so that the percentage difference in mechanical properties can be known. The interesting thing from welding AH36 steel plate with underwater wet welding and applying low hydrogen electrodes is the minimal level of weld porosity defects in the welding results. So that the low hydrogen electrode can be used in welding AH36 steel plate in underwater welding applications.