Jacek Tomków

Bead-on-plate welding on S235JR steel by underwater local dry chamber process

Abstract The article presents the results of the effect of parameters of underwater local dry chamber welding on the properties of padding welds. The effect of heat input and the type of shielding gas on the structure and hardness of welds was established. the functions for estimating the maximum hardness of the heat affected zone have been also elaborated

Weldability of S500MC Steel in Underwater Conditions

Abstract Wet welding with the use of covered electrodes is one of the methods of underwater welding. This method is the oldest, the most economic and the most versatile. The main difficulties during underwater wet welding are: high cooling rates of the joint, the presence of hydrogen in the arc area and formation of hard martensitic structure in the weld. These phenomena are often accompanied by porosity of welds and large number of spatters, which are more advanced with the increase of water depth. In this paper result of non-destructive tests, hardness tests and metallographic observations of S500MC steel joints performed underwater are presented. The weldability of 500MC steel at water environment was determined

Diffusible Hydrogen Control in Flux Cored Arc Welding Process

One of the types of hydrogen degradation of steel welded joints is cold cracking. The direct cause of the formation of cold cracks is simultaneous presence of hydrogen, residual stresses and brittle structure. The way of preventing the occurring of degradation is to eliminate at least one of these factors. Practice has shown that the best solution is to control the amount of hydrogen in deposited metal. In this paper an experimental evaluation of the effect of the welding parameters on the content of diffusible hydrogen in deposited metal obtained from rutile flux cored wire grade H10 was carried out. The state of the art of considered issues was described and results of preliminary investigations were presented. Five factors were considered: the flow rate of shielding gas, the welding current, the arc voltage, the welding speed and the electrode extension. All factors were optimized using a Plackett-Burman design to get the most relevant variables. The level of diffusible hydrogen was determined by a glycerin test. The results of the experiment indicate that appropriate choice of welding parameters may significantly reduce diffusible hydrogen content in deposited metal.

Cold Cracking Of Underwater Wet Welded S355G10+N High Strength Steel

Abstract Water as the welding environment determines some essential problems influencing steel weldability. Underwater welding of high strength steel joints causes increase susceptibility to cold cracking, which is an effect of much faster heat transfer from the weld area and presence of diffusible hydrogen causing increased metal fragility. The paper evaluates the susceptibility to cold cracking of the high strength S355G10+N steel used, among others, for ocean engineering and hydrotechnical structures, which require underwater welding. It has been found from the CTS test results that the investigated steel is susceptible to cold cracking in the wet welding process.

Weldability of S460ML High Strength Low Alloy Steel in Underwater Conditions

The paper presents experimental evaluation of susceptibility of the high strength S460ML steel to cold cracking in the conditions of wet welding with the use of covered electrodes. From the results of Tekken tests it was found out that the investigated steel was characterised, in the conditions of the carried out experiments (underwater wet welding and air welding with rutile electrodes), of high susceptibility to cold cracking. Maximum hardness of HAZ in most cases do not fulfill criterion of PN-EN ISO 15614-1 standard: exceeds 380HV10.