The influence of heat input on the toughness and fracture mechanism of surface weld metal

© 2018 The Authors. Surface welding is a way to extend the exploitation life of damaged parts and constructions and the heat input has a major influence on the weldment properties. In this paper is shown the influence of the heat input on the toughness and the fracture mechanism of the surface welded joint. Surface welding of high carbon steel with self shielded wire was conducted with three different heat inputs (6kJ/cm, 10 kJ/cm and 16 kJ/cm). Total impact energy, crack initiation and crack propagation energy were estimated at room temperature, -20 o C and -40 o C. Fracture analysis of fractured surfaces was also conducted and it has been found that increasing of heat input leads to an increase of share of transgranular brittle fracture, what is in complete accordance with the obtained energy values. Based on all obtained results, the optimum value of heat input for welding procedure applied was defined

Failure analysis of carbon steel screws under the service in the presence of corrosion environment

The aim of this paper was to determine the causes of screws failures in compressor valves, obtained from petroleum industry. The analysed screws were in exploitation and deposition coated. Before the fracture analysis, control calculation of screws is done in order to determine, if the screws are properly dimensioned. After visual and radiographic examination, their chemical composition and structure were analysed. Detail fractography was performed on fractured surfaces to try to obtain an impression about screws failure mechanism. Qualitative analysis of deposit was employed in order to confirm if there was any possible influence of surroundings during their failure in terms of corrosion-assisted cracking. The macrofractography of originally broken surfaces shows a rough and complex topography of fracture surfaces indicating to a possibility that screws failure has been a result of complex loading conditions. Presence of sulfur containing particles on the fracture surfaces of broken screws and in deposit reveals a possibility that failure was environmentally-assisted