Cold weld cracking susceptibility of high strength low alloyed (HSLA) steel NIONIKRAL 70

In view of the importance of high strength low alloy (HSLA) steels, particularly for critical applications such as offshore plat forms, pipeline and pressure vessels, this paper reports on an investigation of how to weld this type of steel without cold cracking. Using manual metal arc welding process and Tekken test (Y - Grove test) has been carried out both to observe the cold cracking phenome non, and to investigate the influencing factors, such as preheating temperature and energy input, as well as electrode strength and diameter. How ever the results of the experiments show that there is a risk of cold cracking

Optimizacija parametra zavarivanja čeličnih cijevi za plinovode

The aim of this paper is to define optimization of welding conditions for Submerged Arc Welding (SAW) of steel pipes for gas transportation. Fine grain steel X-52 with thickness of 8 mm were used as a base material. Welding was performed from inner and outer side. Two wires, inclined under different angles, were feed separately. Eleven samples divided in three series were experimentally welded. Performed investigations indicated that the best properties showed weldments from series III, welded with the highest heat input. On the contrary of our expectations, welds from series II, using self made equipment, showed pretty bead properties and improper geometry. So, improving of this this equipment and obtaining welds with better properties is the target in future investigations.Cilj ovog rada je definirati optimizaciju parametara zavarivanja pod praškom čeličnih cijevi za plinovode. Finozrnati čelik X-52 debljine 8 mm je korišten kao osnovni materijal. Zavarivanje je izvedeno s vanjske i unutarnje strane. Dvije žice, pod različitim kutom su dodavane odvojeno. Jedanaest uzoraka, podeljenih u tri serije ekserimentalno je zavareno. Ispitivanja su pokazala da najbolja svojstva imaju zavari iz serije III, zavareni s najvećom količinom unešene toplote. Suprotno očekivanjima, zavari iz serije II, kod kojih je korištena oprema koju su izradili autori rada, pokazali su vrlo loše karakteristike i neadekvatnu geometriju spoja. Stoga je osnovni cilj u sljedećim istrazivanjima poboljšanje ove opreme u cilju dobijanja kvalitetnijih zavara