Development And Performance Analysis Of Special Welding Material For Austenitic Steel And Pearlitic Heat Resistant Steel

With widely applying of dissimilar material welding for austenitic and pearlite steel inproject engineer, more and more cases happen.The main cause of failure of welded jointsis the existence of carbon migration on both sides of pearlite and austenite heterogeneousjoint fusion line. By simulating actual working environment,this paper taking the power plantboiler system as background analyzes and measures carbon migration. After analysis oftypical austenite and pearlite heterogeneous joint, the carbon distribution around fusion linediffuse from pearlite steel side to austenitic steel side. This paper selectsfour,A402, A102, Ni317, R307commonly used in the heterogeneous steel welding processand prepared welding specimens. The welded samples were divided into welding state, agingtreatment, creep condition three groups Four kinds of welding consumables were selected tocreate an effective welding consumable that can restrain carbon migration. Carbon migrationwas tested and recorded by using scanning electron microscopy (SEM). By the comparisonof organization and the carbon migration, we find the factors which affectthe carbon migration. A new ultra-low carbon welding consumable is created base on thediscovery. Comparison for specimens’ carbon migration/microstructure/facture betweenfour common welding consumables and new ultra-low carbon are performed. Examinationresults show that is the main factor of leading to creep rupture carbon migration. Rupturelocation of A402/A102/Ni317/R307test specimens occur around fusion line of pearlite andaustenitic heterogeneous joint. After observing microstructure and carbon migration andanalysis of creep rupture fracture on rupture position,obvious carbon migration is foundedabove test specimens. Harmful hard and brittle microstructure composed of carbon chromiumcompounds and cementite,were founded around carbon migration layer.Carbon migrationalmost not occurred for test specimens of Ni317and ultra-low carbon. Fracture of creeprupture characteristiced of plastic cracking. By comparing the five test specimens,creeprupture time for ultra-low carbon electrode is longer than A402/R307/A102,only slightlyshorter than Ni317.It can be concluded that the new ultra-low carbon electrode can effectivelyrestrain carbon migration. Mechanical properties of ultra-low carbon electrode are better thanthe welding consumables used commonly in austenitic and pearlite heterogeneous joint. Although mechanical properties of ultra-low carbon are slightly worse than the nickel-basedmaterials, but can meet most of engineering request. This new welding consumable is morepractical than nickel-based material.