Development Of Metal Powder-cored Wire For Submerged Overlaying On Hot Roll

A type of metal powder-cored wire for submerged overlaying on hot roll is studied in this paper. Metal powder-cored wire is the new tendency of the international development recent years, and which is considered a welding material instead of solid wire. This welding wire not only has the inherent properties of metal powder-cored wire, such as with better welding quality, without slag, highly efficiency and conveniently adjusting the alloying elements etc., but also has the advantage of low hardness in as-welded (less than HRC45), good machinability, high hardness in as-aged (more than HRC55) and better wear resistance with customary working procedure on making or repairing equipments such as rollers when reasonable designing the alloys content. The author adequately makes use of the high-tempering in the required stress relieving working procedure. During this working procedure, which causes the hardness of overlaying metal increased by the reason of austenite changes into tempered martensite and more chiefly what is the precipitation of a lot of carbide by secondary hardening simultaneously. This wire can solve the hard rolled problems of some solid wires with higher alloys while it can get over the conflict of existing overlaying materials what are always possesed high hardness with poor machinability or low hardness, good machinability with poor wear resistance. Further, it also can overcome the intenerating phenomena between welding beads and make the external hardness of overlaying metal uniform. Be sure it could be found important meaning in the overlaying of wear-resistant equipments, such as the precise roller.Based on the failure analysis of hot roll, this paper optimizedly adjusts alloy system and summarizes the experience of rolling wiresand improves ail processing properties. Then, it analyses the effects on some natural parameters such as alloy transfer coefficient, surfacing layers, welding current and arc voltage etc.. It confirms the fitting ageing technique. Also, it discusses the microscopic structural transformation back and forth ageing and the effects on hardness change of overlaying metal by some alloying elements including C, Cr, V, W, Mo, Ni, Mn, B, Re through OM, SEM and X-ray diffraction analyses. Finally the abrasive resistance, red hardness, thermal fatigue property and anti-high temperature oxidability are investigated in experimentation.