Study On Overlaying Fe-Al Intermetallic By Double Arc Welding On The Suface Of Steel

In this dissertation, the overlaying of iron and aluminum intermetallic with steel as base metal was conduccted by using double-wire welding process.Problems including cracks occurred in surfacing layer are solved though the combination of Fe and Al wires and adjustment preheat temperature.WhenΦ1.6mm ER1100 aluminum wire is applied to the master engine with involving pulse, with voltage of 21.2V,current of 240 A,iwhileΦ1.2mm ER50S-6 wire to the slave engine, with the voltage of 32.4,current of 340A, nvolving pulse,the welding speed and preheat temperature are expected to reach 60cm/min and 350℃respectively,shaping the surfacing layer with execllent cracking resistance,without inclusion,cracks and non-fusion involved.Also,mechanical properties tests are conducted to the surfacing layer of iron and aluminum intermetallic.The experimental results show that:microhardness of surfacing layer reach 350HV. Shear strength reach 350MPa at least,with the fracture location of surfacing layer.SEM show that fracture mechanism is brittle fracture. Wear resistance test suggests hardfacing layer surpass base matrial in wear resistance. With SEM,EDAX,optical microscope, an analysis on the organizational structure of surfacing layer and contents of Fe and Al in different areas is made. As shown in the rusults that,the Fe-Al alloy layer is mainly composed of Fe3Al and a-Fe(Al).Al content in the weld zone reaches 24%～27%(at).In addition,analog computation is carried out under the temperature field based upon the technique,thus have obtained the temperature distribution at different monents,with thermal recysle curve at different points worked out via calculation.The simulation result shows that the double wires form unique molten pool.The shape of the molten pool is like elongated ellipse.Meanwhile,preheating temperature on the influence of the temperature field is discussed...