Investigation On Properties Of Deposited Metals By Shielded Metal Arc Welding Process D172

Surfacing technology has many characteristics like the low cost, the simplified procedure, the easy operation and so on, so it has been used successfully in repairing the worn parts of the roller, the cold-hot mold or the gear component, and the great economic returns has been obtained. When the surfacing process is conducted on the substrate material 45 steel, the carbon migration in transition zone between 45 steel substrate material and deposited metal happens because of different carbon content and the alloying elements, which is equal to the dissimilar metal welding. The inhomogeneous microstructure and the residual stress will be resulted by the welding temperature field, the cleavage tendency of deposited layer metal is increased. Therefore, the post-weld heat treatment should be carried out to relieve the residual stress. The post-weld heat treatment has a significant influence on microstructure and property of deposited layer metal, especially on hardness and wear-resisting property. The investigation is focused on how to select the reasonable heat treatment temperature for increasing deposited metal property, relieving residual stress and improving bonding ability between substrate and deposited metals in present paper. The experimental basis for the practical production and the reference for studying further the property of deposited metal is provided by present investigation.Surfacing process is conducted by shielded metal arc welding process on the 45 steel substrate using electrode D172. The substrate material is preheated before surfacing, the inter-pass temperature is controlled, and the post-weld heat treatment is performed. The microstructure of transition zone and deposited metal is observed by the metallographic microscope, the phase analysis is discussed by the x-ray diffraction instrument, then the energy spectrum analysis is made using the energy spectrometer, the hardness is measured.The investigation results indicated that the toughness of the transition zone metal is increased, the residual stress is decreased, the cleavage susceptibility is reduced, the bonding ability between substrate material and deposited metal is strengthened with the increase of temper temperature. However, the hardness and the wear-resistant property of deposited metal will be reduced if the very high temper temperature is used. The ideal heat treatment temperature is 550℃in present experiment condition. The experiment results show that the property of deposited metal can be ameliorated, the residual stress can be relieved effectively, and the bonding ability between substrate material and deposited metal can be improved when the ideal heat treatment process is used.