On low carbon steel or low alloy steel substrates such as Q235A, the use of flux-cored wire self-protected open arc wear-resistant plates to prepare wear-resistant parts has good economics, reliability, and high deposition efficiency. It has been widely used in the preparation of wear-resistant plates. For wear-resistant parts such as concrete delivery pipes, cement plant fan impellers, and coal grinding rollers, the steel matrix plays a supporting role, while the wear-resistant alloy layer of the surface wear-resistant plate plays a role in wear resistance or corrosion resistance. Compared with the casting method, the use of wear-resistant plates to prepare wear-resistant parts can reduce the overall material cost, simplify the preparation process, and can be quickly repaired even after surface wear. The wear-resistant alloy layer is generally composed of high-alloy steel. Due to the dilution effect of the matrix, a transition zone with a certain width and uneven distribution of components and structures is formed between the wear-resistant plate and the matrix. The higher the heat input of the weld, the greater the dilution of the base material. The larger, the wider the transition zone. The transition zone often includes dendritic or network carbides at grain boundaries including a hypoeutectic structure. These dendritic or network carbides are difficult to deform under external impact and rolling, and are prone to microscopic cracks that develop along the grain boundaries. Expansion causes cracking and peeling of the deposited alloy layer. Not only that, the size of the dendritic and network carbides as the wear-resistant skeleton is too small, and its wear resistance is lower than that of the wear-resistant plate alloy containing primary carbides, causing premature failure of parts and affecting the normal operation of the equipment. In view of the above reasons, an attempt was made to add TiC to high-chromium flux-cored welding wire to study its effect on the microstructure and properties of each layer of the wear-resistant plate alloy, and to examine the wear resistance and wear mechanism of the deposited surface layer.
The outer skin of flux-cored welding wire is made of H08A steel, and the flux core is made of high-carbon ferrochromium (60% Cr, 8% C), silicon carbide (SiC), titanium carbide (TiC), graphite (carbon content above 98%), reduced iron powder, etc. Powder composition. The powder used is passed through a 60-mesh sieve and mixed evenly. The flux-cored wire forming machine YHZ-1 is used to roll Φ4.6mm thick wire, and the diameter is drawn and reduced until Φ3.2mm. In the middle of the Q235A test plate of 125mm×60mm×16mm, use the MZ-1000 welding machine to use the self-protected open arc method to wear two layers of wear-resistant plates. The parameters of the wear-resistant plates are: current 450~500A, voltage 30~40V, and car walking speed 20 ~25cm/min, interlayer temperature 150~250℃. The open arc welding seam is well formed and has less surface residue. By only changing the TiC content in the flux cored wire powder, the remaining part is supplemented with reduced iron powder, and the TiC content is 0~5%. The alloy composition (mass fraction, %) of the wear-resistant plate is: 19~21Cr, 4.2~5.0C, 0~0.9Ti, 0.8~1.0Mn, 0.6~1.0Si, Fe balance.
Due to the dilution of the base metal, from the fusion line to the surface layer of the wear-resistant plate alloy, the microstructure of the wear-resistant plate alloy layer shows the following distribution: solid solution → hypoeutectic → eutectic → hypereutectic. Carbon is relatively uniformly distributed in the fusion line micro-area, while Cr and Si alloy elements increase and jump to preferential distribution. Flux-cored wire plus TiC particles can reduce the dilution effect of the base metal on the filler metal, reduce the anisotropy of the wear-resistant plate alloy layer, stabilize the structure and performance of each part of the wear-resistant plate layer, and improve the wear resistance of the wear-resistant plate alloy. , improve the service life of parts. The wear resistance of high-chromium open arc wear-resistant plate alloy increases with the increase of TiC content, but the wear resistance decreases due to excessive addition of TiC and refinement of carbides. The main wear mechanism is microscopic fracture.
