Microstructure Evolution And Wear Resistance Of Laser Cladded Fe-based Alloys

Wear is one of the most common failure mechanisms for metal materials.Laser cladding,which has received widespread attention,can significantly improve the wear resistance of metal materials by preparing a dense coating on metal surface with a metallurgical bond.However,the high raw material costs have severely restricted the application of this technology.In present paper,the industrial wastes Fe-Si-Al and Fe-Si-B thin strip were crushed as raw materials to solve this bottleneck.Fe-based alloy coatings with excellent wear resistance were successfully prepared by laser cladding the industrial waste on 45#carbon steel.The microstructure evolution as well as the influence mechanism of microhardness and wear resistance of the coating was studied,which provides important insight into the preparation of wear-resistant coatings with low-cost and high performance.It's found that the Fe-Si-Al coatings prepared are composed of?Fe,Si,Al?single-phase solid solution and exhibit good metallurgical bonding with the 45#steel matrix under different process parameters.The bottom of the coating is of columnar crystals by epitaxial growth.The epitaxial growth is subsequently interrupted,and the columnar crystals gradually transite into equiaxed crystals.The hardness and wear resistance of Fe-Si-Al coating are mainly dominated by its grain size.Under the fixed load and the same wear time,the friction coefficient of the coatings is lower than that of the base metal,and the wear process is relatively smooth.The wear loss of the coatings is only 1/9 to 1/10 of that of the matrix,and adhesive wear and abrasive wear are the wear mechanism.The prepared Fe-Si-B cladding coating consists of?Fe,Si?solid solution,and Fe₂B and?Fe,Si?solid solution eutectic structure.The?Fe,Si?solid solution exists in the form of dendrites with a diameter of about2?m and a length of 10 to 20?m.The Fe₂B and?Fe,Si?solid solution eutectic layers exhibit a feature interval of about 200 nm.The hardness and wear resistance of the coating are mainly affected by the content and distribution of Fe₂B in the eutectic structures.The wear test study shows that Fe₂B in the eutectic structure can effectively strengthen the coating,thereby significantly improving the wear resistance of the coating.Under the same wear condition,the wear loss of the Fe-Si-B coatings is only1/11 to 1/12 of that of the base metal,and the friction coefficient of the coating is lower than that of the matrix.The wear process is relatively gentle.The wear mechanism is mainly dominated by abrasive wear with slight adhesive wear.The experimental results show that laser power and scanning speed have a significant effect on the shape and size of the grain in the cladded coatings.The differences in precipitates and grain size have a significant impact on the hardness and wear resistance of the cladding layer.By optimizing the process parameters,cladding coatings with excellent wear resistance were prepared,which can in turn guides industrial production.