In-situ synthesized WC reinforcement phase on microstructural evolution, toughness and tribological properties of Mo2FeB2-based composite coatings fabricated by laser cladding

Abstract

The Mo2FeB2 composite coatings with in-situ synthesized WC were fabricated using laser cladding technology onto AISI 1045 steel substrate using pre-placed method. The microstructure and phase were characterized using a field emission scanning electron microscope and X-ray diffractometry. Microhardness was measured by a Vickers microhardness tester and analyzed using an optical microscope. Residual stress was evaluated using an X-ray residual stress tester. Wear resistance was assessed by a UMT-2 high load scratch tester. The microhardness, residual tensile stress, fracture toughness, coefficient of friction, and wear rate of Mo2FeB2-7wt.%WC composite coating were 1593.1 HV0.5, 285 MPa, 13.75 MPa‧m1/2, 0.32, and 3.42 × 10−5 mm3/N·m, respectively. Compared to the Mo2FeB2 coating, the microhardness, residual tensile stress, fracture toughness, and wear rate of Mo2FeB2-7wt.%WC composite coating was enhanced by 57%, 22.6%, 3.9% and 65.3%, respectively. The fracture mechanism was typical brittle fracture. Additionally, the wear mechanism shifted from adhesive wear to abrasive wear. The study provides the theoretical and practical guidance for improving the wear resistance and service life of Mo2FeB2 coating.

Keywords

• Laser cladding
• Mo2FeB2-WC composite coating
• Residual stress
• Fracture toughness
• Tribological properties