The microstructure evolution and performance enhancement mechanism of a novel laser cladding 20CrNiMoBSiY high-temperature alloy with high wear and corrosion resistance

Abstract

Wear-resistant and corrosion-resistant Fe-based high-temperature alloys have great potential in laser additive manufacturing of metallurgical high-temperature friction parts. However, due to the operational temperature range of 400–800 °C, the friction parts of traditional Fe-based high-temperature alloys often exhibit issues such as poor laser formability and unstable high-temperature performance, primarily caused by cladding cracks and porosity defects. This study utilized thermodynamic phase diagram calculations to simulate the hardness and pitting resistance equivalent number (PREN) of Fe-based alloys, optimizing and designing a novel 20CrNiMoBSiY high-temperature alloy with high wear and corrosion resistance . The alloy powders were prepared using vacuum induction gas atomization (VIGA), and the formability, microstructure evolution and performance enhancement mechanism of laser cladded alloy samples were investigated. The results indicate that the optimized composition of the alloy is 20Cr17Ni2Mo2B1.1SiY. The alloy powder has a spherical shape, uniform composition, smooth surface and flowability of 16 s/50 g. The microstructure of the cladded alloy samples primarily comprises M, retained austenite , (Fe,Cr) 2 (B,C), (Cr,Fe) 23 (C,B) 6 , and (Cr,Fe) 7 (C,B) 3 . These phases not only exhibit excellent formability but also possess high hardness, corrosion resistance , and superior high-temperature wear resistance. When the laser energy density is optimized to 138 J/mm 3 , the hardness of the cladding sample reaches 622 HV 0.2 , the minimum corrosion current density is 5.72 × 10 −6 A·cm −2 . At 800 °C, the wear rate is 42 % lower than that of the Q235 steel. The mechanism of synergistic enhancement performance of multiphase microstructure evolution in laser cladding alloys was finely clarified. A novel laser cladding 20Cr17Ni2Mo2B1.1SiY high-temperature Fe-based alloy with high wear resistance and corrosion resistance has been obtained. This work provides valuable reference for laser cladding remanufacturing of metallurgical high-temperature friction parts. • A novel laser cladding 20Cr17Ni2Mo2B1.1SiY high-temperature alloy was successfully designed and prepared. • Laser cladded alloy not only has good laser formability but also high corrosion and excellent wear resistance. • The wear rate of laser cladded alloy sample is 42 % lower than that of the Q235 steel at 800 °C • The synergistic enhancement performance mechanism of multiphase microstructure evolution was finely clarified.