Effect of Ti Content on Microstructure and Properties of Laser-Clad Fe-Cr-Ni-Nb-Ti Multi-Principal Element Alloy Coatings

Multi-principal element alloy (MPEA) Fe66.5−xCr24Ni8Nb1.5Tix coatings were fabricated via laser cladding on Q235 steel substrates to enhance their surface performance. This study revealed that the Ti content within these MPEAs directly influences the properties of the resulting coatings. The experimental results demonstrated that increasing the Ti content in the Fe66.5−xCr24Ni8Nb1.5Tix MPEA promoted the formation of a BCC phase, significantly enhancing the coatings’ mechanical properties. Specifically, the effect of Ti content on the microstructure and properties of the laser-clad MPEA coatings was investigated. Detailed analyses of the coatings’ friction and wear performance, as well as cavitation erosion resistance, were conducted. Under a 20 N load for 30 min, increasing Ti content reduced the wear rate from 4.41 × 10−5 mm3/(N·m) to 3.79 × 10−5 mm3/(N·m), resulting in a 14.06% improvement in wear resistance. Cavitation erosion (CE) tests showed that after 20 h of ultrasonic exposure, the sample with x = 2.1 exhibited a cumulative mass loss of 4.92 mg, compared to 8.12 mg for the sample with x = 0.3. This represents a 39.4% reduction in cavitation erosion mass loss for the higher-Ti-content coating. In stark contrast, the Q235 substrate incurred a significantly higher mass loss of 86.78 mg under identical conditions. This signifies a dramatic enhancement in cavitation erosion resistance achieved by the high-Ti MPEA coating. These findings demonstrate a novel approach to enhancing the cavitation erosion resistance of MPEA claddings by optimizing Ti content, thereby broadening their potential application scope in harsh environments.