H13钢等离子堆焊Ni60A/Cr3C2覆层的磨损及热疲劳性能

采用等离子堆焊技术在H13钢基体表面上制备了Ni60A/Cr₃C₂堆焊覆层,研究了覆层的磨损行为和热疲劳性能。在600 ℃下销盘试验的结果表明,镍基碳化铬复合覆层的耐磨性是Ni60A堆焊覆层的2.8倍和基材H13钢的11.6倍。镍基覆层可以显著降低H13钢的摩擦因数,加入碳化铬则会削弱覆层的摩擦性能。随着磨损的进行,主要磨损机理从氧化磨损演变为磨粒磨损和粘着磨损。在800 ℃到室温下的热疲劳测试结果表明,镍基碳化铬复合覆层在48个热循环后疲劳裂纹达到200 μm,早于镍基覆层的62次。这说明高温氧化促进热疲劳裂纹的产生。碳化铬增强相从镍基上剥离,导致镍基复合覆层热疲劳性能下降。

Wear and thermal fatigue properties of Ni60A/Cr3C2 coating prepared by PTA welding on H13 steel

Ni60A/Cr₃C₂ surfacing coating was prepared on the surface of H13 steel by plasma transferred arc welding (PTA) technology, and its wear behavior and thermal fatigue properties were investigated. The results of pin-on-disk wear tests at 600 ℃ show that the wear resistance of the Ni-based Cr₃C₂-reinforced coating, is 2.8 times of that non-reinforced, and 11.6 times of that of the H13 steel. The nickel-based coating can significantly reduce the friction coefficient of H13 steel, and the addition of Cr₃C₂ will weaken the friction performance of the coating. The main wear mechanism evolves from oxidative wear to abrasive wear and adhesive wear as the wear progresses. The results of thermal fatigue test at 800 ℃ to room temperature show that the fatigue crack reaches 200 μm after 48 thermal cycles for the Ni-based Cr₃C₂-reinforced coating, earlier than after 62 cycles for the non-reinforced Ni-based coating. High temperature oxidation promotes the initiation of thermal fatigue cracks. The Cr₃C₂ reinforcing phase is peeled off from the Ni-based substrate, resulting in a decrease in thermal fatigue properties.