WC含量对铁基等离子堆焊层组织及耐磨性能的影响

Influence of WC content on microstructure and wear resistance of Fe-based plasma surfacing layers

  • 摘要:
    目的 旨在提高轧辊耐磨性能、降低损耗,从而延长轧辊的使用寿命。
    方法 采用等离子堆焊技术,在Cr5钢基体表面制备不同WC含量的铁基等离子堆焊层。对堆焊层物相组成、显微组织、硬度及耐磨性能进行测试。
    结果 结果表明,添加WC颗粒后,堆焊层物相主要为α-Fe,M7C3,M23C6,W2C,Fe3W3C和γ-Fe,组织由胞状晶、树枝晶、枝晶间固溶体、等轴晶及未熔WC颗粒等组成;随着WC含量(质量分数)的增加,晶粒尺寸变小,组织更加均匀;但当WC含量超过40%时,堆焊层中出现气孔、裂纹等缺陷,降低了堆焊层性能;随着WC含量的增加,堆焊层顶部硬度呈现先增加后减小的趋势,而磨损量呈现先降低后升高的趋势。
    结论 当WC含量为30%时,组织较为细小均匀,硬度最高,为64 HRC,磨损失重量最小,为3.33 mg,磨损机理为磨粒磨损和轻微疲劳剥落磨损,此时耐磨性能最好。

     

    Abstract: Objective The purpose was to improve wear resistance of roll and reduce the loss, so as to extend service life of roll. Methods Plasma surfacing technology was adopted to prepare Fe-based plasma surfacing layers with different WC content on the surface of Cr5 steel substrate. Phase, microstructure, hardness and wear resistance of the surfacing layer were tested. Results The results showed that with the increase of WC content, main phases of the surfacing layer were α-Fe, M7C3, M23C6, W2C, Fe3W3C and γ-Fe, and microstructure was composed of cellular crystal, dendrite, interdendrite solid solution, equiaxed crystal and unmelted WC particles. With the increase of WC content (wt.%), grain size became smaller and microstructure became more uniform. However, when WC content exceeded 40%, defects such as pores and cracks appeared in the surfacing layer, which reduced performance of the surfacing layer. With the increase of WC content, macroscopic hardness at the top of the surfacing layer increased first and then decreased, while wear quantity decreased first and then increased. Conclusion When WC content was 30 %, microstructure was relatively fine and uniform, the highest hardness is 64 HRC, the minimum weight loss was 3.33 mg. Wear mechanism was abrasive wear and slight fatigue spalling wear, and wear resistance was the best.

     

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