热输入对金属基复合涂层中(Nb,Ti)C颗粒分布及性能的影响

目的 热输入对复合碳化物的析出、分布及耐磨性能具有重要影响。然而，目前热输入对碳化物增强金属基复合堆焊层组织结构与性能方面影响的研究较少。因此，需要探究焊接热输入对(Nb,Ti)C增强金属基复合堆焊层组织及耐磨性的影响，明确(Nb,Ti)C复合颗粒在堆焊层的作用机制。方法 采用Ar保护气体进行堆焊涂层的制备，通过调节堆焊电流和电压，研究不同热输入下堆焊层的形貌、组织及耐磨性能。结果 堆焊层中Ti元素与C元素优先发生了原位反应，生成了以TiC为形核中心的(Nb,Ti)C复合碳化物，弥散分布在马氏体基体组织上。随着热输入的增大，析出的(Nb,Ti)C颗粒数量逐渐减少，块状(Nb,Ti)C尺寸也逐渐变小。采用较低的热输入时，堆焊层硬度达到最高，为734.88HV0.5；随着堆焊热输入的增大，堆焊层的显微硬度呈降低趋势。具有较多(Nb,Ti)C的低热输入试样耐磨性能最佳，磨损量为0.80 mg；而具有较少(Nb,Ti)C的高热输入试样产生了严重的黏着磨损，磨损量较低热输入试样增大了约144%。结论 在摩擦磨损过程中，高硬度的(Nb,Ti)C颗粒会对基体起保护作用，可以提升其耐磨性能，且耐磨损性...

Effects of Heat Input on Distribution and Properties of (Nb,Ti)C Particles in Metal Matrix Composite Coating

The precipitation, distribution and wear resistance of complex carbides have a very close relationship with the heat input. However, the relationship between the heat input and the organizational structure and performance of carbide reinforced metal matrix composite surfacing layer has rarely been reported in the literature. Therefore, the work aims to explore the effects of welding heat input on the microstructure and wear resistance of (Nb,Ti)C reinforced metal matrix composite surfacing layer, and to clarify the action mechanism of (Nb,Ti)C composite particles in the surfacing layer. By adjusting the current and voltage of surfacing, the morphology, microstructure and wear resistance of the surfacing layer under different heat input were studied when Ar was used as protective gas. The results showed that in the surfacing layer, Ti and C elements first reacted in situ, resulting in the formation of (Nb,Ti)C composite carbides with TiC as the nucleation center, which was dispersed on the martensite matrix. With the increase of heat input, the number of precipitated (Nb,Ti)C particles gradually decreased, and the size of massive (Nb,Ti)C gradually decreased. With low heat input, the hardness of the surfacing layer reached the highest, 734.88 HV0.5. The microhardness of the surfacing layer decreased with the increase of heat input. The wear resistance of low heat input samples with more (Nb,Ti)C particles was the best, and the wear loss was 0.80 mg. However, the high heat input sample with less (Nb,Ti)C particles produced serious adhesive wear, increased by about 144% compared with the low heat input sample. In the process of friction and wear, the high hardness (Nb,Ti)C particles can protect the matrix and improve its wear resistance, and the wear resistance decreases with the increase of heat input in surfacing.