基体碳含量对梯度结构硬质合金微观结构与性能的影响

The Effect of Matrix Carbon Content on the Microstructure and Properties of Cemented Carbide with Gradient Structure

Co相梯度结构硬质合金与传统硬质合金(WC-Co)相比具有良好的硬度和韧性组合。本文通过固体渗碳烧结处理制备出了Co相梯度结构硬质合金,研究了贫碳量对固体渗碳后硬质合金中Co相梯度结构、力学性能的影响,探索了Co相梯度结构的形成机制。结果表明,贫碳合金碳含量越低,η相体积分数越大,渗碳时需要消耗更多的活性碳原子,渗碳烧结后,Co相梯度结构厚度减小,富钴层厚度增加。Co相梯度结构硬质合金中,由于存在Co相梯度结构,硬质合金内部硬度呈现由高(1 600 HV5)到低(1 300 HV5)再到高(1 600 HV5)的变化,合金抗弯强度较传统硬质合金有所提升,碳含量为5.26%的贫碳合金在渗碳烧结后抗弯强度为2 860.1 MPa。

Compared with traditional cemented carbide(WC-Co),Co-phase gradient structure cemented carbide has agood combination of hardness and toughness.The Co phase gradient structure cemented carbide is prepared by solidcarburizing and sintering.The effect of the poor carbon amount on the Co phase gradient structure and mechanical propertiesof the solid carburized cemented carbide is studied,and the formation mechanism of the Co phase gradient structure isexplored..The results show that the lower the carbon content of the carbon-depleted alloy,the greater the volume fraction ofthe η phase,and more active carbon atoms need to be consumed during carburization.After carburizing and sintering,thethickness of the Co phase gradient structure decreases and the thickness of the cobalt-rich layer increases.In the Co phasegradient structure cemented carbide,due to the existence of the Co phase gradient structure,the internal hardness of thecemented carbide changes from high hardness(1 600 HV5) to low hardness(1 300 HV5) to high hardness(1 600 HV5),andthe strength is improved compared with traditional cemented carbide.The carbon-lean alloy with a carbon content of 5.26%has a bending strength of 2 860.1 MPa after carburizing and sintering.