烧结压力对低液相Fe基预合金钻头胎体性能的影响

Effect of sintering pressure on the performance of Fe-based pre-alloyed bit matrix with low liquid phase

在烧结温度为950℃、保温时间为5 min及不同烧结压力条件下开展热压烧结试验,对比研究烧结压力对3种低液相Fe基预合金钻头胎体和1种传统Fe基钻头胎体性能的影响,具体包括胎体压入硬度、抗弯强度、致密度和金刚石包镶强度等力学性能,以及金刚石的热损伤情况和钻头胎体的微观组织结构与形貌特征等。结果表明:随着烧结压力增大,低液相空白胎体的压入硬度、抗弯强度和致密度逐渐增大,而传统Fe基空白胎体的压入硬度和抗弯强度呈现先增大后减小的趋势,其致密度为增大趋势;对于含金刚石的胎体,低液相与传统Fe基胎体抗弯强度均随烧结压力增大而增大,当烧结压力为20 MPa时,继续增大压力,低液相含金刚石胎体的抗弯强度趋于稳定,而传统Fe基含金刚石胎体的抗弯强度略有下降。同时,随着烧结压力的增大,低液相胎体的均一性明显增强,但金刚石的热损伤加剧。综合胎体的力学性能与断口形貌特征,优选的烧结压力为20 MPa,此时的低液相Fe基预合金胎体硬度、抗弯强度可满足孕镶金刚石钻头需要。

The hot-pressing sintering experiments were carried out under the conditions of sintering temperature of 950℃,holding time of 5 mins and different sintering pressures.The effects of sintering pressure on the properties of three kinds of low liquid phase Fe-based pre-alloyed bit matrix and one traditional Fe-based bit matrix were compared and studied,including the hardness,the bending strength,the relative density,the diamond embedding strength of the matrix,the thermal damage of diamond.as well as the microstructure and the morphology of drill bit matrix.The results show that with the increase of sintering pressure,the indentation hardness,the bending strength and the relative density of blank matrix with low liquid phase gradually increase,but the hardness and the bending strength of traditional Febased pre-alloyed blank matrix increase at first and then decrease,and the relative density increases.For the matrix containing diamonds,the bending strength of low liquid phase and traditional Fe-based matrix increases with the increase of sintering pressure.When the sintering pressure is 20 MPa,the bending strength of the diamond containing matrix with low liquid phase tends to be stable,while the bending strength of the traditional Fe-based matrix containing diamond decreases slightly.At the same time,with the increase of sintering pressure,the homogeneity of the low liquid phase matrix is enhanced,but the thermal damage of the diamond is gradually aggravated.According to the analysis of the mechanical properties and the fracture morphology of the matrix,the optimal sintering pressure is 20MPa.At this time,the hardness and the bending strength of the low liquid phase Fe-based pre-alloy matrix can meet the requirements of impregnated diamond bits.