硬质合金强度随温度的变化及失效机理的研究  

Effect of temperature on bending strength and failure mechanism of cemented carbide

作　　者：黄道远[1] 易丹青[1] 刘会群[1] 蔡志刚[1] 刘瑞[1] 李荐[1] 

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《材料热处理学报》2007年第5期105-108,共4页Transactions of Materials and Heat Treatment

摘　　要：研究了温度对3555和471硬质合金抗弯强度的影响。结果表明，3555和471硬质合金的抗弯强度在室温至300℃的范围内基本保持不变，在300～400℃开始下降，在400～500℃范围内剧烈下降，在500～600℃范围内下降变缓，在600～700℃时，抗弯强度值出现一个平台，比室温时强度降低30％左右。这是由于高温下合金的软化，hepγ→fccγ相变，W、C在粘结相中的固溶以及热应力共同作用的结果。3540和3475合金高温下断面的粗糙度降低，孔洞增多，沿晶断裂比例增加。高温下合金表面发生氧化，形成疏松的垂直于表面生长的柱状晶氧化层，3555抗氧化能力比471合金高。The influence of temperature on bending strength of 3555 and 471 cemented carbide was investigated. The results show that bending strength remains unchange from room temperature to 300℃, begins to decrease in 300 - 400℃, and decreases dramatically in 400 - 500℃. In 500 - 600℃, the bending strength changes gently and appears a strength platform at higher temperature. This is due to the combined effects of high temperature soften and hcp γ to fcc γ phase transformation, solution of W and C atoms in the binding phase and the thermal stress. With the increase of temperature, roughness of the fracture surface decreases, while the percentage of intererystalline fracture increases. Oxidation of the cemented carbide occurs at temperature above 400℃, which forms column shaped crystalline oxide layer, the oxide resistance of 3555 alloy is higher than that of 471 alloy.

关 键 词：硬质合金 高温 抗弯强度 失效 

分 类 号：TG135.5[一般工业技术—材料科学与工程] TG115.5[金属学及工艺—合金]