WC-Co硬质合金的强度

对两相 WC- Co硬质合金的研究表明 ,并非由钴含量 XCo而是由碳含量 XC 所决定的 相成分 (钨和碳在 相中的浓度 )才是制约 WC在 相中溶解—析出过程的决定性因素 ,因而也是影响 WC- Co合金 WC平均晶粒尺寸 LWC的重要因素。求得了相应于最大抗弯强度 σTRSmax的 LWC～ XCo反比关系式和最佳 相平均自由程 λ。 的取值范围。提出了在 相质量分数 X 增大引起 λ。 增大的情况下 λ 对应的合金结构由连续的 WC骨架向连续的 相网络的过渡的概念 ,从而较合理地解释了σTRSmax～λ 双支线关系和粗、细晶合金的σTRS～ XC关系。两相 WC- Co合金的强度取决于合金的钴含量、碳含量和WC平均晶粒尺寸并归因于 相平均自由程和 相中钨和碳固溶度的影响。在σTRS～λ 左支线范围内合金的断裂韧性 KIC同σTRS呈线性关系。在求得显微结构参数、成分和强度同磁性、密度和硬度的定量关系的基础上提出了无损鉴定两相 WC- Co硬质合金的结构、成分和强度的原理。

STRENGTH OF WC-Co CEMENTED CARBIDE

The study of two-phase WC-Co cemented carbide showed that the γ-phase composition i.e.the wolfram and carbon solubilities in γ-phase decided by alloy carbon content X_C instead of the cobalt content X_ Co in alloy is the decisive factor restricting the dissolve-preciptation process in γ-phase of WC grains and so controling the WC average grain size L_ WC .The L_ WC ～X_ Co inverse ratio formula corresponding to the maximum transverse rupture strength σ_ TRS max and the size limit of the best γ-phase average free path λ ?_γ were obtained.The concept was put forward that the λ ?_γ corresponds to the transition structure from the continuous WC skeleton to the continuous γ-phase network when λ_γ is increasing as γ-phase content X_γ is increasing,so the σ_ TRS max ～λ_γ double-branch line relation and the σ_ TRS max ～X_C relations corresponding to different WC grain size alloy could be explained reasonably.The strength of two-phase WC-Co alloy is decided by cobalt content,carbon content and average WC grain size in alloy and so is affected essentially by λ_γ and the wolfram and carbon solubilities in γ-phase. The fracture toughness K_ IC is directly proportional to the σ_ TRS within the λ_γ range of the left brange line of σ_ TRS max ～λ_γ relation curve.The nondestructive examination princaple for microstructure parameters,composition and strength of two-phase WC-Co cemented carbide has been put forward on the basis of deducing the quantitative relations of them with magnetism,denisity and hardness.