硬质合金的断裂韧性及其无损评估

FRACTURE TOUGHNESS K_(1c), OF CEMENTED CANBIDES AND ITS NONDESTRUCTIVE EVALUATION

用Ｘ射线衍射相分析、扫描电镜、Ｐａｌｍｑｖｉｓｔ压痕试验和磁性分析对烧结态两相ＷＣ－Ｃｏ硬质合金断裂韧性Ｋｌｃ的研究表明，在两相区碳成分范围内，随合金碳含量的变化，合金的Ｋｌｃ（ＭＰａｍ^（１／２））和比矫顽磁力Ｈ_（ＳＣ）（Ａ·ｍ~２·ｋｇ^（－１））间具有正向相关的变化规律：Ｈ_（ＳＣ）＝７．６５２－０．３３０４１－７．３５６Ｘ_（Ｃｏ）－１２０．０Ｘ_ｃ，Ｋ_（１ｃ）＝１７．３９＋２６．０４ｌｇ＋２２．２９Ｈ_（ｓｃ）＝６２０．８－５６． ５７Ｈ_（ｓｃ）－９４６２Ｘ_ｃ－５８０．１Ｘ_（Ｃｏ）。用比饱和磁化强度４πσ（Ａ·ｍ~２·ｋｇ^（－１））和矫顽磁力Ｈｃ（ｋ·Ａ·ｍ^（－１））测定值预先确定合金试样的碳含量 Ｘｃ、真实钻含量 Ｘ_（Ｃｏ）（Ｗｔ．）和比矫顽磁力Ｈ_（ｓｃ）Ａ·ｍ~２·ｋｇ^（－１））可通过上式用磁性无损评估烧结态两相 ＷＣ－Ｃｏ硬质合金的断裂韧性Ｋ_（１ｃ），评估精度优于５％。

The fracture toughness K_(1c) of sintered two-phase WC-Co cemented carbides was studied by means of XRD, SEM, Palmqvist pressure mark test and magnetic analysis. The result shows that the change regularity of K_(1c) of two-phase WC-Co alloy bears a simple positive-going relation to that of H_(sc) when alloy carbon content varies: H_(sc)= 7.652-0.33041g() - 7.356X_(Co) - 120.OX_c, K_(1c) = 17.39 + 26.05lg(L_(wc)) + 22.29H_(sc) = 620.8 - 580.1X_(Co) - 9462X_c- 56.57H_(sc). The K_(1c)(MPam^(1/2)) of sintered two-phase WC-Co alloy can be evaluated nondestructively by means of above formulas and by H_(sc)(A·m^2·kg^(-1)) when the carbon content X_c(wt.), the true cobalt content X_(Co)(wt.) in alloy and the specific coercive force H_(sc)(A·m^2·kg^(-1)) were beforehand examined by the specific saturation magnetization 4πσ(A·m·~2kg^(-1)) and the coercive force H_c (A. m-1). An accuracy of 5%(relative error) for evaluating K1c of sintered two-phase WC-Co alloy can be obtained.