Modification of Fe-Cr-C alloys using mischmetal
Modification of Fe-Cr-C alloys using mischmetal
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DOI：
10.1007/bf00416817
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
K. Peev;M. Radulovic;M. Fiset
中科院分区：
文献类型：
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作者：
K. Peev;M. Radulovic;M. Fiset
高铬白口铸铁作为一种耐磨材料被广泛使用。最常用的是含有18-22% Cr的亚共晶合金[1-4]。这些合金的显微组织由初生奥氏体枝晶和共晶碳化物组成，由m7c3碳化物和奥氏体组成[5-8]。对技术进步和成本效益的需求强调了提高Fe-Cr-C合金质量的必要性。通过热处理、改性或附加合金化可以提高合金质量。混合稀土多年来一直被用作灰口铸铁和球墨铸铁的改性剂。有报道表明混合稀土对非合金和低合金白口铸铁的组织和性能有积极影响[9-16]。然而，关于混合稀土[17]对高铬白口铁的改性效果的资料很少。本文考察了混合稀土在铸态和热处理后对高铬铁的组织和性能的影响。选择含3.03% C、16.2% Cr、0.55% Si、0.85% Mn、0.72% Cu、0.92% Mo和0.30% Ni的碱性合金，并采用感应炉进行熔炼。在混合稀土处理前后，将样品（用于磨损测试的10 mm × 20 mm × 55 mm测试块和用于断裂韧性测试的13 mm × 13 mm × 55 mm测试块）倒入膨润土砂混合模具中。用于结构分析和硬度分析的样品选自磨损试验块。中子活化分析表明，改性合金的稀土元素含量为0.23% （Ce 0.13%, La 0.06%, Nd 0.04%）。样品在无保护气氛的电炉中950℃热处理1小时，在静止空气中冷却至室温。用常规光学显微镜观察其微观结构。用图像分析仪测定了共晶碳化物的含量。磨料耐磨性通过测量质量损失来确定，遵循美国材料试验协会（ASTM）标准规程G-65，程序B（橡胶轮磨损试验）[18]中描述的程序。动态断裂韧性的测量采用了配备仪器查比盘的冲击试验机。通过电火花加工（EDM）在标准Charpy试样上刻槽，槽深为2mm，半径为0.2 mm。断裂载荷用于计算Kid
High-chromium white cast iron is widely used as a wear-resistant material. The use of hypoeutectic alloys containing 18-22% Cr is most common [1-4]. The microstructure of these alloys consists of primary austenite dendrites and eutectic carbides, composed of M7C 3 carbides and austenite [5-8]. The demand for technological advancements and cost-effectiveness has underscored the need to improve the quality of Fe-Cr-C alloys. The alloy quality can be improved by means of heat treatment, modifying or additional alloying. Mischmetal has been used for many years as a modifying agent to improve the properties of grey and ductile irons. Reports have demonstrated the positive influence of mischmetal on the microstructure and properties of non-alloyed and low-alloyed white cast irons [9-16]. However, there is little information available on the effects of modifying high-chromium white iron using mischmetal [17]. This letter examines how mischmetal affects the microstructure and properties of high-chromium iron in the as-cast condition and after heat treatment.A basic alloy containing 3.03% C, 16.2% Cr, 0.55% Si, 0.85% Mn, 0.72% Cu, 0.92% Mo and 0.30% Ni with the usual impurities was selected and an induction furnace was used for melting. Before and after treatment with mischmetal, samples (10 mm x 20 mmx 55 mm test blocks for abrasion tests and 13 mm x 13 mm x 55 mm test blocks for fracture toughness) were poured into bentonite sand mixture moulds. Samples for structural analysis and hardness were selected from abrasion test blocks. Neutronic activation analysis revealed that the modified alloy contained 0.23% rare-earth elements (0.13% Ce, 0.06% La and 0.04% Nd). Samples were heat-treated at 950 C for 1 h in an electric furnace with no protective atmosphere and were cooled to room temperature in still air. The microstructure was examined using conventional optical microscopy. The amount of eutectic carbide was determined by means of an image analyser. The abrasive wear resistance was determined by measuring the loss of mass, following the procedure described in American Society for Testing and Materials (ASTM) Standard Practice G-65, Procedure B (Rubber Wheel Abrasion Test)[18]. The dynamic fracture toughness was measured using an impact testing machine equipped with an instrumental Charpy tup. The standard Charpy specimen was notched by electrical discharge machining (EDM) with a 0.2 mm-radius slot 2 mm in depth. The fracture load was used to calculate Kid