含铌铸铁冶金学基础

论述了铌对铸铁显微组织和性能的影响,铌在铸铁中以NbC形式与奥氏体形成共晶体。在共晶体中NbC呈条形放射状。在铌铸铁中加入钛,形成TiC先于NbC析出,随后NbC围绕TiC结晶,最终形成团块状。     

铌对高铬锰白口铸铁断裂韧度和耐磨性的影响

研究了铌对高铬锰白口铸铁断裂韧度和耐磨性的影响规律。结果表明：在高铬锰白口铸铁中加入适量的铌，能提高断裂韧度和耐磨性，在使用较软磨料时，含铌0．5％的高铬白口铸铁，经650℃预处理和850℃淬火后，具有较好的耐磨性和断裂韧度的配合。     

铌白口铸铁抗磨料磨损性能的研究

在白口铸铁中加入微量铌元素，通过其抗磨损试验，组织，磨面及磨电镜观察分析，研究了铌元素及热处理工艺对白口铸铁抗磨损性能的影响     

铌在铸铁中的应用及其作用情况介绍

介绍了铌合金在灰铸铁、球墨铸铁、不完全激冷（indefinite chill）铸铁和镍抗可焊接（weldable Ni-Resist）铸铁中的应用情况;分析了铌合金在铸铁中的作用机理,认为NbC能为共晶团提供核心是加Nb细化共晶团的原因,而且NbC的弥散分布可以提高铸铁耐磨性、硬度和强度;综述了铌合金化技术原理,指出铸铁加铌合金化主要有与固体废铁料一起加入大块料和出铁时加入细颗粒两种较为经济的方法。     

耐磨铸铁30年发展展望

概述了含铌铸铁,含硼铸铁,含钒、钛、稀土白口铸铁,镍硬铸铁和高铬白口铸铁生产工艺的进展情况;介绍了在各种不同磨料磨损条件下高铬铸铁的化学成分及显微组织的恰当选择;指出通过细化碳化物,高铬白口铸铁的冲击韧性可以得到提高。     

TiC-NbC超硬质相耐磨堆焊焊条的研究

本文采用廉价钛铁、铌铁和含碳材料等．以焊条药皮合金化，通过电弧冶金反应，获得含TiC、NbC超硬质相的堆焊层。极大地提高了堆焊层的耐磨性。研制出含TiC－NbC新型耐磨合金堆焊条。具有广泛地应用前途。     

Nb强化铸铁机理的基础研究

介绍了Nb在铸铁中的应用现状,对富铌相在铸铁中的存在形式和形成条件进行了热力学分析。通过NbC和铸铁组织中的γ-Fe和石墨的晶格点阵的二维错配度计算,证实了NbC可以成为石墨异质晶核的衬底。提出了进一步研究Nb元素对铸铁作用机理的方向。     

铌对高铬锰白口铸铁组织和性能的影响

研究了铌对高铬锰白口铸２的组织和性能的影响规律。结果表明，在高铬锰白口铸铁中加入微量的铌能细化晶粒。改善碳化物的形貌和分布。当铌加入量为０．２％时，在８５０℃淬火，力学性能获得最佳配合，冲击韧度为７ｊ／ｃｍ＾２，硬度的６２ＨＲＣ。     

铌、钒含量对碳化物增强型无限冷硬铸铁轧辊显微组织的影响

利用光学显微镜、扫描电子显微镜以及X-射线能谱议,分析了碳化物增强型无限冷硬铸铁轧辊的基体组织特性、碳化物和石墨的形态及分布特点。显微观察分析结果表明,熔化过程中加入钒会显著降低石墨含量;随着铌含量的增加,NbC的数量相应增多;添加的铌含量超过一定限度, NbC大量偏聚于轧辊外层。     

原位自生NbC陶瓷增强铁基复合材料研究

采用原位反应与两步法热处理结合方法,使铌丝提供的铌原子与灰口铸铁中石墨提供的碳原子发生原位自生反应,制备了NbC增强铁基复合材料。采用XRD、SEM、TEM等检测手段对复合材料的物相组成与组织结构进行分析,利用显微硬度计对复合材料进行硬度与显微压痕形貌及压痕裂纹分析。结果表明,通过原位反应成功制备了NbC增强铁基复合材料,该复合材料的主要物相组成为α-Fe、Nb、NbC、G。NbC/Fe陶瓷层的厚度约为242±3μm,NbC/Fe陶瓷层与Nb丝、铁基体之间呈现良好的冶金结合。NbC陶瓷颗粒形貌为标准的立方体,NbC/Fe陶瓷层的显微硬度是铁基体的3～4倍。     

Enhancement of wear resistance and impact toughness of as cast hypoeutectic high chromium cast iron using niobium

The effect of niobium additions on the as-cast microstructure of a hypoeutectic high-Cr cast iron containing 2.2 wt.% C and 16.5 wt.% Cr was investigated. With increasing niobium content, the eutectic M₇C₃ carbides were refined and became less elongated as well as its volume fraction was decreased gradually. The first precipitated NbC particles could be act as heterogeneous substrate of proeutectic austenite and a barrier to M₇C₃ grain growth. The morphology of NbC carbides changed with increasing niobium content. Such NbC particles were increased with increasing Nb content and subsequently contributed to increased hardness. Optimum toughness was obtained for the irons alloyed with 2.14% Nb. The effects of applied load and Nb-additions on wear resistance of high chromium cast iron have been studied. The results showed that wear resistance increases with increasing Nb addition. Furthermore, the effectiveness of the NbC particles on the weight loss was more evident at higher loads.     

Nb在铸铁中的物理冶金学作用原理

介绍了Nb在铁基合金中的存在形式,根据NbC和NbN在不同铁基合金中的溶度积公式,分析了Nb在铸铁中的存在形式。在此基础上,分析了Nb在铸铁中的作用机理。固溶Nb具有非常重要的调节共析相变及强化铁素体基体的作用,凝固过程析出的Nb（C,N）可显著提高耐磨性,在奥氏体温度区间晶界析出的Nb（C,N）能有效阻止晶粒长大,合适的成分设计和工艺措施可充分发挥Nb的作用效果。     

Niobium alloying effect in high carbon equivalent grey cast iron

The effect of niobium on the formation of NbC phase and solidification structure in high carbon equivalent grey cast iron was investigated.The experimental results indicated that an increase in the niobium content is favorable to refining the graphite and eutectic cell;and the pearlite lamellar spacing is reduced.Based on the thermodynamic calculation the formation of NbC is prior to the eutectic reaction.The reduction in the pearlite lamellar spacing is mainly attributed to the decrease of eutectic tempera...     

Microstructure of vanadium-, niobium- and titanium-alloyed high-chromium white cast irons

In the present work, additions of 2% vanadium, 2% niobium and 2% titanium were respectively made to a high-chromium white iron (17% Cr) to analyse the effect of these elements on the as-cast structure of the alloy, and their influence on the material's hardness. This study was carried out for different solidification rates, so the alloys were cast into wedge-shaped copper moulds. The recorded solidification rates for the ingots ranged from 1.5 K sec^?1 for a 2 mm thickness section, to 35 K sec^?1 for a 40 mm section. It was found that the addition of these carbide forming elements considerably increased the alloy's hardness by different mechanisms. Vanadium was shown to partition completely to the eutectic carbide phase which increased hardness and the volume fraction of this phase. Niobium and titanium formed extremely hard NbC and TiC respectively, which in turn produced a refinement in the structure and contributed to the increase in hardness of the iron. There was no evidence that these elements influenced the size and morphology of the eutectic carbide M₇C₃ for the experienced solidification rates.     

含钨量对铸态290Cr26MoW耐磨铸铁组织和硬度的影响

铸态合金耐磨铸铁适用于大型或复杂结构耐磨件。通过金相组织观察、X射线衍射相结构分析、图像分析仪定量金相测试和力学性能检测,研究了含钨量对铸态290Cr26MoW耐磨铸铁组织、结构和硬度的影响规律。结果表明,在含0～2.79%W的范围内,随着含W量的增加,铸态290Cr26MoW耐磨白口铸铁的初生基体数量减少,共晶团数量增加,共晶碳化物数量增加;铸态290Cr26MoW耐磨白口铸铁的碳化物结构类型没有改变,M7C3型碳化物为共晶碳化物;铸态290Cr26MoW耐磨白口铸铁基体的奥氏体比例增加,马氏体减少。马氏体多位于共晶团,即共晶碳化物周围。铸态290Cr26MoW耐磨白口铸铁的硬度由共晶碳化物数量和硬度以及基体中奥氏体和马氏体数量比共同决定。     

C、Cr、Si、Mn对低铬白口铸铁组织和力学性能的影响

应用湿砂铸型浇注低铬白口铸铁，采用正交试验研究了C、Cr、Si、Mn对低铬白口铸铁组织和力学性能的影响。结果表明：含碳量2．4％和2．7％时碳化物基本上是呈网状分布的，形成了离异共晶的网状碳化物组织；而含碳量3．0％时，离异共晶组织不再出现。高碳、低硅、高铬和低锰有利于提高硬度；低碳、低硅、中铬和高锰有利于提高冲击韧度；高碳、低硅、低铬和高锰有利提高耐磨性。新开发的低铬白、口铸铁的硬度、冲击韧度和耐磨性远高于目前在生产排沙潜水泵过流部件中所使用材料的各项性能，使用寿命是其5倍左右。     

Effect of Ti-V-Nb-Mo addition on microstructure of high chromium cast iron

The effects of trace additions of multi-alloying elements (Ti,Nb,V,Mo) on carbides precipitation and ascast microstructure of eutectic high chromium cast iron containing 2.85wt.％C and 31.0wt.％Cr were i...     

Semisolid heat treatment of chromium cast iron

Abstract

The effect of semisolid heat treatment on the microstructures of three chromium white cast irons has been studied. The primary objective was to examine the effect of semisolid heat treatment on the microstructures with specific emphasis on revealing the variations related to the carbide morphology of the selected materials. It is found that graphitization of carbide in a 1·5 wt.% chromium cast iron is enhanced during isothermal heat treatment in the semisolid state. The eutectic carbide in high chromium cast irons is fully or partially modified into discrete particles during heat treatment in the semisolid state.