Preparation of TiC reinforced steel composites and their characterisation

Abstract

Carbide reinforced steel composites are useful in extensive wear resistance applications. Titanium carbide reinforced steel composites have been prepared by dissolving a TiC rich Fe–TiC master alloy in a liquid steel. The composites have been characterised by optical microscopy, energy dispersive X-ray scanning electron microscope analysis, image analysis, and X-ray diffraction studies. Tensile strength measurements showed that the ultimate tensile strengths varied between 790 and 880 MPa for composites containing 0·7–0·34 wt-%Ti. Some composites show better wear resistance properties in comparison with low alloy steels.     

A Review on the various synthesis routes of TiC reinforced ferrous based composites

The major thrust underlying the processing of Fe-based composites has been directed towards improving the wear resistance of steel or castiron by incorporating some reinforcing phase, e.g., carbides, oxides, etc. The present article provides a review on the various synthesis routes of TiC reinforced Fe-based composites, i.e., powder metallurgy, conventional melting and casting, carbothermic reduction, combustion synthesis, aluminothermic reduction, electron beam radiation, laser surface melting, and plasma spray synthesis, highlighting the advantages and disadvantages associated with the different routes of synthesis.     

Fabrication of in situ TiC reinforced aluminum matrix composites

In the present work, the room and elevated temperature mechanical behavior of Al/TiC, high-strength Al-Si/TiC and the elevated temperature-resistant Al-Fe(-V-Si)/TiC composites has been evaluated. The microstructural characteristics of ingot metallurgy (IM) or rapid solidification (RS) Al-Si/TiC and Al-Fe(-V-Si)/TiC composites could be thought of as a combination of the related alloy matrix microstructures and the IM or RS Al/TiC composites. The IM Al/TiC and the Al-Si/TiC composites show superior strength and ductility to the relevant aluminum based composites.The RS Al/TiC and the Al-Fe-V-Si/TiC exhibit high Young's moduli and substantial improvements in room and elevated temperature tensile properties compared to those of rapidly solidified alloys and conventional composites.The Young's modulus values of RS Al/TiC and Al-Fe-V-Si/TiC composites are well within Hashin-Shtrikman limits in keeping with the strong interfacial bonding. In the micromechanics approach, the principal strengthening mechanisms for the present dispersed particle-hardened RS in situ Al-TiC composites would include Orowan strengthening, grain-size and substructure strengthening, and solid-solution strengthening. The RS technique was used in the present work to maximize strength and ductility for a particular volume fraction, and influence the degree of flexibility available to meet these requirements: a fine, uniform particle size distribution; a high interfacial strength; control of particle shape; and a ductile matrix.     

TiC+TiB2协同增强Al-Cu原位复合材料

为利用TiC和TiB2的协同增强作用,采用基于熔体接触反应法和混合盐反应法的新工艺"两步法"制备了(TiC TiB2)/Al-2Cu原位复合材料.利用扫描电子显微镜及差式扫描量热计对热处理前后的原位复合材料进行了组织及热分析,结果表明:组织中两相粒子的分布比单相粒子增强的情况更加均匀,而且T4处理实现了两相粒子真正意义上的均匀相间分布;相对于单一的Al-2Cu合金,(TiC TiB2)/Al-2Cu的熔化开始温度和凝固开始温度升高,熔化潜热和凝固潜热增大,体系稳定性从而得以提高,T4处理进一步增大了这一趋势.     

Shrinkage of steel fibre reinforced cement composites

The paper presents results of an experimental investigation on the influence of steel fibres on the free shrinkage of cement-based matrices. Shrinkage tests were carried out on cement paste, mortar and two types of concrete mixes for a period of up to 520 days. Melt extract, crimped and hooked steel fibres were used for reinforcement at volume fractions ranging between 1 and 3%. The results indicate that fibres restrain the shrinkage of the various cement matrices to a significant extent, resulting in reductions of up to 40%. Crimped fibres are the most efficient in providing shrinkage restraint. The paper also presents a theoretical expression and an empirical expression which can be used to predict shrinkage strains of steel fibre reinforced cement matrices. The analysis requires a knowledge of the values of coefficient of friction, μ, at the fibre-matrix interface, which are also derived in this paper. The μ values for steel fibres in normal concrete, mortar and cement paste range between 0.07 and 0.12.     

Fibre spacing in steel fibre reinforced composites

A method is presented which makes it possible to evaluate the fibre content or to estimate the distribution of fibres in steel fibre reinforced composite materials from the analysis of X-ray pictures. The basic notion in this method is an apparent fibre spacing defined as the average spacing between the intersections of individual fibre projections upon a certain plane and an arbitrary base line drawn on that plane. Such apparent spacing may be estimated analytically, it may also be measured directly on the radiogram. The comparison of analytical and experimental data shows satisfactory agreement.

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Résumé On présente une méthode qui, par l'analyse des diagrammes de rayons-X, permet d'évaluer la teneur en fibre ou d'estimer leur distribution dans des composites renforcés de fibres d'acier. On suppose que la distribution des fibres est homogène et isotropique, toutes les fibres ayant même longueur et même diamètre. En tant que notion de base de cette méthode, on définit un espacement de fibres apparent comme l'espacement moyen entre d'une part les intersections des projections des fibres individuelles, et d'autre part une ligne de base arbitraire tracée sur le même plan. Un tel espacement apparent (s _{app. anl.} ) peut être évalué analytiquement comme une fonction de la longueur de la fibre (l), du diamètre (d) de la teneur en volume (β) et de l'épaisseur de l'échantillon (w)-équation (7). On peut aussi le mesurer directement sur le radiogramme commes _{app. exp.} [voirfig. 2, équation 12)]. La comparaison des résultats analytiques et expérimentaux (tableau I) montre une bonne concordance. On peut aussi se servir de la méthode pour évaluer l'épaisseur d'échantillons soumis aux rayons-X, ce qui prouverait une bonne lisibilité du radiogramme.

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Evaluation of electroslag remelting in TiC particle reinforced 304 stainless steel

This study is focused on the effect of electroslag remelting (ESR) on microstructure and mechanical properties of TiC particle reinforced 304 stainless steel synthesized by in situ reaction in vacuum introduction melting (VIM). Microstructure observations revealed that applying ESR process resulted in a more uniform distribution of TiC particles with reduced size, however, a slight aggregation with large TiC particles existed in the VIM ingot was found. Additionally, some tiny TiC precipitates with nano-scale were observed in the microstructure of the TiC reinforced steel after ESR process. Introduction of in situ TiC particles into the 304 stainless steel caused a significant increase of tensile properties, creep properties and wear resistance, but a decrease in ductility. Moreover, further improvement on tensile properties, creep properties, wear resistance as well as the ductility of the steel were obtained by using ESR process successfully.     

TiB2 and TiC stainless steel matrix composites

Stainless steel matrix composites reinforced with TiB₂ or TiC particulates have been in situ produced through the reactive sintering of Ti, C and FeB. X-ray diffraction analysis confirmed the completion of reaction. The TiB₂, TiC and steel were detected by X-ray diffraction analysis. No other reaction product or boride was found, indicating the stability of TiB₂ and TiC in steel matrix. The SEM micrographs revealed the morphology and distribution of in situ synthesized TiB₂ and TiC reinforcements in steel matrix. During sintering the reinforcements TiB₂ and TiC grew in different shapes. TiB₂ grew in hexagonal prismatic and rectangular shape and TiC in spherical shape.     

Anisotropic corrosion resistance of TiC reinforced Ni-based composites fabricated by selective laser melting

Electrochemical measurements on three planes of TiC/Inconel 718 composites fabricated by selective laser melting (SLM) were performed to study the corrosion property. The results showed that the YZ-plane with dense and fine columnar structures possessed high microhardness and superior corrosion resistance in 3.5 wt% NaCl solution. For the XZ-plane, a decreased anti-corrosion property was observed owing to its inhomogeneous microstructures. While the XY-plane with large irregular pores and clustered ring-like structures was more susceptible to corrosion compared with the other two planes. Comparative analysis suggested that the anisotropic corrosion behaviors were significantly dependent on the surface defects, microstructure characteristics and added reinforcements.     

Compression creep behaviour of steel fibre reinforced cement composites

The paper presents the results of an experimental investigation to determine the influence of steel fibre reinforcement on the creep of cement matrices under compression. Creep tests were carried out at a number of applied stress-strength ratios ranging between 0.3 to 0.9. Melt extract and hooked steel fibres were used at volume fractions ranging between 0 and 3% by volume of a mix. Three types of cement matrices were used namely cement paste, mortar and two mix proportions of concrete. The results indicate that steel fibres restrain the creep of cement matrices at all stress-strength ratios, the restraint being greater at lower stresses and at higher fibre contents. Steel fibres are effective in restraining only the flow component of creep of cement matrices, the delayed elastic component being unaffected. The reduction in creep of cement pastes, due to fibre reinforcement, is much greater than that for mortar or concrete matrices. Mathematical expressions are given for the creep of steel fibre reinforced cement matrices.

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Résumé Cet article présente les résultats d’une étude expérimentale en vue de déterminer l’influence du renforcement de fibres d’acier sur le fluage de matrices de ciment en compression. On a exécuté les essais de fluage à un certain nombre d’intervalles correspondant à des rapports contrainte/déformation allant de 0,3 à 0,9. On a utilisé des fibres d’acier dans des proportions se situant entre 0 et 3% par volume de mélange, et on s’est servi de trois types de matrices de ciment: pate de ciment, mortier et béton selon deux dosages. Les résultats montrent que les fibres d’acier empêchent le fluage des matrices de ciment dans tous les rapports de contrainte/déformation, l’effet étant plus important pour les contraintes faibles et les teneurs en fibres plus élevées. Les fibres d’acier n’agissent qu’en s’opposant à la déformation plastique des matrices de ciment sans que l’élasticité différée en soit affectée. La diminution du fluage des pates de ciment due au renforcement des fibres est beaucoup plus importante que pour le mortier ou les matrices de béton. On donne des formules mathématiques pour le fluage des matrices de ciment renforcé de fibres d’acier.

     

Microstructure and properties of austenitic stainless steel reinforced with in situ TiC particulate

Austenitic stainless steel reinforced with 5 vol.% TiC particulate was in situ synthesized by in situ reaction during melting process successfully and its microstructure, mechanical properties as well as oxidation behavior were investigated. Microstructure observations revealed that in situ TiC particulates with an average size of 2–10 μm distributed uniformly in the matrix and the interface boundaries between TiC particulates and austenite matrix were clean without any impurities and contaminations. Addition of TiC particulates refined the grain structure of austenitic matrix, but did not cause formation of any new phases in microstructure. Beneficial effects of TiC addition to austenitic stainless steel on both mechanical properties and oxidation resistance were found. Both at ambient and elevated temperature, tensile strengths of the steel with TiC addition were notably higher than those of its matrix alloy, however, a decrease in ductility also appeared, as exhibited by other particulate reinforced alloys. Besides tensile strengths, creep resistance of austenitic stainless steel was also significantly increased by TiC addition at elevated temperature of 923 K. Oxidation test at 1073 K revealed that TiC addition to austenitic stainless steel raised the oxidation resistance of the steel remarkably.     

Rapid in-situ reaction synthesis of novel TiC and carbon nanotubes reinforced titanium matrix composites

In-situ TiC and remained multi-walled carbon nanotubes(MWCNTs) reinforced Ti composites were synthesized using vacuum hot-press sintering and hot rolling. The effect of weight fraction of MWCNTs on microstructural evolution and mechanical properties of the Ti composites was investigated. The results indicated that both proportion and particle size of TiC increased in proportion to MWCNTs content, which resulted in different matrix microstructure, and the grains were obviously refined after rolling deformation. The hardness tests indicated that MWCNTs addition could make the composites harden, and 18.4%improvement in hardness was obtained after hot rolling. The significant improvement in both strength and hardness could be attributed to grain refinement, solid solution strengthening of carbon and dispersion strengthening of TiC particles and remained MWCNTs. A good combination of strength and ductility were achieved in Ti–1 wt% MWCNTs composites, which were in accordance with the uniform distribution of smaller-sized TiC particles in Ti matrix.     

Rapid fabrication of in situ TiC particulates reinforced Fe-based composites by spark plasma sintering

TiC particulates reinforced Fe-based composites have been fabricated using ferrotitanium and carbon black powders with the combination of in situ and spark plasma sintering (SPS) technique. The sintering and densification behaviors were investigated. The results show that when the composite was sintered at 1150 °C for 5 min, the maximum relative density and hardness are 99.2% and 83.2 HRA, respectively. The phase evolution during sintering indicates that the in situ reaction occurs evidently between 850 °C and 1050 °C. The microstructure investigation demonstrates that with the rapid in situ SPS technique, fine TiC particulates with a size of ~ 1 μm are homogeneously distributed in the matrix.     

Fabrication of in situ TiC reinforced aluminum matrix composites Part I: Microstructural characterization

In the present work traditional ingot metallurgy plus rapid solidification techniques were used to in situ produce Al-TiC composites with refined microstructures and enhanced dispersion hardening of the reinforcing phases. Microstructural characterization of the experimental materials were comprehensively done by optical, electron microscopy and X-ray diffraction. The results show that the in situ synthesized TiC particles possess a metastable fcc crystal structure with an atomic composition of TiC08 and a lattice parameter of 0.431 nm. The typical ingot metallurgy microstructures exhibit aggregates of TiC particle phase segregated generally at the -Al subgrain or grain boundaries and consisted of fine particles of 0.2–1.0 m. After re-melting of the ingots and hence rapid solidification, the microstructures formed under certain thermal history conditions contained uniform fine-scale dispersion of TiC phase particles with a size range of 40–80 nm in an Al supersaturated matrix of 0.30–0.85 m grain size. In the most case these dispersed TiC particles have a semi-coherent relationship with the -Al matrix.     

粉末冶金制备工艺对TiC增强高铬铸铁基复合材料性能的影响EI北大核心CSCD

采用高能球磨和真空烧结的方法制备TiC增强高铬铸铁(HCCI)基复合材料。利用SEM,DSC等方法对不同球磨时间的粉末进行分析,研究不同烧结温度对高铬铸铁基复合材料的显微组织、硬度及密度的影响,比较相同工艺下复合材料与高铬铸铁材料的耐磨性。结果表明:球磨12 h后的粉末颗粒大小趋于稳定,粉末活性提高,烧结性能改善,烧结试样中TiC均匀地分布在基体中。随着烧结温度的升高,复合材料内部晶粒逐渐长大,密度和硬度逐渐提高。在1280℃超固相线液相烧结的条件下烧结2 h后,致密度达94.17%,硬度和抗弯强度分别为49.2HRC和980 MPa。在销盘磨损实验中复合材料的耐磨性为单一高铬铸铁材料的1.52倍,磨损机制为磨粒磨损+轻微氧化磨损。     

Impression creep behaviour of TiB2 particles reinforced steel matrix composites

Impression creep behaviour of the powder metallurgy processed steel matrix composites was investigated under constant stress at different temperatures in the range of 873–973?K. By using the power-law relationship, the estimated activation energy for unreinforced steel was found to be 149?kJ?mol^?1 and steel reinforced with 2 and 4?vol.-% TiB₂ was found to be 298 and 338?kJ?mol^?1, respectively indicating better creep resistance of the reinforced steel matrix composites. Dislocation creep is the dominant creep mechanism based on the calculated values of stress exponent and activation energy. Hence, this method can be used to assess the potential of steel matrix composites for use as structural materials for high-temperature application.     

Investigation of mixed-mode fracture of aligned steel fibre reinforced cementitious composites

International Journal of Fracture - Mixed-mode fracture experiments were conducted on aligned steel fibre reinforced cementitious composite (ASFRC) and ordinary steel fibre reinforced cementitious...     

Influence of coating on short steel fiber reinforcements on corrosion behavior of aluminium base short steel fiber reinforced composites

Steel fiber reinforced aluminium composites are attractive materials of high specific strength but exhibit poor resistance against electrochemical corrosion. The study discusses the electrochemical corrosion behavior of uncoated, copper and nickel coated short steel fiber reinforced aluminium and Al–2Mg matrix composites in 1 (N) NaCl solution. Galvanic corrosion between the steel fiber and aluminium governs the corrosion behavior of these composites. It has been observed that open circuit potential (OCP) is shifted to more negative side with copper coating on the fibers and to the more positive side on coating the fibers with nickel. Compared to the uncoated fiber higher corrosion current density indicates corrosion rate was observed for the copper coated fiber reinforced composites where as a lower current density was noted for the nickel coated fiber reinforced composites was observed. Addition of 2 wt% magnesium to aluminium alloy matrix increased the corrosion current density. The corrosion mechanism in these composites is dominated by galvanic cell formation that is evident from the dissolution of Al matrix near the peripheral region of steel fibers.