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Effect of titanium and rare earth microalloying on microsegregation,eutectic carbides of M2 high speed steel during ESR process

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Journal of Rare Earths 2020年第9期38卷 1030-1038,I0005页

作者： Fuxing Yin Lu Wang Zhixia Xiao Jianhang Feng Lin Zhao School of Materials Science and Engineering Hebei University of TechnologyTianjin 300130China Research Institute for Energy Equipment Materials Hebei University of TechnologyTianjin 300130China Tianjin Key Laboratory of Materials Laminating Fabrication and Interfacial Controlling Technology Tianjin 300130China Central Iron and steel Research Institute Beijing 100081China

The effects of RE and Ti microalloying during electroslag remelting(ESR)process on the microsegregation and morphology of eutectic M2C carbides in M2 high speed steel were investigated.The results show that the addition of 0.2 wt%RE can alleviate the segregation of C,W,Mo,V and Cr,while the morphology of eutectic M2C carbides hardly changes.The microalloying with the addition of 0.5 wt%Ti has the lowest degree of microsegregation due to the improvement of primary dendrites by the effective heterogeneous nucleating agent of(Ti,V)(C,N)particles.The addition of Ti makes the mo rphology of M2C carbides change from rod-like or maze-like shape into a coarse feathery shape,exhibiting anisotropic facet growth characteristics.For the microalloying of 0.2 wt%RE and 0.5 wt%Ti,the segregation of the main metal alloying elements is slightly more severe than that of the addition of only RE or Ti.Under the combined action of RE and Ti,the feathery eutectic M2C becomes thinner and shorter and tends to be isolated or distributed in a discontinuous network.

关键词： Microsegregation Morphology Eutectic carbides high speed steel Electroslag remelting Rare earths

Development and Application of Die-Casting high speed steel Rolls

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Journal of Iron and steel Research(International) 2005年第1期12卷 22-27页

作者： JIANGZhi-qiang FUHan-guang DINGYu-cheng ZhengzhouInstituteofAeronautics Zhengzhou450015China Xi＇anJiaotongUniversity Xi＇an710049China Xi＇anJiaotongUniversity Xi＇an710049China／／ZhengzhouInstituteofAeronauticsZhengzhou450015China

Due to its high hardness,good red hardness and excellent wear resistance at high temperature,high speed steel(HSS)is fit for the roll manufacture.In order to overcome the segregation of centrifugal casting of HSS roll,die-cast processes were developed and its effects on the properties of the HSS roll were investigated.It was found that pressure,pressing time and speed are three important factors affecting shrinkage cavity.For pouring temperature of 1 400-1 450 ℃,pressure of 150-160 MPa,pressing time of 120-150 sand pressing speed of 14-16mm/s,a compact HSS roll was obtained,which has no segregation and small working allowance.In the high speed wire rod rolling mill,service life of the HSS roll is 5to 8times longer than that of high nickel chromium infinite chilled cast iron roll.

关键词： high speed steel roll die-cast shrinkage

Study on stable and meta-stable carbides in a high speed steel for rollers during tempering processes

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International Journal of Minerals,Metallurgy and Materials 2013年第2期20卷 146-151页

作者： Jing Guo Hong-wei Qu Li-gang Liu Yan-liang Sun Yue Zhang Qing-xiang Yang State Key Laboratory of Meta-stable Materials Science and Technology Yanshan University School of Material Science and Engineering University of Science and Technology Beijing

A high speed steel （HSS） was studied for rollers in this work. The steel was quenched at 1150℃ and tempered at 520℃. The phase structures of the steel were determined by X-ray diffraction （XRD）, and the hardness of specimens was measured. The volume fraction of carbides was counted by Image-Pro Plus software. The typical microstructures were observed by field emission scanning electron microscope （FESEM）. Stable and meta-stable carbides were deduced by removing the existing phases one by one in the Fe-C equilibrium calculation. It is found that the precipitated carbides are bulk-like MC, long stripe-like M2C, fishbone-like M6C, and daisy-like M7C3 during the tempering process. The stable carbides are MC and M6C, but the meta-stable ones are M2C, M7C3, and M3C.

关键词： high speed steel phase diagrams tempering carbides

Morphology,microstructure and decomposition behavior of M2C carbides in high speed steel

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Journal of Iron and steel Research(International) 2017年第1期24卷 43-49页

作者： Xue-feng Zhou Di Liu Wang-long Zhu Feng Fang Yi-you Tu Jian-qing Jiang Jiangsu Key Laboratory of Advanced Metallic Materials School of Materials Science and EngineeringSoutheast University Nanjing 211189JiangsuChina Jiangsu Engineering Research Center of Tool and Die steel Danyang 212312JiangsuChina Nanjing University of Information Science and Technology Nanjing 210044JiangsuChina

The morphology,microstructure and decomposition behavior of M2C carbides in high speed steels with different chemical compositions have been investigated by scanning electron microscopy,transmission electron microscopy,electron backscatter diffraction and X-ray diffraction.The results show that the morphology and substructure of M2C carbides are very sensitive to chemical compositions of high speed steels.M2C carbides present the plate-like shape in tungsten-molybdenum steel and present the polycrystal orientation in the eutectic cell.In contrast,they show the fibrous shape in molybdenum-base steel and exhibit the monocrystal orientation.Plate-like and fibrous M2C carbides are both metastable and decompose into M6 C together with MC at high temperatures.MC nucleates inside the plate-like M2C while it is formed at the fibrous M2C/matrix interface during the decomposition process.Such differences are expected to arise from different compositions of plate-like and fibrous M2C carbides.

关键词： high speed steel Carbide M2C Morphology Substructure Decomposition

high temperature oxidation behavior of high speed steel for hot rolls material

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Journal of University of Science and Technology Beijing 2005年第2期12卷 166-171页

作者： LiZhou FangLiu ChangshengLiu DaleSun LisongYao SchoolofMaterialandMetallurgy NortheasternUniversityShenyang110004China TechnologyCenter BaoshanIron＆SteelCo.Ltd.Shanghai201900China

The oxidation characteristics of high speed steel (HSS) were studied at 500 to 800°C. The non-isothermal oxidation and isothermal oxidation (500, 575, 650, 725, 800°C) of HSS were investigated by thermo-gravimetric analysis (TGA). The microstruc- ture, morphology and oxide scale thickness of the isothermal oxidation samples were analyzed by optical microscope (OM), electron probe micro analyzer (EPMA), X-ray diffraction spectrum (XRD) and scanning electron microscope (SEM). The results indicate that the oxidation rate of HSS is very slow at 500 to 650°C, increasing gradually at 650 to 750°C, and drastically at 750 to 800°C, be- cause the phase transformation happens at about 750°C.

关键词： high speed steel high temperature oxidation isothermal oxidation non-isothermal oxidation oxide kinetics

Microstructure and Eutectic Carbide Morphology of the high speed steel Strips Produced by Twin Roll Strip Casting Process

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Journal of Materials Science & Technology 2003年第5期19卷 472-474页

作者： Hongshuang DI, Xiaoming ZHANG, Guodong WANG and Xianghua LIUState Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110004, China State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 China

The M2 high-speed steel strip was produced by using the laboratory scale twin roll strip caster. The microstructure and eutectic carbide morphology of thus produced products were observed and analyzed, and the comparison of those with conventional products was carried out. The effects of the processing parameters such as the melting temperature, the pouring temperature, rolling speed and separating force on the microstructure and eutectic carbide morphology and their distribution were analyzed. The spheroidizing process of the strips in the annealing process was investigated. The relations between the growth and spheroidizing of the eutectic carbide and the annealing technology were obtained, and the mechanism of the twin roll strip casting process improving the eutectic carbide spheroidizing was discussed. The theoretical instruction for determining the subsequent treatment process was provided.

关键词： Twin roll strip casting high speed steel Eutectic carbide Microstructure

STUDY ON CRYOGENIC PHASE CHANGE & WEAR CHARACTERISTIC OF high speed steel

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Acta Metallurgica Sinica(English Letters) 2003年第6期16卷 524-530页

作者： M.C.Huang C.H.Gao L.G.Huang DepartmentofMechanicalEngineering FuzhouUniversityFuzhou350002China HefeiUniversityofTechnology Hefei230009China

The microscopic structure change rule in high speed steel (HSS) after an additional cryogenic treatment was studied in this paper. highly dispersed nano-carbide (η-Fe2 C) separated from tempering martensite was found distributed on twin planes of marten-site and dislocation places. Retained austenite was found sheared into martensite and nano-carbide separated at the same time. In addition, the tempering martensite was fine-grained. The stated changes of HSS evidently improve the lifespan of HSS cutter and fully show the advantages of nano-structure. The cryogenic treatment of HSS also improves the roughness of HSS cutter (decrease Ra number by about 50%) and greatly increases the wear resistance of HSS cutter. Further experiments on the wear characteristic of HSS cutter supported the findings mentioned above. The stated HSS treatment technology would implement nano-structure of traditional tool steel through phase change. It could be a new method to improve the performance of HSS cutter.

关键词： high speed steel cryogenic treatment phase change wear char-acteristic nano-structure

Development of centrifugal casting high speed steel rolls

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Journal of University of Science and Technology Beijing 2003年第6期10卷 61-66页

作者： HanguangFu AiminZhao JiandongXing SchoolofMechanicalEngineering Xi‘anJiaotongUniversityXi’an710049China MaterialsScienceandEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083China

The present study aims at developing the high speed steel (HSS) as rollmaterials to replace the traditional roll materials such as the alloy cast iron and powdermetallurgical (PM) hard alloy. The HSS roll billet was formed by centrifugal casting, and the billetwas rough machined alter soften annealing heat treatment, then it was quenched and tempered to getsuitable hardness and toughness. After that the HSS roll was finish machined to the final dimensionof phi 285 mm in the outer diameter, phi 160 mm in the inner diameter and 120 mm in width and itssurface hardness was tested. Finally the HSS roll was used in high speed wire rod mill. The testresults show that a high and homogeneous hardness can obtain on the work surface of HSS rolls, thesurface hardness is 63-65HRC and its variation is smaller than 2HRC. The impact toughness of thiskind of HSS is about 16 J/cm^2. The results of on-line service investigation in high speed wire rodmill indicate that the HSS rolls have excellent wear resistance, the steel rolling quantity per mmof HSS rolls is 3120 t, the service life-span of HSS rolls is 4 times longer than that of highchromium cast iron rolls and it is close to that of the PM hard alloy rolls. The manufacturingburden of HSS rolls is obviously lower than that of the PM hard alloy rolls, it is only 25 percentof that of the PM hard alloy rolls.

关键词： high speed steel centrifugal casting roll segregation crack modification thermal fatigue

Influence of rare earths on eutectic carbides in AISI M2 high speed steel

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Journal of Rare Earths 2012年第10期30卷 1075-1078页

作者：周雪峰殷晓燕方峰蒋建清朱旺龙 Jiangsu Key Laboratory of Advanced Metallic Materials Southeast University Jiangsu Engineering Research Center of Tool and Die steel

The effect of rare earths on the morphology and microstructure of eutectic carbides in M2 high speed steel was studied. The results showed that rare earths promoted the forrmation of fishbone-like M6C eutectic carbides, compared to plate-like M2C carbides in ingots without modification. The formation of M6C was expected to be caused by rare earth inclusions which acted effectively as the substratc for nucleation of M6C carbides during solidification. M2C and M6C eutectic carbides exhibited different stability during heating. M2C eutectic carbides were much less stable than M6C carbides, and decomposed at high temperatures, favoring the spheroidization and refmement of carbides inhigh speed steels.

关键词： rare earths eutectic carbide morphology microstructure high speed steel