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Comparisons of corrosion behaviour for X65 and low Cr steels in high pressure CO2-saturated brine

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Journal of Materials Science & Technology 2020年第6期41卷 21-32页

作者： Yong Hua Sikiru Mohammed Richard Barker Anne Neville Institute of Functional Surfaces School of Mechanical Engineering University of Leeds Leeds LS2 9JT United Kingdom

Appropriate materials for injection pipelines and tubing for carbon dioxide geologic storage is fundamental to ensure asset integrity and save cost.This paper evaluates the corrosion behaviour of X65,1Cr,3Cr and 5Cr,which have the potential to be injection pipeline/tubing materials.The influence of steel Cr content on the general and localised corrosion behaviour was investigated at time periods from 6 to 192 h at 60℃and 100 bar.The evolution,morphology and chemistry of corrosion products on the surface of each material were evaluated using a combination of scanning electron microscopy,energy dispersive X-ray spectroscopy and X-ray diffraction and related to their overall corrosion protection.Results indicate that prior to the formation of protective films on the steel surfaces,the resistance of the materials to corrosion increase with increasing Cr content(Corrosion resistance:X65steels significantly varies and decreases with increasing Cr content.×65 becomes the material with the lowest general corrosion rate by the end of the 192 h experiments and 5Cr exhibits the highest corrosion rate(ranking of corrosion resistance:X65>1Cr>3Cr>5Cr).In terms of the corrosion products on X65,both inner amorphous and outer crystalline corrosion layers consist of FeCO3.For the Cr-containing steels,the outer layer also comprises FeCO3,but the inner layer is enriched with Cr,and is predominantly amorphous Cr(OH)3.The extent of localised corrosion(determined using surface profilometry)is noticeably less for X65 compared to the Cr-containing steels.The paper raises questions about the benefits that low Cr steels offer towards extending component design life compared to carbon steel under the test conditions considered here.

关键词： Carbon dioxide Corrosion X65 Low-Cr steels Iron carbonate Chromium hydroxide

AlTiN and AlTiON-coated hot work tool steels for tooling in steel thixoforming

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中国有色金属学会会刊：英文版 2010年第S3期20卷 1022-1028页

作者： Y.BIROL D.ISLER Materials Institute Marmara Research CentreGebzeKocaeliTurkey Department of Metallurgy and Materials Engineer ing Istanbul Technical UniversityIstanbulTurkey

X32CrMoV33 hot work tool steel samples coated with AlTiN and AlTiON were submitted to thermal cycling under conditions that approximate thixoforming of steels and to sliding wear tests at 750 ℃,measured to be the cavity surface temperature shortly after the steel slurry is forced into the thixoforming die.AlTiN and AlTiON coatings provide adequate protection against oxidation of the tool steel substrate,but fail to avoid thermal fatigue cracking.This is attributed to the extensive softening of the substrate,the thermal expansion mismatch between the hot work tool steel and the coatings and residual compressive stresses inherited from the deposition process.The impact of AlTiN and AlTiON coatings on the high temperature wear resistance,on the other hand,is favourable.The improved wear resistance is attributed to the stable,protective surface oxide films.

关键词： thixoforming physical vapor deposition coating tooling steels thermal fatigue wear

Formation of FeMo_2B_2 phase in boron containing 9Cr-1.5Mo ferritic steels

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Rare Metals 2006年第Z2期25卷 213-219页

作者： JUNG Woo-Sang HONG Suk-Woo SONG Sang-Min SOOK-In Kwun CHUNG Soon-Hyo Materials Science & Technology Division Korea Institute of Science & Technology Seoul 136-791 Korea Department of Materials Science and Engineering Korea University Seoul 136-713 Korea

The segregation and diffusion of boron during heat treatments were studied. The influence of boron contents, aging time and applied stress on FeMo2B2 formation was also studied. Finally, the effects of boron contents and FeMo2B2 formation on the high temperature strength were studied. Boron atoms were segregated to prior austenite grain boundary during normalizing treatment. And these boron atoms were slowly diffused into the grain interior during tempering and aging at 700 ℃. The FeMo2B2 phase was only formed after 1,000 h aging at 700 ℃ in alloy containing 196 ppm boron. The formation of FeMo2B2 phase is accelerated by the applied stress. It was expected that the formation of FeMo2B2 is closely related to the redistribution of boron atoms. The tensile strengths at 700 ℃ are increased with the increase of boron contents. However, the formation of FeMo2B2 phase results in lower tensile strength.

关键词： 9Cr-1.5Mo ferritic steels precipitation behavior boron effect FeMo2B2 phase tensile strength

Tribological behavior of CrN-coated Cr–Mo–V steels used as die materials

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International Journal of Minerals,Metallurgy and Materials 2017年第12期24卷 1394-1402页

作者： Gulsah Aktas Celik Seyda Polat S.Hakan Atapek Kocaeli University Faculty of EngineeringDepartment of Metallurgical and Materials EngineeringUmuttepe Campus41380 KocaeliTurkey

DIN 1.2343 and 1.2367 steels are commonly used as die materials in aluminum extrusion, and single/duplex/multi-coatings enhance their surface properties. The design of an appropriate substrate/coating system is important for improving the tribological performance of these steels under service conditions because the load-carrying capacity of the system can be increased by decreasing the plastic deformation of the substrate. In this study, the tribological behavior of CrN-coated Cr–Mo–V steels(DIN 1.2343, 1.2367, and 1.2999 grades) was investigated using different setups and tribological pairs at room and elevated temperatures. The aim of this study was to reveal the wear resistance of a suggested system(1.2999/CrN) not yet studied and to understand both the wear and the failure characteristics of coated systems. The results showed that(i) among the steels studied, the DIN 1.2999 grade steel exhibited the lowest friction coefficient because it had the highest load-carrying capacity as a result of secondary hardening at elevated temperatures;(ii) at room temperature, both abrasive tracks and adhesive layers were observed on the worn surfaces; and(iii) a combination of chemical reactions and progressive oxidation caused aluminum adhesion on the worn surface, and the detachment of droplets and microcracking were the characteristic damage mechanisms at high temperatures.

关键词： Cr–Mo–V steels CrN coating aluminum extrusion tribological behavior

Twinned substructure in lath martensite of water quenched Fe-0.2%C and Fe-0.8%C steels

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Journal of Materials Science & Technology 2020年第14期47卷 126-132页

作者： Haidong Sun Yuhui Wang Zuohua Wang Ning Liu Yan Peng Xiujuan Zhao Ruiming Ren Hongwang Zhang National Engineering Research Center for Equipment and Technology of Cold Strip Rolling College of Mechanical EngineeringYanshan UniversityQinhuangdao066004China Liren College of Yanshan University Yanshan UniversityQinhuangdao066004China School of Materials Science&Engineering Dalian Jiaotong UniversityDalian116028China

In the present investigation,twinned substructures within lath martensite of two water quenched steels(0.2 wt.%C and 0.8 wt.%C)were studied.The lath martensite has typical hierarchical packet-block-lath with dislocation substructure.Besides,laths that are misoriented by/70.5°or/60° and bordered by{011}plane,namely twinned laths,are observed,of which the density increases and the scale decreases as more carbons were presented.Such twinned laths have body centered cubic(bcc)crystal structure,belonging to twinned variants following the classical Kurdjumov-Sachs(K-S)orientation relationship with respect to the parent austenite.Unlike bcc{112}twins,twinned variants produce strong double diffraction and in turn the extra diffraction spots that are commonly observed in the martensite in steels with wide range of carbon contents.

关键词： Twinned variant Lath martensite Double electron diffraction Orientation relationship steels

Effect of partial replacement of carbon by nitrogen on intergranular corrosion behavior of high nitrogen martensitic stainless steels

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Journal of Materials Science & Technology 2019年第10期35卷 2357-2364页

作者： Wei-Chao Jiao Hua-Bing Li Jing Dai Hao Feng Zhou-Hua Jiang Tao Zhang Da-Ke Xu Hong-Chun Zhu Shu-Cai Zhang School of Metallurgy Northeastern UniversityShenyang 110819China Corrosion and Protection Division Shenyang National Laboratory for Materials ScienceNortheastern UniversityShenyang110819China

The microstructure evolution and intergranular corrosion(IGC) behavior of high nitrogen martensitic stainless steels(MSSs) by partial replacing C by N were investigated by using microscopy, X-ray diffraction, nitric acid tests and double-loop electrochemical potentiokinetic reactivation(DL-EPR) tests. The results show that the partial replacement of C by N first reduces and then increases the size and content of precipitates in high nitrogen MSSs, and converts the dominant precipitates from M23C6 to M2N,furthermore first improves and then deteriorates the IGC resistance. The high nitrogen MSS containing medium C and N contents provides good combination of mechanical properties and IGC resistance.

关键词： High nitrogen martensitic stainless steels Precipitation Intergranular corrosion DL-EPR

Microstructural Characteristics and Mechanical Properties of Low-Alloy, Medium-Carbon steels After Multiple Tempering

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Acta Metallurgica Sinica(English Letters) 2019年第1期32卷 74-88页

作者： Erfan Abbasi Quanshun Luo Dave Owens Materials and Engineering Research Institute Sheffield Hallam University Tyzack Machine Knives Ltd

The microstructure and mechanical properties of NiCrMoV-and NiCrSi-alloyed medium-carbon steels were investigated after multiple tempering. After austenitising, the steels were hardened by oil quenching and subsequently double or triple tempered at temperatures from 250 to 500 °C. The samples were characterised using scanning electron microscopy and X-ray diffraction, while the mechanical properties were evaluated by Vickers hardness testing, V-notched Charpy impact testing and tensile testing. The results showed that the retained austenite was stable up to 400 °C and the applied multiple tempering below this temperature did not lead to a complete decomposition of retained austenite in both steels. It was also found that the microstructure, hardness and impact toughness varied mainly as a function of tempering temperature,regardless of the number of tempering stages. Moreover, the impact toughness of NiCrMoV steel was rather similar after single/triple tempering at different temperatures, while NiCrSi steel exhibited tempered martensite embrittlement after single/double tempering at 400 °C. The observed difference was mainly attributed to the effect of precipitation behaviour due to the effect of alloying additions in the studied steels.

关键词： Medium-carbon steels Multiple tempering Alloying addition Mechanical properties Retained austenite Precipitation behaviour

Tempering stability of Fe–Cr–Mo–W–V hot forging die steels

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International Journal of Minerals,Metallurgy and Materials 2017年第10期24卷 1145-1157页

作者： Yuan-ji Shi Xiao-chun Wu Jun-wan Li Na Min School of Materials Science and Engineering Shanghai University Shanghai 200072 China

The tempering stability of three Fe–Cr–Mo–W–V hot forging die steels(DM, H21, and H13) was investigated through hardness measurements and transmission electron microscopy(TEM) observations. Both dilatometer tests and TEM observations revealed that DM steel has a higher tempering stability than H21 and H13 steels because of its substantial amount of M_2C(M represents metallic element) carbide precipitations. The activation energies of the M_2C carbide precipitation processes in DM, H21, and H13 steels are 236.4, 212.0, and 228.9 kJ/mol, respectively. Furthermore, the results indicated that vanadium atoms both increase the activation energy and affect the evolution of M_2C carbides, resulting in gradual dissolution rather than over-aging during tempering.

关键词： tempering stability hot forging die steels carbide precipitation

Effect of TiN Particles and Grain Size on the Charpy Impact Transition Temperature in steels

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Journal of Materials Science & Technology 2012年第10期28卷 878-888页

作者： J.Du M.Strangwood C.L.Davis School of Metallurgy and Materials University of Birmingham

The toughness of ferritic steels is influenced by the grain size distribution, second phase, precipitates and coarse inclusions. In this work an examination of the effect of coarse TiN particles （〉0.5 μm） and ferrite grain size on the Charpy impact transition temperature in high strength low alloyed steels has been carried out. steels with high Ti content （up to 0.045 wt%）, have been heat-treated and furnace cooled to obtain a ferrite-pearlite microstructure with different ferrite grain sizes. Coarse TiN particle size and ferrite grain size distributions have been measured and Charpy impact testing has been carried out. Scanning electron microscopy （SEM） analysis has been used to measure the grain boundary carbide thickness and to determine if the coarse TiN particles are acting as cleavage initiation sites by fractographic analysis. The Charpy ductile-brittle transition temperatures （DBTT） have been predicted using standard literature equations, and compared to the measured values. The relationship between the ferrite grain size and coarse TiN particle size and number density in terms of whether the coarse TiN particles act as effective cleavage initiation sites is discussed in this paper.

关键词： TiN particles Grain size Charpy impact test Ductile-brittle transitiontemperatures （DBTT） steels