检索结果-南通市图书馆

Ni segregation and thermal stability of reversed austenite in a Fe–Ni alloy processed by QLT heat treatment

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2015年第11期34卷 776-782页

作者： Tao Pan Jing Zhu Hang Su cai-fu yang Division of Structural Materials Central Iron and Steel Research Institute School of Materials Science and Engineering Tsinghua University

High-resolution transmission electron microscopy(HRTEM) and X-ray diffraction(XRD) were used to investigate Ni segregation and thermal stability of reversed austenite(RA) in a Fe–Ni alloy processed by quench–lamellarize–temper(QLT) heat treatment. The results show that the 77 K impact energy of the alloy increases with RA content increasing. As an austenite-stabilizing element, Ni is found to segregate in RA, though Ni is not evenly distributed within RA. The amount of segregations increases near the boundary(twice as high as the balanced content)and decreases to some extent in the center of the RA regions. Ni concentration in matrix near the boundary is lower than that in matrix far from the boundary because of Ni atom transportation from a to c near the boundary. RA in this alloy has high heat and mechanical stability but is likely to lose its stability and transform to martensite when a mechanical load is applied at ultralow temperatures(77 K), which induces plasticity.

关键词： Reversed austenite Quench–lamellarize–temper Compo

Hot roll bonding between commercially pure titanium and high-strength low-alloy steel using Fe interlayer

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2019年第10期26卷 1126-1136页

作者： Xi-yang Chai Gang Chen Feng Chai Tao Pan Zhi-gang yang cai-fu yang Department of Structural Steel Central Iron and Steel Research InstituteBeijing 100081China School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China

Hot roll bonding was carried out between commercially pure titanium TA2 and high-strength low-alloy steel Q390 using no interlayer and Fe interlayer at temperatures of 850,900,950 and 1000℃with a total reduction ratio of 86.7%.Interfacial microstructure and bonding property of clad plates were investigated by electron microscopy and shear *** results showed that with the increase in heating temperature,the shear strength of titanium clad steel plates decreases *** with that of titanium clad steel plates with no interlayer,inserting Fe interlayer between titanium and steel can improve the shear strength at 850 and 900℃but deteriorate the shear strength at 950 and 1000℃.The reason for this consequence was that Fe interlayer prevented the reaction diffusion of C in titanium to form a thinner TiC layer at 850 and 900℃,while Fe interlayer promoted the reaction diffusion of Fe in titanium to generate thicker Fe2Ti and FeTi intermetallic compound layers at 950 and 1000℃.

关键词： Titanium clad steel plate Fe interlayer TiC Intermetallic compound Hot roll bonding

Effect of modifying matrix microstructures and nanosized precipitates on strengthening mechanisms and ductile-to-brittle-transitiontemperature in a 1000 MPa Ni-Cr-Mo-Cu steel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2022年第8期29卷 1257-1276页

作者： Fei Zhu Li yang Feng Chai Xiao-bing Luo cai-fu yang Zheng-yan Zhang Department of Structural Steels Central Iron and Steel Research InstituteBeijing 100081China Material Digital R&D Center China Iron and Steel Research Institute GroupBeijing 100081China

A superior combination of yield strength(1001 MPa)and-20℃ impact toughness(166 J)was obtained in Nb-V-Timicroalloyed Ni-Cr-Mo-Cu steel treated by direct quenching and tempering route(DQT).The tested steels treated by DQT route and re-austenitization and tempering route(QT)were compared with each other in terms of mechanical properties and microstructures characterized by optical microscopy,transmission electron microscopy,X-ray diffraction,electron back-scattered diffraction method and so *** and Vickers hardness of the tested steel treated by the above two routes vary with isothermal aging temperature(400-600℃),shown as under-aged state,peak-aged state and overaged *** DQT specimens show higher strength and Vickers hardness than QT specimens with the same aging ***,the largest difference of yield strength between DQT and QT specimens was shown in DQT600 and QT600 ***600 or QT600 specimens refers to direct quenched(DQ)or quenched(Q)specimens isothermally aged at 600℃.The main disparities in quenched microstructure between DQ and Q specimens are mainly in morphology of prior austenite grains,dislocation density of martensite matrix and solution amount of Nb and Mo elements dissolving in martensite matrix,which play key roles in affecting microstructure and mechanical properties of DQT and QT *** dislocation density of matrix and finer average diameter of both MC(M is any combination of Nb,Mo and V)and Cu-rich particles were shown in DQT600 specimens than in QT600 *** from dislocations and nanosized MC and Cu-rich particles mainly leads to the largest difference of yield strength between DQT600 and QT600 *** addition,strong dislocation strengthening and precipitation strengthening in DQT600 specimen also elevated its ductile-to-brittle-transition-temperature,compared with QT600 specimen.

关键词： Cu-bearing high-strength low-alloy steel Direct quenching Nanosized precipitate Strengthening Ductile-to-brittle-transition-temperature

Nucleation Behavior Analysis of Intragranular Acicular Ferrite in a Ti-killed C-Mn Steel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2014年第3期21卷 369-374页

作者： Feng CHAI Hang SU cai-fu yang Dong-mei XUE Division of Structural Material Central Iron and Steel Research Institute

By using a Gleeble 350013 thermo-mechanical simulator, the nucleation behavior of intragranular acicular ferrites （IAF） was studied in a Ti-killed C-Mn steel. During continuous cooling transformation, the allotriomorphic ferrite （AF） and ferrite side plate （FSP） microstructures grew more rapidly with the temperature decreasing from 800 to 650 ℃, and the IAF microstructure was dominant within austenite grain with further cooling to 600 ℃. The diffusion bonding experiment and the effect of C, Mn and Si concentrations on the Ao3 temperature by thermodynam- ic calculation confirm that Ti2O3 itself absorbs neighboring Mn atoms to form Mn-depleted zone （MDZ）, which pro- motes the nucleation of IAF microstructure effectively. High temperature holding tests indicate that the nucleation potential of IAF microstructure was lowered in the Ti-killed C-Mn steel when it was treated at high temperature （1250 ℃ ） for a longer time, which is attributed to the saturated absorption degree of Mn atoms by titanium oxide.

关键词： intragranular aeicular ferrite Ti-killed C-Mn steel Ti2O3 Mn depleted zone

Corrosion behavior of low alloy steel for cargo oil tank under upper deck conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2018年第1期25卷 120-130页

作者： Hao Li Feng Chai cai-fu yang Chao Li Xiao-bing Luo Central Iron and Steel Research Institute Beijing 100081China Qingdao NCS Testing Protection Technology Co. Ltd.Qingdao 266071 Shandong China

A simulated corrosion test apparatus was used to investigate the corrosion behavior of a low alloy steel under simulated upper deck conditions in a cargo oil tank. The estimated corrosion loss of conventional E36 class ship plate steel is 4.27 mm, which is clearly inadequate compared with the standard adopted by International Maritime Organization. Outer rust layer of specimens starts to peel off after 77 days and becomes fragmented after 98 days. X-ray diffraction, scanning electron micros- copy, and Raman spectroscopy revealed that the resulting rust is composed of σ-FeOOH （the main protective phase）, Fe2O3, FeS, elemental S, and FeSO4. FeSO4 in the interface of the base and rust layer leads to localized corrosion. Elemental sulfur forms on the surface of σ-FeOOH, and the quantity and size thereof increase with increasing corrosion time. furthermore, layered elemental sulfur promotes fracture and peels off the rust layer.

关键词： Low alloy steel Cargo oil tank Upper deck Corrosion film Elemental sulfur

Strengthening and toughening mechanism of a Cu-bearing high-strength low-alloy steel with refined tempered martensite/bainite(M/B)matrix and minor inter-critical ferrite

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2021年第4期28卷 464-478页

作者： Fei Zhu Feng Chai Xiao-bing Luo Zheng-yan Zhang cai-fu yang Department of Structural Steels Central Iron and Steel Research InstituteBeijing 100081China

The microstructure–mechanical property relationship of a Cu-bearing low-carbon high-strength low-alloy steel,subjected to a novel multistage heat treatment including quenching(Q),lamellarization(L)and tempering(T),is *** strength of 989.5 MPa and average toughness at-80℃of 41 J were obtained in this steel after quenching and tempering(QT)heat *** QLT gained a little lower yield strength(982.5 MPa),but greatly enhanced average toughness at-80℃(137 J).To further clarify the strengthening and toughening mechanisms in specimen QLT,parameters of microstructural characteristic and crack propagation process were compared and analyzed for specimens Q,QL,QT and *** microstructure of tempered martensite/bainite(M/B)in specimen QT changed to refined tempered M/B matrix mixed with minor IF(inter-critical ferrite)in specimen ***-rich precipitates existed in tempered M/B for both specimens QT and QLT,as well as in *** with QT,adding a lamellarization step before tempering made the effective grains of specimen QLT refined and also led to coarser Cu-rich precipitates in tempered M/B *** weaker strengthening effect of coarser Cu-rich precipitates should be a key reason for the slightly lower yield strength in specimen QLT than in specimen *** austenite was found in all specimens Q,QL,QT and *** QLT showed purely ductile fracture mode at-80℃due to the refined effective *** greatly improved toughness is mainly attributed to the enhanced energy of crack *** combination of refined microstructure,softened matrix and deformation of minor'soft'IF during crack propagation led to the most superior toughness of specimen QLT among all specimens.

关键词： High-strength low-alloy steel Multistage heat treatment Low-temperature toughness Strengthening mechanism Grain refinement Crack propagation

Precipitation Behavior of V-N Microalloyed Steels during Normalizing

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2015年第11期22卷 1037-1042页

作者： Tao PAN Xi-yang CHAI Jin-guang WANG Hang SU cai-fu yang Division of Structural Steels Central Iron and Steel Research Institute Division of Equipment Construction China Sinopec Engineering Incorporation

The precipitation behavior of V-N microalloyed steel during normalizing process was studied by physicochemical phase analysis and transmission electron microscopy（TEM）. The effect of precipitation behavior on mechanical properties was investigated by theoretical calculations. The results showed that 32.9% of V（C,N） precipitates remained undissolved in the austenite during the soaking step of the normalizing process. These precipitates prevented the growth of the austenite grains. During the subsequent cooling process, the dissolved V（C,N） re-precipitated and played a role in precipitation strengthening. The undissolved V（C,N） induced intragranular ferrite nucleation and refined the ferrite grains. Consequently, compared with hot-rolled steel, the normalized steel exhibited increased grain-refining strengthening but diminished precipitation strengthening, leading to an improvement of the impact energy at the expense of about 40 MPa yield strength.

关键词： normalizing V-N microalloyed steel precipitation strengthening grain-refining strengthening

Interlayer engineering for titanium clad steel by hot roll bonding

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2018年第7期25卷 739-745页

作者： Xi-yang Chai Tao Pan Feng Chai Xiao-bing Luo Hang Su Zhi-gang yang cai-fu yang Department of Structural Steels Central Iron and Steel Research Institute Beijing 100081 China School of Materials Science and Engineering Tsinghua University Beijing 100084 China

Hot roll bonding was carried out between commercially pure titanium TA2 and high-strength low-alloy steel Q390 using pure Nb or Mo interlayer at 950 ~C with a total reduction ratio of 86.7%. Interfacial microstructure and bonding properties of titanium clad steel plates were investigated by electron microscopy and mechanical tests. The results showed β-Ti, TiC and Fe2Ti reaction phases were generated at Ti/steel interface for the clad plates with no interlayer. Inserting Nb or Mo interlayer can effectively suppress the formation of brittle phases, while the weak bonding joint transferred to Nb/steel or Mo/steel interface. And some micro-voids were found at the interface of Nb/steel and Mo/steel. The improved shear strength of clad plates with Nb interlayer might be attributed to the elimination of brittle phases at bonding interface. The small size and little quantities of the micro-voids at Nb/steel interface had a relatively weak effect on shear strength. However, the large number and big size of micro-voids were responsible for the degradation of shear strength for the clad plates with Mo interlayer.

关键词： Titanium clad steel Interlayer - Interfacial microstructure Brittle phase Micro-void

High Temperature Oxidation Resistance of 9Ni Steel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2014年第10期21卷 956-963页

作者： Yi-zhi LIU cai-fu yang Feng CHAI Tao PAN Hang SU Institute of Engineering Steel Central Iron and Steel Research Institute

Oxidation rates and scale/steel interface configuration of 9Ni steels were investigated at 1000--1 250 ℃ in air. The results revealed that Cu addition caused high temperature oxidation resistance to deteriorate. High tempera ture oxidation rates increased and scale/steel interface configuration became complicated due to Cu addition. Scale/ steel interface appeared to be network above certain temperature. Temperature required to form network scale/steel interface dropped more than 100 ℃ for 1.5% Cu-containing steel. （Fe,Ni,Cu）x Oy in inner oxidation layer dissocia ted to Fe-Ni-Cu phase and released active oxygen which can react with base steel easily. So the inner oxidation layer became the second source of oxidizing agent besides atmosphere. Internal stress at austenite grain boundary caused local oxide to fragment. So the scale/steel interface appeared to be network. Liquid Si-rich phase formed at sufficient ly high temperature. Penetration of the liquid Si-rich phase along austenite grain enhanced austenite grain oxidizing.

关键词： 9Ni steel high temperature oxidation scale/steel interface Thermo-Calc calculation