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The Study of Plasma Nitriding of AISI304 Stainless Steel

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材料热处理学报 2004年第5期25卷 422-424页

作者： WANGLiang JIShi-jun GAOYu-zhou SUNJun-cai InstituteofMetalandTechnology DalianMaritimeUniversity

This paper presents results on the plasma nitriding of AISI 304 stainless steel at different temperatures in NH 3 gas. The working pressure was 100-200 Pa and the discharge voltage was 700-800V. The phase of nitrided layer formed on the surface was confirmed by X-ray diffraction. The hardness of the samples was measured by using a Vickers microhardness tester with the load of 50g. After nitriding at about 400 °C for two hours a nitrided layer consisting of single YN phase with thickness of 5um was obtained. Microhardness measurements showed significant increase in the hardness from 240 HV (for untreated samples) up to 950 HV (for nitrided samples at temperature of 420°C). The phase composition, the thickness, the microstructure and the surface topography of the nitrided layer as well as its properties depend essentially on the process parameters.

关键词：等离子渗氮扩展奥氏体不锈钢 AISI304

High Carbon Alloy Steels with Multiple Types of Ultra-fine Carbides and Their Characteristics

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材料热处理学报 2004年第5期25卷 117-121页

作者： MAYong-qing GAOHong-tao QIYu-hong ZHANGZhan-Ping DAIYu-mei LIUYan-xia dalianmaritimeuniversity DalianChina

Under normal forging and annealing conditions, there are different ultra fine carbides (M3C, M23C6, M7Cj, M6C and MC) in high carbon alloy steels when alloy composition design is carried out properly. On the basis of carbides transformation orderliness, the alloy composition design of the high carbon alloy steels is conducted by phase-equilibrium thermodynamic calculation for Fe-Cr-W-Mo-V-C system. The nucleation and growth of new carbides, dissolution of previous partial carbides in these steels during annealing process, all these lead to ultra-fine distribution of carbides. Due to different crystal structures of carbides and different thermodynamics as well dynamics parameters of the carbides dissolution and precipitation, the range of quenching temperature of these steels is widened, and the good temper-resistance is obtained. The characteristics of heat treatment process and microstructure variance, and the carbides transformation for different temperature are explained by the phase-equilibrium component satisfactorily. Their bend and yield strength, flexibility and toughness all are advanced markedly comparing with that of kindred steels. Results of the applications have proved that the microstructure of ultra-fine carbides in these steels played importance roles in the enhancement of edginess and fatigue crack resistance of the die and knives.

关键词：超细硬质合金高碳钢结构设计成分设计

Microstructures and Hardness of 8CrWMoV Steel with Multiple Types of Ultra Fine Carbides

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材料热处理学报 2004年第5期25卷 279-283页

作者： DAIYu-mei ZHANGZhan-ping MAYong-qing QIYu-hong LIUYan-xia YUTao Instituteofmaterialsandtechnology DalianMaritimeUniversityDalian116026

The structure and hardness of 8CrWMoV steel with multiple types of ultra fine carbides are studied after annealing, quenching and tempering in this paper. The results show that multiple types of carbides M3C, M7C3, M23C6, M6C and MC were observed in the annealed steel. Nucleation and coalescence of new carbides, partial dissolution of original carbides in γ phase region during annealing at 800～840℃, result in ultra-fine carbides. Average size of the carbides is0.33～0.34μm in the steel annealed at 800～840℃. Because M3C and M23C6 dissolve easily in austenite, the high hardness HRC63～65 can be obtained by quenching at 840～860℃. Un-dissolved carbides M6C and MC (VC) can effectively prevent the coarsening of austenitic grain, and conduce to obtain very fine martensite. The retained austenite can be easy to decompose during tempering at low and middle temperature due to the precipitation of multiple types of carbides and the good tempering-resistance of the steel is obtained. The microstructure and property of the steel after heat treatment can be accurately explained by calculating based on phase equilibrium *** Words: 8CrWMoV steel, ultra-fine carbide, heat treatment, microstructure,

关键词：显微结构 8CrWMoV钢超细硬质合金硬度热处理

Changes of Tempering Microstructure and Properties of Fe-Cr-V-Ni-Mn-C Cast Alloys

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材料热处理学报 2004年第5期25卷 631-634页

作者： LIUYan-xia MAYong-qing WANGYue-hua ZHANGZhan-ping ZHANGYang InstituteofMaterialsandTechnology DalianMaritimeUniversityDalianChina／DepartmentofPhysicsLiaoningUniversityShenyangChina InstituteofMaterialsandTechnology DalianMaritimeUniversityDalianChina DepartmentofPhysics LiaoningUniversityShenyangChina

The changes of tempering microstructure and properties of Fe-Cr-V-Ni-Mn-C cast alloys with martensite matrix and much retained austenite are studied. The results showed that when tempering at 200 °C the amount of retained austenite in the alloys is so much that is nearly to as-cast, and a lot of retained austenite decomposes when tempering at 350°C and the retained austenite decomposes almost until tempering at 560 °C. When tempering at 600 °C, the retained austenite in the alloys all decomposes. At 560°C the hardness is highest due to secondary hardening. The effect of nickel and manganese on the microstructure and properties of Fe-Cr-V-C cast alloy were also studied. The results show that the Fe-Cr-V-C cast alloy added nickel and manganese can obtain martensite matrix and much retained austenite microstructure, and nickel can also prevent pearlite transformation. With the increasing content of nickel and manganese, the hardness of as-cast alloy will decreases gradually, so one can improve the hardness of alloy by tempering process. When the content of nickel and manganese is 1.3-1.7%, the hardness of secondary hardening is the highest (HRC64). But when the content of nickel and manganese increase continually, the hardness of secondary hardening is low slightly, and the tempering temperature of secondary hardening rises.

关键词： Fe-Cr-V-Ni-Mn-C合金显微结构调温过程热处理

Investigation of Adhesion and Fracture Toughness of Thermally Grown Oxide Scales by Interface Indentation Test

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材料热处理学报 2004年第5B期25卷 1233-1236页

作者： QIYu-hong P.Bruckel P.Lours ZHANGZhan-ping InstituteofMaterialsandTechnology.dalianmaritimeuniversity DalianChina ResearchCentreonTools MaterialsandProcessesEcoledesAlinesd＇Albi-Carmaux.France InstituteofMaterialsandTechnology.dalianmaritimeuniversity DalianChina／／ResearchCentreonToolsMaterialsandProcessesEcoledesAlinesd＇Albi-Carmaux.France InstituteofMaterialsandTechnology.DalianMaritimeUniversity

The adhesion and the fracture toughness of thermally grown oxide scales for pure nickel were investigated using Vickers indentation technique. The nickel samples were oxidised at 1200°C for 100h-600h. The crack length induced by Vickers indentation test at NiO/Ni interface increases linearly with the incresing of the applied load in a logarithmic scale for each oxide thickness. There is a critical load Pc, when the applied load P>PC, the crack is produced at the oxide/metal interface. The critical load PC decreases with the increasing of the oxide thickness. Therefore, the relation between the critical load PC and the oxide thickness ho may be used as describing the adhesion of of thermally grown oxide scales. For pure nickel, the Pc-ho relation can be represented by the equation Pc = 761439e"°’°695’1" The fracture toughness in oxide and at the interface decrease with the increasing of the oxide thickness in equation K0 —1.02l4Ln(h0) + 7.3382 (in oxide) and KJ = 529.7In,,"**424 (at the interface). And there is a higher fracture toughness at the NiO/Ni interface. Therefore, for pure nickel, the oxide/metal interface is stronger than the oxide.

关键词：离合面压痕试验氧化物附着断裂韧度氧化镍

Study of Composite Hardcoat Anodizing of Aluminum Alloy 6063 and Its Friction Behaviors

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材料热处理学报 2004年第5B期25卷 1146-1148页

作者： LIUShi-yong ZHANGHui-chen GAOXue-min LIUWei SHIYa-qin InstituteofMetafandTechnology DalianMaritimeUniversity Datian116026 China

A composite hard-anodized coating containing micro PTFE (polytetrafluoroethylene) particles on aluminum alloy 6063 was produced by adding micro PTFE particles into the traditional hardcoat anodizing solution. The size of the PTFE particles is around 2 v- m in diameter and the content of the PTFE particles in the composite coating is within 2%-3% by area percentage. Thickness of the composite coating can reach up to 70 v m after one hour’s anodizing. Surface hardness of the composite coating is between 400-480 HVo.i- The average friction coefficient of the composite coating against steel under dry friction test is 0.11, which is 17% lower than that obtained by traditional hardcoat anodizing.

关键词： 6063铝合金硬盖阳极氧化复合涂层 PTEE 摩擦系数

Influence of Tempering Temperature on Cyclic Viscoplastic Behaviour of 55NiCrMoV7 Steel

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材料热处理学报 2004年第5期25卷 623-626页

作者： ZHANGZhan-ping DELAGNESDenis BERNHARTGerard InstituteofMaterialsandTechnotogy DalianMaritimeUniversityDalianChina ResearchCentreonTools MaterialsandProcessesEcoledesMinesd＇Atbi-CarmauxFrance

Low cycle fatigue behaviour of a steel 55NiCrMoV7 under four tempered conditions is reported. One special type of total strain controlled isothermal cyclic deformation tests were performed in the temperature range 20°C to 600°C for the steel tempered 2h at 350 °C, 460 °C, 560 °C and 600 °C. The influence of temperature on cyclic behaviour was investigated. Generally, the cyclic stress response shows an initial exponential softening for the first few cycles, followed by a gradual softening without cyclic softening saturation. At 10"2 strain rate, amax,A(T/2 decrease with the test temperature for all hardness levels. They decrease linearly with tempering temperature when testing temperature is lower than that of tempering, but rest nearly constant when test temperature is equal to or exceed tempering temperature of steel. Cyclic softening intensity increases with testing temperature from 300°C to 600°C, but the maximal softening intensity occurs at room temperature. The strain rate influences notably the cyclic behaviour when T>500°C. The time dependence of cyclic behaviour is closely related to test temperature and the tempering history of the steel.

关键词：回火温度 55NiCrMoV7钢循环低温处理粘塑状态

Fuzzy robust attitude controller design for hydrofoil catamaran

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Journal of Systems Engineering and Electronics 2005年第1期16卷 110-115页

作者： RenJunsheng YangYansheng NavigationCollege DalianMaritimeUniversityDalian116026P.R.China

A robust attitude controller for hydrofoil catamaran throughout its operating envelope is proposed, based on Tagaki-Sugeno (T-S) fuzzy model. Firstly, T-S fuzzy model and robust attitude control strategy for hydrofoil catamaran is presented by use of linear matrix inequality (LMI) techniques. Secondly, a nonlinear mathematical model of hydrofoil catamaran is established, acting as the platform for further researches. The specialty in interpolation of T-S fuzzy model guarantees that feedback gain can be obtained smoothly, while boat's speed is shifting over the operating envelope. The external disturbances are also attenuated to achieve H ∞ control performance, meanwhile. Finally, based on such a boat, HC200B-A1, simulation researches demonstrate the design procedures and the effectiveness of fuzzy robust attitude controller.

关键词： hydrofoil catamaran robust attitude controller Tagaki-Sugeno (T-S) fuzzy model linear matrix inequality.

The Twisted-Cube Connected Networks

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Journal of Computer Science & Technology 1999年第2期14卷 181-187页

作者：王德强赵连昌 DepartmentofBasicSciences DalianMaritimeUniversityDalian116026PR.China DepartmentofBasicSciences D

This paper presents a new interconnection net work topology ,called The twisted-cube connected network is a variant of the hypercube, and it has a better recursive structure . The regularity, connectivities, subgraphs of the twisted- cube conaected aetwork are studied . The twisted-cube connected network is proved to be a 3-cube-free network, which is the essential difference from the hypercube and variants of the hypercube. An efficient routing algorithm is proposed, and the diameter of n-dimensional twisted-cube connected network is proved to be just which is less than that of the hypercube.

关键词： connectivity hypercube interconnection network routing algo- rithm .