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Static Recrystallization Behavior of Hot Deformed Austenite for Micro-Alloyed steel

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Journal of Materials Science & Technology 2003年第Z1期19卷 117-118页

作者： Jie HUANG Zhou XU Xin XING Key Laboratory for High Temperature Materials and Tests of Ministry of Education Shanghai Jiaotong UniversityShanghai 200030 China Key Laboratory for High Temperature Materials and Tests of Ministry of Education Shanghai Jiaotong UniversityShanghai 200030 China Key Laboratory for High Temperature Materials and Tests of Ministry of Education Shanghai Jiaotong UniversityShanghai 200030 China

Static recrystallization behavior of austenite for micro-alloyed steel during hot rolling was studied and the influence (τ-ε diagram) of holding time and deformation at different deformations and isothermal temperatures on microstructuralstate of austenite were discussed. Corresponding to parameter Z in the dynamic recrystallization diagram, parameterY was then introduced to simplify static recrystallization diagrams.

关键词： Micro-alloyed steel, Hot deformation of austenite, Static recrystallization

Numerical Simulation of Welding Deformation for Hull Superstructure steel Based on the Finite Element Analysis

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Journal of Materials Science & Technology 2003年第Z1期19卷 212-214页

作者： Liu, Liming Liang, Guoli Liu, Yujun Zhan, Zheng Dalian Univ. of Technol. Dalian 116024 China Dalian Dockyard Dalian 116020 China Lab. of Adv. Welding Technol. Harbin Inst. of Technol. Harbin 150001 China

Using finite analysis element software, the transient displacement field of automatic submerged arc welding is established. It was also considered that the thermal physical properties changes were depended on the temperatureand the heat loss on the surface. At the same time, it analyzed the influence of the deformation and stress, whichgenerated in the plate butt-welding process, to the superstructure steel welding deformation. The result showedthat the deformation and stress generated in the steel plate butt-welding process are considered to be the mainfactors to influence the welding deformation of superstructure steel. It found the effective ways to reduce the weldingdeformation of the hull superstructure steel is to relieve the butt-welding deformation and release butt-welding stressbefore welding the hull superstructure steel.

关键词： Hull superstructure steel, Finite element analysis, Welding deformation

Theoretical calculation of the finishing rolling impact work in non-quenched and tempered Si-Mn steel

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Science China(Technological Sciences) 2006年第2期49卷 137-146页

作者： LIU Zhilin1, LIN Cheng1 & WANG Ping2 1. Department of Materials and Chemical Engineering, Liaoning Institute of Technology, Jinzhou 121001, China 2. Mechanical Department, Armor technique Institute of PLA, Changchun 130117, China Department of Materials and Chemical Engineering Liaoning Institute of Technology Jinzhou China Mechanical Department Armor technique Institute of PLA Changchun China

Based on the hot-continuous rolling technology, the finishing rolling impact work α k of the non-quenched and tempered Si-Mn steel is theoretically calculated with the covalent electron number nA of the strongest bond in alloying phases, and the smallest interface electron density difference Δρ of alloying phase interface and the number of atom states σ which keep the interface electron density continuous. Calculations show that the solution strengthening, the precipitation strengthening, and the interface strengthening will result in the decrease of the finishing rolling impact work α k, and the effects of the number of atom states σ which keep the interface electron density continuous on the finishing rolling impact work α k are different. Taking the impact work and the number of atom states σ 0 keeping the electron density continuous of the phase interface α-Fe/α-Fe-C between α-Fe and α-Fe-C as reference values, the impact work of the interface will increase when σ of some interface is larger than σ 0; otherwise, the impact will decrease. Therefore, the finishing rolling impact work α k can be calculated with the impact value of the refined α-Fe matrix and the influence amounts caused by the solution strengthening, the precipitation strengthening, the interface strengthening, and the number of atom states σ which keep the interface electron density continuous. The calculated results agree well with the measured ones. In this paper, the effect of S on the impact work is also discussed.

关键词： electron structure parameters, non-quenched and tempered steel, impact work and calculation.

Microstructure effect on nanohardness distribution for medium-carbon martensitic steel

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Science China(Technological Sciences) 2006年第1期49卷 10-19页

作者： OHMURA Takahito TSUZAKI Kaneaki steel Research Center National Institute for Materials Science Tsukuba 305-0047 Japan

Nanoindentation measurement was performed to evaluate the local hardness distribution for quenched and tempered martensitic steel with ferrite-cementite constituent. The ratio of standard deviation to the average nanohardness was 15.4% when nanoin-dentation tests were carried out at the peak load of 1000 μN, while that of the Vickers hardness was only 1.5% at 9.8 N. Electron backscatter diffraction analysis and SEM ob-servation all showed that the large scattering of nanohardness did not depend on the crystallographic orientation of each grain but from the inhomogeneous microstructure in the sub-micron scale such as cementite distribution. Compared with the results on tung-sten single crystals with different surface orientations as well as another martensite proc-essed by modified-ausforming with the same chemical composition but more homogene-ous cementite distribution, the nanohardness showed smaller scattering, supporting the conclusion.

关键词： martensitic steel, cementite, hardness distribution, nanoindentation.

Theoretical calculation of the impact work in the alloying non-quenched and tempered steel

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Science China(Technological Sciences) 2006年第3期49卷 257-273页

作者： LIU Zhilin1, LIN Cheng1 & GUO Yanchang2 1. Department of Materials and Chemical Engineering, Liaoning Institute of Technology, Jinzhou 121001, China 2. The Technical Center of Benxi Iron and steel Group Corporation, Benxi 117000, China Department of Materials and Chemical Engineering Liaoning Institute of Technology Jinzhou China The Technical Center of Benxi Iron and steel Group Corporation Benxi China

Coupled with hot-continuous rolling technology and based on the calculation of the finishing rolling impact work in the non-quenched and tempered Si-Mn steel, the calculations of the finishing rolling impact work in the alloying non-quenched and tempered steel with the elements of Cr, Ni, Mo, W, Cu, V, Nb and Ti are studied with the covalent electron number nA of the strongest bond in alloying phases, the smallest electron density difference ?ρ of phase interfaces, and the number of atom states σ (σ′) which keep the interface electron density continuous. The calculated results show that the finishing rolling impact work of the alloying non-quenched and tempered steel intensely depends on strengthening mechanisms. The solution strengthening, interface strengthening, precipita- tion strengthening of pearlite, and dispersion strengthening will result in the decrease of the finishing rolling impact work; the refinement strengthening, the precipitation strength- ening of V, Nb and Ti in α-Fe-C-V(Nb, Ti), and the residual austenite containing Ni on the boundary of α-Fe-C-Ni will increase the impact work; and the increments or decrements can be calculated with nA, ?ρ, σ (σ′) and weights of alloying elements. The calculation formulas of the finishing rolling impact work in this paper are intergraded with the sug- gested ones of the finishing rolling tensile strength, yield strength, and elongation of the non-quenched and tempered steel. The calculated results agree well with the measured ones.

关键词： alloying non-quenched and tempered steel, electron structure, impact work, calculation.

Electrolytic surface hardening of steel, cast iron and aluminium-bronze

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China Foundry 2006年第3期3卷 184-189页

作者： Suhas Keshav Paknikar National Centre for Technical Services Pune India

Electrolytic hardening process was developed in USSR in the 1950s. The process was developed but was not commercially exploited. There is no evidence of work done on this process in India. The author has done this original work applied to different materials like steel, cast iron and aluminum-bronze. This paper gives details of microstructural transformations along with hardness value achieved. There is vital scope for this process to become viable for surface hardening and selective hardening of small components.

关键词： electrolytic hardening process variables, S. G. iron, steel, aluminum-bronze

Influence of rooftop telecommunication tower on set back-step back building resting on different ground slopes

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Earthquake Engineering and Engineering Vibration 2019年第2期18卷 351-362页

作者： Amit Thakur Deepankar Kumar Ashish Surender Kumar Verma Civil Engineering Department Kurukshetra University Civil Engineering Department Maharaja Agrasen Institute of Technology Maharaja Agrasen University Civil Engineering Department Punjab Engineering College (Deemed to be University)

In the hilly region due to scarcity of the plain area, buildings like set back-step back are more often used and also as a big surge in the telecommunication industries, rooftop tower adaptation is very common story nowadays. In the present study an analogy has been drawn to find out the influence of the rooftop telecommunication tower on the setback-step back building resting on ground at 20° and 30° slopes. A dynamic analysis has been performed and compared on the 4 legged angled section telecommunication tower which is located on the roof top of set back-step back building by varying positions of tower with the existing host structure built up on ground slope of 20° and 30° in both directions(X and Y).

关键词： rooftop telecommunication tower set back-step back building response spectrum analysis steel, RC frame, earthquake SAP2000

Sprayformed Hot Work steels for Rapid Tooling

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Journal of Materials Science & Technology 2003年第Z1期19卷 169-172页

作者： Yunfeng Yang Simo-Pekka Hannula VTT Industrial Systems P.O.BOX 1703 FIN-02044 VTT Finland VTT Industrial Systems P.O.BOX 1703 FIN-02044 VTT Finland

The present work compares microstructures of hot work steels made by different processes, that is, by sprayforming,by casting, and a commercially supplied H13 steel. Material benefits are recognized by sprayforming hot working tools such as die inserts for hot forging. The sprayformed hot work steels present a fine and homogeneous microstructure,which implies that, at a similar toughness level, the sprayformed steel can be higher alloyed, so that the thermal fatigue and wear resistance at elevated temperatures can be improved. A series of steels with higher vanadium content than commercial hot work steels are developed. There are no segregation and carbide network problems usually encountered in conventional ingot/forging processed high-vanadium steels. Microstructure and hardness of the new sprayformed steels are studied under different heat treatment conditions. It is justified that these sprayformed steels can be directly used for tooling without high temperature hardening. Sprayforming the tool steels onto a precision ceramic mould is demonstrated to extend the technoeconomical benefits, so that a net shape production tool can be rapidly *** of the rapid tooling process are also discussed.

关键词： Rapid tooling, Sprayforming, Hot working steel, Die insert