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Effect of continuous annealing parameters on the mechanical properties and microstructures of a cold rolled dual phase steel

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International Journal of Minerals,Metallurgy and Materials 2009年第2期16卷 159-164页

作者： Shuang Kuang Yong-lin Kang Hao Yu Ren-dong Liu School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Technology Center Anshan Iron ＆ Steel Group Corporation Anshan 114001 China

A cold rolled dual phase （DP） steel with the C-Si-Mn alloy system was trial-produced in the laboratory, utilizing a Gleeble-3800 thermal simulator. The effects of continuous annealing parameters on the mechanical properties and microstructures of the DP steel were investigated by mechanical testing and microstructure observation. The results show that soaking between 760 and 820℃ for more than 80 s, rapid cooling at the rate of more than 30℃/s from the quenching temperature between 620 and 680℃, and overaging lower than 300℃ are beneficial for the mechanical properties of DP steels. An appropriate proportion of the two phases is one of the key factors for the favorable properties of DP steels. If the volume fraction of martensite and, thereby, free dislocations are deficient, the tensile strength and n value of DP steels will decrease, whereas, the yield strength will increase. But if the volume fraction of martensite is excessive to make it become a dominant phase, the yield and tensile strength will increase, whereas, the elongation will decrease obviously. When rapid cooling rate is not fast enough, pearlite or cementite will appear, which will degrade the mechanical properties. Even though martensite is sufficient, if it is decomposed in high temperature tempering, the properties will he unsatisfied.

关键词： austenization intercritical annealing dual phase steel cold rolling diffusion

Factors Influencing dual phase steel Flanging Limit Punching

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Journal of Iron and steel Research International 2014年第12期21卷 1124-1128页

作者： Jian-qing QIAN Yuan YUE Anhui University of Technology

Based on pre punching to hot rolled martensitic and bainitic dual phase steels with similar elongation and work hardening index （n）, as well as similar thickness and hole expansion test using taper die, analysis of the hole expansion rate indicated significant difference in their flanging performance. The results indicated that mechanical property was not the only major factor that influenced flanging. Further analysis of the hole border microstructure, work hardening condition, and fracture property showed that the fracture property of sheets was the major factor that influenced flanging performance.

关键词： flanging fracture property mechanical property dual phase steel

3D Micromechanical Modeling of Failure and Damage Evolution in dual phase steel Based on a Real 2D Microstructure

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Acta Mechanica Solida Sinica 2016年第1期29卷 95-110页

作者： M.R.Ayatollahi A.Ch.Darabi H.R.Chamani J.Kadkhodapour Fatigue and Fracture Lab. Center of Excellence in Experimental Solid Mechanics and DynamicsSchool of Mechanical EngineeringIran University of Science and Technology

A plate of dual phase steel was produced from low carbon steel with intercritical annealing treatment. Its optically determined surface microstructure was utilized to construct three different microstructural models. To describe the ductile damage in the ferritic matrix, the Gurson-Tvergaard-Needleman model was used with the failure in the martensite phase being ignored. The numerical results obtained for the mechanism of void initiation and coalescence were compared with the experimental observations. The numerical results obtained from the randomly extruded 3D model showed a significantly better agreement with the experimental ones than those obtained from the 2D model or the uniformly extruded 3D model.

关键词： dual phase steel 3D model microstructure micromechanical modeling GTN dam-age model

Stress-strain partitioning analysis of constituent phases in dual phase steel based on the modified law of mixture

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International Journal of Minerals,Metallurgy and Materials 2009年第4期16卷 393-398页

A more accurate estimation of stress-strain relationships for martensite and ferrite was developed, and the modified law of mixture was used to investigate the stress-strain partitioning of constituent phases in dual phase （DP） steels with two different martensite volume fractions. The results show that there exist great differences in the stress-strain contribution of martensite and ferrite to DP steel. The stress-strain partitioning coefficient is not constant in the whole strain range, but decreases with increasing the true strain of DP steel. The softening effect caused by the dilution of carbon concentration in martensite with the increase of martensite volume fraction has great influence on the strain contribution of martensite. The strain ratio of ferrite to martensite almost linearly increases with increasing the true strain of DP steel when the martensite volume fraction is 22%, because martensite always keeps elastic. But the strain ratio of ferrite to martensite varies indistinctively with the further increase in true strain of DP steel above 0.034 when the martensite volume fraction is 50%, because plastic deformation happens in martensite. The stress ratio ofmartensite to ferrite decreases monotonously with increasing the true strain of DP steel whether the martensite volume fraction is 22% or 50%.

关键词： stress and strain partitioning dual phase steel ferrite martensite

Effect of controlled rolling on the martensitic hardenability of dual phase steel

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International Journal of Minerals,Metallurgy and Materials 2009年第2期16卷 165-169页

作者： Mohammad Ajmal Masood Ahmed Tindyala Ron Priestner Department of Metallurgical & Materials Engineering University of Engineering & TechnologyG.T. Road Lahore-54890Pakistan Manchester Materials Science Center University of Manchester Institute of Science and Technology (UMIST)ManchesterM1 7HSUK

The C-Mn and C-Mn-Nb steels were thermo-mechanically processed to develop dual phase steel and to study the effect of controlled rolling on the martensitic hardenability of austenite. The steel specimens were intercritically annealed at 790℃, rolled at that temperature to the reductions of 10%, 23%, and 47% and immediately cooled at different rates. Quantitative metallography was used to construct the microstructure map, which illustrated that increasing deformation progressively reduced the proportion of new ferrite formed at all cooling rates and increased the amount of martensite at fast and intermediate rates. The martensitic hardenability of austenite remaining after all the rolling reductions was plotted as a function of cooling rates. It was observed that for the austenite-martensite conversion efficiencies greater than about 25%, controlled rolling increased the martensitic hardenability of austenite.

关键词： controlled rolling dual phase steel intercritical annealing hardenability phase transformation

Dry Sliding Oxidative Wear in Plain Carbon dual phase steel

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Journal of Iron and steel Research International 2007年第4期14卷 43-48页

作者： V Abouei H Saghafian Sh Kheirandish Department of Metallurgy and Materials Engineering Iran University of Science and TechnologyNarmak 16844TehranIran

To investigate the tribological potential of the dual phase （DP） steel as a wear resistant material, the wear and the friction characteristics of this steel, which consists of hard martensite islands embedded in a ductile ferrite matrix, have been investigated and compared with those observed in plain carbon hardened （H） steel that has the same carbon content of 0.2%. Dry sliding wear tests have been carried out using a pin-on-disk wear testing machine at different normal loads of 21.3 N, 28. 5 N, 35.7 N, and 42.6 N and at a constant sliding velocity of 1.20 m/s. The analysis of surface and wear debris of samples showed that the wear mechanism was mainly mild oxidative. The friction and the wear rate of the H steel and the DP steel have been explained with respect to the microstructure and the wear mechanism.

关键词： dual phase steel wear microstructure heat treatment

Development of 600MPa High Aluminum Cold Rolled dual phase steel and Its Application

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Journal of Iron and steel Research International 2011年第S1期18卷 994-998页

作者： WANG Hui 1,2,LIN Cheng-jiang 1,DENG Zhao-jun 1,GONG Tao 1,TAN Yun-gang 2,YAN Fei 2,YANG Peng 2 (1.Research and Development Center,WISCO,Wuhan 430080,Hubei,China 2.Cold Rolling Mill,WISCO,Wuhan 430081,Hubei,China) WISCO Ctr Res & Dev Wuhan 430080 Hubei Peoples R China WISCO Cold Rolling Mill Wuhan 430081 Hubei Peoples R China

An original 600MPa high aluminum dual phase steel had been successfully developed in this *** microstructure analysis showed that the microstructures of the steel mainly consist of ferrite and 16% martensite which distributed around the ferrite grain *** analysis demonstrated that there exist lots of high density dislocations in ferrite as well as an obvious twin-structure and some ribbon structures in *** tensile test and the bake-hardening test showed that the steel delivers an excellent mechanical properties of R p0.2 =350-390MPa,R m =620-660MPa,R p0.2 /R m =0.55-0.65,A 80mm =25-29%,n=0.18-0.21 and an excellent bake-hardening property of BH 2 =50-60MPa as well as an excellent of work-hardening (WH) property of WH=120MPa。The spot-welding test showed that this dual phase steel has a good welding *** to the excellent formability,the steel has been successfully used in the production of some auto parts.

关键词： dual phase steel martensite high density dislocation bake hardening welding property

Influence of Mo on Dynamic Continuous Cooling Transformation of 1000 MPa Cold Rolled dual phase steel

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Journal of Iron and steel Research International 2011年第S1期18卷 296-299页

作者： ZHAO Xian-meng,KANG Yong-lin,HAN Qi-hang (School of Material Science and Engineering.University of Science and Technology Beijing,Beijing 100083,China) Univ Sci & Technol Beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

The expanding curves of two kinds of 1000 MPa ultra-high strength cold rolled dual phase steels,which were C-Si-Mn-Cr and C-Si-Mn-Cr-Mo steel respectively,were detected on Gleeble-1500 thermal-mechanical simulator at different cooling *** with metallographic and hardness methods,the continuous cooling transformation curves (CCT) of the two steels were *** results showed that Mo could raise the A r3 temperature,and strongly restrain the pearlite and bainite *** reason for this was the interaction that the addition of Mo could increase the chemical driving force of ferrite transformation and the activation energy for the diffusion of carbon in austenite,which could decelerate the ferrite *** hardness of the two steels was similar in the cooling rates range of this experiment and got higher with the increase of the cooling *** the cooling rates were above 7 ℃/s,the hardness almost kept constant because the most part of the microstructure was martensite.

关键词： Mo dual phase steel cold rolled CCT ultra-high strength

RELATIONSHIP BETWEEN TENSILE DEFORMATION BEHAVIOUR AND MICROSTRUCTURAL PARAMETERS OF A dual phase steel

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Acta Metallurgica Sinica(English Letters) 1994年第1期7卷 36-44页

作者： JIANG Zhonghao, GUAN Zhenzhong, ZHANG ZuomeiChangchun Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Changchun, ChinaLIA N JiansheJilin University of Technology, Changchun, China

Bused on the deformation model of dual phase steels, an expression for the stress of martensite in dual phase steels is derived, it predictes that the onset of plastic deformation of martensite (transition strain) depends on the strain hardening of ferrite and on the strength of martensile. The relationship between the flow stress and microstructural parameters of a 0.12C-0.9Mn dual phase steel was investigated using the expression for the flow stress of dual phase steel[1] . By calculating the stress ratio and the stress-strain partition coefficient, the loud transition and the stress-strain partition between two phases are studied. It shows that the deformation of dual phase steel lies between the isostress and isostrain states and the stress-strain pratition changes continuously during the deloramtion.

关键词： dual phase steel flow stress microstructural parameters stress-strain partition