Bipolar plates are a multifunctional component of PEMFC. Comparing with the machined graphite and stainless steels, the plain carbon steel is a very cheap commercial metal material. In this paper, the possibility of a...Bipolar plates are a multifunctional component of PEMFC. Comparing with the machined graphite and stainless steels, the plain carbon steel is a very cheap commercial metal material. In this paper, the possibility of applying the plain carbon steels in the bipolar plate for PEMFC was exploited. In order to improve the corrosion resistance of the low carbon steel in the PEMFCs′ environments, two surface modification processes was developed and then the electrochemical performances and interfacial contact resistance (ICR) of the surface modified plate of plain carbon steel were investigated. The results show that the surface modified steel plates have good corrosion resistance and relatively low contact resistance, and it may be a candidate material as bipolar plate of PEMFC.展开更多
The effects of cooling rate and coiling temperature on microstructure and mechanical properties of a plain carbon steel were investigated by combining metallography and tensile experiments. The results indicate that f...The effects of cooling rate and coiling temperature on microstructure and mechanical properties of a plain carbon steel were investigated by combining metallography and tensile experiments. The results indicate that ferrite grain size is refined and bainite transformation occurs to ensure high strength and elongation, as the cooling rate is quick enough. Yield strength and tensite strength improve with the decreased finish cooling temperature, but the elongation decreases too significantly to meet the requirements. Thus, the cooling rate must be quick enough, and the appropriate coiling temperature should be carefully selected to obtain refined ferrite and a small amount of bainite to improve the strength while the plasticity is also ensured. Under this condition, the Mn element concentration can be reduced to save cost or produce higher strength steel with same chemical composition.展开更多
A model based on Avrami equation and Scheil's additivity rule was proposed to simulate the phase transformation in plain carbon steels during continuous cooling in hot strip mill. In this model, a wide range of co...A model based on Avrami equation and Scheil's additivity rule was proposed to simulate the phase transformation in plain carbon steels during continuous cooling in hot strip mill. In this model, a wide range of composition, cooling rate, primary austenite grain size and retained strain has been taken into account. It can be used to calculate the phase fraction transformed at different temperatures during continuous cooling. The phase equilibrium and transformation starting temperature can be determined by using Thermo-Calc and DICTRA. The simulated results containing the transformation at starting and finishing temperatures, Ae1, Ae3 and the maximum volume fraction for Q235B, were obtained. The calculated phase volume fractions are in good agreement with .the experimental results.展开更多
Grain growth kinetics of austenite in a hypoeutectoid steel（containing carbon of 0.35%）at 920 ℃ and in a hypereutectoid steel（containing carbon of 1%）at 980 ℃ for holding time ranging from 1 h to 6 h was investi...Grain growth kinetics of austenite in a hypoeutectoid steel（containing carbon of 0.35%）at 920 ℃ and in a hypereutectoid steel（containing carbon of 1%）at 980 ℃ for holding time ranging from 1 h to 6 h was investigated.The hypoeutectoid steel exhibited normal grain growth without solute drag hindrance with a time exponent（0.51）close to the theoretical value（0.5）.However,the grain growth of austenite in the hypereutectoid steel held up to 3 h was extremely slow,characterizing by a low value of time exponent（0.08）.Thereafter,a breakaway occurred and the grain growth in the hypereutectoid steel held from 3 h to 6 h progressed normally with a time exponent（0.52）close to the theoretical value（0.5）.展开更多
The fracture of pipelines caused by corrosion cracks and the resulting oil and gas leakage can lead to great environmentalpollution and economic losses. These negative effects are due to serious corrosion of the plain...The fracture of pipelines caused by corrosion cracks and the resulting oil and gas leakage can lead to great environmentalpollution and economic losses. These negative effects are due to serious corrosion of the plain carbon steels used for armorof flexible pipe in oil and gas transmission medium. However, corrosion resistance of carbon steel armors has yet to beimproved. In this study, the relationship between corrosion resistance and pearlite fraction in the plain carbon steels hasbeen investigated through the application of pulsed electric current. Based on immersion test and electrochemical mea-surement, pulsed electric current increases the corrosion resistance of the plain carbon steels by reducing the fraction ofpearlite phase. Pitting corrosion, which tends to initiate by galvanic corrosion of ferrite and cementite, is therefore inhibiteddue to the decrease in pearlite fraction （mixture of ferrite and cementite） under electropulsing.展开更多
The microstructure evolution during deformation enhanced transformation of undercooled austenite of a plain low carbon steel has been investigated by means of hot compression simulation experiment under various condit...The microstructure evolution during deformation enhanced transformation of undercooled austenite of a plain low carbon steel has been investigated by means of hot compression simulation experiment under various conditions of strain rate, deformation temperature and strain. The effect of austenite grain size on the strain enhanced ferrite transformation has been studied. The ferrite dynamic recrystallization involved in successive hot deformation has been explored.展开更多
Considering the specialities of the steel plate production, the TMCP study has been carried out with Gleeble 2000 tester to explore the possibility of fine grained ferrite in the low carbon steel plates with the chemi...Considering the specialities of the steel plate production, the TMCP study has been carried out with Gleeble 2000 tester to explore the possibility of fine grained ferrite in the low carbon steel plates with the chemical composition of C 0.13--0.18, Si 0.12-0.18, Mn 0.50-0. 65, P 0. 010-0. 025, and S 0. 005-0. 028. The plates with thickness of 8. 7 mm in which the ferrite grain size is smaller than 8μm have been produced by special de- formation process in the laboratory. Furthermore, the trial production of special plain carbon steel plates of 16-25 mm in thickness and 2 000- 2 800 mm in width with fine grained ferrite has been successfully carried out in the Shougang Steel Plate Rolling Plant. The ferrite grain size is 5.5-7μm in the surface layers and 9.5-15μm in the central layer respectively. The yield strength is 320- 360 MPa, tensile strength is 440-520 MPa and the elongation is 25%- 34 %. It is very important for the rolling plants to improve the low carbon steel plates＇ mechanical properties. The results show that the ferrite grains in the surface layer can be refined effectively by the appropriate rolling process, and the strength can be also increased.展开更多
This paper presents the report of corrosion prevention study carried out on plain carbon steel lined with calcite, magnesium carbonate and dolomite as coats. Eight samples each of the steel were dipped into solutions ...This paper presents the report of corrosion prevention study carried out on plain carbon steel lined with calcite, magnesium carbonate and dolomite as coats. Eight samples each of the steel were dipped into solutions of CaCO3, CaCO3 and MgCO3, and MgCO3. Pipe borne water obtained from Obafemi Awolowo University, Ile-Ife water works was used as the environment. The corroded sample surfaces were subject to microstructural characterization using optical microscopy technique. The results obtained showed that the steel exhibited minimum corrosion rate of less than 0.5 mm/yr in dolomite, followed by MgCO3 and then by CaCO3 with corrosion rate far above 0.5 mm/yr bench mark. The unlined (control) samples have maximum corrosion rate of 0.8 mm/yr. the microstructures revealed widespread localized attacks and to a uniform corrosion. The dolomite lined samples are recommended for corrosion prevention of plain carbon steel in pipe borne water.展开更多
文摘Bipolar plates are a multifunctional component of PEMFC. Comparing with the machined graphite and stainless steels, the plain carbon steel is a very cheap commercial metal material. In this paper, the possibility of applying the plain carbon steels in the bipolar plate for PEMFC was exploited. In order to improve the corrosion resistance of the low carbon steel in the PEMFCs′ environments, two surface modification processes was developed and then the electrochemical performances and interfacial contact resistance (ICR) of the surface modified plate of plain carbon steel were investigated. The results show that the surface modified steel plates have good corrosion resistance and relatively low contact resistance, and it may be a candidate material as bipolar plate of PEMFC.
文摘The effects of cooling rate and coiling temperature on microstructure and mechanical properties of a plain carbon steel were investigated by combining metallography and tensile experiments. The results indicate that ferrite grain size is refined and bainite transformation occurs to ensure high strength and elongation, as the cooling rate is quick enough. Yield strength and tensite strength improve with the decreased finish cooling temperature, but the elongation decreases too significantly to meet the requirements. Thus, the cooling rate must be quick enough, and the appropriate coiling temperature should be carefully selected to obtain refined ferrite and a small amount of bainite to improve the strength while the plasticity is also ensured. Under this condition, the Mn element concentration can be reduced to save cost or produce higher strength steel with same chemical composition.
基金This work was financially supported by the National Key Foundational Research Project(grant No.G1998061512).
文摘A model based on Avrami equation and Scheil's additivity rule was proposed to simulate the phase transformation in plain carbon steels during continuous cooling in hot strip mill. In this model, a wide range of composition, cooling rate, primary austenite grain size and retained strain has been taken into account. It can be used to calculate the phase fraction transformed at different temperatures during continuous cooling. The phase equilibrium and transformation starting temperature can be determined by using Thermo-Calc and DICTRA. The simulated results containing the transformation at starting and finishing temperatures, Ae1, Ae3 and the maximum volume fraction for Q235B, were obtained. The calculated phase volume fractions are in good agreement with .the experimental results.
文摘Grain growth kinetics of austenite in a hypoeutectoid steel（containing carbon of 0.35%）at 920 ℃ and in a hypereutectoid steel（containing carbon of 1%）at 980 ℃ for holding time ranging from 1 h to 6 h was investigated.The hypoeutectoid steel exhibited normal grain growth without solute drag hindrance with a time exponent（0.51）close to the theoretical value（0.5）.However,the grain growth of austenite in the hypereutectoid steel held up to 3 h was extremely slow,characterizing by a low value of time exponent（0.08）.Thereafter,a breakaway occurred and the grain growth in the hypereutectoid steel held from 3 h to 6 h progressed normally with a time exponent（0.52）close to the theoretical value（0.5）.
基金financially supported by the National Natural Science Foundation of China(No.51601011)the Fundamental Research Funds for the Central Universities+2 种基金the Recruitment Program of Global Expertsthe State Grid Scientific and Technological Research Program of China(No.5211DS17001X)the Zhejiang Electric Power Corporation Scientific and Technological Research Program of China(No.5211DS5002 M).
文摘The fracture of pipelines caused by corrosion cracks and the resulting oil and gas leakage can lead to great environmentalpollution and economic losses. These negative effects are due to serious corrosion of the plain carbon steels used for armorof flexible pipe in oil and gas transmission medium. However, corrosion resistance of carbon steel armors has yet to beimproved. In this study, the relationship between corrosion resistance and pearlite fraction in the plain carbon steels hasbeen investigated through the application of pulsed electric current. Based on immersion test and electrochemical mea-surement, pulsed electric current increases the corrosion resistance of the plain carbon steels by reducing the fraction ofpearlite phase. Pitting corrosion, which tends to initiate by galvanic corrosion of ferrite and cementite, is therefore inhibiteddue to the decrease in pearlite fraction （mixture of ferrite and cementite） under electropulsing.
基金Acknowledgements-Financial support of National Science and Technology Ministry to the research projectfundamental research of
文摘The microstructure evolution during deformation enhanced transformation of undercooled austenite of a plain low carbon steel has been investigated by means of hot compression simulation experiment under various conditions of strain rate, deformation temperature and strain. The effect of austenite grain size on the strain enhanced ferrite transformation has been studied. The ferrite dynamic recrystallization involved in successive hot deformation has been explored.
文摘Considering the specialities of the steel plate production, the TMCP study has been carried out with Gleeble 2000 tester to explore the possibility of fine grained ferrite in the low carbon steel plates with the chemical composition of C 0.13--0.18, Si 0.12-0.18, Mn 0.50-0. 65, P 0. 010-0. 025, and S 0. 005-0. 028. The plates with thickness of 8. 7 mm in which the ferrite grain size is smaller than 8μm have been produced by special de- formation process in the laboratory. Furthermore, the trial production of special plain carbon steel plates of 16-25 mm in thickness and 2 000- 2 800 mm in width with fine grained ferrite has been successfully carried out in the Shougang Steel Plate Rolling Plant. The ferrite grain size is 5.5-7μm in the surface layers and 9.5-15μm in the central layer respectively. The yield strength is 320- 360 MPa, tensile strength is 440-520 MPa and the elongation is 25%- 34 %. It is very important for the rolling plants to improve the low carbon steel plates＇ mechanical properties. The results show that the ferrite grains in the surface layer can be refined effectively by the appropriate rolling process, and the strength can be also increased.
文摘This paper presents the report of corrosion prevention study carried out on plain carbon steel lined with calcite, magnesium carbonate and dolomite as coats. Eight samples each of the steel were dipped into solutions of CaCO3, CaCO3 and MgCO3, and MgCO3. Pipe borne water obtained from Obafemi Awolowo University, Ile-Ife water works was used as the environment. The corroded sample surfaces were subject to microstructural characterization using optical microscopy technique. The results obtained showed that the steel exhibited minimum corrosion rate of less than 0.5 mm/yr in dolomite, followed by MgCO3 and then by CaCO3 with corrosion rate far above 0.5 mm/yr bench mark. The unlined (control) samples have maximum corrosion rate of 0.8 mm/yr. the microstructures revealed widespread localized attacks and to a uniform corrosion. The dolomite lined samples are recommended for corrosion prevention of plain carbon steel in pipe borne water.
