Papers by Keyword: Weathering Steel

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Authors: Zhi Fen Wang, Jian Rong Liu, Li Xin Wu, Hai E Huang, Qian Xue Zhou
Abstract: The weatherability of a weathering steel W450QN was compared with a carbon steel Q345 after 5 years atmospheric corrosion. The results indicated that the corrosion resistance was better for W450QN than Q345 based on the corrosion rate. The characteristics of the rust layers indicated the rust layer on W450QN was denser and thicker than that of Q345. The rust layers were mainly composed of goethite (α-FeOOH) with a few of lepidocrocite (γ-FeOOH). W450QN had better weatherability attributed to the alloying elements of copper, chromium and phosphorus enriched in the rust layer.
Authors: Rui Shan Xin, Hui Long An, Shuai Ren, Ji Tan Yao, Jin Pan
Abstract: Continuous cooling transformation (CCT) diagram of a high strength weathering prefabricated building steel was determined using a DIL805L thermal dilatometer by means of the expansion method combined with metallography hardness method. Effect of cooling rate on microstructure and hardness of the steel was also studied. The results show that the austenite transformation products of the steel are ferrite and pearlite when cooling rate is lower than 3°C/s. In the cooling rate range of 3 to 20°C/s, the mixed microstructure of ferrite, pearlite and bainite can be obtained. When cooling rate is higher than 20°C/s but lower than 100°C/s, the microstructure is composed of ferrite, bainite and martensite. When cooling rate is above 100°C/s, ferrite disappeared completely, and transformation products are bainite and martensite.
Authors: Vit Křivý, Lukáš Fabián
Abstract: The aim of this paper is an introduction of the new developed method for calculation of corrosion losses on structures designed from weathering steels. Apposite calculation of corrosion losses is an essential requirement for resulting determination of corrosion allowances that must be considered when designing steel structures from weathering steels.
Authors: Hui Shu Zhang, Dong Ping Zhan, Song Lian Bai, Zhou Hua Jiang
Abstract: The corrosion behaviors of Al-Si-Cr-Cu bearing low carbon steel and a reference steel Q235 were tested in a cyclic dry/wet environment containing 0.01mol/L NaHSO3 in laboratory. Rust layers were observed by optical microscope (OM), scanning electron microscopy (SEM) and XRD. The electrochemical behaviors of the steels were studied on the polarization curves and electrochemical impedance spectroscopy (EIS). The results indicate that after 120h corrosion test, the annual corrosion rates of the designed steels reduce 42 % than Q235 at least. The corrosion products are generally iron oxyhydroxides and oxides such as FeOOH, γ-FeOOH, α-FeOOH, γ-Fe2O3, Fe3O4. The α-FeOOH possesses good stabilization mainly exits and can improve the corrosion resistance. There are the enrichments of Cu, Cr, Si and Al in the rust layer close to the matrix, which make the rust layer be more compact and protected. The corrosion currents of the two designed steels are lower than that of Q235, the corrosion potentials are higher than that of Q235 after Tafel fitting. The rust layer impedances of the designed steels are higher than that of Q235.
Authors: Toshiyasu Nishimura
Abstract: The iron rust phase has been analyzed by using EPMA, TEM and EIS after simulating marine corrosion tests. The ultrafine grained (UFG) weathering steel containing Si and Al showed higher corrosion resistance than carbon steel in the test. Si and Al were identified as Si 2+ and Al 3+ in the complex oxide of inner rust by EPMA and TEM. It was demonstrated by EIS that the resistance at the low frequency region corresponded to that of corrosion reaction of rusted steels (Rt). The Rt value of this steel increased after the continuous formation of inner rust, which implied that Si and Al took part in the conversion of complex oxides into fine structure that prevented the penetration of Cl ions.
Authors: Chun Ling Zhang, Da Yong Cai, Ke Qin Zhang, Bo Liao
Abstract: Dual-phase steels of 09CuPCrNi are prepared through intercritical quenching process. The influences of dual-phase treatment on the corrosion resistant property of the steels have been studied by electrochemical potentiodynamic tests and artificial salt spray tests. The results indicate that the corrosion behavior of DP780 and the as-received weathering steel in 5% sodium hydroxide, 3.5% sodium chloride, 5% sulphuric acid and various concentrations of hydrochloric acid solutions are identical, but dual-phase steels show least corrosion current as compared to the as-received steel. Rust layers of the as-received steel and DP780 are identical mainly consisting of three iron (hydr) oxides, goethite, akaganeite and lepidocrocite, and magnetite. Both the relative amount and morphology of phase constituents affect on the corrosion behavior of DP steels.
Authors: Z.R. Hou, H.L. Yi, X.M. Zhao
Abstract: Based on the 355MPa high weather-resistant steel, three different kinds of high weather-resistant steels were designed by varying the content of Ni. The the corrosion resistance of the high weather-resistant steel as well as the influence of Ni content on the corrosion resistance were studied in the present investigation. The results of the cycle corrosion tests indicated that with the addition of Ni, the corrosion resistance was improved to some extent. The rust layer of the weathering steel was composed of α-FeOOH and γ-FeOOH at the beginning of corrosion, and the α-FeOOH turned to γ-FeOOH which enhanced the corrosion resistance.
Authors: Rui Liu, Xiao Ping Chen, Qing Nan Shi
Abstract: Corrosion behavior of a low alloy steel A with 3% nickel content was studied by a wet/dry cyclic test. A commercial weathering steel Q450NR1 was used for comparison. The classical weight loss method was used to evaluate the weatherability of weathering steel, while the iron rust layers formed on weathering steel were analyzed by using SEM, XRD and electrochemical measurements. The results indicated that the corrosion resistance of steels A was better than that of commercial weathering steel Q450NR1 in the wet/dry cyclic test. The addition of Ni promoted the formation of α-FeOOH so as to improve the resistance of the rust. The EIS results indicated that the charge transfer resistance of steel A was bigger than that of steel Q450NR1.
Authors: Qiang Zhang, Zhe Wu, Hong Wu Li
Abstract: In this paper, the mechanical properties of Q355NH resistant steel welded joints are studied. Through the analysis of mechanical properties of welded joints, the results showed that the tensile strength of the welded joints decreased after annealing and the elongation increased. The impact test results of tensile specimens before and after annealing showed that the impact energy of the weld area increased greatly after annealing, while the impact energy of the heat affected zone changed little. Furtherly, fatigue strength of specimens before and after annealing was compared, and the results showed that under the condition of high cycle fatigue, the un-annealed specimens were broken and the fracture position was located on the parent metal, whereas the annealed specimens did not break.
Authors: Xiao Liu, Hu Fei Zhang
Abstract: The effects of RE on the inclusions and the mechanical properties of 10PCuRE steel were studied. The results show that the morphologies and sizes of inclusions in 10PCuRE steel are changed, and RE played a very good role of modifying inclusions. Fracture is changed from cleavage to ductile fracture by adding RE to 10PCuRE steel. And the mechanical properties of 10PCuRE are improved. In comparison with 10PCuRE steel without RE, the transverse impact toughness of 10PCuRE steel with RE is increased 30.15% at -20°C, and the tensile strength and reduction of area have been improved 27.14%, 8.9%, respectively.
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