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Anomalous residual austenite formation in root of welding layers of 9% Cr/CrMoV dissimilar welded joint

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Journal of Iron and Steel Research International 2018年第8期25卷 839-846页

作者： Kai Ding Hui-jun Ji Quan-liang Zhang Xia Liu Peng Wang Xiao-hong Li Ling Zhang Yu-lai Gao State Key Laboratory of Advanced Special Steel State Shanghai Key Laboratory of Advanced FerrometallurgySchool of Materials Science and Engineering Shanghai University Shanghai 200444 China Shanghai Turbine Plant Shanghai Electric Power Generation Equipment Co. Ltd. Shanghai 200240 China

The morphology and distribution of residual austenite in the welded zone of 9% Cr/CrMoV dissimilar welded joint were observed by color metallographic method. Moreover, the details of the distribution, shape, length, length-to-width ratio, and the content of residual austenite in each welding layer were systematically characterized using Image-Pro Plus image analysis software. Different from the techniques such as X-ray diffraction, vibrating sample magnetometer, and electron backscatter diffraction that only involve the content of residual austenite, color metallographic method can offer much more details of the residual austenite, including the location, shape, size, and content, helping evaluate the overall characteristics of the residual austenite produced in the weld. It is interesting that a large amount of block-like and film-like residual austenite was found in the root of each welding layer, while rare at the top. The area fraction of residual austenite located in this zone was approximately 7.5% compared with only 0.5% at the top. In addition, the average area, length, and length-to-width ratio of dispersed residual austenite were quantitatively evaluated to be （4.7 ± 0.6）μm2, （5.1 ±0.6） μm, and （1.1 ± 0.1） μm, respectively. This variety of residual austenite was resulted from the tempering effect by latter welding layer on the previous one and different cooling rates in these two regions during the welding process.

关键词： Residual austenite Color metallographic method dissimilar welded joint Narrow gap submerged arcwelding Multilayer and multi-pass welding

Prevention of carbon migration in 9% Cr/CrMoV dissimilar welded joint by adding tungsten inert gas overlaying layer

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Journal of Iron and Steel Research International 2018年第8期25卷 847-853页

作者： Kai Ding Hui-jun Ji Xia Liu Peng Wang Quan-liang Zhang Xiao-hong Li Yu-lai Gao State Key Laboratory of Advanced Special Steel Shanghai Key Laboratory of Advanced Ferrometallurgy School of Materials Science and Engineering Shanghai University Shanghai 200072 China Shanghai Electric Power Generation Equipment Co. Ltd.Shanghai Turbine Plant Shanghai 200240 China

High chromium （9-12% Cr） steels with excellent heat resistance and CrMoV steels with good toughness were potential candidates for combined rotor for steam turbine operated over 620℃. Two welding techniques were used to fabricate 9% Cr and CrMoV dissimilar welded joint. The results show that the carbon migration only appears in the specimen using narrow gap submerged arc welding （NG-SAW） technique, yet it can be effectively prevented by adding tungsten inert gas （TlG） overlaying process before the NG-SAW. The carbon migration occurred in NG-SAW resulting from the sharp transition of the strong carbide-forming element Cr between the weld （-2.7 wt%） and the base metal （- 9 wt%）. On the contrary, the application of TIG overlaying layers can promote the diffusion of Cr element, and therefore result in its much smaller concentration gradient. That is to say, a gentle transition zone of Cr element can be created among the SAW weld, TIG overlaying layers and the base metal, which effectively prevents the carbon migration and therefore produces a decreased carbon concentration adjacent to the fusion line.

关键词： Carbon migration Tungsten inert gas overlaying Gentle transition zone Narrow gap submerged arc welding dissimilar welded joint

Study of fractal character of the fusion line in dissimilar welded joint

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China Welding 1999年第1期8卷 48-51页

作者：屈朝霞张汉谦王宝 Tianjin Univ Tianjin China

The fractal dimension of the fusion line in different dissimilar welded joints is measured with Box Dimension *** non scale region of the fusion line with fractal character is calculated. The fusion line in the dissimilar welded joint is proved to be a fractal structure. The change and influence factors of the fractal dimension of the fusion line are studied.

关键词： dissimilar welded joint fusion line fractal

EFFECT OF CARBON MIGRATION ON CREEP PROPERTIES OF Cr5Mo dissimilar welded jointS WITH Ni-BASED AND AUSTENITIC WELD METAL

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 560-568页

作者： J.M.Gong Y.Jiang S.T.Tu Nanjing University of Technology Nanjing 210009 ChinaNanjing University of Technology Nanjing 210009 ChinaNanjing University of Technology Nanjing 210009 China East China University of Science and Technology Shanghai 200237 China

In this paper, the effect of carbon migration on creep properties of Cr5Mo dissimilar welded joints with Ni-based (Inconel 182) and Cr23Nil3 (A302) austenitic weld metal was investigated. Carbon migration near the weld metal/ferritic steel interface of Cr5Mo dissimilar welded joints was analyzed by aging method. Local creep deformations of the dissimilar welded joints were measured by a long-term local creep deformation measuring technique. The creep rupture testing was performed for Cr5Mo dissimilar welded joints with Inconel 182 and A302 weld metal. The research results show that the maximum creep strain rate occurs in the decarburized zone located on heat affect zone (HAZ) of Cr5Mo ferritic steel. The creep rupture life of Cr5Mo dissimilar welded joints with A 302 weld metal decreases due to carbon migration and is about 50% of that welded with Inconel 182 weld metal.

关键词： dissimilar welded joint carbon migration creep rupture localized deformation

Changing Rule of Carbon-Enriched Zone and Diffusion Behavior of Carbon in Aging 0Cr6Mn13Ni10MoTi/1Cr5Mo dissimilar welded joints

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Journal of Materials Science & Technology 2004年第3期20卷 307-310页

作者： Zheng LIU Ligang WANG Lai WANG Department of Materials Engineering, Dalian University of Technology, Dalian 116024,China Dept. of Mat. Eng. Dalian Univ. of Technol. Dalian 116024 China

The microstructures, the changing rule of carbon-enriched zone, the diffusion behaviors of elements C and Cr, and thecarbide type of 0Cr6Mn13Ni10MoTi/1Cr5Mo dissimilar welded joints after aging at 500℃ for various times and afterlong-term service in technical practice were investigated by using the optical microscopy electron probe microanalysis,scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results show that in aging0Cr6Mn13Ni10MoTi/1Cr5Mo dissimilar welded joints, the main carbides are M_3C and a few carbides are M_7C_3 andM_(23)C_6. The M_3C carbide decomposition and dissolution with increasing aging time or aging temperature and theanti-diffusion of C and Cr cause the decrease and disappearance of the carbon-enriched zone. The results are differentfrom those of the A302/1Cr5Mo dissimilar welded joints in previous studies.

关键词： dissimilar welded joint Aging Diffusion Carbides

Impact wear properties of dissimilar joints between bainitic frogs and pearlite rails

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Journal of Iron and Steel Research International 2024年第1期31卷 275-287页

作者： Pin-yong Zeng Chun-guang Zuo Xiao-yu Zhang Wei Li Tribology Research Institute Southwest Jiaotong UniversityChengdu610031SichuanChina

The impact wear behavior and damage mechanism of dissimilar welded joints between U26Mn frog and U75 V rail before and after normalizing treatment were studied by cyclic impact *** experiment indicated that the impact wear volume of the joints increased with the increasing number of impact *** main wear mechanisms include pitting wear,mild fatigue wear,delamination wear,and fatigue wear,and plastic deformation was the primary impact wear *** them,fatigue wear had the greatest influence on wear volume,while other wear mechanisms had limited *** impact wear resistance of the base material was better than that of the heat-affected *** treatment was beneficial to improving the impact wear resistance of welded joints owing to its effect to promote pearlite recovery,grain refinement,and uniform distribution of *** martensite generated in the rail welded joints aggravated the impact wear damage to the materials,which should be avoided.

关键词： dissimilar welded joint Impact wear Bainitic steel Damage mechanism Wear rate