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Development Study of Welding Rod for the Purpose of T91/P91 Heat Resistant-steel

Author: ZhangYaWei
Tutor: TangWenBo
School: Zhengzhou University
Course: Materials Processing Engineering
Keywords: T91/P91 steel Electrode manufacturability Rare earths Inclusions Grain refinement
CLC: TG422.1
Type: Master's thesis
Year: 2011
Downloads: 55
Quote: 0
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Abstract


With the rapid development of China's power industry, high-parameter, high-capacity thermal power units are emerging, of T91/P91 martensitic steel increasingly wide range of applications because of its excellent performance. However, domestic T91/P91 steel electrode, compared with the products of the industrial countries, electrode process is poor, and the weld microstructure and mechanical properties are not stable. T91/P91 steel welding material is still almost entirely dependent on imports, so the development of high-performance electrode can reduce manufacturing costs. Conducted a series of experiments for the development of the T91/P91 special steel welding rod through orthogonal test study and analyze the main component of a the electrode covering marble, fluorite, quartz electrode process of determining the optimal marble , fluorite and quartz ratio micro adjustment on the basis of the other ingredients of the electrode covering T91/P91 special steel welding rod has excellent electrode process. Added to the electrode process optimal formula based on trace rare earth, rare earth elements on the shape, size and distribution of the metal in the non-metallic inclusions electrodes deposited, and the role of grain refinement, using an optical microscope ( OM), scanning electron microscopy (SEM), energy spectrum analysis instrument (EDS), X-ray diffractometer (XRD) electrode deposited metal organizational structure characterization using a Vickers hardness tester, tensile testing machine and impact testing machine test electrodes deposited metal mechanical properties. The results show that: in the test range, marble content of welding spatter, slag detachability performance and weld forming a greater impact the fluorite content spatter impact larger quartz content greater impact on Weld Form optimize electrode welding spatter than small, easy slag removal, weld appearance. Adding rare earth based on the optimization of welding rod, with the increasing amount of the rare earth alloy electrode covering a decreasing trend in the grain size of the deposited metal, rare earth alloys for drug skin test within 2.0%, the smallest grain RE addition little effect on the deposited metal hardness. Number of inclusions and particle diameter tended to decrease with the increase of the rare earth content in the deposited metal inclusions when drug skin content of about 2.0% rare earth alloy alumina inclusions mainly the smallest particles evenly dispersed. After high-temperature tempering deposited metal is tempered martensite, light microscope to the original martensite lath bit longer obvious drug skin 2.0% rare earth alloy electrodes deposited 55 # metal, verified by XRD and SEM, the tempered martensite, fine chromium carbide particles dispersed in the martensite internal slightly concentrated, while at the interface in the martensite lath. In all tests, 55 # electrode process excellent arc stability, spatter small, molding appearance, automatic slag detachability; most small deposited metal grains, the alumina-based inclusions are dispersed, smallest size; high temperature tempering After the tempered martensite, fine chromium carbides dispersed in the martensite internal; hardness value within a reasonable range, tensile and impact test results show that the mechanical properties to comply with the European standard, acceptable performance. # 55 welding rod the optimal formula electrodes for experimental and research.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding materials > Arc welding material > Welding rod
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