M. R. Ahmadi, F. Meixner, M. Dománková, M. Raus, B. Sonderegger, C. Sommitsch
Ferritic 15 %-Cr steels have better oxidation resistance, due to their higher chromium content, and creep strength, their lower dislocation density and lack of lath microstructure than conventional martensitic steels such as MarBN. Their mechanical properties are sensitive to chemical composition and heat treatment. In this study, we first simulated the formation of stable phases in two ferritic steels containing 2 % nickel (wt.%) and an alloy without nickel using the thermomechanical software MATCALC. Microstructural analysis using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) reveals the formation of carbides and intermetallic phases after diffusion annealing, both during rapid cooling in oil and slow cooling in the furnace. Dilatometry and XRD studies confirm the gradual phase transformation of ferrite to austenite from 650 °C onwards during heating. Dilatometry also shows that ferritic steels have a lower coefficient of thermal expansion than martensitic steels, austenitic steels, and superalloys, which results in lower thermal stresses during frequent start-up and shutdown of power plants.
与传统的马氏体钢（如 MarBN）相比，15%-Cr 铁素体钢由于铬含量高、蠕变强度高、位错密度低和缺乏板条微结构而具有更好的抗氧化性。它们的机械性能对化学成分和热处理很敏感。在本研究中，我们首先使用热力学软件 MATCALC 模拟了两种含 2% 镍（重量百分比）的铁素体钢和一种不含镍的合金中稳定相的形成。利用扫描电子显微镜（SEM）和能量色散 X 射线光谱（EDS）进行的微观结构分析表明，无论是在油中快速冷却还是在炉中缓慢冷却，扩散退火后都会形成碳化物和金属间相。稀释测量法和 XRD 研究证实，在加热过程中，从 650 °C 开始，铁素体逐渐转变为奥氏体。稀释测量法还表明，铁素体钢的热膨胀系数低于马氏体钢、奥氏体钢和超合金，因此在发电厂频繁启动和关闭期间，热应力较低。
{"title":"Microstructural characterization of 15Cr steel after quenching and slow cooling rates","authors":"M. R. Ahmadi, F. Meixner, M. Dománková, M. Raus, B. Sonderegger, C. Sommitsch","doi":"10.1515/pm-2023-1063","DOIUrl":"https://doi.org/10.1515/pm-2023-1063","url":null,"abstract":"\u0000 Ferritic 15 %-Cr steels have better oxidation resistance, due to their higher chromium content, and creep strength, their lower dislocation density and lack of lath microstructure than conventional martensitic steels such as MarBN. Their mechanical properties are sensitive to chemical composition and heat treatment. In this study, we first simulated the formation of stable phases in two ferritic steels containing 2 % nickel (wt.%) and an alloy without nickel using the thermomechanical software MATCALC. Microstructural analysis using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) reveals the formation of carbides and intermetallic phases after diffusion annealing, both during rapid cooling in oil and slow cooling in the furnace. Dilatometry and XRD studies confirm the gradual phase transformation of ferrite to austenite from 650 °C onwards during heating. Dilatometry also shows that ferritic steels have a lower coefficient of thermal expansion than martensitic steels, austenitic steels, and superalloys, which results in lower thermal stresses during frequent start-up and shutdown of power plants.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139596453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract A clear characterization of layers of scale on hot-rolled steels does not only require a careful preparation of the samples but also a delineation of the individual scale phases. In this work, it could be shown that etching using dilute hydrochloric acid improved the distinction of the individual oxide phases during the light microscope examination of layers of scale. Furthermore, metallurgical analyses provide valuable information on the quantitative composition as well as on the qualitative element distribution in the layer of scale thus also facilitating the distinction of the scale phases.
{"title":"Metallographic preparation, contrasting, and examination of layers of scale on hot-rolled low-alloy steels","authors":"R. Mathe, D. Mirković","doi":"10.1515/pm-2024-0003","DOIUrl":"https://doi.org/10.1515/pm-2024-0003","url":null,"abstract":"Abstract A clear characterization of layers of scale on hot-rolled steels does not only require a careful preparation of the samples but also a delineation of the individual scale phases. In this work, it could be shown that etching using dilute hydrochloric acid improved the distinction of the individual oxide phases during the light microscope examination of layers of scale. Furthermore, metallurgical analyses provide valuable information on the quantitative composition as well as on the qualitative element distribution in the layer of scale thus also facilitating the distinction of the scale phases.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139176190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Gruber, V. Melcher, W. Harrer, A. Tilz, M. Engelmayer, W. Fimml, A. Wimmer, R. Bermejo
Abstract Large gas engines play a key role in energy supply and transport. Due to emission regulations and high fuel prices, engines achieving both high efficiency and low emissions are required. Development efforts to that effect have resulted in combustion methods relying on lean air-fuel mixtures as well as high ignition pressures. The conditions in the combustion chamber cause high wear on the spark plug electrodes. Conventional electrodes have a limited lifetime and they are expensive due to the use of precious metal alloys. Compared with conventional materials, alternative ceramic electrode materials offer advantages in terms of high thermal stability, high oxidation and corrosion resistance, as well as lower material prices. Disadvantages include insufficient electrical conductivity, brittleness and the difficulty of joining them with metallic materials. In this paper wear and oxidation behavior of selected materials are evaluated, using ceramographic methods. Microsections of the joining zone are used to analyse the change in the microstructure resulting from the bonding process. The results show the strengths, weaknesses and limitations of the selected ceramics as electrode materials, based on ceramographic methods, which helped essentially to understand the oxidation behavior, the bonding process and wear.
{"title":"The contribution of ceramography to the development of ceramic spark plug electrode materials for large gas engines","authors":"M. Gruber, V. Melcher, W. Harrer, A. Tilz, M. Engelmayer, W. Fimml, A. Wimmer, R. Bermejo","doi":"10.1515/pm-2024-0002","DOIUrl":"https://doi.org/10.1515/pm-2024-0002","url":null,"abstract":"Abstract Large gas engines play a key role in energy supply and transport. Due to emission regulations and high fuel prices, engines achieving both high efficiency and low emissions are required. Development efforts to that effect have resulted in combustion methods relying on lean air-fuel mixtures as well as high ignition pressures. The conditions in the combustion chamber cause high wear on the spark plug electrodes. Conventional electrodes have a limited lifetime and they are expensive due to the use of precious metal alloys. Compared with conventional materials, alternative ceramic electrode materials offer advantages in terms of high thermal stability, high oxidation and corrosion resistance, as well as lower material prices. Disadvantages include insufficient electrical conductivity, brittleness and the difficulty of joining them with metallic materials. In this paper wear and oxidation behavior of selected materials are evaluated, using ceramographic methods. Microsections of the joining zone are used to analyse the change in the microstructure resulting from the bonding process. The results show the strengths, weaknesses and limitations of the selected ceramics as electrode materials, based on ceramographic methods, which helped essentially to understand the oxidation behavior, the bonding process and wear.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138994742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Transformations in microstructural characteristics and mechanical attributes of friction stir welded 3 mm thick Ti–6Al–4V alloy plates was investigated by employing distinctive tool rotational and traverse speeds. Impact of these parameters on microstructural transitions, generation of flaws, hardness, and tensile properties of the joints were analyzed. Increase in rotational speed from 1200 rpm to 1600 rpm have contributed for escalation in temperature, even above the β transus temperature. Large sized lamellar alpha grains was found to be transformed into finely refined lamellar alpha + altered beta grains in uppermost portion of nugget zone of joints fabricated at 1600 rpm and 50 mm/min combinations. This transformation have occurred due to the impact of the thermal cycles and stirring mechanism. These joints were found to be free from flaws including volumetric related defects, kissing bond, tunnel flaws. Majority of the fabricated joints possessed lowest value of mechanical properties in their heat affected zone and exhibited fracture in this zone. Properties of Ti–6Al–4V alloy joints were evaluated with respect to pseudo index of heat and it was observed that rotational speed of the tool is a dominant parameter in impacting both the mechanical attributes and microstructural transformations of the joints.
{"title":"Impact of process parameters on transitions in the microstructural characteristics and mechanical attributes of Ti–6Al–4V alloy joints during FSW","authors":"D. Srinivasan, P. Sevvel, J. .. Gunasekaran","doi":"10.1515/pm-2023-1039","DOIUrl":"https://doi.org/10.1515/pm-2023-1039","url":null,"abstract":"Abstract Transformations in microstructural characteristics and mechanical attributes of friction stir welded 3 mm thick Ti–6Al–4V alloy plates was investigated by employing distinctive tool rotational and traverse speeds. Impact of these parameters on microstructural transitions, generation of flaws, hardness, and tensile properties of the joints were analyzed. Increase in rotational speed from 1200 rpm to 1600 rpm have contributed for escalation in temperature, even above the β transus temperature. Large sized lamellar alpha grains was found to be transformed into finely refined lamellar alpha + altered beta grains in uppermost portion of nugget zone of joints fabricated at 1600 rpm and 50 mm/min combinations. This transformation have occurred due to the impact of the thermal cycles and stirring mechanism. These joints were found to be free from flaws including volumetric related defects, kissing bond, tunnel flaws. Majority of the fabricated joints possessed lowest value of mechanical properties in their heat affected zone and exhibited fracture in this zone. Properties of Ti–6Al–4V alloy joints were evaluated with respect to pseudo index of heat and it was observed that rotational speed of the tool is a dominant parameter in impacting both the mechanical attributes and microstructural transformations of the joints.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138963606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract A heavy-duty gas turbine engine at the heart of a seawater desalination plant on the Arabian Peninsula exhibited multiple impact damages on their compressor airfoils that were detected during an inspection. Many blades showed heavily damaged airfoils and some even lost fractured-off parts. One moving blade in row 8 lost 50 % of its airfoil. Most compressor blade tips from stages 4 to 15 were damaged and bent. It was reported from the site that turning gear operation had been omitted once after engine shut-down in the recent past, i. e., the still hot rotor had not been turned until cool-down, resulting in rotor bend. This is believed to have caused the tip rubbing and airfoil break-off during the next engine start.
{"title":"Tip Rubbing as a Rare Metallurgical Root Cause of Gas Turbine Compressor Blade Failure","authors":"A. Neidel, T. Gädicke, J. Rockel","doi":"10.1515/pm-2023-0069","DOIUrl":"https://doi.org/10.1515/pm-2023-0069","url":null,"abstract":"Abstract A heavy-duty gas turbine engine at the heart of a seawater desalination plant on the Arabian Peninsula exhibited multiple impact damages on their compressor airfoils that were detected during an inspection. Many blades showed heavily damaged airfoils and some even lost fractured-off parts. One moving blade in row 8 lost 50 % of its airfoil. Most compressor blade tips from stages 4 to 15 were damaged and bent. It was reported from the site that turning gear operation had been omitted once after engine shut-down in the recent past, i. e., the still hot rotor had not been turned until cool-down, resulting in rotor bend. This is believed to have caused the tip rubbing and airfoil break-off during the next engine start.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139238933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In the second half of the 19th century, a wonder material reached worldwide fame. The chilled cast iron developed by Magdeburgbased industrialist and inventor Hermann Gruson was characterized by its extraordinary wear resistance which was far superior to that of the traditional wrought steels. Chilled cast iron was in demand all over the globe as a protective material, for example. Many stories surround Gruson’s long forgotten chilled cast iron and for the first time, this material has now been examined for its mechanical and microstructural properties using modern analytical methods. The microstructure property correlations determined during the study provide interesting insights both into the material and its inventor, who was one of the most innovative engineers of his time.
{"title":"Gruson’s chilled cast iron – a legendary wonder material of the 19th century","authors":"S. Dieck, O. Michael, M. Wilke, T. Halle","doi":"10.1515/pm-2023-1046","DOIUrl":"https://doi.org/10.1515/pm-2023-1046","url":null,"abstract":"Abstract In the second half of the 19th century, a wonder material reached worldwide fame. The chilled cast iron developed by Magdeburgbased industrialist and inventor Hermann Gruson was characterized by its extraordinary wear resistance which was far superior to that of the traditional wrought steels. Chilled cast iron was in demand all over the globe as a protective material, for example. Many stories surround Gruson’s long forgotten chilled cast iron and for the first time, this material has now been examined for its mechanical and microstructural properties using modern analytical methods. The microstructure property correlations determined during the study provide interesting insights both into the material and its inventor, who was one of the most innovative engineers of his time.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139240772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract OpenMicroscopyEnvironment Remote Objects (OMERO) is an open-source client-server system for archiving, visualizing and analyzing image data and associated meta-data in a repository and making the data usable in a database [1]. For this paper, OMERO has been studied as an image data repository and was selected as a central data space for metallography. Based on use cases examples from the Fraunhofer Institute for Mechanics of Materials (IWM), various possibilities of automated microstructural analysis using OMERO will be presented and discussed.
{"title":"Automated quantitative microstructural analysis using the open-source server-client platform OMERO","authors":"V. Friedmann, M. Bellmer, R. Antons, H. Hafok","doi":"10.1515/pm-2023-0068","DOIUrl":"https://doi.org/10.1515/pm-2023-0068","url":null,"abstract":"Abstract OpenMicroscopyEnvironment Remote Objects (OMERO) is an open-source client-server system for archiving, visualizing and analyzing image data and associated meta-data in a repository and making the data usable in a database [1]. For this paper, OMERO has been studied as an image data repository and was selected as a central data space for metallography. Based on use cases examples from the Fraunhofer Institute for Mechanics of Materials (IWM), various possibilities of automated microstructural analysis using OMERO will be presented and discussed.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139238884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"“Corrosion” on multi-layer composite pipes – the case of damage","authors":"Gunther Pajonk","doi":"10.1515/pm-2023-0063","DOIUrl":"https://doi.org/10.1515/pm-2023-0063","url":null,"abstract":"","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134907098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：