Abstract Powder production for additive manufacturing is currently mainly done by inert gas atomization. A new process is the production of low-oxygen and highly spherical metal powders by ultrasonic atomization from a wire or rod feedstock. As a crucible-free process and because of an electric arc as an energy source, even materials with a high liquidus temperature up to 1800 °C can be processed. A limitation of this technique can be found in the continuous processing of high-strength materials, like martensitic hardenable tool steels, from a stiff wired feedstock because of the limited feed ability. This paper investigates the possibility of processing high-strength steel powder using cored wire as the starting material for the ultrasonic atomization process to circumvent the feeding problem of high-strength materials. Thereby, two carbon martensitic hardenable hot work tool steels with a carbon content of 0.12 wt. % and 0.4 wt. % are considered as reference materials. After the atomization process with varying parameters, powders are characterized concerning their morphology, chemical composition, phases formed, and related powder properties. In addition to flowability, the bulk density are also determined. Based on these results, a conclusion will finally be given on the suitability of ultrasonically atomized powders for additive manufacturing and fast sintering techniques.
{"title":"Potentials of Ultrasonically Atomized Cored Wires for Powder Metallurgy and Additive Manufacturing","authors":"S. Jäger, F. Großwendt, S. Weber, A. Röttger","doi":"10.1515/htm-2022-1043","DOIUrl":"https://doi.org/10.1515/htm-2022-1043","url":null,"abstract":"Abstract Powder production for additive manufacturing is currently mainly done by inert gas atomization. A new process is the production of low-oxygen and highly spherical metal powders by ultrasonic atomization from a wire or rod feedstock. As a crucible-free process and because of an electric arc as an energy source, even materials with a high liquidus temperature up to 1800 °C can be processed. A limitation of this technique can be found in the continuous processing of high-strength materials, like martensitic hardenable tool steels, from a stiff wired feedstock because of the limited feed ability. This paper investigates the possibility of processing high-strength steel powder using cored wire as the starting material for the ultrasonic atomization process to circumvent the feeding problem of high-strength materials. Thereby, two carbon martensitic hardenable hot work tool steels with a carbon content of 0.12 wt. % and 0.4 wt. % are considered as reference materials. After the atomization process with varying parameters, powders are characterized concerning their morphology, chemical composition, phases formed, and related powder properties. In addition to flowability, the bulk density are also determined. Based on these results, a conclusion will finally be given on the suitability of ultrasonically atomized powders for additive manufacturing and fast sintering techniques.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":"121 1","pages":"181 - 192"},"PeriodicalIF":0.6,"publicationDate":"2023-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75683297","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 Quenching with aqueous polymer solutions has some distinct advantages over classical oil quenching. Among these are the good environmental properties and the possibility to adjust the quenching performance between oil and water quenching. Nevertheless, critical aspects must also be taken into account. When quenching steel parts with polymer solutions, “explosion-like” phenomena can occur, often accompanied by large cooling rate changes. These “explosions” can lead to pressure waves and vibrations in the quenching tank, which in the long run can even destroy weld seams of the quenching tank. In the framework of a research project, experimental investigations were carried out in a laboratory quenching bath and in an industrial quenching tank. The polymer type, the type of incident flow, the flow velocity, the bath temperature and the size of the test shafts were varied. Near-surface temperature measurements inside the shafts were performed to characterize the resulting quenching processes. Simultaneously, electrical conductivity measurements and audio and video recordings were made to localize insulating films on the surface and their collapse. To systematize and characterize the large number of measurement results, characteristic types of cooling processes and characteristic numbers for their characterization were defined and will be presented in this paper.
{"title":"Quenching with Aqueous Polymer Solutions","authors":"T. Lübben, F. Frerichs","doi":"10.1515/htm-2022-1045","DOIUrl":"https://doi.org/10.1515/htm-2022-1045","url":null,"abstract":"Abstract Quenching with aqueous polymer solutions has some distinct advantages over classical oil quenching. Among these are the good environmental properties and the possibility to adjust the quenching performance between oil and water quenching. Nevertheless, critical aspects must also be taken into account. When quenching steel parts with polymer solutions, “explosion-like” phenomena can occur, often accompanied by large cooling rate changes. These “explosions” can lead to pressure waves and vibrations in the quenching tank, which in the long run can even destroy weld seams of the quenching tank. In the framework of a research project, experimental investigations were carried out in a laboratory quenching bath and in an industrial quenching tank. The polymer type, the type of incident flow, the flow velocity, the bath temperature and the size of the test shafts were varied. Near-surface temperature measurements inside the shafts were performed to characterize the resulting quenching processes. Simultaneously, electrical conductivity measurements and audio and video recordings were made to localize insulating films on the surface and their collapse. To systematize and characterize the large number of measurement results, characteristic types of cooling processes and characteristic numbers for their characterization were defined and will be presented in this paper.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":"18 1","pages":"121 - 140"},"PeriodicalIF":0.6,"publicationDate":"2023-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84471655","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 Carbonitriding enhances properties of many steels and is therefore an attractive alternative for surface hardening of steel components in the mechanical industry. However, pore formation in the carbon and nitrogen enriched surface layer may occur under certain process conditions. For a given steel and case depth specification, pore formation can be managed by reducing the nitrogen activity of the carbonitriding atmosphere below a defined limit, depending on process temperature and process time. Recent progress in process control allows automatic and independent adjustments of the carbon and nitrogen activities and corresponding potentials of the carbonitriding atmosphere. This study contributes to the practical evaluation of pore formation limits under selected carbonitriding conditions for a range of commonly used engineering steel grades.
{"title":"Mechanism and Observation of Pore Formation during Carbonitriding","authors":"M. Skalecki, M. Sommer, M. Steinbacher, S. Hoja","doi":"10.1515/htm-2022-1028","DOIUrl":"https://doi.org/10.1515/htm-2022-1028","url":null,"abstract":"Abstract Carbonitriding enhances properties of many steels and is therefore an attractive alternative for surface hardening of steel components in the mechanical industry. However, pore formation in the carbon and nitrogen enriched surface layer may occur under certain process conditions. For a given steel and case depth specification, pore formation can be managed by reducing the nitrogen activity of the carbonitriding atmosphere below a defined limit, depending on process temperature and process time. Recent progress in process control allows automatic and independent adjustments of the carbon and nitrogen activities and corresponding potentials of the carbonitriding atmosphere. This study contributes to the practical evaluation of pore formation limits under selected carbonitriding conditions for a range of commonly used engineering steel grades.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":"10 1","pages":"105 - 118"},"PeriodicalIF":0.6,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85300641","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":"Imprint / Impressum","authors":"","doi":"10.1515/htm-2023-8002","DOIUrl":"https://doi.org/10.1515/htm-2023-8002","url":null,"abstract":"","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":"147 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135374872","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}
J. E. Menzler, M. Klusmann, Markus Wulfmeier, D. Büschgens, H. Pfeifer
Abstract Gas impingement jets are widely applied in industrial cooling processes. In continuous heat treatment lines of steel, aluminium and copper strips, impingement jet nozzle systems are utilised to achieve rapid cooling or heating. The heat transfer depends on the flow but also on the geometric parameters such as nozzle to strip distance and the nozzle shape. The key challenge while designing cooling sections is to determine the performance of those nozzle systems or their Nusselt number respectively. Jet cooling sections are challenging to model with computational fluid dynamics or in an experimental set up. Yet, RANS-turbulence models are a cost-effective way to predict Nusselt numbers. In this work the capability of the ANSYS generalized k-omega (GEKO) two-equation turbulence model to determine the local and integral Nusselt number of an impinging air jet is evaluated. The results are contrasted to experimental investigations.
{"title":"Simulation of Gas Jet Impingement Cooling in Continuous Heat Treatment Lines with the ANSYS GEKO Turbulence Model*","authors":"J. E. Menzler, M. Klusmann, Markus Wulfmeier, D. Büschgens, H. Pfeifer","doi":"10.1515/htm-2022-1042","DOIUrl":"https://doi.org/10.1515/htm-2022-1042","url":null,"abstract":"Abstract Gas impingement jets are widely applied in industrial cooling processes. In continuous heat treatment lines of steel, aluminium and copper strips, impingement jet nozzle systems are utilised to achieve rapid cooling or heating. The heat transfer depends on the flow but also on the geometric parameters such as nozzle to strip distance and the nozzle shape. The key challenge while designing cooling sections is to determine the performance of those nozzle systems or their Nusselt number respectively. Jet cooling sections are challenging to model with computational fluid dynamics or in an experimental set up. Yet, RANS-turbulence models are a cost-effective way to predict Nusselt numbers. In this work the capability of the ANSYS generalized k-omega (GEKO) two-equation turbulence model to determine the local and integral Nusselt number of an impinging air jet is evaluated. The results are contrasted to experimental investigations.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":"139-140 1","pages":"91 - 104"},"PeriodicalIF":0.6,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73221572","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":"HTM Praxis","authors":"","doi":"10.1515/htm-2023-2004","DOIUrl":"https://doi.org/10.1515/htm-2023-2004","url":null,"abstract":"","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135374871","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 Within the research work of the Transregional Collaborative Research Center TRR 136, process signatures were determined for processes that generate essentially thermal loading of the component surface layer. These process signatures represent correlations between material modifications (e. g. changes of residual stress, microstructure, hardness profile, etc.) and characteristic values of the material loading. The underlying idea is that the material does not know any processes but only loads caused by processes. In particular, the same loads lead to the same material modifications regardless of the kind of process. A decisive advantage of this concept over conventional approaches is the possibility of calculating the necessary internal material loads backwards on the basis of concrete specifications for the material modifications. If there are additional correlations between internal material loads and process quantities as well as between process quantities and machining parameters, the necessary machining parameters can be determined, too. In this paper, this procedure will be introduced using the example of one-sided induction hardening of cuboidal components made of 42CrMo4. The determination of the process signature by experimental and numerical investigations is described and work for experimental verifications are presented.
{"title":"Determination of Machining Parameters for a Specific Adjustment of the Residual Stress Profile by Induction Hardening*","authors":"F. Frerichs, T. Lübben","doi":"10.1515/htm-2022-1040","DOIUrl":"https://doi.org/10.1515/htm-2022-1040","url":null,"abstract":"Abstract Within the research work of the Transregional Collaborative Research Center TRR 136, process signatures were determined for processes that generate essentially thermal loading of the component surface layer. These process signatures represent correlations between material modifications (e. g. changes of residual stress, microstructure, hardness profile, etc.) and characteristic values of the material loading. The underlying idea is that the material does not know any processes but only loads caused by processes. In particular, the same loads lead to the same material modifications regardless of the kind of process. A decisive advantage of this concept over conventional approaches is the possibility of calculating the necessary internal material loads backwards on the basis of concrete specifications for the material modifications. If there are additional correlations between internal material loads and process quantities as well as between process quantities and machining parameters, the necessary machining parameters can be determined, too. In this paper, this procedure will be introduced using the example of one-sided induction hardening of cuboidal components made of 42CrMo4. The determination of the process signature by experimental and numerical investigations is described and work for experimental verifications are presented.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":"581 1","pages":"65 - 78"},"PeriodicalIF":0.6,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85324812","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 To elucidate the mechanisms of residual stress generation in quenched steel parts has been a longstanding problem. Qualitative explanations for the changes in the stress distribution in quenched cylinders appeared in the 1930s when it became possible to measure residual stresses in specimens. The explanation at that time used the concept of thermal and transformation stresses, which is still included in current textbooks. This concept is referred to here as the estimated stresses-based approach. To simplify the explanation of stress generation due to the combined effects of temperature change and phase transformations, quenching experiments were devised using Fe-Ni alloys in which only martensitic transformation occurs. On the other hand, since heat treatment simulations provide strains resulting from thermal, phase transformation, plastic, transformation plastic, and creep phenomena, a method to elucidate the mechanism using these strains was devised in the early 2000s and named the simulated strains-based approach. This paper contrasts the estimated stresses-based and simulated strains-based approaches to the mechanism of residual stress generation in quenched Fe-Ni alloy cylinders and highlights the superiority of the latter.
{"title":"Mechanism of Residual Stress Generation in Quenched Fe-Ni Alloy Cylinders Using Simulated Strains-Based Approach*","authors":"K. Arimoto","doi":"10.1515/htm-2022-1047","DOIUrl":"https://doi.org/10.1515/htm-2022-1047","url":null,"abstract":"Abstract To elucidate the mechanisms of residual stress generation in quenched steel parts has been a longstanding problem. Qualitative explanations for the changes in the stress distribution in quenched cylinders appeared in the 1930s when it became possible to measure residual stresses in specimens. The explanation at that time used the concept of thermal and transformation stresses, which is still included in current textbooks. This concept is referred to here as the estimated stresses-based approach. To simplify the explanation of stress generation due to the combined effects of temperature change and phase transformations, quenching experiments were devised using Fe-Ni alloys in which only martensitic transformation occurs. On the other hand, since heat treatment simulations provide strains resulting from thermal, phase transformation, plastic, transformation plastic, and creep phenomena, a method to elucidate the mechanism using these strains was devised in the early 2000s and named the simulated strains-based approach. This paper contrasts the estimated stresses-based and simulated strains-based approaches to the mechanism of residual stress generation in quenched Fe-Ni alloy cylinders and highlights the superiority of the latter.","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":"63 1","pages":"79 - 90"},"PeriodicalIF":0.6,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78882373","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}
Pub Date : 2023-03-30DOI: 10.1515/htm-2023-frontmatter2
{"title":"Contents / Inhalt","authors":"","doi":"10.1515/htm-2023-frontmatter2","DOIUrl":"https://doi.org/10.1515/htm-2023-frontmatter2","url":null,"abstract":"","PeriodicalId":44294,"journal":{"name":"HTM-Journal of Heat Treatment and Materials","volume":"182 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135374873","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}
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