{"title":"Picture of the Month","authors":"","doi":"10.1515/pm-2023-0044","DOIUrl":"https://doi.org/10.1515/pm-2023-0044","url":null,"abstract":"","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135397951","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 One of the objectives of this series of case studies presented in section Failure Analysis of Practical Metallography is to educate colleagues who are new in the field, to inform them about failure mechanisms, not least about the rarer, more exotic ones and about metallurgical causes of failure that were utterly unexpected to occur in the particular failure case studies presented here. The subject of this contribution is a failure mechanism called Strain-assisted Grain Boundary Oxidation (SAGBO). This failure mechanism is not rare at all in hot-going nickel-base components in the aerospace industries. However, SAGBO was certainly unexpected to occur in large pipes that remained well below 400 °C in service.
{"title":"SAGBO on Inner and Outer Surface of Large Alloy 800H Pipe","authors":"A. Neidel, J. Rockel, B. Fischer","doi":"10.1515/pm-2023-0043","DOIUrl":"https://doi.org/10.1515/pm-2023-0043","url":null,"abstract":"Abstract One of the objectives of this series of case studies presented in section Failure Analysis of Practical Metallography is to educate colleagues who are new in the field, to inform them about failure mechanisms, not least about the rarer, more exotic ones and about metallurgical causes of failure that were utterly unexpected to occur in the particular failure case studies presented here. The subject of this contribution is a failure mechanism called Strain-assisted Grain Boundary Oxidation (SAGBO). This failure mechanism is not rare at all in hot-going nickel-base components in the aerospace industries. However, SAGBO was certainly unexpected to occur in large pipes that remained well below 400 °C in service.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86772228","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 Super 304HCu is an advanced ultra-super critical (A-USC) boiler grade austenitic stainless steel with the distinct addition of 3 wt.-% of Copper. A-USC power plants intended to operate in chloride rich environments (sea shore, feed water residues, etc.) are susceptible to chloride assisted corrosion failures. In this study, the pitting corrosion behaviour of the Super 304HCu parent material and tungsten inert gas weld joints was studied using a potentiodynamic cyclic polarization test in 3.5 % NaCl solution at three different pH levels (pH = 3, pH = 7, and pH = 11). The Epit values of the parent material is found to be much nobler than that of the weld joints. The micrographs of the pitted weld joints and the oxalic acid etched structure of Super 304HCu joints are presented. From the micrographs it is revealed that the heat affected zone is the most susceptible region to pitting corrosion.
Super 304HCu是一种先进的超超临界(A-USC)锅炉级奥氏体不锈钢，其铜含量为3wt .-%。打算在氯化物丰富的环境中运行的A-USC发电厂(海岸，给水残留物等)容易受到氯化物辅助腐蚀故障的影响。采用动电位循环极化试验，研究了超304HCu母材与钨惰性气体焊接接头在3.5% NaCl溶液中3种不同pH值(pH = 3、pH = 7、pH = 11)的点蚀行为。母材的Epit值比焊缝的Epit值高得多。给出了超级304HCu接头的点蚀和草酸腐蚀组织的显微照片。显微形貌表明，热影响区是最易发生点蚀的区域。
{"title":"Microstructure and Pitting Corrosion Characteristics of Tig Welded Joints of Super 304HCu Austenitic Stainless Steel","authors":"M. Vinoth kumar, C. Rajendran, V. Balasubramanian","doi":"10.1515/pm-2022-1034","DOIUrl":"https://doi.org/10.1515/pm-2022-1034","url":null,"abstract":"Abstract Super 304HCu is an advanced ultra-super critical (A-USC) boiler grade austenitic stainless steel with the distinct addition of 3 wt.-% of Copper. A-USC power plants intended to operate in chloride rich environments (sea shore, feed water residues, etc.) are susceptible to chloride assisted corrosion failures. In this study, the pitting corrosion behaviour of the Super 304HCu parent material and tungsten inert gas weld joints was studied using a potentiodynamic cyclic polarization test in 3.5 % NaCl solution at three different pH levels (pH = 3, pH = 7, and pH = 11). The Epit values of the parent material is found to be much nobler than that of the weld joints. The micrographs of the pitted weld joints and the oxalic acid etched structure of Super 304HCu joints are presented. From the micrographs it is revealed that the heat affected zone is the most susceptible region to pitting corrosion.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90384999","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 Steels with different mechanical and chemical properties are used together in the oil and gas industry. In this case, it has brought about the necessity of joining steels with different properties by welding. Most of the time, there are problems in welding these steels with different chemical properties. Therefore, in this study, AISI 304 stainless steel, AISI 4140 tempered steel, and S235JR structural steel with different chemical and mechanical properties used in the oil and gas industry were joined by friction welding. Then, macro and microstructure studies as well as hardness measurements, tensile tests, and torsion tests were applied to the produced samples. As a result of the micro-structure studies, it was observed that the martensitic structure was formed in the full deformation region of the joint made of AISI 304 stainless and AISI 4140 tempered steel, while it was determined that the other joints were formed of recrystallized fine grains in the full deformation region with the effect of friction. When the hardness measurement results were examined, it was determined that the hardest region was the full deformation region in all welded joints produced. As a result of the tensile tests, the highest tensile strength obtained was 622.94 N/mm2 in the joint made of AISI 304 stainless steel and AISI 4140 tempered steel. As a result of the torsion tests, the highest torsion moment was measured as 250 Nm in the sample produced from AISI 304 stainless steel and AISI 4140 tempered steel.
{"title":"Investigation of Friction Welding Properties of Steels with Different Chemical and Mechanical Properties Used in the Oil and Gas Industry","authors":"A. Yürük","doi":"10.1515/pm-2022-1023","DOIUrl":"https://doi.org/10.1515/pm-2022-1023","url":null,"abstract":"Abstract Steels with different mechanical and chemical properties are used together in the oil and gas industry. In this case, it has brought about the necessity of joining steels with different properties by welding. Most of the time, there are problems in welding these steels with different chemical properties. Therefore, in this study, AISI 304 stainless steel, AISI 4140 tempered steel, and S235JR structural steel with different chemical and mechanical properties used in the oil and gas industry were joined by friction welding. Then, macro and microstructure studies as well as hardness measurements, tensile tests, and torsion tests were applied to the produced samples. As a result of the micro-structure studies, it was observed that the martensitic structure was formed in the full deformation region of the joint made of AISI 304 stainless and AISI 4140 tempered steel, while it was determined that the other joints were formed of recrystallized fine grains in the full deformation region with the effect of friction. When the hardness measurement results were examined, it was determined that the hardest region was the full deformation region in all welded joints produced. As a result of the tensile tests, the highest tensile strength obtained was 622.94 N/mm2 in the joint made of AISI 304 stainless steel and AISI 4140 tempered steel. As a result of the torsion tests, the highest torsion moment was measured as 250 Nm in the sample produced from AISI 304 stainless steel and AISI 4140 tempered steel.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76341118","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}
K. Mallieswaran, C. Rajendran, R. Padmanabhan, S. Rajasekaran
Abstract The best aluminum alloys for construction are those that incorporate copper. However, welding engineers find it difficult to join aluminium and its alloys as a result of cracking. One of the popular methods for joining nonferrous materials, especially aluminum alloys, is friction stir welding (FSW). A tensile strength of 75 % to 85 % of the basic material strength is produced by FSW joints. The majority of studies have documented a reduction in strength as a result of incomplete melting, creating a soft region at the boundary between the thermo – mechanically influenced zone and the stir zone. The current effort has focused on using the shot peening method to reduce the softness at the interface. According to the test findings, the nickel shot-peened joint produced a stronger joint than the traditional FSW joint. The shot-peened joint has gained 7 % additional strength compared to untreated joint.
{"title":"Evaluation of nickel shot peening process on strength of friction stir welded AA2014-T6 aluminum alloy joints","authors":"K. Mallieswaran, C. Rajendran, R. Padmanabhan, S. Rajasekaran","doi":"10.1515/pm-2022-1038","DOIUrl":"https://doi.org/10.1515/pm-2022-1038","url":null,"abstract":"Abstract The best aluminum alloys for construction are those that incorporate copper. However, welding engineers find it difficult to join aluminium and its alloys as a result of cracking. One of the popular methods for joining nonferrous materials, especially aluminum alloys, is friction stir welding (FSW). A tensile strength of 75 % to 85 % of the basic material strength is produced by FSW joints. The majority of studies have documented a reduction in strength as a result of incomplete melting, creating a soft region at the boundary between the thermo – mechanically influenced zone and the stir zone. The current effort has focused on using the shot peening method to reduce the softness at the interface. According to the test findings, the nickel shot-peened joint produced a stronger joint than the traditional FSW joint. The shot-peened joint has gained 7 % additional strength compared to untreated joint.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75703695","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":"Picture of the Month","authors":"","doi":"10.1515/pm-2023-0038","DOIUrl":"https://doi.org/10.1515/pm-2023-0038","url":null,"abstract":"","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136064798","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 Production and structural investigations of Cu-based FeCr reinforced composite were performed by using mechanical alloying, optical microscope, scanning electron microscope, X-ray diffraction and hardness test. The increment in FeCr addition caused the increment in the cold deformation rate. This situation resulted in breakage of the powder particles throughout mechanical alloying. Thus, the grain dimension of the FeCr powders decreased and the Fe wt.% in the CuCr powders advanced. The collision force between the Cu-Cr powder and the grinding ball weakened with the increase of FeCr concentration and resulted as higher reinforcement size. After mechanical milling, FeCr grains decreased in size more than copper grains due to the ductility of copper grains. The smaller crystals occurred after grinding, and increased the grain boundary zone for further spread of Cr into the Cu. Despite the high sintering process, the high sintering temperature improved the compactness of the alloys, but caused coarsening of the nanoparticles. The mechanical alloying time, reinforcement wt.% and sinter temperature were effective on the micro-hardness of the microstructure.
{"title":"Structural analysis of Cu-based FeCr reinforced composites prepared by mechanical alloying","authors":"S. Yilmaz, T. Teker, S. Aydin","doi":"10.1515/pm-2022-1036","DOIUrl":"https://doi.org/10.1515/pm-2022-1036","url":null,"abstract":"Abstract Production and structural investigations of Cu-based FeCr reinforced composite were performed by using mechanical alloying, optical microscope, scanning electron microscope, X-ray diffraction and hardness test. The increment in FeCr addition caused the increment in the cold deformation rate. This situation resulted in breakage of the powder particles throughout mechanical alloying. Thus, the grain dimension of the FeCr powders decreased and the Fe wt.% in the CuCr powders advanced. The collision force between the Cu-Cr powder and the grinding ball weakened with the increase of FeCr concentration and resulted as higher reinforcement size. After mechanical milling, FeCr grains decreased in size more than copper grains due to the ductility of copper grains. The smaller crystals occurred after grinding, and increased the grain boundary zone for further spread of Cr into the Cu. Despite the high sintering process, the high sintering temperature improved the compactness of the alloys, but caused coarsening of the nanoparticles. The mechanical alloying time, reinforcement wt.% and sinter temperature were effective on the micro-hardness of the microstructure.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79155287","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 This paper is a compilation of failure analysis case studies exploring the subject of inadequate heat treatment. As with other papers in this series, the presented failure cases are rather simple and may appear trivial to the experienced failure analyst. The authors can guarantee however, that minor heat treatment errors are committed easily and have a considerable damage potential which may entail heavy financial losses. Therefore, cases of inadequate heat treatment or a complete lack of necessary heat treatment belong by all means in the column Failure Analysis. The metallurgical subject of these failure cases are low-alloy hardenable steels without exception. Common heat treatment processes such as induction hardening, case hardening, nitriding as well as through-hardening and tempering will be touched upon.
{"title":"How inadequate heat treatment or complete lack thereof can cause component failures","authors":"A. Neidel, M. Giller, S. Riesenbeck","doi":"10.1515/pm-2023-0037","DOIUrl":"https://doi.org/10.1515/pm-2023-0037","url":null,"abstract":"Abstract This paper is a compilation of failure analysis case studies exploring the subject of inadequate heat treatment. As with other papers in this series, the presented failure cases are rather simple and may appear trivial to the experienced failure analyst. The authors can guarantee however, that minor heat treatment errors are committed easily and have a considerable damage potential which may entail heavy financial losses. Therefore, cases of inadequate heat treatment or a complete lack of necessary heat treatment belong by all means in the column Failure Analysis. The metallurgical subject of these failure cases are low-alloy hardenable steels without exception. Common heat treatment processes such as induction hardening, case hardening, nitriding as well as through-hardening and tempering will be touched upon.","PeriodicalId":20360,"journal":{"name":"Practical Metallography","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78375301","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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