L. Hesami, R. Taghiabadi, M. Ghoncheh, M. Emami, M. Saghafi Yazdi
Abstract The Cu effect on the microstructure and corrosion resistance of Al–15Mg2Si composites was studied. The results showed that Cu addition decreased the average size of primary Mg2Si (Mg2SiP) particles, changed the hopper-like Mg2SiP particles to polyhedrals, and caused the formation of θ-Al2Cu and Q-Al5Mg8Si6Cu2 compounds in the composite matrix. According to the image analysis results, increasing the Cu content from 0.01 to 5 wt% halved the average size of Mg2SiP particles, increased their fraction by about 40 %, and increased the composite porosity content. The electrochemical impedance spectroscopy showed that adding 5 wt% of Cu resulted in an increase of about 3.7 times in the corrosion resistance as compared to Al–15Mg2Si composite. The beneficial effects of Cu were also confirmed by the potentiodynamic polarization experiments. Cu addition seems to promote less intense general corrosion than the base alloy’s localized attack.
{"title":"Effect of Cu addition on microstructure and corrosion behavior of Al–15Mg2Si composite","authors":"L. Hesami, R. Taghiabadi, M. Ghoncheh, M. Emami, M. Saghafi Yazdi","doi":"10.1515/mt-2023-0217","DOIUrl":"https://doi.org/10.1515/mt-2023-0217","url":null,"abstract":"Abstract The Cu effect on the microstructure and corrosion resistance of Al–15Mg2Si composites was studied. The results showed that Cu addition decreased the average size of primary Mg2Si (Mg2SiP) particles, changed the hopper-like Mg2SiP particles to polyhedrals, and caused the formation of θ-Al2Cu and Q-Al5Mg8Si6Cu2 compounds in the composite matrix. According to the image analysis results, increasing the Cu content from 0.01 to 5 wt% halved the average size of Mg2SiP particles, increased their fraction by about 40 %, and increased the composite porosity content. The electrochemical impedance spectroscopy showed that adding 5 wt% of Cu resulted in an increase of about 3.7 times in the corrosion resistance as compared to Al–15Mg2Si composite. The beneficial effects of Cu were also confirmed by the potentiodynamic polarization experiments. Cu addition seems to promote less intense general corrosion than the base alloy’s localized attack.","PeriodicalId":18231,"journal":{"name":"Materials Testing","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82248356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this paper, the CoFeMoNiAlCr x coatings with different chromium content (x = 0, 0.3, 0.6, 0.9 and 1.2) were prepared by argon arc cladding technology on Q235 steel. The microstructure and phases of the coatings were analyzed by OM, SEM, EDS and XRD. The hardness, wear resistance and corrosion resistance of the coatings were tested by microhardness tester, friction and wear tester and electrochemical workstation. The results show that the highest hardness is obtained in the CoFeMoNiAlCr x=0 high entropy alloy coatings, about 500 HV, which is about 3 times than the hardness of Q235 steel (the substrate). With the chromium content of the CoFeMoNiAlCr x coatings increasing, the wear resistance increases first, and then decreases. When the chromium content is 0.9, the wear resistance of the coating is the highest with the wear loss about 2.6 mg and the friction coefficient about 0.52. The corrosion resistance of the coatings decreases with a small amount of chromium addition. When the Cr content in the coating is close to the atomic ratio, the content of the body-centered cubic phase structure increases, and the face-centered cubic phase structure appears in the coating.
{"title":"Microstructure and properties of argon arc cladded CoCr x FeMoNiAl high entropy alloy coatings on Q235 steel","authors":"Xiaowei Wang, Bensheng Huang, Jingli Tang, Tianning Li, Siyu Huang","doi":"10.1515/mt-2023-0129","DOIUrl":"https://doi.org/10.1515/mt-2023-0129","url":null,"abstract":"Abstract In this paper, the CoFeMoNiAlCr x coatings with different chromium content (x = 0, 0.3, 0.6, 0.9 and 1.2) were prepared by argon arc cladding technology on Q235 steel. The microstructure and phases of the coatings were analyzed by OM, SEM, EDS and XRD. The hardness, wear resistance and corrosion resistance of the coatings were tested by microhardness tester, friction and wear tester and electrochemical workstation. The results show that the highest hardness is obtained in the CoFeMoNiAlCr x=0 high entropy alloy coatings, about 500 HV, which is about 3 times than the hardness of Q235 steel (the substrate). With the chromium content of the CoFeMoNiAlCr x coatings increasing, the wear resistance increases first, and then decreases. When the chromium content is 0.9, the wear resistance of the coating is the highest with the wear loss about 2.6 mg and the friction coefficient about 0.52. The corrosion resistance of the coatings decreases with a small amount of chromium addition. When the Cr content in the coating is close to the atomic ratio, the content of the body-centered cubic phase structure increases, and the face-centered cubic phase structure appears in the coating.","PeriodicalId":18231,"journal":{"name":"Materials Testing","volume":"12 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86670075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guanping Dong, Shanwei Sun, X. Kong, Nanshou Wu, Hong Zhang, Xiangyang Chen, Hao Feng, Pingnan Huang, Zixi Wang
Abstract Mosaic ceramic art pattern with noble, elegant features, it is a unique form of art creation in ancient Greece and the ancient Rome period has been loved by artists and created a lot of classic large-scale exterior mosaic ceramic art works. Small size square mosaic ceramic as the basic raw material for the creation of large exterior mosaic art, it directly affects the quality of the work created by the artist, so these ceramic mosaic ceramic materials need to undergo rigorous inspection to meet the needs of the artist’s high-quality art creation. However, small size multi-color square mosaic ceramics are different from ordinary large target ceramics, they have the characteristics of small size and easy reflection, currently mainly using manual inspection, the existing automatic inspection methods have the problem of low efficiency and accuracy, cannot meet the needs of artists for the quantity and quality of mosaic ceramics. To solve these problems, this paper proposes a new convolutional network-based fast nondestructive testing method for detecting square mosaic tiles. The detection method is based on the convolutional neural network YOLOv5s model, and by introducing the AF-FPN module and the data enhancement module, the method further improves the recognition performance of the model relative to the original YOLOv5s model and achieves the fast detection of surface defects on square mosaic ceramics. The experimental results show that the detection method for small size multicolor square mosaic ceramic tile surface minor defects detection rate of up to 94 % or more, a single square mosaic ceramic detection time of 0.41 s. The method takes into account the detection accuracy and speed, can be fast and accurate screening of high-quality, defect-free small size multicolor square mosaic ceramic, to meet the artist’s requirements for high-quality mosaic ceramic raw materials Quality and quantity requirements, to ensure the quality of the creation of mosaic art patterns, to better show the charm of the mosaic art patterns role. At the same time, the method can not only be applied to the detection of mosaic ceramics, the method can also be applied to have a similar small volume, easy to reflect the characteristics of small target object defect detection.
{"title":"Non-destructive detection for mosaic ceramic surface defects based on convolutional neural networks","authors":"Guanping Dong, Shanwei Sun, X. Kong, Nanshou Wu, Hong Zhang, Xiangyang Chen, Hao Feng, Pingnan Huang, Zixi Wang","doi":"10.1515/mt-2023-0051","DOIUrl":"https://doi.org/10.1515/mt-2023-0051","url":null,"abstract":"Abstract Mosaic ceramic art pattern with noble, elegant features, it is a unique form of art creation in ancient Greece and the ancient Rome period has been loved by artists and created a lot of classic large-scale exterior mosaic ceramic art works. Small size square mosaic ceramic as the basic raw material for the creation of large exterior mosaic art, it directly affects the quality of the work created by the artist, so these ceramic mosaic ceramic materials need to undergo rigorous inspection to meet the needs of the artist’s high-quality art creation. However, small size multi-color square mosaic ceramics are different from ordinary large target ceramics, they have the characteristics of small size and easy reflection, currently mainly using manual inspection, the existing automatic inspection methods have the problem of low efficiency and accuracy, cannot meet the needs of artists for the quantity and quality of mosaic ceramics. To solve these problems, this paper proposes a new convolutional network-based fast nondestructive testing method for detecting square mosaic tiles. The detection method is based on the convolutional neural network YOLOv5s model, and by introducing the AF-FPN module and the data enhancement module, the method further improves the recognition performance of the model relative to the original YOLOv5s model and achieves the fast detection of surface defects on square mosaic ceramics. The experimental results show that the detection method for small size multicolor square mosaic ceramic tile surface minor defects detection rate of up to 94 % or more, a single square mosaic ceramic detection time of 0.41 s. The method takes into account the detection accuracy and speed, can be fast and accurate screening of high-quality, defect-free small size multicolor square mosaic ceramic, to meet the artist’s requirements for high-quality mosaic ceramic raw materials Quality and quantity requirements, to ensure the quality of the creation of mosaic art patterns, to better show the charm of the mosaic art patterns role. At the same time, the method can not only be applied to the detection of mosaic ceramics, the method can also be applied to have a similar small volume, easy to reflect the characteristics of small target object defect detection.","PeriodicalId":18231,"journal":{"name":"Materials Testing","volume":"240 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80455149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This study aims to manufacture sandwich composite structures consisting of fully fiber-reinforced composites and then to investigate experimentally and numerically the impact and compressive strength and damage mechanisms of these structures for different cell and core types. To achieve this, firstly, composite sandwich plates with triangular, square and rectangular cell structures were manufactured. Low-velocity impact tests were run on sandwich structures with these three different cell geometries and the effect of cell shape on impact strength was determined. Although the maximum contact force of the square structure under impact load was smaller than the maximum contact force of the triangular and rectangular specimens, the specific contact force was 15.52 % greater than the triangular specimen and 16.29 % greater than the rectangular specimen. Then, the specimens with square, egg box and lattice core types were manufactured and compression tests were performed. The specific peak load value for square specimens was 33.2 % greater than that of egg box specimens and 78.1 % greater than that of lattice specimens. In the numerical study, the experimental results were confirmed by applying the progressive failure analysis with the LS-DYNA finite element program.
{"title":"Low-velocity impact behaviours of sandwiches manufactured from fully carbon fiber composite for different cell types and compression behaviours for different core types","authors":"Ilyas Bozkurt, M. O. Kaman, M. Albayrak","doi":"10.1515/mt-2023-0024","DOIUrl":"https://doi.org/10.1515/mt-2023-0024","url":null,"abstract":"Abstract This study aims to manufacture sandwich composite structures consisting of fully fiber-reinforced composites and then to investigate experimentally and numerically the impact and compressive strength and damage mechanisms of these structures for different cell and core types. To achieve this, firstly, composite sandwich plates with triangular, square and rectangular cell structures were manufactured. Low-velocity impact tests were run on sandwich structures with these three different cell geometries and the effect of cell shape on impact strength was determined. Although the maximum contact force of the square structure under impact load was smaller than the maximum contact force of the triangular and rectangular specimens, the specific contact force was 15.52 % greater than the triangular specimen and 16.29 % greater than the rectangular specimen. Then, the specimens with square, egg box and lattice core types were manufactured and compression tests were performed. The specific peak load value for square specimens was 33.2 % greater than that of egg box specimens and 78.1 % greater than that of lattice specimens. In the numerical study, the experimental results were confirmed by applying the progressive failure analysis with the LS-DYNA finite element program.","PeriodicalId":18231,"journal":{"name":"Materials Testing","volume":"37 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81736570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Junfu Gao, C. Zhou, N. Ding, Weijie Ma, Long Liu, Huixia Xu, N. Hou
Abstract Honeycomb sandwich composites play an important role in the aviation structural components, especially in aircraft radomes. Due to the multiple production processes, failure of the honeycomb sandwich composite usually occurs. This would affect the working stability of mechanical components made mainly of the honeycomb structural materials. In the present work, collapse failure of the honeycomb sandwich composite in an aircraft radome was investigated. The observation and analysis results show that the failure mode of the honeycomb structure is compression instability failure. There are a lot of pore defects in some local bonding areas of the honeycomb structure, forming a weak bonding area. In the process of curing and pressurization, debonding occurs at the adjacent honeycomb cells near the weak bonding area, forming a cracking band and resulting in the decrease of the stiffness and the instability failure under pressure. The work would provide reference information for the application of honeycomb sandwich composites in mechanical equipment.
{"title":"Collapse of a honeycomb sandwich composite in an aircraft radome","authors":"Junfu Gao, C. Zhou, N. Ding, Weijie Ma, Long Liu, Huixia Xu, N. Hou","doi":"10.1515/mt-2023-0183","DOIUrl":"https://doi.org/10.1515/mt-2023-0183","url":null,"abstract":"Abstract Honeycomb sandwich composites play an important role in the aviation structural components, especially in aircraft radomes. Due to the multiple production processes, failure of the honeycomb sandwich composite usually occurs. This would affect the working stability of mechanical components made mainly of the honeycomb structural materials. In the present work, collapse failure of the honeycomb sandwich composite in an aircraft radome was investigated. The observation and analysis results show that the failure mode of the honeycomb structure is compression instability failure. There are a lot of pore defects in some local bonding areas of the honeycomb structure, forming a weak bonding area. In the process of curing and pressurization, debonding occurs at the adjacent honeycomb cells near the weak bonding area, forming a cracking band and resulting in the decrease of the stiffness and the instability failure under pressure. The work would provide reference information for the application of honeycomb sandwich composites in mechanical equipment.","PeriodicalId":18231,"journal":{"name":"Materials Testing","volume":"13 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87116152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this current research paper, the modelling of boron diffusion during the powder-pack boronizing was achieved by utilizing two kinetics approaches: the integral method and average diffusion coefficient (ADC) method. This integral method used a general solution of algebraic differential equations (DAEs) system. The powders mixture composed of: 33.5 wt% B4C, 5.4 wt% KBF4 and 61.1 wt% SiC was employed to generate the Fe2B layers on AISI 4147 steel in the interval of 1123–1273 K for 2–8 h. The obtained surface layers have been characterized by Scanning electron microscopy (SEM) to examine the growth front with a typical saw-toothed morphology. The crystalline nature of boride phase has been verified by X-ray diffraction technique (XRD). The calculation results arising from the two models led to the similar boron activation energy in Fe2B equal to 196.19 kJ mol−1. Additionally, both models were checked out empirically by selecting three extra boronizing conditions obtained at 1273 K for increasing times (2.5, 4.5 and 8.5 h). The predicted layers’ thicknesses were found to be in line with the experimental results.
{"title":"Modelling boron diffusion for Fe2B layer formation: comparative kinetics analysis in pack-boronized AISI 4147 steel","authors":"M. Ortiz-Domínguez, M. Keddam","doi":"10.1515/mt-2023-0214","DOIUrl":"https://doi.org/10.1515/mt-2023-0214","url":null,"abstract":"Abstract In this current research paper, the modelling of boron diffusion during the powder-pack boronizing was achieved by utilizing two kinetics approaches: the integral method and average diffusion coefficient (ADC) method. This integral method used a general solution of algebraic differential equations (DAEs) system. The powders mixture composed of: 33.5 wt% B4C, 5.4 wt% KBF4 and 61.1 wt% SiC was employed to generate the Fe2B layers on AISI 4147 steel in the interval of 1123–1273 K for 2–8 h. The obtained surface layers have been characterized by Scanning electron microscopy (SEM) to examine the growth front with a typical saw-toothed morphology. The crystalline nature of boride phase has been verified by X-ray diffraction technique (XRD). The calculation results arising from the two models led to the similar boron activation energy in Fe2B equal to 196.19 kJ mol−1. Additionally, both models were checked out empirically by selecting three extra boronizing conditions obtained at 1273 K for increasing times (2.5, 4.5 and 8.5 h). The predicted layers’ thicknesses were found to be in line with the experimental results.","PeriodicalId":18231,"journal":{"name":"Materials Testing","volume":"26 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87192171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract New alloy materials developed to meet the increasing technological needs of people come into our lives with some difficulties in terms of machinability. New cooling and lubrication techniques have been developed to facilitate the workability of such difficult-to-process materials and protect the world ecologically and the quality of the produced product. The workpiece used in this study, Vanadis 10 SuperClean, is a high vanadium alloyed powder metallurgy tool steel offering a unique combination of excellent abrasive wear resistance in combination with a good chipping resistance. The present study investigated the effects of dry, cryo, and CryoMQL cutting conditions on cutting tool vibration amplitude, cutting temperature, surface roughness, tool wear, and tool life in turning of Vanadis 10 tool steel used in the automotive industry. The experiments were performed using TiCN/Al2O3/TiN coated cemented carbide tools and cutting parameters as the constant depth of cut (1 mm), feed rates (0.08, 0.1, 0.12 mm rev−1), and cutting speeds (80, 100, 120 m min−1). The results obtained from experiments showed that spraying liquid nitrogen into the cutting zone provided significant improvements on cutting temperature, tool wear, cutting tool vibration amplitude, and surface roughness. The best results in terms of all output were achieved in the CryoMQL cutting environment. CryoMQL environment has reduced surface roughness up to 65.03 %, flank wear 56.99 %, cutting temperature 32.77 %, and cutting tool vibration amplitude up to 42.76 % compared to dry machining.
为满足人们日益增长的技术需求而开发的新型合金材料进入我们的生活，但在可加工性方面存在一些困难。新的冷却和润滑技术已经被开发出来，以促进这些难以加工的材料的可加工性，保护世界生态和生产产品的质量。本研究中使用的工件Vanadis 10 SuperClean是一种高钒合金粉末冶金工具钢，具有优异的磨料耐磨性和良好的抗切屑性。本研究研究了汽车工业中使用的Vanadis 10工具钢在车削过程中，干燥、低温和CryoMQL切削条件对刀具振动幅度、切削温度、表面粗糙度、刀具磨损和刀具寿命的影响。实验采用TiCN/Al2O3/TiN涂层硬质合金刀具，切削参数为恒定切削深度(1 mm)、进给速度(0.08、0.1、0.12 mm rev−1)和切削速度(80、100、120 m min−1)。实验结果表明，在切削区喷施液氮可显著改善切削温度、刀具磨损、刀具振动幅值和表面粗糙度。在CryoMQL切割环境中实现了所有输出的最佳结果。与干式加工相比，CryoMQL环境将表面粗糙度降低了65.03 %，侧面磨损降低了56.99 %，切削温度降低了32.77 %，刀具振动幅度降低了42.76 %。
{"title":"Effect of vibration and cutting zone temperature on surface topography during hybrid cooling/lubrication assisted machining of Vanadis 10","authors":"O. Özbek, Nursel Altan Özbek, F. Kara, H. Saruhan","doi":"10.1515/mt-2023-0057","DOIUrl":"https://doi.org/10.1515/mt-2023-0057","url":null,"abstract":"Abstract New alloy materials developed to meet the increasing technological needs of people come into our lives with some difficulties in terms of machinability. New cooling and lubrication techniques have been developed to facilitate the workability of such difficult-to-process materials and protect the world ecologically and the quality of the produced product. The workpiece used in this study, Vanadis 10 SuperClean, is a high vanadium alloyed powder metallurgy tool steel offering a unique combination of excellent abrasive wear resistance in combination with a good chipping resistance. The present study investigated the effects of dry, cryo, and CryoMQL cutting conditions on cutting tool vibration amplitude, cutting temperature, surface roughness, tool wear, and tool life in turning of Vanadis 10 tool steel used in the automotive industry. The experiments were performed using TiCN/Al2O3/TiN coated cemented carbide tools and cutting parameters as the constant depth of cut (1 mm), feed rates (0.08, 0.1, 0.12 mm rev−1), and cutting speeds (80, 100, 120 m min−1). The results obtained from experiments showed that spraying liquid nitrogen into the cutting zone provided significant improvements on cutting temperature, tool wear, cutting tool vibration amplitude, and surface roughness. The best results in terms of all output were achieved in the CryoMQL cutting environment. CryoMQL environment has reduced surface roughness up to 65.03 %, flank wear 56.99 %, cutting temperature 32.77 %, and cutting tool vibration amplitude up to 42.76 % compared to dry machining.","PeriodicalId":18231,"journal":{"name":"Materials Testing","volume":"61 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79141330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Based on observation of gas bubbles evolving from crevices on slow strain rate test pieces during anodic corrosion the effect of applied potentials in chloride aqueous solutions on amount and composition of the gas together with fracture strains from the slow strain rate test of a 17-4 PH steel was investigated. As a result, increasing applied potentials provide a reduction of fracture strains together with an initial increase in volume of released hydrogen gas. The fracture surfaces exhibit increasing brittle appearance, as found in hydrogen cracking failures. The results confirm that during local anodic corrosion, hydrogen is produced that provokes hydrogen induced cracking following anodic dissolution. Respective local pH measurements under varying applied electric potentials, show the acidification of the pit-electrolyte. Additional model calculations elucidate the stepwise local anodic corrosion and its acidification process together with the hydrogen supported cracking. The model shows that the relative amount of hydrogen cracking will depend on the provided material data as well as on solution properties such as pH, chloride level, temperature and oxygen content. As an all over result, together with the model calculations, the experimental evidence of hydrogen evolution during anodic local corrosion confirms the contribution of hydrogen cracking to anodic stress corrosion cracking.
{"title":"Experimental evidence of hydrogen evolution from local anodic corrosion sites and its consequences for corrosion cracking mechanisms","authors":"H. Hoffmeister, Eike Heuser","doi":"10.1515/mt-2023-0185","DOIUrl":"https://doi.org/10.1515/mt-2023-0185","url":null,"abstract":"Abstract Based on observation of gas bubbles evolving from crevices on slow strain rate test pieces during anodic corrosion the effect of applied potentials in chloride aqueous solutions on amount and composition of the gas together with fracture strains from the slow strain rate test of a 17-4 PH steel was investigated. As a result, increasing applied potentials provide a reduction of fracture strains together with an initial increase in volume of released hydrogen gas. The fracture surfaces exhibit increasing brittle appearance, as found in hydrogen cracking failures. The results confirm that during local anodic corrosion, hydrogen is produced that provokes hydrogen induced cracking following anodic dissolution. Respective local pH measurements under varying applied electric potentials, show the acidification of the pit-electrolyte. Additional model calculations elucidate the stepwise local anodic corrosion and its acidification process together with the hydrogen supported cracking. The model shows that the relative amount of hydrogen cracking will depend on the provided material data as well as on solution properties such as pH, chloride level, temperature and oxygen content. As an all over result, together with the model calculations, the experimental evidence of hydrogen evolution during anodic local corrosion confirms the contribution of hydrogen cracking to anodic stress corrosion cracking.","PeriodicalId":18231,"journal":{"name":"Materials Testing","volume":"23 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82090291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The disc under diametral compression is one of the preferred specimens for the calibration of photoelastic materials. Current calibration methods have some limitations from a metrological point of view, because they do not provide measurement uncertainties and they assume that observations are independent and with the same accuracy. In this work, a new calibration method is proposed to avoid the above-mentioned metrological limitations: The generalized least squares by Lagrange multipliers method. This methodology accepts correlated input quantities or with different accuracy through the input covariance matrix, and it provides, through a least-squares adjustment, the estimates of the quantities to be measured and their associated standard uncertainties. The application of the method shows coherent results and it also provides a chi-square value that can be used to test the consistency of the measurement model, and the normalized deviations between the input estimates and their fitted values, which are a tool to identify potential outliers. Results reveal a great influence of the radius of the specimen on the uncertainty of the stress-optic coefficient measurement, which casts serious doubt on previous affirmations about the disc in compression is preferable over other specimens.
{"title":"Calibration of photoelastic materials with the disc under diametral compression","authors":"M. Solaguren-Beascoa Fernández","doi":"10.1515/mt-2023-0076","DOIUrl":"https://doi.org/10.1515/mt-2023-0076","url":null,"abstract":"Abstract The disc under diametral compression is one of the preferred specimens for the calibration of photoelastic materials. Current calibration methods have some limitations from a metrological point of view, because they do not provide measurement uncertainties and they assume that observations are independent and with the same accuracy. In this work, a new calibration method is proposed to avoid the above-mentioned metrological limitations: The generalized least squares by Lagrange multipliers method. This methodology accepts correlated input quantities or with different accuracy through the input covariance matrix, and it provides, through a least-squares adjustment, the estimates of the quantities to be measured and their associated standard uncertainties. The application of the method shows coherent results and it also provides a chi-square value that can be used to test the consistency of the measurement model, and the normalized deviations between the input estimates and their fitted values, which are a tool to identify potential outliers. Results reveal a great influence of the radius of the specimen on the uncertainty of the stress-optic coefficient measurement, which casts serious doubt on previous affirmations about the disc in compression is preferable over other specimens.","PeriodicalId":18231,"journal":{"name":"Materials Testing","volume":"14 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74884399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deepak Kumar Madhappan, Ponnusamy Kumaraswamy Palani, D. Thirumalaikumarasamy, Tushar Sonar
Abstract The main objective of this investigation is to study the mechanical properties and microstructural features of rotary friction welded (RFW) UNS S42000 martensitic stainless-steel joints. The welded joints were stress relieved at 316 °C for 1 h holding followed by air cooling. The joints welded using the friction pressure of 60 MPa, forging pressure of 64 MPa, friction time of 18 s and forging time of 4 s exhibited superior tensile properties. Microstructure showed carbide precipitates and strain induced and partial strain induced martensite in weld zone for heat treated condition and coarser martensite and retained austenite for non-heat treated condition. Fractography for tensile tested samples reveals predominantly ductile mode of fracture for heat treated samples than non-heat treated condition. The Microhardness showed a higher value of hardness for the weld zone due to strain induced martensite and lesser hardness at PDZ due to partial strain hardened martensite.
摘要本研究的主要目的是研究旋转摩擦焊接(RFW) UNS S42000马氏体不锈钢接头的力学性能和显微组织特征。焊接接头在316 °C保温1 h后进行空冷去应力处理。摩擦压力为60 MPa、锻造压力为64 MPa、摩擦时间为18 s、锻造时间为4 s的焊接接头具有较好的拉伸性能。显微组织表现为:热处理时焊缝区有碳化物析出、应变诱发和部分应变诱发马氏体，未热处理时焊缝区有粗马氏体和残余奥氏体。拉伸试样的断口形貌显示，热处理试样的断裂模式主要是延性断裂，而非热处理试样的断裂模式主要是延性断裂。显微硬度显示，焊接区由于应变诱发马氏体的存在，硬度值较高，而PDZ处由于部分应变硬化马氏体的存在，硬度值较低。
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