Conventional electrospark deposition (ESD) processes used in industry are well suited to the coating and repair of small areas for the purpose of hardfacing, corrosion resistance, or dimensional restoration. Although significant advances have been made in the range of materials that can be processed, the comparatively slow deposition rate limits the potential applications of a traditional manually operated ESD process. In this study, an automated ESD system was demonstrated for the application of Ni-based superalloy (Inconel 718) coatings on Ni- and Fe-based substrates. A preliminary study was used to determine the influence of process parameters on an automated system, with capacitance, voltage, electrode force, and electrode travel speed parameters chosen to provide higher deposition rates while maintaining high deposition quality. A comparison of Inconel 718 and 316L stainless steel substrates found that the influence of substrate composition on coating hardness and coating composition was limited to the first 40um. These results pave the way for ESD of larger-area coatings and longer-duration repairs without the need for human operators.
{"title":"Parametric Study of Automated Electrospark Deposition for Ni-Based Superalloys","authors":"P. Enrique, Stephen Peterkin, N. Zhou","doi":"10.29391/2021.100.021","DOIUrl":"https://doi.org/10.29391/2021.100.021","url":null,"abstract":"Conventional electrospark deposition (ESD) processes used in industry are well suited to the coating and repair of small areas for the purpose of hardfacing, corrosion resistance, or dimensional restoration. Although significant advances have been made in the range of materials that can be processed, the comparatively slow deposition rate limits the potential applications of a traditional manually operated ESD process. In this study, an automated ESD system was demonstrated for the application of Ni-based superalloy (Inconel 718) coatings on Ni- and Fe-based substrates. A preliminary study was used to determine the influence of process parameters on an automated system, with capacitance, voltage, electrode force, and electrode travel speed parameters chosen to provide higher deposition rates while maintaining high deposition quality. A comparison of Inconel 718 and 316L stainless steel substrates found that the influence of substrate composition on coating hardness and coating composition was limited to the first 40um. These results pave the way for ESD of larger-area coatings and longer-duration repairs without the need for human operators.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47519449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polymers are widely used in automotive parts and fields like mechatronics and biomedical engineering because of their excellent properties, such as high durability and light weight. Welding of polymers has grown to be an important field of research due to its relevance among products of everyday life. Through transmission laser welding (TTLW) has been frequently selected by the contemporary re-searchers in the field of welding as it is relatively modern and more efficient than other welding processes. This pa-per reviews the influence of different processing parameters, including laser power, scanning speed, standoff distance, and clamping pressure. The present article is expected to provide the reader with a comprehensive under-standing of TTLW and research on the aforementioned four welding parameters in TTLW. The significance of finite element modeling, a few simulation studies, different optimization approaches, morphological characteristics, and other behaviors of laser welded polymers will be included in the next part of the review.
{"title":"A State-of-the-Art Review of Laser Welding of Polymers - Part I: Welding Parameters","authors":"Nitesh Kumar, Nikhil Kumar, A. Bandyopadhyay","doi":"10.29391/2021.100.019","DOIUrl":"https://doi.org/10.29391/2021.100.019","url":null,"abstract":"Polymers are widely used in automotive parts and fields like mechatronics and biomedical engineering because of their excellent properties, such as high durability and light weight. Welding of polymers has grown to be an important field of research due to its relevance among products of everyday life. Through transmission laser welding (TTLW) has been frequently selected by the contemporary re-searchers in the field of welding as it is relatively modern and more efficient than other welding processes. This pa-per reviews the influence of different processing parameters, including laser power, scanning speed, standoff distance, and clamping pressure. The present article is expected to provide the reader with a comprehensive under-standing of TTLW and research on the aforementioned four welding parameters in TTLW. The significance of finite element modeling, a few simulation studies, different optimization approaches, morphological characteristics, and other behaviors of laser welded polymers will be included in the next part of the review.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45024875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Pessoa, A. Bracarense, V. Santos, R. R. Marinho, Henrique Leite Assunção, F. Rizzo
Wet welding procedures of Class A structural ship steels frequently fail to comply with the American Welding Society (AWS) D3.6M, Underwater Welding Code, in the maximum hardness criterion for the heat-affected zone (HAZ). The maximum hardness accepted in a welded joint is 325 HV for higher-strength steel (yield strength > 350 MPa). In multi-pass welds, this problem occurs frequently and is restricted to the HAZ of the capping passes. The HAZ of the root and filling passes are softened by the reheating promoted by their respective subsequent passes. This paper presents the results of exploratory research into postweld underwater electromagnetic induction heating. The objective of the research was to evaluate the ability of induction heating to soften the specific high-hardness HAZs in underwater conditions. The results showed that this technique could reduce the maximum HAZ hardness of low-carbon structural ship steel welds to values below 325 HV, which is the maximum accepted by AWS for Class A welds. The induction-heated zone reached a maximum depth of about 10 mm, which is considered adequate to treat the HAZ of cap-ping passes in underwater wet welds.
{"title":"Post Underwater Wet Welding Heat Treatment by Underwater Wet Induction Heating","authors":"E. Pessoa, A. Bracarense, V. Santos, R. R. Marinho, Henrique Leite Assunção, F. Rizzo","doi":"10.29391/2021.100.020","DOIUrl":"https://doi.org/10.29391/2021.100.020","url":null,"abstract":"Wet welding procedures of Class A structural ship steels frequently fail to comply with the American Welding Society (AWS) D3.6M, Underwater Welding Code, in the maximum hardness criterion for the heat-affected zone (HAZ). The maximum hardness accepted in a welded joint is 325 HV for higher-strength steel (yield strength > 350 MPa). In multi-pass welds, this problem occurs frequently and is restricted to the HAZ of the capping passes. The HAZ of the root and filling passes are softened by the reheating promoted by their respective subsequent passes. This paper presents the results of exploratory research into postweld underwater electromagnetic induction heating. The objective of the research was to evaluate the ability of induction heating to soften the specific high-hardness HAZs in underwater conditions. The results showed that this technique could reduce the maximum HAZ hardness of low-carbon structural ship steel welds to values below 325 HV, which is the maximum accepted by AWS for Class A welds. The induction-heated zone reached a maximum depth of about 10 mm, which is considered adequate to treat the HAZ of cap-ping passes in underwater wet welds.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48269658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Muhammad Shehryar Khan, E. Biro, Yixiang Zhou, A. Macwan
During laser welding of an Al-Si coated 22MnB5 steel to produce tailor-welded blanks, the Al-Si coating mixes into the weld and causes the formation of the lower strength ferrite phase dispersed in an otherwise martensitic matrix. It has been shown that the presence of the ferrite phase is the principal reason for premature failure of hot-stamped laser-welded joints. Currently, the Al-Si coating is removed prior to welding, which can be time consuming. This work showed that adding Ni to the fusion zone of laser welded Al-Si coated 22MnB5 steel by welding through a pure Ni coating of a specified thickness, ferrite formation can be suppressed, whereby improving the weld strength and successfully shifting failure from the fusion zone, where it normally occurs, to the base material to achieve 100%joint strength. This work also showed that laser welding Al-Si coated 22MnB5 steel through a Ni coating eliminated the need to mechanically or chemically remove the Al-Si coating prior to welding.
{"title":"∝-Ferrite Suppression during Fiber Laser Welding of Al-Si Coated 22MnB5 Press-Hardened Steel","authors":"Muhammad Shehryar Khan, E. Biro, Yixiang Zhou, A. Macwan","doi":"10.29391/2021.100.018","DOIUrl":"https://doi.org/10.29391/2021.100.018","url":null,"abstract":"During laser welding of an Al-Si coated 22MnB5 steel to produce tailor-welded blanks, the Al-Si coating mixes into the weld and causes the formation of the lower strength ferrite phase dispersed in an otherwise martensitic matrix. It has been shown that the presence of the ferrite phase is the principal reason for premature failure of hot-stamped laser-welded joints. Currently, the Al-Si coating is removed prior to welding, which can be time consuming. This work showed that adding Ni to the fusion zone of laser welded Al-Si coated 22MnB5 steel by welding through a pure Ni coating of a specified thickness, ferrite formation can be suppressed, whereby improving the weld strength and successfully shifting failure from the fusion zone, where it normally occurs, to the base material to achieve 100%joint strength. This work also showed that laser welding Al-Si coated 22MnB5 steel through a Ni coating eliminated the need to mechanically or chemically remove the Al-Si coating prior to welding.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48409058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tong Zhao, Deqing Mo, Li Yu, Yu Wang, Jun Li, Xue Li, D. Liu, Xiao Kun Wang, H. Gong
A Si3N4 ceramic was successfully joined to molybdenum(Mo) using an Ag-Cu-Ti filler alloy. The interfacial microstructure of the Si3N4/Ag-Cu-Ti/Mo joint was investigated by scanning an electron microscopy, energy dispersive spectrometer, and x-ray diffraction. The results showed the joint brazed at 900˚C for 10 min was smooth, and there were no holes and cracks at the interface. A continuous reaction layer, which is composed of TiN and TiSi2, was formed near the Si3N4 ceramic, with TiN being located near the ceramic. The central part of the joint was composed of Ag- and Cu-based solid solutions. At the side near the Mo metal, there was a formation of the MoTi solid solution. The typical structure of the Si3N4/Mo joint was Si3N4/TiN TiSi2 reaction layer/Ag(s,s) Cu(s,s)/MoTi/Mo. Because TiN and TiSi2 com-pounds are generated on the ceramic side, the microhardness of the reaction layer on the ceramic side was de-creased but still much higher than the hardness of the brazing seam and the Mo base material. The shear strength of the brazed joint was 204 MPa at room temperature.
{"title":"Brazing Si3N4 Ceramic to Molybdenum Using an Ag-Cu-Ti Filler","authors":"Tong Zhao, Deqing Mo, Li Yu, Yu Wang, Jun Li, Xue Li, D. Liu, Xiao Kun Wang, H. Gong","doi":"10.29391/2021.100.017","DOIUrl":"https://doi.org/10.29391/2021.100.017","url":null,"abstract":"A Si3N4 ceramic was successfully joined to molybdenum(Mo) using an Ag-Cu-Ti filler alloy. The interfacial microstructure of the Si3N4/Ag-Cu-Ti/Mo joint was investigated by scanning an electron microscopy, energy dispersive spectrometer, and x-ray diffraction. The results showed the joint brazed at 900˚C for 10 min was smooth, and there were no holes and cracks at the interface. A continuous reaction layer, which is composed of TiN and TiSi2, was formed near the Si3N4 ceramic, with TiN being located near the ceramic. The central part of the joint was composed of Ag- and Cu-based solid solutions. At the side near the Mo metal, there was a formation of the MoTi solid solution. The typical structure of the Si3N4/Mo joint was Si3N4/TiN TiSi2 reaction layer/Ag(s,s) Cu(s,s)/MoTi/Mo. Because TiN and TiSi2 com-pounds are generated on the ceramic side, the microhardness of the reaction layer on the ceramic side was de-creased but still much higher than the hardness of the brazing seam and the Mo base material. The shear strength of the brazed joint was 204 MPa at room temperature.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45140311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Weld residual stress can contribute to the reduction of structure lifetime and accelerate the formation of fatigue cracks, brittle fractures, or stress corrosion cracking. Distortion can have a significant impact on the dimensional ac-curacy of assembly, structure strength, and fabrication cost. In the past two decades, there have been many significant and exciting developments in the prediction and mitigation of weld residual stress and distortion. This paper reviews the recent advances in mitigation techniques that have been applied in the structure design, manufacturing, and postweld stages. The techniques used in the structure design stage include selecting the type of weld joint and weld groove, using balanced welding, determining appropriate plate thickness and stiffener spacing, and considering distortion compensation. Mitigation techniques used in the manufacturing stage include welding sequence optimization, reducing welding heating input, selecting low-transformation-temperature filler metals, prebending, precambering, constraints, trailing and stationary cooling, in-processing rolling, transient thermal tensioning, and additional heat sources. Postweld mitigation techniques include postweld heating and mechanical treatment. Finally, the remaining challenges and new development needs were discussed to guide future development in the field of mitigating weld residual stress and distortion.
{"title":"Recent Advances in the Prediction of Weld Residual Stress and Distortion - Part 2","authors":"Yu-ping Yang","doi":"10.29391/2021.100.016","DOIUrl":"https://doi.org/10.29391/2021.100.016","url":null,"abstract":"Weld residual stress can contribute to the reduction of structure lifetime and accelerate the formation of fatigue cracks, brittle fractures, or stress corrosion cracking. Distortion can have a significant impact on the dimensional ac-curacy of assembly, structure strength, and fabrication cost. In the past two decades, there have been many significant and exciting developments in the prediction and mitigation of weld residual stress and distortion. This paper reviews the recent advances in mitigation techniques that have been applied in the structure design, manufacturing, and postweld stages. The techniques used in the structure design stage include selecting the type of weld joint and weld groove, using balanced welding, determining appropriate plate thickness and stiffener spacing, and considering distortion compensation. Mitigation techniques used in the manufacturing stage include welding sequence optimization, reducing welding heating input, selecting low-transformation-temperature filler metals, prebending, precambering, constraints, trailing and stationary cooling, in-processing rolling, transient thermal tensioning, and additional heat sources. Postweld mitigation techniques include postweld heating and mechanical treatment. Finally, the remaining challenges and new development needs were discussed to guide future development in the field of mitigating weld residual stress and distortion.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47486248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Residual stresses and distortions are the result of complex interactions between welding heat input, the material’s high-temperature response, and joint constraint conditions. Both weld residual stress and distortion can significantly impair the performance and reliability of welded structures. In the past two decades, there have been many significant and exciting developments in the prediction and mitigation of weld residual stress and distortion. This paper reviews the recent advances in the prediction of weld residual stress and distortion by focusing on the numerical modeling theory and methods. The prediction methods covered in this paper include a thermo-mechanical-metallurgical method, simplified analysis methods, friction stir welding modeling methods, buckling distortion prediction methods, a welding cloud computational method, integrated manufacturing process modeling, and integrated computational materials engineering (ICME) weld modeling. Remaining challenges and new developments are also discussed to guide future predictions of weld residual stress and
{"title":"Recent Advances in the Prediction of Weld Residual Stress and Distortion - Part 1","authors":"Yu-ping Yang","doi":"10.29391/2021.100.013","DOIUrl":"https://doi.org/10.29391/2021.100.013","url":null,"abstract":"Residual stresses and distortions are the result of complex interactions between welding heat input, the material’s high-temperature response, and joint constraint conditions. Both weld residual stress and distortion can significantly impair the performance and reliability of welded structures. In the past two decades, there have been many significant and exciting developments in the prediction and mitigation of weld residual stress and distortion. This paper reviews the recent advances in the prediction of weld residual stress and distortion by focusing on the numerical modeling theory and methods. The prediction methods covered in this paper include a thermo-mechanical-metallurgical method, simplified analysis methods, friction stir welding modeling methods, buckling distortion prediction methods, a welding cloud computational method, integrated manufacturing process modeling, and integrated computational materials engineering (ICME) weld modeling. Remaining challenges and new developments are also discussed to guide future predictions of weld residual stress and","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":"100 1","pages":"151-170"},"PeriodicalIF":2.2,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45405078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Developments in underwater wet welding (UWW) over the past four decades are reviewed, with an emphasis on the re-search that has been conducted in the last ten years. Shielded metal arc welding with rutile-based coated electrodes was established as the most applied process in the practice of wet welding of structural steels in shallow water. The advancements achieved in previous decades had already led to control of the chemical composition and microstructure of weld metals. Research and development in consumables formulation have led to control of the amount of hydrogen content and the level of weld porosity in the weld metal. The main focus of research and development in the last decade was on weldability of naval and offshore structural steels and acceptance of welding procedures for Class A weld classification according to American Welding Society D3.6, Underwater Welding Code. Applications of strictly controlled welding techniques, including new postweld heat treatment procedures, allowed for the welding of steels with carbon equivalent values greater than 0.40. Classification societies are meticulously scrutinizing wet welding procedures and wet weld properties in structural steels at depths smaller than 30 m prior to qualifying them as Class A capable. Alternate wet welding processes that have been tested in previous decades — such as friction stir welding, dry local habitat, and gas metal arc welding — have not achieved great success as originally claimed. Almost all of the new UWW process developments in the last decade have focused on the flux cored arc welding (FCAW) process. Part 1 of this paper covered developments in microstructural optimization and weld metal porosity control for UWW. Part 2 discusses the hydrogen pickup mechanism, weld cooling rate control, design, and qualification of consumables. It ends with a description of the advancements in FCAW applications for UWW.
{"title":"The State of the Art of Underwater Wet Welding Practice: Part 2","authors":"E. Pessoa, Stephen Liu","doi":"10.29391/2021.100.014","DOIUrl":"https://doi.org/10.29391/2021.100.014","url":null,"abstract":"Developments in underwater wet welding (UWW) over the past four decades are reviewed, with an emphasis on the re-search that has been conducted in the last ten years. Shielded metal arc welding with rutile-based coated electrodes was established as the most applied process in the practice of wet welding of structural steels in shallow water. The advancements achieved in previous decades had already led to control of the chemical composition and microstructure of weld metals. Research and development in consumables formulation have led to control of the amount of hydrogen content and the level of weld porosity in the weld metal. The main focus of research and development in the last decade was on weldability of naval and offshore structural steels and acceptance of welding procedures for Class A weld classification according to American Welding Society D3.6, Underwater Welding Code. Applications of strictly controlled welding techniques, including new postweld heat treatment procedures, allowed for the welding of steels with carbon equivalent values greater than 0.40. Classification societies are meticulously scrutinizing wet welding procedures and wet weld properties in structural steels at depths smaller than 30 m prior to qualifying them as Class A capable. Alternate wet welding processes that have been tested in previous decades — such as friction stir welding, dry local habitat, and gas metal arc welding — have not achieved great success as originally claimed. Almost all of the new UWW process developments in the last decade have focused on the flux cored arc welding (FCAW) process. Part 1 of this paper covered developments in microstructural optimization and weld metal porosity control for UWW. Part 2 discusses the hydrogen pickup mechanism, weld cooling rate control, design, and qualification of consumables. It ends with a description of the advancements in FCAW applications for UWW.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44365679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
While penetration occurs underneath the workpiece, the raw information used to detect it during welding must be measurable to a sensor attached to the torch. Challenges are apparent because it is difficult to find such measurable raw information that fundamentally correlates with the phenomena occurring underneath. Additional challenges arise because the welding process is extremely complex such that analytically correlating any raw information to the underneath phenomena is practically impossible; therefore, handcrafted methods to propose features from raw information are human dependent and labor extensive. In this paper, the profile of the weld pool surface was proposed as the raw information. An innovative method was proposed to acquire it by projecting a single laser stripe on the weld pool surface transversely and intercepting its reflection from the mirror-like weld pool surface. To minimize human intervention, which can affect success, a deep-learning-based method was proposed to automatically recognize features from the single-stripe active vision images by fitting a convolutional neural network (CNN). To train the CNN, spot gas tungsten arc welding experiments were designed and conducted to collect the active vision images in pairs with their actual penetration states measured by a camera that views the backside surface of the workpiece. The CNN architecture was optimized by trying different hyperparameters, including kernel number, kernel size, and node number. The accuracy of the optimized model is about 98% and the cycle time in the personal computer is ~ 0.1 s, which fully meets the required engineering application.
{"title":"Automated Recognition of Weld Pool Characteristics from Active Vision Sensing","authors":"Yongchao Cheng, Qiyue Wang, Wenhua Jiao, Jun Xiao, Shujun Chen, Yuming Zhang","doi":"10.29391/2021.100.015","DOIUrl":"https://doi.org/10.29391/2021.100.015","url":null,"abstract":"While penetration occurs underneath the workpiece, the raw information used to detect it during welding must be measurable to a sensor attached to the torch. Challenges are apparent because it is difficult to find such measurable raw information that fundamentally correlates with the phenomena occurring underneath. Additional challenges arise because the welding process is extremely complex such that analytically correlating any raw information to the underneath phenomena is practically impossible; therefore, handcrafted methods to propose features from raw information are human dependent and labor extensive. In this paper, the profile of the weld pool surface was proposed as the raw information. An innovative method was proposed to acquire it by projecting a single laser stripe on the weld pool surface transversely and intercepting its reflection from the mirror-like weld pool surface. To minimize human intervention, which can affect success, a deep-learning-based method was proposed to automatically recognize features from the single-stripe active vision images by fitting a convolutional neural network (CNN). To train the CNN, spot gas tungsten arc welding experiments were designed and conducted to collect the active vision images in pairs with their actual penetration states measured by a camera that views the backside surface of the workpiece. The CNN architecture was optimized by trying different hyperparameters, including kernel number, kernel size, and node number. The accuracy of the optimized model is about 98% and the cycle time in the personal computer is ~ 0.1 s, which fully meets the required engineering application.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48897313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Developments in underwater wet welding (UWW) over the past four decades are reviewed, with an emphasis on the research that has been conducted in the last ten years. Shielded metal arc welding with rutile-based coated electrodes was established as the most applied process in the practice of wet welding of structural steels in shallow water. The advancements achieved in previous decades had already led to control of the chemical com-position and microstructure of weld metals. Research and development in consumables formulation have led to control of the amount of hydrogen content and the level of weld porosity in the weld metal. The main focus of research and development in the last decade was on weldability of naval and offshore structural steels and acceptance of welding procedures for Class A weld classification according to American Welding Society D3.6, Under-water Welding Code. Applications of strictly controlled welding techniques, including new postweld heat treatment procedures, allowed for the welding of steels with carbon equivalent values greater than 0.40. Classification societies are meticulously scrutinizing wet welding procedures and wet weld properties in structural steels at depths smaller than 30 m prior to qualifying them as Class A capable. Alternate wet welding processes that have been tested in previous decades — such as friction stir welding, dry local habitat, and gas metal arc welding —have not achieved great success as originally claimed. Al-most all of the new UWW process developments in the last decade have focused on the flux cored arc welding (FCAW) process. Part 1 of this paper covers developments in microstructural optimization and weld metal porosity control for UWW. Part 2 discusses the hydrogen pickup mechanism, weld cooling rate control, design, and qualification of consumables. It ends with a description of the advancements in FCAW applications for UWW.
{"title":"The State of the Art of Underwater Wet Welding Practice: Part 1","authors":"E. Pessoa, Stephen Liu","doi":"10.29391/2021.100.011","DOIUrl":"https://doi.org/10.29391/2021.100.011","url":null,"abstract":"Developments in underwater wet welding (UWW) over the past four decades are reviewed, with an emphasis on the research that has been conducted in the last ten years. Shielded metal arc welding with rutile-based coated electrodes was established as the most applied process in the practice of wet welding of structural steels in shallow water. The advancements achieved in previous decades had already led to control of the chemical com-position and microstructure of weld metals. Research and development in consumables formulation have led to control of the amount of hydrogen content and the level of weld porosity in the weld metal. The main focus of research and development in the last decade was on weldability of naval and offshore structural steels and acceptance of welding procedures for Class A weld classification according to American Welding Society D3.6, Under-water Welding Code. Applications of strictly controlled welding techniques, including new postweld heat treatment procedures, allowed for the welding of steels with carbon equivalent values greater than 0.40. Classification societies are meticulously scrutinizing wet welding procedures and wet weld properties in structural steels at depths smaller than 30 m prior to qualifying them as Class A capable. Alternate wet welding processes that have been tested in previous decades — such as friction stir welding, dry local habitat, and gas metal arc welding —have not achieved great success as originally claimed. Al-most all of the new UWW process developments in the last decade have focused on the flux cored arc welding (FCAW) process. Part 1 of this paper covers developments in microstructural optimization and weld metal porosity control for UWW. Part 2 discusses the hydrogen pickup mechanism, weld cooling rate control, design, and qualification of consumables. It ends with a description of the advancements in FCAW applications for UWW.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43757447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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