Richard E. Baumer, Ezequiel Caires Pereira Pessoa, Karthik Krishnan, Thanh NAM VU
Supermartensitic stainless steels with 15Cr- 6Ni-2Mo-1Cu with 135 ksi minimum yield strength (15Cr-135 SMSS) offer high strength and good toughness through a complex hierarchical microstructure of nanoscale precipitates, tempered martensite, and reverted austenite. Upon welding and postweld heat treatment, substantial changes to heat-affected zone microstructure and hardness may occur. Here, we reveal spatially heterogeneous microstructure and microhardness in the HAZ of 15Cr-135 SMSS; correlate these changes to measured phase transformation temperatures; and demonstrate that HAZ hardness changes depend strongly on postweld heat treatment temperatures. Furthermore, we demonstrate that PWHT may lead to undesired reductions in base metal yield strength and formulate a design guide for PWHT that quantifies the trade-offs in desired reductions of HAZ hardness with undesired changes to base metal yield strength. These findings have important practical implications for welding procedure design and qualification.
{"title":"Postweld Heat Treatment of 15Cr-6Ni-2Mo-1Cu Supermartensitic Stainless Steel Welds","authors":"Richard E. Baumer, Ezequiel Caires Pereira Pessoa, Karthik Krishnan, Thanh NAM VU","doi":"10.29391/2024.103.022","DOIUrl":"https://doi.org/10.29391/2024.103.022","url":null,"abstract":"Supermartensitic stainless steels with 15Cr- 6Ni-2Mo-1Cu with 135 ksi minimum yield strength (15Cr-135 SMSS) offer high strength and good toughness through a complex hierarchical microstructure of nanoscale precipitates, tempered martensite, and reverted austenite. Upon welding and postweld heat treatment, substantial changes to heat-affected zone microstructure and hardness may occur. Here, we reveal spatially heterogeneous microstructure and microhardness in the HAZ of 15Cr-135 SMSS; correlate these changes to measured phase transformation temperatures; and demonstrate that HAZ hardness changes depend strongly on postweld heat treatment temperatures. Furthermore, we demonstrate that PWHT may lead to undesired reductions in base metal yield strength and formulate a design guide for PWHT that quantifies the trade-offs in desired reductions of HAZ hardness with undesired changes to base metal yield strength. These findings have important practical implications for welding procedure design and qualification.","PeriodicalId":509696,"journal":{"name":"Welding Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140763917","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}
The GMAW process for titanium alloy is not commonly applied within the industry due to the occurrence of severe spatter. This research endeavors to elucidate the mechanism underlying spatter formation and explore efficacious strategies to suppress spatter. The experimental results demonstrated the existence of two distinct spatter types: large and small spatter particles. The high- speed images and synchronous electrical signals were utilized for determining the spatter formation mechanism, with force analysis serving to mutually validate the inferences. The large spatter particles originated from the whole transitional molten droplet as it descended within the arc space, while the small spatter particles were formed by the partial transitional molten droplet as it contacted the weld pool. The cathode jet force accounted for the formation of large spatter particles, whereas the electromagnetic force was responsible for the small spatter particles. To suppress spatter, increasing detachment current and decreasing pulsing frequency were employed. Consequently, the spatter rate witnessed a remarkable decrease from 14.00% to 3.33% with a progressive increment in detachment current from 100 A to 300 A, and a corresponding decline from 12.67% to 1.33% upon decrementing the pulsing frequency from 90 Hz to 50 Hz. This research suggests that a judicious increase in the detachment current can effectively decrease the spatter rate while concurrently preserving welding efficiency.
{"title":"The Formation Mechanism and Suppression Strategies of Spatter in Pulsed Gas Metal Arc Welding for Titanium Alloy","authors":"Zhendan Zheng, Shaojie Wu, Limin Fan, Hao Wu, Fangjie Cheng","doi":"10.29391/2024.103.020","DOIUrl":"https://doi.org/10.29391/2024.103.020","url":null,"abstract":"The GMAW process for titanium alloy is not commonly applied within the industry due to the occurrence of severe spatter. This research endeavors to elucidate the mechanism underlying spatter formation and explore efficacious strategies to suppress spatter. The experimental results demonstrated the existence of two distinct spatter types: large and small spatter particles. The high- speed images and synchronous electrical signals were utilized for determining the spatter formation mechanism, with force analysis serving to mutually validate the inferences. The large spatter particles originated from the whole transitional molten droplet as it descended within the arc space, while the small spatter particles were formed by the partial transitional molten droplet as it contacted the weld pool. The cathode jet force accounted for the formation of large spatter particles, whereas the electromagnetic force was responsible for the small spatter particles. To suppress spatter, increasing detachment current and decreasing pulsing frequency were employed. Consequently, the spatter rate witnessed a remarkable decrease from 14.00% to 3.33% with a progressive increment in detachment current from 100 A to 300 A, and a corresponding decline from 12.67% to 1.33% upon decrementing the pulsing frequency from 90 Hz to 50 Hz. This research suggests that a judicious increase in the detachment current can effectively decrease the spatter rate while concurrently preserving welding efficiency.","PeriodicalId":509696,"journal":{"name":"Welding Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140796153","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}
This paper is a sequel to the previous paper. In the previous research (Ref. 1), a REI-TPA model was established to quantitively relate reversed electrode images (REIs) to welding torch position and attitude (TPA). In this research, the REI-TPA model was validated with bead-on-plate welding experiments on S304 stainless steel plates. The contours of the REI and electrode as well as the weld pool geometry were extracted from the image with a developed, robust algorithm, and the arc length was calculated with welding voltage. The offset distance and deflection angle of the welding torch relative to the correct position and attitude were calculated by inputting the extracted parameters into the REI-TPA model. The computational result was compared to the experimental data. The result showed that the model is correct and the monitoring of the welding torch with the REI-TPA model is available. The REI- TPA model can be applied to real-time control of TPA, which is a supplement to the application of the weld passive visual image and an extension of multi- information acquisition and processing methods in the welding process.
{"title":"Monitoring Welding Torch Position and Posture Using Reversed Electrode Images – Part II, Experimental and Analysis for the REI-TPA Model","authors":"YU Fu, Runquan Xiao, Shanben Chen","doi":"10.29391/2024.103.021","DOIUrl":"https://doi.org/10.29391/2024.103.021","url":null,"abstract":"This paper is a sequel to the previous paper. In the previous research (Ref. 1), a REI-TPA model was established to quantitively relate reversed electrode images (REIs) to welding torch position and attitude (TPA). In this research, the REI-TPA model was validated with bead-on-plate welding experiments on S304 stainless steel plates. The contours of the REI and electrode as well as the weld pool geometry were extracted from the image with a developed, robust algorithm, and the arc length was calculated with welding voltage. The offset distance and deflection angle of the welding torch relative to the correct position and attitude were calculated by inputting the extracted parameters into the REI-TPA model. The computational result was compared to the experimental data. The result showed that the model is correct and the monitoring of the welding torch with the REI-TPA model is available. The REI- TPA model can be applied to real-time control of TPA, which is a supplement to the application of the weld passive visual image and an extension of multi- information acquisition and processing methods in the welding process.","PeriodicalId":509696,"journal":{"name":"Welding Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140770529","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}
A. Marzocca, C. A. Danón, M. Luppo, Flavio Soldera, M. Zalazar
The microstructure of the heat affected zone (HAZ) and fusion zone (FZ) in the as-welded condition of a single-pass weld performed by the flux-cored arc welding (FCAW) process was studied in a P91 steel using microhardness measurements, field-emission scanning electron microscopy, transmission electron microscopy, and x-ray diffraction. The evolution of precipitates in each region of the single-pass weld was analyzed, and particular attention was paid to the presence of retained austenite (RA). Experimental observations indicated that M23 C6 carbide played a major role in the thermal cycle associated with the weldment. On one hand, the dissolution of M23 C6 led to the precipitation of spherical NbCN in the finegrained HAZ (FGHAZ) near the coarse-grained HAZ (CGHAZ). On the other hand, the total or partial dissolution of M23 C6 carbides changed the chemical composition of the initially formed austenite. In the regions where the M23 C6 carbides were completely dissolved (i.e., the CGHAZ and FZ), retained austenite was observed as a thin, continuous film along primary austenite grains and lath boundaries. Instead, a shell of retained austenite was observed around some partially dissolved M23 C6 of the intercritical HAZ (ICHAZ) and FGHAZ.
{"title":"Characterization of As-Welded Microstructure in a P91 Steel","authors":"A. Marzocca, C. A. Danón, M. Luppo, Flavio Soldera, M. Zalazar","doi":"10.29391/2024.103.006","DOIUrl":"https://doi.org/10.29391/2024.103.006","url":null,"abstract":"The microstructure of the heat affected zone (HAZ) and fusion zone (FZ) in the as-welded condition of a single-pass weld performed by the flux-cored arc welding (FCAW) process was studied in a P91 steel using microhardness measurements, field-emission scanning electron microscopy, transmission electron microscopy, and x-ray diffraction. The evolution of precipitates in each region of the single-pass weld was analyzed, and particular attention was paid to the presence of retained austenite (RA). Experimental observations indicated that M23 C6 carbide played a major role in the thermal cycle associated with the weldment. On one hand, the dissolution of M23 C6 led to the precipitation of spherical NbCN in the finegrained HAZ (FGHAZ) near the coarse-grained HAZ (CGHAZ). On the other hand, the total or partial dissolution of M23 C6 carbides changed the chemical composition of the initially formed austenite. In the regions where the M23 C6 carbides were completely dissolved (i.e., the CGHAZ and FZ), retained austenite was observed as a thin, continuous film along primary austenite grains and lath boundaries. Instead, a shell of retained austenite was observed around some partially dissolved M23 C6 of the intercritical HAZ (ICHAZ) and FGHAZ.","PeriodicalId":509696,"journal":{"name":"Welding Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140090666","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}
In this paper, the effects of the shield gas on cut quality in plasma arc cutting were quantified experimentally. Measurements were performed on plasma arc cutting kerfs (PACs) cut through a 4 mm (1/8 in.) S355 steel plates with a Gys Neocut105 cutter equipped with a Toparc AT-125 torch. This system uses compressed air as both cutting and shield gas. Separate circuits for shielding air and cutting air were used. This way, the influences of the shield air and the cutting air could be studied independently. A full 3-factor, 3-level Taguchi design was followed. The studied factors are the cutting air pressure, the shield air pressure, and the arc current. The measured responses are the removed steel surface and the right and left bevel angles. As expected, the current proved to have the greatest influence on the kerf surface. The cutting air pressure significantly influenced the kerfs’ shapes while the shield air flow rate proved less important yet sensitive. Some negative bevel angles at high plasma, high cutting, and high shield air pressures have also been observed.
{"title":"Cutting and Shield Gases Pressure Effects on Plasma Cutting Quality","authors":"S. Chabert, Jean-Jacques Gonzalez, P. Freton","doi":"10.29391/2024.103.007","DOIUrl":"https://doi.org/10.29391/2024.103.007","url":null,"abstract":"In this paper, the effects of the shield gas on cut quality in plasma arc cutting were quantified experimentally. Measurements were performed on plasma arc cutting kerfs (PACs) cut through a 4 mm (1/8 in.) S355 steel plates with a Gys Neocut105 cutter equipped with a Toparc AT-125 torch. This system uses compressed air as both cutting and shield gas. Separate circuits for shielding air and cutting air were used. This way, the influences of the shield air and the cutting air could be studied independently. A full 3-factor, 3-level Taguchi design was followed. The studied factors are the cutting air pressure, the shield air pressure, and the arc current. The measured responses are the removed steel surface and the right and left bevel angles. As expected, the current proved to have the greatest influence on the kerf surface. The cutting air pressure significantly influenced the kerfs’ shapes while the shield air flow rate proved less important yet sensitive. Some negative bevel angles at high plasma, high cutting, and high shield air pressures have also been observed.","PeriodicalId":509696,"journal":{"name":"Welding Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140089442","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}
Kauê Correa Riffel, R. H. Gonçalves e Silva, Antonio Ramirez, Andres FABRICIO FISCHDICK ACUNA, G. Dalpiaz, Marcelo TORRES PIZA PAES
In-service welding simulations were carried out using a multiphysics finite element analysis (FEA). Calculated data as temperature and thermal cycles were validated by comparing them with experimental welding results carried out in a carbon steel pipe attached to a water loop. Two in-service welding cases were tested using the GMAW-P process with and without the assistance of induction preheating. The molten zone of weld macrographs and the simulated models were matched with excellent accuracy. The great agreement between the simulation and experimental molten zone generated a maximum error in the peak temperature of 1%, while in the cooling curve, the error was about 10% at lower temperatures. A higher hardness zone appeared in the weld’s toe within the CGHAZ, where the maximum induction preheating temperature achieved was 90°C with a power of 35 kW. Induction preheating reduced the maximum hardness from 390 HV to 339 HV.
{"title":"Multiphysics Simulation of In-Service Welding and Induction Preheating: Part 2","authors":"Kauê Correa Riffel, R. H. Gonçalves e Silva, Antonio Ramirez, Andres FABRICIO FISCHDICK ACUNA, G. Dalpiaz, Marcelo TORRES PIZA PAES","doi":"10.29391/2024.103.008","DOIUrl":"https://doi.org/10.29391/2024.103.008","url":null,"abstract":"In-service welding simulations were carried out using a multiphysics finite element analysis (FEA). Calculated data as temperature and thermal cycles were validated by comparing them with experimental welding results carried out in a carbon steel pipe attached to a water loop. Two in-service welding cases were tested using the GMAW-P process with and without the assistance of induction preheating. The molten zone of weld macrographs and the simulated models were matched with excellent accuracy. The great agreement between the simulation and experimental molten zone generated a maximum error in the peak temperature of 1%, while in the cooling curve, the error was about 10% at lower temperatures. A higher hardness zone appeared in the weld’s toe within the CGHAZ, where the maximum induction preheating temperature achieved was 90°C with a power of 35 kW. Induction preheating reduced the maximum hardness from 390 HV to 339 HV.","PeriodicalId":509696,"journal":{"name":"Welding Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140089533","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. C. Riffel, R. H. Gonçalves e Silva, Antonio Ramirez, Andres Fabricio FISCHDICK ACUNA, G. Dalpiaz, Marcelo Torres Piza Paes
A finite element model was developed using a multiphysics finite element analysis (FEA) coupling heat transfer, fluid flow, and electromagnetic heating. Part 1 presents the software implementation and model equations beside the mesh setting and modeling approach to simulate circumferential welding of Type B sleeve repair. The simulation was divided into four steps running sequentially for each physic solved in the model. Induction preheating was simulated and validated by comparing simulated temperature with experimental measurements. The multiphysics model differs from the usual simulations present in the literature, expressing more reliability in the results and making way for more-complete modeling for in-service applications.
利用多物理场有限元分析（FEA）将传热、流体流动和电磁加热耦合在一起，建立了一个有限元模型。第 1 部分介绍了模拟 B 型套筒修复圆周焊接的软件实现、模型方程、网格设置和建模方法。模拟分为四个步骤，对模型中的每个物理问题依次进行求解。对感应预热进行了模拟，并通过比较模拟温度和实验测量结果进行了验证。多物理场模型不同于文献中常见的模拟，其结果更加可靠，可为在役应用提供更完整的模型。
{"title":"Multiphysics Simulation of In-Service Welding and Induction Preheating: Part 1","authors":"K. C. Riffel, R. H. Gonçalves e Silva, Antonio Ramirez, Andres Fabricio FISCHDICK ACUNA, G. Dalpiaz, Marcelo Torres Piza Paes","doi":"10.29391/2024.103.005","DOIUrl":"https://doi.org/10.29391/2024.103.005","url":null,"abstract":"A finite element model was developed using a multiphysics finite element analysis (FEA) coupling heat transfer, fluid flow, and electromagnetic heating. Part 1 presents the software implementation and model equations beside the mesh setting and modeling approach to simulate circumferential welding of Type B sleeve repair. The simulation was divided into four steps running sequentially for each physic solved in the model. Induction preheating was simulated and validated by comparing simulated temperature with experimental measurements. The multiphysics model differs from the usual simulations present in the literature, expressing more reliability in the results and making way for more-complete modeling for in-service applications.","PeriodicalId":509696,"journal":{"name":"Welding Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139884834","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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