Welding Journal最新文献

{"title":"Weldability of Duplex Stainless Steels - Thermal Cycle and Nitrogen Effects","authors":"B. Varbai, Y. Adonyi, R. Baumer, T. Pickle, J. Dobránszky, K. Májlinger","doi":"10.29391/2019.98.006","DOIUrl":"https://doi.org/10.29391/2019.98.006","url":null,"abstract":"Much development work has been performed worldwide on the welding of duplex stainless steels (DSSs), where losses in base metal nitrogen during welding have been compensated by filler metal and nitrogen additions to the shielding gas. However, some heat-affected zone (HAZ) microstructural changes have not always responded consistently to nitrogen mixtures added to the shielding gas. In this work, DSS weld microstructures were investigated as a function of weld thermal cycles and shielding gas nitrogen content. Physical simulations, actual gas tungsten arc welding (GTAW) in controlled atmospheres, and entrapped nitrogen measurements were used to relate to the weld austenite-to-ferrite (A/F) phase ratios. Results showed the thermal cycles had a stronger effect on the weld A/F ratio than shielding gas nitrogen content. Physical simulations and actual GTAW trials also showed the A/F ratio changes in the opposite way in the fusion zone than in the HAZ. Reheating was also found to have an important effect on the microstructure. The above findings should allow fabricators to better design the welding process with DSS. Better control of nitrogen-containing shielding gas mixtures, along with heat input limitations, should result in more consistent weld properties and wider use of DSS by industry.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70003240","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}

{"title":"Laser-Enhanced Short-Circuiting Metal Transfer in GMAW","authors":"BY S. J. Chen, Y. Jia, J. Xiao, T. Wen","doi":"10.29391/2019.98.016","DOIUrl":"https://doi.org/10.29391/2019.98.016","url":null,"abstract":"Previously, pulsed laser-enhanced gas metal arc welding (GMAW) was studied toward the goal of realizing current-independent free-flight metal transfer. However, controlled low-spatter or even spatter-free short-circuiting transfer would be more preferred in applications requiring even lower heat input. Thereby, laser-enhanced metal transfer was expanded to short-circuiting transfer by using a relatively short arc. A constant current (CC) power source was employed to avoid the current boost during the short-circuiting period. The arc variables and metal transfer dynamics were synchronously recorded. The short-circuiting transfer behavior under constant and pulsed laser irradiation were both observed and analyzed in this study. The experimental results show the laser irradiation does enhance the short-circuiting metal transfer under CC power mode in the ways of controlling the transfer frequency and improving the process stability. The role of the laser recoil force changes to first actively initiate and then terminate the short-circuiting process between the droplet and molten pool. The start and end of the short-circuiting process both become controllable. A sufficiently high short-circuiting current is no longer needed to severely pinch the droplet and thus guarantee termination of the short circuit. On the other hand, welding spatter produced by the current boost in constant voltage (CV) power mode is nearly eliminated. What is more, the transfer frequency can be precisely controlled when using pulsed laser irradiation. A kind of one-droplet-per-pulse (ODPP) short-circuiting transfer, almost without spatter, is obtained as desirable.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":"49 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70003455","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}

{"title":"Bubble Evolution in Ultrasonic Wave-Assisted Underwater Wet FCAW","authors":"J. Wang, Q. Sun, J. Teng, J. Feng","doi":"10.29391/2019.98.012","DOIUrl":"https://doi.org/10.29391/2019.98.012","url":null,"abstract":"Ultrasonic wave-assisted underwater wet welding (UUWW) is a newly developed welding method. The principle of this method is to apply the acoustic radiation force to the arc bubble as an extra retaining force. The dynamic feature of the bubble under an acoustic field was demonstrated and analyzed by visual sensing and welding electrical signals. Comparative experiments indicated that, under the same conditions, the additional ultrasonic wave caused the bubble’s motion with a certain angle with respect to the welding torch axis so the welding process was not easily affected by the rising of lateral bubbles. Meanwhile, there was always a relatively large bubble maintained in the weld pool surface. The oscillation of the bubble with small amplitude was observed and no necking was present at the bubble bottom. The measurement results revealed that the exertion of ultrasonic wave resulted in a reduced fluctuation of welding electrical signals and an improvement in the arc burning process. For the variation coefficient, the difference between underwater wet welding and U-UWW became significant with varying experimental groups, the maximum difference of which occurred at Group 4.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70003707","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}

{"title":"Effect of Multiple Weld Thermal Cycles on HSLA-100 Steel","authors":"","doi":"10.29391/2019.98.007","DOIUrl":"https://doi.org/10.29391/2019.98.007","url":null,"abstract":"High-strength low-alloy (HSLA)-100 is a precipitatestrengthened low-alloy steel that is often used for its good combination of high yield strength and impact toughness. During initial fabrication and service, multipass welds and weld repairs often need to be made. Work has been done to determine the properties in the heat-affected zone (HAZ) for HSLA-100, but fewer results are available to understand microstructural evolution and the resultant properties of the HAZ under multipass welding conditions. Variations in the HAZ hardness were observed and shown to be associated with compositional banding. These differences between the enriched and depleted solute bands led to differences in hardenability. Thermodynamic and diffusion simulations demonstrated that carbon preferentially segregates to the regions of higher concentration of substitutional elements, thus increasing the hardness. This difference in composition also led to changes in the transformation temperatures and caused local differences in the HAZ microstructure. Multiple-pass autogenous welds confirmed that this compositional banding has a greater effect on hardness than multiple weld thermal cycles. HAZ simulations showed the hardness in all regions of the HAZ was higher than that of the base metal (BM). The impact toughness of the HAZ was equal to or higher than the BM, except for the coarse-grain HAZ (CGHAZ), which was slightly below the acceptable minimum for the BM. However, the CGHAZ toughness did not degrade further after three weld thermal cycles. The reheated CGHAZ showed a rejuvenation in toughness for subsequent thermal cycles with peak temperatures of 810° and 900°C. The phase transformations in the intercritical HAZ (ICHAZ) region were still unfinished after three weld thermal cycles, and the progressive transformation with each successive pass increased the hardness and decreased the toughness. However, fully transformed ICHAZ samples still maintained excellent impact toughness and high hardness. Additional samples underwent weld simulations after a 10% prestrain to study how plastic strain from residual stress and service would influence the resulting properties. Except for the CGHAZ, all regions of the strained BM and HAZ still exhibited toughness values above the minimum requirements.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70002889","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}

{"title":"Assessment of Thermoplastic Weldability Using the Deformation Technique","authors":"B. Panda","doi":"10.29391/2019.98.013","DOIUrl":"https://doi.org/10.29391/2019.98.013","url":null,"abstract":"The joining of similar/dissimilar materials by using conventional and nonconventional techniques is a challenging task to produce cost-effective joints without overweighing the product. Traditionally, adhesive welding is the preferred technique used to join polymers at the cost of increase in product weight. The use of nonconventional techniques in welding polymers is limited due to an expensive source of energy. However, all of these techniques have limited applications for the joining of polymers. To overcome this limitation, constant efforts are given to develop a new technique to join the polymer through the Y-shape die channel. The Yshape die channel is the reliable method to join two similar natures of polymers without the use of additive materials, hence product overweight can be avoided. The joint employed through the preheated die channel at 150°C and developed back pressure cause proper blending between the polymers. The reason for the development of back pressure is the nature of joint interface with exploring the scope of metal forming operation such as extrusion and equal channel angular pressing (ECAP) into a new joining procedure. Channel design, joining procedures, dynamic mechanical analysis (DMA), and x-ray diffraction (XRD) of the joints were used to assess the weldability of polymers.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70003262","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}

{"title":"Root Pass Microstructure in Super Duplex Stainless Steel Multipass Welds","authors":"D. Wagner","doi":"10.29391/2019.98.010","DOIUrl":"https://doi.org/10.29391/2019.98.010","url":null,"abstract":"Superduplex stainless steels (SDSS) have twice the base strength and pitting corrosion resistance of austenitic stainless steels and are commonly used when stresscorrosion cracking is a concern. During multipass welding of SDSS, a 50-50 austenite-ferrite phase balance is recommended in the exposed root pass fusion zone and heataffected zone (HAZ), although 35–65% of austenite is acceptable. Systematic studies with the arc energy and number of weld passes with mechanized multipass gas tungsten arc welding (GTAW) of 6-mm(0.24-in.-) and 12.7-mm(0.5-in.-) thick substrates (UNS S32750) reveal that multiple thermal cycles experienced in the root result in an increased root fusion zone austenite-ferrite ratio and presence of secondary austenite. Gleeble® 1500 physical reheating simulations, applying experimental thermal cycles directly measured in the root of multipass GTA welds, con-","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70003612","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}

{"title":"Laser Heat Treatment of Low-Alloy Ultrahigh-Strength Steel Laser-Welded Joints","authors":"L. Zhao, J. Shan","doi":"10.29391/2019.98.020","DOIUrl":"https://doi.org/10.29391/2019.98.020","url":null,"abstract":"The poor bending property of laser-welded joints limits the application of low-alloy ultrahigh-strength steel (LAUHSS). In this work, two stages of laser heat treatment (LHT) were performed to enhance the faceand back-bending property of joints with minimized strength loss. The microstructures and mechanical properties were evaluated, and the influence mechanism of LHT on the bending property was discussed. The first LHT aimed to improve the back-bending property, after which the joints were comprised of the austenized and tempering zones. In the tempering zone, the original inhomogeneous microstructures transformed into similar tempered martensite. This smoothed out the steep hardness gradient to relatively uniform values. In the austenized zone, austenization occurred and the hardness valley still existed around the sides of the zone. The mechanical property test results showed the back-bending angle could be improved from 30 deg to more than 90 deg, while the face-bending angle showed unsatisfactory results with more than 1280 MPa tensile strength. The second LHT was performed based on the first LHT to improve the face-bending property of joints. With lower power in the second LHT, the dual-phase microstructures in the austenized zone tempered. Additionally, the hardness distributions of joints tended to be more uniform without valleys. A more than 90-deg face-bending angle and about 1205 MPa tensile strength were obtained. After LHT, the range of plastic deformation during the bending process expanded instead of concentrating in the hardness valley zone, which led to a larger relative bending radius and less tensile stress on the bending surface. This is beneficial for the improvement of the bending property.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":"1 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70003689","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}

{"title":"Weld Pool Surface Fluctuations Sensing in Pulsed GMAW","authors":"Z. Wang, P. Bai, LU T., Y. Cao","doi":"10.29391/2018.97.028","DOIUrl":"https://doi.org/10.29391/2018.97.028","url":null,"abstract":"This work addresses the sensing and monitoring of joint penetration in pulsed gas metal arc welding (GMAW-P). The issue being addressed is challenging because the joint penetration is not directly observable, and its solution lies on the successful identification of easily measurable signals that have an inherent relationship with the joint penetration. The metal transfer in gas metal arc welding and the pulsing of the current add additional complexities in the process, causing the significant fluctuation in weld pool that disqualifies state-of-the-art methods in weld pool measurement. Through critical analysis of the complex process, the authors hypothesize that the fluctuation behavior of the weld pool under pulsing current is determined by the joint penetration. To test this hypothesis, a series of experiments were designed, and the reflection from the weld pool surface during the peak current period was used to derive a measurement to quantify the fluctuation. Experimental results showed that the fluctuation of structured laser reflection during the peak current period, which was represented by the cover area of laser reflections (Ac) in the fixed window during a peak current period, can reflect the joint penetration in GMAW-P but with a time delay. The change in arc voltage during a peak current period (U) and the average voltage during a peak current period (U) can both be used to characterize joint penetration in GMAW-P. The U decreases before the weld gets penetrated and then increases, while U increases before the weld gets penetrated and then decreases. These two electrical variables could be fused together to control joint penetration in GMAW-P in manufacturing plants.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43722254","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}

{"title":"Alloy Composition and Critical Temperatures in Type 410 Steel Welds","authors":"B. Alexandrov, J. Penso","doi":"10.29391/2018.97.025","DOIUrl":"https://doi.org/10.29391/2018.97.025","url":null,"abstract":"The design of experiment (DoE) approach using thermodynamic simulations with ThermoCalcTM was applied to evaluate the effect of alloy composition on the critical temperatures in Type 410 steels and welding consumables. A predictive equation and predictive diagram for the A1 temperature were developed and verified through experimentation and comparison with published data. This was also complemented with the development of a predictive equation for the A3 temperature. The results of this study show that the combined ASTM and American Welding Society (AWS) compositional specifications for Type 410 materials provide a range of A1 temperatures that is significantly wider than the postweld heat treatment (PWHT) temperature range specified by the American Society of Mechanical Engineers (ASME). This creates a potential risk of exceeding the A1 temperature during PWHT, resulting in formation of fresh martensite, and can be related to difficulties meeting hardness and toughness requirements for Type 410 welds experienced in industry. Narrowing the ASTM and AWS compositional specifications by introduction of lower limits for all alloying elements, including nitrogen and copper, was identified as a potential solution to this problem. The predictive tools developed in this study can be applied for selection of welding consumables and base metals, postweld heat treatment (PWHT) temperature selection, and compositional optimization of Type 410 steels and welding consumables.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42948700","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}

{"title":"Rotating-Tungsten Narrow-Groove GTAW for Thick Plates","authors":"B. C. Jia, Q. Yan, B. Wei, W. C.","doi":"10.29391/2018.97.024","DOIUrl":"https://doi.org/10.29391/2018.97.024","url":null,"abstract":"A novel rotating-tungsten narrow-groove gas tungsten arc welding (RT-NG-GTAW) process was proposed based on a specially designed nonaxisymmetric and rotating tungsten electrode. The tungsten electrode was ground with its tip deviated from the axis and located on the column wall. The rotation made the tungsten tip continue circling in the narrow groove. The distance from the tungsten tip to the sidewalls and the bottom weld pool periodically changed. According to the principle of minimum voltage, the arc burning was controlled and maintained periodically from the left sidewall, bottom of the weld pool, and the right sidewall. The rotating arc heated the base metal reliably and evenly on the sidewalls and bottom metal. This technology can solve the key problem of incomplete fusion on sidewalls in narrow-groove welding. A novel welding torch was designed and manufactured. Experiments were conducted, including single-pass narrow-groove welding and narrow-groove butt joint welding experiments using 16-mm-thick alloy steel plates. Results verified that the new technology could improve sidewall fusion and ensure a uniform and smooth weld appearance. The periodically rotating arc kept constantly stirring the molten pool throughout from its formation to solidification. The preliminary investigation showed the novel technology has prospects for thick-plate welding in industry.","PeriodicalId":23681,"journal":{"name":"Welding Journal","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47540624","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}