共查询到20条相似文献,搜索用时 46 毫秒
1.
M. Grujicic S. Ramaswami J. S. Snipes C.-F. Yen B. A. Cheeseman J. S. Montgomery 《Journal of Materials Engineering and Performance》2013,22(10):2950-2969
A multiphysics computational model has been developed for the conventional Gas Metal Arc Welding (GMAW) joining process and used to analyze butt-welding of MIL A46100, a prototypical high-hardness armor martensitic steel. The model consists of five distinct modules, each covering a specific aspect of the GMAW process, i.e., (a) dynamics of welding-gun behavior; (b) heat transfer from the electric arc and mass transfer from the electrode to the weld; (c) development of thermal and mechanical fields during the GMAW process; (d) the associated evolution and spatial distribution of the material microstructure throughout the weld region; and (e) the final spatial distribution of the as-welded material properties. To make the newly developed GMAW process model applicable to MIL A46100, the basic physical-metallurgy concepts and principles for this material have to be investigated and properly accounted for/modeled. The newly developed GMAW process model enables establishment of the relationship between the GMAW process parameters (e.g., open circuit voltage, welding current, electrode diameter, electrode-tip/weld distance, filler-metal feed speed, and gun travel speed), workpiece material chemistry, and the spatial distribution of as-welded material microstructure and properties. The predictions of the present GMAW model pertaining to the spatial distribution of the material microstructure and properties within the MIL A46100 weld region are found to be consistent with general expectations and prior observations. 相似文献
2.
M. Grujicic A. Arakere S. Ramaswami J. S. Snipes R. Yavari C-F. Yen B. A. Cheeseman J. S. Montgomery 《Journal of Materials Engineering and Performance》2013,22(6):1541-1557
A conventional gas metal arc welding (GMAW) butt-joining process has been modeled using a two-way fully coupled, transient, thermal-mechanical finite-element procedure. To achieve two-way thermal-mechanical coupling, the work of plastic deformation resulting from potentially high thermal stresses is allowed to be dissipated in the form of heat, and the mechanical material model of the workpiece and the weld is made temperature dependent. Heat losses from the deposited filler-metal are accounted for by considering conduction to the adjoining workpieces as well as natural convection and radiation to the surroundings. The newly constructed GMAW process model is then applied, in conjunction with the basic material physical-metallurgy, to a prototypical high-hardness armor martensitic steel (MIL A46100). The main outcome of this procedure is the prediction of the spatial distribution of various crystalline phases within the weld and the heat-affected zone regions, as a function of the GMAW process parameters. The newly developed GMAW process model is validated by comparing its predictions with available open-literature experimental and computational data. 相似文献
3.
M. Grujicic S. Ramaswami J. S. Snipes R. Yavari A. Arakere C.-F. Yen B. A. Cheeseman 《Journal of Materials Engineering and Performance》2013,22(5):1209-1222
A fully coupled (two-way), transient, thermal-mechanical finite-element procedure is developed to model conventional gas metal arc welding (GMAW) butt-joining process. Two-way thermal-mechanical coupling is achieved by making the mechanical material model of the workpiece and the weld temperature-dependent and by allowing the potential work of plastic deformation resulting from large thermal gradients to be dissipated in the form of heat. To account for the heat losses from the weld into the surroundings, heat transfer effects associated with natural convection and radiation to the environment and thermal-heat conduction to the adjacent workpiece material are considered. The procedure is next combined with the basic physical-metallurgy concepts and principles and applied to a prototypical (plain) low-carbon steel (AISI 1005) to predict the distribution of various crystalline phases within the as-welded material microstructure in different fusion zone and heat-affected zone locations, under given GMAW-process parameters. The results obtained are compared with available open-literature experimental data to provide validation/verification for the proposed GMAW modeling effort. 相似文献
4.
M. Balakrishnan V. Balasubramanian G. Madhusudhan Reddy 《Journal of Materials Engineering and Performance》2013,22(3):806-814
Ballistic performance of armor steel welds is very poor due to the usage of low strength and low hardness austenitic stainless steel fillers, which are traditionally used to avoid hydrogen induced cracking. In the present investigation, an attempt has been made to study the effect of plasma transferred arc hardfaced interlayer thickness on ballistic performance of shielded metal arc welded armor steel weldments. The usefulness of austenitic stainless steel buttering layer on the armor grade quenched and tempered steel base metal was also considered in this study. Joints were fabricated using three different thickness (4, 5.5, and 7 mm) hardfaced middle layer by plasma transferred arc hardfacing process between the top and bottom layers of austenitic stainless steel using shielded metal arc welding process. Sandwiched joint, in addition with the buttering layer served the dual purpose of weld integrity and ballistic immunity due to the high hardness of hardfacing alloy and the energy absorbing capacity of soft backing weld deposits. This paper will provide some insight into the usefulness of austenitic stainless steel buttering layer on the weld integrity and plasma transferred arc hardfacing layer on ballistic performance enhancement of armor steel welds. 相似文献
5.
The recent development of high-performance-modified spray arc processes in gas metal arc welding due to modern digital control technology and inverter power sources enables a focused spray arc,which results in higher penetration depths and welding speed.However,microcracks occurred in the weld metal while approaching the process limits of the modified spray arc,represented by a 20-mm double layer DV-groove butt-weld.These cracks were detected in structural steel exhibiting a yield strength level of up to 960 MPa and are neither dependent on the used weld power source nor a consequence of the modified spray arc process itself.The metallographic and fractographic investigations of the rather exceptional fracture surface lead to the classification of the microcracks as hot cracks.The effects of certain welding parameters on the crack probability are clarified using a statistical design of experiment.However,these microcracks do not impact the design specification for toughness in the Charpy V-notch test(absorbed energy at —40 ℃ for the present material is 30 J). 相似文献
6.
7.
This investigation examined the feasibility of using flux modification in the form of the addition of oxidizing ingredients
to reduce the as-deposited hydrogen content of basic-type shielded metal arc welds. Additions of up to 16.3% micaceous iron
oxide (MIO) to the flux formulation of an E7018-1 type electrode lowered the diffusible weld hydrogen content by approximately
70%. This can be attributed to the formation of oxygen, which lowers the partial pressure of hydrogen in the arc atmosphere,
and the reaction of FeO (formed on dissociation of MIO) with hydrogen. The partitioning of deoxidizing elements (manganese
and silicon) between the weld metal and slag on addition of MIO to the flux coating was also examined, but the influence of
flux additions on the weld mechanical properties and the electrode operating characteristics was not evaluated during the
course of this investigation. 相似文献
8.
Fatigue Crack Growth Behavior of Gas Metal Arc Welded AISI 409 Grade Ferritic Stainless Steel Joints
A.K. Lakshminarayanan K. Shanmugam V. Balasubramanian 《Journal of Materials Engineering and Performance》2009,18(7):917-924
The effect of filler metals such as austenitic stainless steel, ferritic stainless steel, and duplex stainless steel on fatigue
crack growth behavior of the gas metal arc welded ferritic stainless steel joints was investigated. Rolled plates of 4 mm
thickness were used as the base material for preparing single ‘V’ butt welded joints. Center cracked tensile specimens were
prepared to evaluate fatigue crack growth behavior. Servo hydraulic controlled fatigue testing machine with a capacity of
100 kN was used to evaluate the fatigue crack growth behavior of the welded joints. From this investigation, it was found
that the joints fabricated by duplex stainless steel filler metal showed superior fatigue crack growth resistance compared
to the joints fabricated by austenitic and ferritic stainless steel filler metals. Higher yield strength and relatively higher
toughness may be the reasons for superior fatigue performance of the joints fabricated by duplex stainless steel filler metal. 相似文献
9.
Effect of Pulse Parameters on Weld Quality in Pulsed Gas Metal Arc Welding: A Review 总被引:4,自引:0,他引:4
The weld quality comprises bead geometry and its microstructure, which influence the mechanical properties of the weld. The
coarse-grained weld microstructure, higher heat-affected zone, and lower penetration together with higher reinforcement reduce
the weld service life in continuous mode gas metal arc welding (GMAW). Pulsed GMAW (P-GMAW) is an alternative method providing
a better way for overcoming these afore mentioned problems. It uses a higher peak current to allow one molten droplet per
pulse, and a lower background current to maintain the arc stability. Current pulsing refines the grains in weld fusion zone
with increasing depth of penetration due to arc oscillations. Optimum weld joint characteristics can be achieved by controlling
the pulse parameters. The process is versatile and easily automated. This brief review illustrates the effect of pulse parameters
on weld quality. 相似文献
10.
Weld cladding is a process for producing surfaces with good corrosion resistant properties by means of depositing/laying of
stainless steels on low-carbon steel components with an objective of achieving maximum economy and enhanced life. The aim
of the work presented here was to investigate the effect of auxiliary preheating of the solid filler wire in mechanized gas
metal arc welding (GMAW) process (by using a specially designed torch to preheat the filler wire independently, before its
emergence from the torch) on the quality of the as-welded single layer stainless steel overlays. External preheating of the
filler wire resulted in greater contribution of arc energy by resistive heating due to which significant drop in the main
welding current values and hence low dilution levels were observed. Metallurgical aspects of the as welded overlays such as
chemistry, ferrite content, and modes of solidification were studied to evaluate their suitability for service and it was
found that claddings obtained through the preheating arrangement, besides higher ferrite content, possessed higher content
of chromium, nickel, and molybdenum and lower content of carbon as compared to conventional GMAW claddings, thereby giving
overlays with superior mechanical and corrosion resistance properties. The findings of this study not only establish the technical
superiority of the new process, but also, owing to its productivity-enhanced features, justify its use for low-cost surfacing
applications. 相似文献
11.
根据模式识别原理和方法,在Windows环境下以Visual Basic为开发语言,成功地开发了一套熔化极气体保护焊(MIG、MAG、CO2)熔滴过渡模式识别软件系统,通过试验在特征谱线下,采集了大量熔化极气体保护焊五种熔滴过渡光谱信号波形。该软件系统根据熔滴过渡与光谱信号的对应关系,以及溶化极气体保护焊五种熔滴过渡的光谱信号波形的几何特征,经数据的预处理,创造性地抽取了多个关键性的特征参数,建立了相应的识别函数和最小距离法分类器,结果表明,利用该系统较好地对MIG、MAG和CO2焊熔滴过渡类型进行自动识别,具有较高的准确性和识别精度,为实现熔化极气体保护焊溶滴过渡自动控制提供了信号处理基础。 相似文献
12.
熔化极气体保护焊发展中的问题及对策 总被引:2,自引:3,他引:2
熔化极气体保护焊(GMAW)是焊接生产中最常采用的焊接方法这一。目前GMAW工艺的研究着重于:抑制焊接飞溅,提高焊接效率,以及实现焊接设备的脱技能化。本文综述了该领域近年来的研究成果,并对将来的研究方向和重点作一展望。 相似文献
13.
14.
通过对CO2焊、MAG焊、焊条电弧焊三种焊接方法的焊接工艺对比试验,表明CO2焊具有成本低、效率高、焊接质量好等优点。介绍了CO2焊、MAG焊对接焊缝工艺和角焊缝工艺在工程机械制造中的应用 相似文献
15.
通过对CO2焊、MAG焊、焊条电弧焊三种焊接方法的焊接工艺对比试验,表明CO2焊具有成本低、效率高、焊接质量好等优点。介绍了CO2焊、MAG焊对接焊缝工艺和角焊缝工艺在工程机械制造中的应用 相似文献
16.
研究了X65管线钢与316L不锈钢、Inconel 625双金属复合管的异种金属焊缝在CO2环境下的电偶腐蚀行为,以及油酸咪唑啉的缓蚀作用。结果表明,随着电偶电位差的增大,异种金属焊缝的腐蚀速率明显升高,并且都显著高于母材。添加油酸基咪唑啉缓蚀剂能降低异种金属焊缝在CO2环境下的均匀腐蚀速率。但是,当缓蚀剂浓度添加较低时,异种金属焊接试样的碳钢一侧出现了严重的沟槽腐蚀或密集的点蚀坑;进一步增加缓蚀剂浓度才能消除沟槽腐蚀现象。讨论了缓蚀剂对异种金属焊缝电偶腐蚀的抑制机理,该项研究可为异金属焊接接头处的腐蚀防护提供借鉴。 相似文献
17.
S.P. Kumaresh Babu S. Natarajan 《Journal of Materials Engineering and Performance》2007,16(5):620-625
Welding plays an essential role in fabrication of components such as boiler drum, pipe work, heat exchangers, etc., used in
power plants. Gas tungsten arc welding (GTAW) is mainly used for welding of boiler components. Pulsed GTAW is another process
widely used where high quality and precision welds are required. In all arc-welding processes, the intense heat produced by
the arc and the associated local heating and cooling lead to varied corrosion behavior and several metallurgical phase changes.
Since the occurrence of corrosion is due to electrochemical potential gradient developed in the adjacent site of a weld metal,
it is proposed to study the effects of welding on the corrosion behavior of these steels. This paper describes the experimental
work carried out to evaluate and compare corrosion and its inhibition in SA 516 Gr.70 carbon steel by pulsed GTAW process
in HCl medium at 0.1, 0.5, and 1.0 M concentrations. The parent metal, weld metal and heat affected zone are chosen as regions
of exposure for the study made at room temperature (R.T.) and at 100 °C. Electrochemical polarization techniques such as Tafel
line extrapolation (Tafel), linear polarization resistance (LPR), and ac impedance method have been used to measure the corrosion
current. The role of hexamine and mixed inhibitor (thiourea + hexamine in 0.5 M HCl), each at 100 ppm concentration is studied
in these experiments. Microstructural observation, surface characterization, and morphology using SEM and XRD studies have
been made on samples exposed at 100 °C in order to highlight the nature and extent of film formation. 相似文献
18.
S. G. Lambrakos 《Journal of Materials Engineering and Performance》2013,22(9):2467-2476
Case study inverse thermal analyses of Vanadium and Tantalum laser welds are presented. These analyses employ a methodology that is in terms of analytic basis functions for inverse thermal analysis of steady-state energy deposition in plate structures. The results of the case studies presented provide parametric representations of weld temperature histories that can be adopted as input data to various types of computational procedures, such as those for prediction of solid-state phase transformations. In addition, these temperature histories can be used to construct parametric-function representations for inverse thermal analysis of welds corresponding to other process parameters or welding processes process conditions of which fall within similar regimes. This study also discusses specific aspects the inverse-analysis methodology relevant to further development of algorithms for its application in practice. 相似文献
19.
Spiros N. Samaras 《Journal of Materials Engineering and Performance》2016,25(5):1729-1740
Laser welding (LW) offers an attractive joining technique for Al-alloys. The performance of laser welds usually suffers from mechanical strength degradation in the heat-affected zone (HAZ). In the present study, the effect of the initial-aged microstructure on the post-welded state of 6XXX Al-alloys laser welds was examined via computational modeling techniques. A well-established and detailed precipitation model was used, coupled with a strength model. The influence of the main process variables for aging heat treatment (time and temperature) and LW (power and speed) on the mechanical integrity of weld joints and specifically in the yield strength profile in the HAZ was analyzed. Also, a simple method for the prediction of the width of HAZ is provided. It is concluded that more coarsened microstructures show better performance (compared with the aged state) due to lower degradation of mechanical strength and narrower width of HAZ on the post-welded state. This study provides a method for the selection of the appropriate process parameters for aging and LW of 6XXX Al-alloys. 相似文献
20.
Reduction in grain size in weld fusion zones (FZs) presents the advantages of increased resistance to solidification cracking and improvement in mechanical properties. Transverse mechanical arc oscillation was employed to obtain grain refinement in the weldment during tungsten inert gas welding of Al-Mg-Si alloy. Electron backscattered diffraction analysis was carried out on AA6061-AA4043 filler metal tungsten inert gas welds. Grain size, texture evolution, misorientation distribution, and aspect ratio of weld metal, PMZ, and BM have been observed at fixed arc oscillation amplitude and at three different frequencies levels. Arc oscillation showed grain size reduction and texture formation. Fine-grained arc oscillated welds exhibited better yield and ultimate tensile strengths and significant improvement in percent elongation. The obtained results were attributed to reduction in equivalent circular diameter of grains and increase in number of subgrain network structure of low angle grain boundaries. 相似文献