共查询到20条相似文献,搜索用时 46 毫秒
1.
K. N. Gowtham M. Vasudevan V. Maduraimuthu T. Jayakumar 《Metallurgical and Materials Transactions B》2011,42(2):385-392
Modified 9Cr-1Mo ferritic steel is used as a structural material for steam generator components of power plants. Generally,
tungsten inert gas (TIG) welding is preferred for welding of these steels in which the depth of penetration achievable during
autogenous welding is limited. Therefore, activated flux TIG (A-TIG) welding, a novel welding technique, has been developed
in-house to increase the depth of penetration. In modified 9Cr-1Mo steel joints produced by the A-TIG welding process, weld
bead width, depth of penetration, and heat-affected zone (HAZ) width play an important role in determining the mechanical
properties as well as the performance of the weld joints during service. To obtain the desired weld bead geometry and HAZ
width, it becomes important to set the welding process parameters. In this work, adaptative neuro fuzzy inference system is
used to develop independent models correlating the welding process parameters like current, voltage, and torch speed with
weld bead shape parameters like depth of penetration, bead width, and HAZ width. Then a genetic algorithm is employed to determine
the optimum A-TIG welding process parameters to obtain the desired weld bead shape parameters and HAZ width. 相似文献
2.
Type 316 LN stainless steel is the major structural material used in the construction of nuclear reactors. Activated flux
tungsten inert gas (A-TIG) welding has been developed to increase the depth of penetration because the depth of penetration
achievable in single-pass TIG welding is limited. Real-time monitoring and control of weld processes is gaining importance
because of the requirement of remoter welding process technologies. Hence, it is essential to develop computational methodologies
based on an adaptive neuro fuzzy inference system (ANFIS) or artificial neural network (ANN) for predicting and controlling
the depth of penetration and weld bead width during A-TIG welding of type 316 LN stainless steel. In the current work, A-TIG
welding experiments have been carried out on 6-mm-thick plates of 316 LN stainless steel by varying the welding current. During
welding, infrared (IR) thermal images of the weld pool have been acquired in real time, and the features have been extracted
from the IR thermal images of the weld pool. The welding current values, along with the extracted features such as length,
width of the hot spot, thermal area determined from the Gaussian fit, and thermal bead width computed from the first derivative
curve were used as inputs, whereas the measured depth of penetration and weld bead width were used as output of the respective
models. Accurate ANFIS models have been developed for predicting the depth of penetration and the weld bead width during TIG
welding of 6-mm-thick 316 LN stainless steel plates. A good correlation between the measured and predicted values of weld
bead width and depth of penetration were observed in the developed models. The performance of the ANFIS models are compared
with that of the ANN models. 相似文献
3.
V. Maduraimuthu M. Vasudevan V. Muthupandi A. K. Bhaduri T. Jayakumar 《Metallurgical and Materials Transactions B》2012,43(1):123-132
A novel variant of tungsten inert gas (TIG) welding called activated-TIG (A-TIG) welding, which uses a thin layer of activated
flux coating applied on the joint area prior to welding, is known to enhance the depth of penetration during autogenous TIG
welding and overcomes the limitation associated with TIG welding of modified 9Cr-1Mo steels. Therefore, it is necessary to
develop a specific activated flux for enhancing the depth of penetration during autogeneous TIG welding of modified 9Cr-1Mo
steel. In the current work, activated flux composition is optimized to achieve 6 mm depth of penetration in single-pass TIG
welding at minimum heat input possible. Then square butt weld joints are made for 6-mm-thick and 10-mm-thick plates using
the optimized flux. The effect of flux on the microstructure, mechanical properties, and residual stresses of the A-TIG weld
joint is studied by comparing it with that of the weld joints made by conventional multipass TIG welding process using matching
filler wire. Welded microstructure in the A-TIG weld joint is coarser because of the higher peak temperature in A-TIG welding
process compared with that of multipass TIG weld joint made by a conventional TIG welding process. Transverse strength properties
of the modified 9Cr-1Mo steel weld produced by A-TIG welding exceeded the minimum specified strength values of the base materials.
The average toughness values of A-TIG weld joints are lower compared with that of the base metal and multipass weld joints
due to the presence of δ-ferrite and inclusions in the weld metal caused by the flux. Compressive residual stresses are observed in the fusion zone
of A-TIG weld joint, whereas tensile residual stresses are observed in the multipass TIG weld joint. 相似文献
4.
D. Katherasan Sameer Srivastava P. Sathiya 《Transactions of the Indian Institute of Metals》2013,66(2):123-132
Bead on plate welds were carried out on AISI 316L(N) austenitic stainless steel using flux cored arc welding process. The bead on plates weld was conducted as per L25 orthogonal array with statistical design of experiment technique. In this paper, the welding parameters will be optimized based on the weld bead geometry such as depth of penetration, bead width and weld reinforcement. Grey relational analysis and desirability approach are used to optimize the input parameters like wire feed rate, voltage, travel speed and torch angle while considering the multiple output variables simultaneously. Confirmation experiment has also been conducted to validate the optimized parameters. 相似文献
5.
Akio Hirose Nobutaka Kurosawa Kojiro F. Kobayashi Hirotaka Todaka Hiroto Yamaoka 《Metallurgical and Materials Transactions A》1999,30(8):2115-2120
In welding 6061-T6 aluminum alloy, softening caused by the dissolution of strengthening β″ (Mg2Si) precipitates occurs in heat-affected zones (HAZs). Laser beam welding is advantageous in view of narrower softened regions.
The width of the softened region in a laser beam weld with a welding speed of 133 mm/s is 1/7 that of a tungsten inert gas
(TIG) weld with a speed of 5 mm/s. The hardness distributions and width of softened regions in the HAZ have been quantitatively
predicted to characterize the laser beam welding process. To this end, a kinetic equation describing the dissolution of age
precipitates has been established and has been applied to 6061-T6 aluminum weldments. The hardness profiles and the width
of softened zones have been successfully predicted in both welding processes. Prediction of the width of softened regions
with varying power inputs and welding speeds reveals that a high energy density and a high welding speed in laser beam welding
result in significantly narrower softened regions, in which the width is insensitive to variations in welding parameters compared
to that of TIG welding. 相似文献
6.
《钢铁研究学报(英文版)》2015,(9)
Submerged arc welding(SAW)is one of the main welding processes with high deposition rate and high welding quality.This welding method is extensively used in welding large-diameter gas transmission pipelines and high-pressure vessels.In welding of such structures,the selection process parameters has great influence on the weld bead geometry and consequently affects the weld quality.Based on Fuzzy logic and NSGA-II(Non-dominated Sorting Genetic Algorithm-II)algorithm,a new approach was proposed for weld bead geometry prediction and for process parameters optimization.First,different welding parameters including welding voltage,current and speed were set to perform SAW under different conditions on API X65 steel plates.Next,the designed Fuzzy model was used for predicting the weld bead geometry and modeling of the process.The obtained mean percentage error of penetration depth,weld bead width and height from the proposed Fuzzy model was 6.06%,6.40% and 5.82%,respectively.The process parameters were then optimized to achieve the desired values of convexity and penetration indexes simultaneously using NSGA-II algorithm.As a result,a set of optimum vectors(each vector contains current,voltage and speed within their selected experimental domains)was presented for desirable values of convexity and penetration indexes in the ranges of(0.106,0.168)and(0.354,0.561)respectively,which was more applicable in real conditions. 相似文献
7.
8.
CO2 laser beam welding of 6061-T6 aluminum alloy thin plate 总被引:1,自引:0,他引:1
Akio Hirose Kojiro F. Kobayashi Hirotaka Todaka 《Metallurgical and Materials Transactions A》1997,28(12):2657-2662
Laser beam welding is an attractive welding process for age-hardened aluminum alloys, because its low heat input minimizes
the width of weld fusion and heat-affected zones (HAZs). In the present work, 1-mm-thick age-hardened Al-Mg-Si alloy, 6061-T6,
plates were welded with full penetration using a 2.5-kW CO2 laser. Fractions of porosity in the fusion zones were less than 0.05 pct in bead-on-plate welding and less than 0.2 pct in
butt welding with polishing the groove surface before welding. The width of a softened region in the-laser beam welds was
less than 1/4 times that of a tungsten inert gas (TIG) weld. The softened region is caused by reversion of strengthening β″
(Mg2Si) precipitates due to weld heat input. The hardness values of the softened region in the laser beam welds were almost fully
recovered to that of the base metal after an artificial aging treatment at 448 K for 28.8 ks without solution annealing, whereas
those in the TIG weld were not recovered in a partly reverted region. Both the bead-on-plate weld and the butt weld after
the postweld artificial aging treatment had almost equivalent tensile strengths to that of the base plate. 相似文献
9.
The study of surface-active element oxygen on flow patterns and penetration in A-TIG welding 总被引:1,自引:0,他引:1
A three-dimensional mathematical model was developed to simulate the flow patterns and temperature distributions in a moving
A-TIG weld pool of 304 stainless steels with different oxygen content using PHOENICS software. It is shown that the surface-active
element, oxygen, is important, because it affects the weld shape by changing the flow patterns in the weld pool. The weld
bead penetration and the depth/width ratio increase first sharply and then remain nearly a constant with increasing oxygen
content. Depending upon the oxygen contents, three, one, or two vortexes that have different positions, strength, and directions
may be found in the weld pool. Oxygen can cause significant changes in the weld shape by varying the sign of the surface tension
coefficient. The situation with the maximum surface tension moves from the edge to the center with increasing oxygen content.
As oxygen content exceeds a critical value, a positive surface tension coefficient dominates the flow patterns. The vortexes
with opposite directions caused by positive surface tension coefficient can efficiently transfer the thermal energy from the
arc, creating a deep weld pool. The critical oxygen content increases with the increase of the welding current. 相似文献
10.
G. Chandrasekar C. Kailasanathan Dhanesh Kant Verma K. Nandagopal 《Transactions of the Indian Institute of Metals》2017,70(3):671-684
This research investigation articulates the joining of AISI 316 L austenitic stainless steel plates of thickness 5 mm by activated tungsten inert gas (A-TIG) welding. Prior to the welding, the optimization of process parameters and the selection of suitable flux have been carried out to join the plates in a single pass welding. The experimental results show that the complete weld penetration can be achieved by using activating flux. The microscopic study divulges the presence of delta ferrite, sigma phase and various forms of austenite in the weld zone. Fischer Feritscope result indicates that the delta ferrite content in the weld is higher (7.8 FN) than the base metal (1.3 FN) which results in superior mechanical properties of the weld. Field Emission-Scanning Electron Microscope (FE-SEM) fractography reveals that the failure of weldments occurs in ductile mode. 180° bend test study reveals the good ductility of the joint. 相似文献
11.
Weld metal grain structure and mechanical properties of the Ir-0.3 pct W alloy (DOP-26) doped with 60 ppm Th and 50 ppm Al
have been investigated by use of a gas tungsten arc (GTA) welding process. The fusion zone grain structure is strongly influenced
by heat input and puddle shape and therefore by the bead width. With increasing bead width from 2.5 to 3.7 mm, the grains
in the fusion zone show a sharp change in growth direction near the centerline region and develop a fine columnar structure
with grains growing parallel to the welding direction. Mechanical properties of the welds and base metal were characterized
by tensile and impact tests from 650 to 1150 °C. The ductility and fracture behavior of DOP-26 welds are sensitive to weld
bead width, postweld heat treatment, and weld-test orientation. The ductility of the welded specimens increases with increasing
test temperature and decreasing weld bead width. The transverse weld specimen with a wide-bead width (3.7 mm) has the lowest
impact ductility, and the longitudinal weld with a narrow-bead width (2.5 mm) has the highest elongation at all the test temperatures.
The impact ductility of the transverse weld specimen with the narrow-bead width falls between the limits. All the results
are discussed in terms of the fusion zone grain structure and fracture path of the welds. 相似文献
12.
Ultra‐fine grained ferrite steels have higher strength and better toughness than the normal ferrite steels because of their micrometer or sub‐micrometer sized grains. In this paper the ultra‐fine grained steel SS400 is welded by CO2 laser. The shape of weld, cooling rate of HAZ, width of HAZ, microstructures and mechanical properties of the joint are discussed. Experimental results indicate that laser beam welding can produce weld with a large ratio of depth to width. The cooling rate of HAZ of laser beam welding is fast, the growth of prior austenite grains of HAZ is limited, and the width of weld and HAZ is narrow. The microstructures of weld metal and coarse‐grained HAZ of laser beam welding mainly consist of BL + M (small amount). With proper laser power and welding speed, good comprehensive mechanical properties can be acquired. The toughness of weld metal and coarse‐grained HAZ are higher than that of base metal. There is no softened zone after laser beam welding. The tensile strength of a welded joint is higher than that of base metal. The welded joint has good bending ductility. 相似文献
13.
Steeliswidelyusedbecauseofitsgoodcompre hensive properties ,plentyofresourceandlowerprice .Thestrengthandtoughnessaretwoimpor tantpropertiesofsteels ,andpeoplemakeeffortstoincreasetheirvalues .Addingalloyingelementandcontrollingmicrostructurearetwobasicwaystoac complishtheaim .Therefinedmicrostructureob tainedbyprocessingtechniqueenablesthestrengthandtoughnessofsteeltobeincreasedwithoutaddingalloyingelementandtheratioofperformance costtobeincreased .Theultra finegrainedsteelshavefer ritegrains… 相似文献
14.
Experiments on Laser butt welding of 904L super austenitic stainless steel was conducted using diffusion cooled 3.5 kW slab CO2 laser welding system. The weld geometries such as bead width and depth of penetration were measured. The laser welding process has also been simulated using ANSYS a Finite Element Analysis tool. The effect of laser power, welding speed and focal point position on the bead geometry was investigated. The experimental plan was developed based on the Taguchi technique. The comparison of the results of the simulation indicates that Finite Element Method (FEM) can predict the responses adequately within the limits of welding parameters being used. It is suggested that FEM can be used as a tool for predicting the bead geometry at low values of heat input on laser welding. 相似文献
15.
G. Venkatesan V. Muthupandi Abdul Bari Fathaha 《Transactions of the Indian Institute of Metals》2017,70(6):1455-1462
Flux Bounded Tungsten Inert Gas (FBTIG) welding is a modified TIG welding process in which increased depth of penetration (DoP) can be achieved by laying thin flux coatings on either side of the weld centerline. The effect of three single component fluxes viz., SiO2, TiO2 and Cr2O3 on bead geometry of autogenous melt runs in AISI 304L stainless steel for the gap between the flux layers varying from 2 to 7 mm, is studied. Results show that DoP can be improved significantly in FBTIG process using single component fluxes. Nature of the flux and the gap between the flux layers influence the weld bead geometry. Among the three fluxes used, SiO2 is more efficient in improving the DoP. Arc constriction is the predominant mechanism operative in improving the DoP in FBTIG welding. Possibility of change in solidification mode in FBTIG weld metals of stainless steels is highlighted. 相似文献
16.
Prediction of weld pool and reinforcement dimensions of GMA welds using a finite-element model 总被引:5,自引:0,他引:5
Mathematical models of the gas metal arc (GMA) welding process may be used to study the influence of various welding parameters
on weld dimensions, to assist in the development of welding procedures, and to aid in the generation of process control algorithms
for automated applications. In this work, a three-dimensional (3-D), steady-state thermal model of the GMA welding process
has been formulated for a moving coordinate framework and solved using the finite-element method. The model includes temperature-dependent
material properties, a new finite-element formulation for the inclusion of latent heat of fusion, a Gaussian distribution
of heat flux from the arc, plus the effects of mass convection into the weld pool from the melted filler wire. The influence
of weld pool convection on the pool shape was approximated using anisotropically enhanced thermal conductivity for the liquid
phase. Weld bead width and reinforcement height were predicted using a unique iterative technique developed for this purpose.
In this paper, the numerical model is shown to be capable of predicting GMA weld dimensions for individual welds, including
those with finger penetration. Also, good agreement is demonstrated between predicted weld dimensions and experimentally derived
relations that describe the effects of process variables and their influence on average weld dimensions for bead-onplate GMA
welds on steel plate.
E. PARDO, formerly Postdoctoral Fellow, Department of Mechanical Engineering, University of Waterloo, Waterloo, ON, Canada
N2L 3G1, 相似文献
17.
对钽钢复合板的钽覆层采用敷设盖板的方式焊接,研究了直流氩弧焊与交流脉冲氩弧焊两种焊接工艺对钽钢复合板焊接质量的影响。结果表明,直流氩弧焊的焊接热影响区较宽,焊接熔深为1~1.5mm,在钢与过渡金属层之间形成了中间夹层;交流脉冲氩弧焊的焊接热影响区较窄,焊接熔深为0.5~1mm,复合板焊接质量较好。与直流氩弧焊相比,交流脉冲氩弧焊焊接参数范围较宽,对焊工技能的要求相对较低,可实现连续化生产,因此更适合用于钽钢复合板钽覆层的焊接。 相似文献
18.
本文主要分析了不锈钢薄板的焊接方法及其研究现状,分析认为,钨极氩弧焊即非熔化极氩弧焊最适合焊接较薄的不锈钢钢板。因为TIG焊焊接时热量集中,热影响区小,变形小。 相似文献
19.
L. Srinivasan Khan Mohammad Chand T. Deepan Bharathi Kannan P. Sathiya S. Biju 《Transactions of the Indian Institute of Metals》2018,71(2):373-382
In this article, an attempt was made to optimize the welding parameters of gas tungsten arc welding of 15CDV6 steel. Experiments based on Taguchi’s L9 orthogonal array were carried out in this research paper. The input parameters such as current, voltage, travel speed were considered for joining 15CDV6 plates of thickness 3.7 mm. Aftermath, the welds were subjected to post weld heat treatment. The performance characteristics such as bead width, reinforcement, tensile strength, hardness and depth of penetration of the welds were also measured. Grey relational analysis (GRA) and technique for order preference by similarity to ideal solution method (TOPSIS) were used for identifying the optimised input parameters. Analysis of variance was used to identify the influence of each individual parameter on the multi-objective function. The metallurgical characterisations of the optimised weld were compared with the microstructures obtained using optical microscope. It was made clear that both GRA and TOPSIS produced different set of optimized parameters. But on experimentation, it was found that optimized parameters obtained from TOPSIS produced weld with better properties. At the initial stage, the base metal reflected inferior properties to weldments but there was a significant improvement in the properties of base metal after post weld heat treatment. 相似文献
20.
Manabu Tanaka Hidenori Terasaki Ph.D. Masao Ushio John J. Lowke 《Metallurgical and Materials Transactions A》2002,33(7):2043-2052
In order to clarify the formative mechanism of weld penetration in an arc welding process, the development of a numerical
model of the process is quite useful for understanding quantitative values of the balances of mass, energy, and force in the
welding phenomena because there is still lack of experimentally understanding of the quantitative values of them because of
the existence of complicated interactive phenomena between the arc plasma and the weld pool. The present article is focused
on a stationary tungsten-inert-gas (TIG) welding process for simplification, but the whole region of TIG arc welding, namely,
tungsten cathode, arc plasma, workpiece, and weld pool is treated in a unified numerical model, taking into account the close
interaction between the arc plasma and the weld pool. Calculations in a steady state are made for stationary TIG welding in
an argon atmosphere at a current of 150 A. The anode is assumed to be a stainless steel, SUS304, with its negative temperature
coefficient of surface tension. The two-dimensional distributions of temperature and velocity in the whole region of TIG welding
process are predicted. The weld-penetration geometry is also predicted. Furthermore, quantitative values of the energy balance
for the various plasma and electrode regions are given. The predicted temperatures of the arc plasma and the tungsten-cathode
surface are in good agreement with the experiments. There is also approximate agreement of the weld shape with experiment,
although there is a difference between the calculated and experimental volumes of the weld. The calculated convective flow
in the weld pool is mainly dominated by the drag force of the cathode jet and the Marangoni force as compared with the other
two driving forces, namely, the buoyancy force and the electromagnetic force. 相似文献