Showing papers in "Science and Technology of Welding and Joining in 1999"
TL;DR: In this article, the feasibility of friction stir welding (FSW) of steel has been investigated and it has been shown that the mechanical properties of FSW of 12% chromium alloy and low carbon steel joints compare favorably with the properties of the parent metal.
Abstract: The feasibility of friction stir welding (FSW) of steel is demonstrated. Tensile and bend testing have confirmed that the mechanical properties of friction stir welded 12% chromium alloy and low carbon steel joints compare favourably with the properties of the parent metal. Some initial feasibility studies of FSW of both 12% chromium alloy and low carbon steel are described. Although more development work is needed, particularly to improve tool materials, the prognosis for continued developments in FSW of steel is shown to be good.
320 citations
TL;DR: In this article, electron beam welding was performed on three different aluminium alloys, namely alloys 2024, 5005, and 6061, to establish the local microstructure-property relationships that would satisfy the service requirements for an electron beam welded aluminium alloy component with weld zone strength undermatching.
Abstract: Electron beam (EB) welding was performed on three different aluminium alloys, namely alloys 2024, 5005, and 6061 (plate thickness 5 mm except alloy 5005 which was 3 mm in thickness), to establish the local microstructure–property relationships that would satisfy the service requirements for an electron beam welded aluminium alloy component with weld zone strength undermatching. Microstructural characterisation of the weld metals was carried out by optical and scanning electron microscopy. A very low level of porosity was observed in all EB welds owing to surface cleaning before welding and the vacuum environment of the EB welding process. Extensive microhardness measurements were also conducted in the weld regions of the joints. Global tensile properties and fracture toughness properties (in terms of crack tip opening displacement, CTOD) of the EB joints were determined at room temperature. The effects of strength mismatch and local microstructure on fracture toughness of the EB joints are discuss...
120 citations
TL;DR: In this article, an axisymmetric finite element model employing coupled thermal-electrical-mechanical analysis of resistance spot welding is presented, and the welding parameters considered include: heat generation at the faying surface and the workpiece-electrode surface, Joule heating at the work piece and the electrode; and the thermal contact conductance between the electrode and workpiece.
Abstract: An axisymmetric finite element model employing coupled thermal–electrical–mechanical analysis of resistance spot welding is presented. The welding parameters considered include: heat generation at the faying surface and the workpiece–electrode surface; Joule heating at the workpiece and the electrode; and the thermal contact conductance between the electrode and the workpiece. The latent heat of phase change due to melting is accounted for. The effect of friction coefficient on the workpiece interface is also studied. The computed results agree well with the experimental data. Heat generation at the faying surface in the initial stages of welding dominates the nugget development, and Joule heating at long times governs the weld nugget growth. A parametric study is carried out for the nugget growth with specific consideration of resistance spot welding of Al alloys. Process control and modelling of resistance spot welding of Al alloys is more difficult than that for steel because of their high elec...
103 citations
TL;DR: In this paper, the synergic effect of a laser beam and a welding arc was investigated for fusion welding, where the main advantage of the use of both heat sources is more efficient use of the energy supplied.
Abstract: This paper deals with a combination of two different welding processes, i.e. the synergic action of two different heat sources for fusion welding. The major part of the paper is focused on the combined action of a welding arc and a laser beam. The main advantage of the use of both heat sources is more efficient use of the energy supplied. With certain parameters, the quantity of molten material increases by 100% compared with the sum of the individual quantities of molten material in the individual processes. The paper further presents several practical applications of the combined welding process. Eventually, development of arc augmented laser welding may progress in two directions; the first being the synergic effect of a laser beam and plasma welding arc and the second the combination of tandem laser welding and consumable electrode welding. This paper presents two such cases schematically.
92 citations
TL;DR: In this article, the effect of scandium and titanium-boron (Tibor) additions on the solidification behavior of castings and welds of aluminium alloy 7108 has been investigated.
Abstract: The effect of scandium and titanium–boron (Tibor) additions on the solidification behaviour of castings and welds of aluminium alloy 7108 has been investigated. A circular patch test was adopted to evaluate the effects of these elements on the hot cracking suscepti bility of welds made on cast coupons treated with different grain refiner additions. It was observed that grain size, as well as cracking susceptibility, decreased with increasing amounts of scandium and that hot cracking was completely eliminated at scandium additions above 0·25 wt-%. A more pronounced grain refining effect in welds was observed with Tibor and, in addition, no hot cracking was observed with Tibor additions as low as 0·02 wt-%Ti (0·004 wt-%B). Castings, however, were more effectively grain refined with scandium, achieving a finer grain size than with Tibor.
78 citations
TL;DR: In this article, gas tungsten arc welding was carried out, during which transverse oscillations of the arc were induced through the use of an alternating external magnetic field, and considerable refinement of the fusion zone grain structure was achieved.
Abstract: In an effort to refine the weld metal grain structure in α–β titanium alloys, gas tungsten arc welding was carried out, during which transverse oscillations of the arc were induced through the use of an alternating external magnetic field. At optimum values of oscillation amplitude and frequency in both the alloys investigated, considerable refinement of the fusion zone grain structure was achieved. This could be attributed to factors that include enhanced fluid flow, reduced temperature gradients, and a continually changing weld pool size and shape owing to the action of the imposed magnetic field. The reduction in the prior β grain size was shown to result in a notable increase in fusion zone tensile ductility. Post-weld annealing increased ductility in all cases, but the magnetically treated material continued to show a higher elongation than that of the untreated material even after post-weld heat treatment.
71 citations
TL;DR: In this paper, the resistance spot welding of steel and aluminium sheets using aluminium clad steel sheets as insert metals was reported and the strength of these joints was of the same order as that of the aluminium joints.
Abstract: The present paper reports the resistance spot welding of steel and aluminium sheets using aluminium clad steel sheets as insert metals. Intermetallic compound layers were formed in the weld zones in direct spot welding of steel sheets to aluminium sheets. Thus, the strength of these joints was lower than that of aluminium to aluminium joints. Intermetallic compound layers were also formed at the steel/aluminium interfaces of the insert metal in welding of steel to aluminium using an insert metal sheet. However, the strength of these joints was of the same order as that of the aluminium joints. The fracture mode of these joints varied with the welding current. The suitable welding current for steel to aluminium joints varied between the values suitable for steel to steel and aluminium to aluminium joints. The fatigue strength of joints using insert metals was somewhat lower than that of the aluminium joints.
67 citations
TL;DR: In this paper, a model of the depth of penetration in gas metal arc welding is presented based on the assumption that the heat and mass transfer to the weld pool and the depth-of-penetration may be correlated by a dimensionless relation.
Abstract: A model is presented of the depth of penetration in gas metal arc welding. This model is based on the assumption that the heat and mass transfer to the weld pool and the depth of penetration may be correlated by a dimensionless relation. This correlation leads to an analytical expression for depth of penetration, which involves empirical constants that are related to the efficiency of heat and mass transfer to the pool. The accuracy of the model is examined by comparing the theoretical depth of penetration and the measured depth of the weld pool for a range of processing variables encompassing short arc and free flight mass transfer. Measurements are obtained from bead on plate welds of stainless steel using a stainless steel electrode and a shielding gas that is rich in argon. The results confirm that the depth of penetration is affected by variations in the rate of mass transfer.
35 citations
TL;DR: In this paper, microfissuring susceptibility of electron beam (EB) welds was evaluated by measuring the microcracks formed in the heat affected zone (HAZ) around EB welds and by examining the hot ductility behaviour of the material.
Abstract: Microfissuring in the heat affected zone (HAZ) around electron beam (EB) welds was studied in two Inconel 718 based superalloys containing the minimum possible concentrations of C, S and P, and 11 and 43 wt-ppm concentrations of B. The microfissuring susceptibility was evaluated by measuring the microcracks formed in the HAZs of EB welds and by examining the hot ductility behaviour of the material. Bead on plate type EB welding, and on cooling hot ductility tests in a Gleeble 1500 thermomechanical simulator were performed on the two alloys with different grain sizes. The results of the hot ductility tests and crack measurements on EB welded samples correlated very well with each other. Using both techniques it was observed that the HAZ microfissuring of Inconel 718 increased with an increase in B concentration and an increase in grain size. The effect of B was attributed to its segregation to the grain boundaries, which resulted in a reduction in the melting point of the grain boundary material. T...
35 citations
TL;DR: In this article, the authors report that low ductility failures as a consequence of creep cavitation at interfacial carbides have been reported in these welds within less than 10 years of operation.
Abstract: The high temperature performance of welds manufactured between ferritic low alloy steels and austenitic stainless steels is critical to power plant operation. The fabrication of these joints via established procedures using nickel based consumables should ensure adequate service life. However, low ductility failures as a consequence of creep cavitation at interfacial carbides have been reported in these welds within less than 10 years of operation. Accurate assessment of damage develop ment in plant welds is therefore required to prevent unplanned outages. Remaining life predictions can be made using post-exposure testing provided material is available. Non-destructive assessments are preferred and the potential exists for establishing techniques based on monitoring cavity density or strain accumulation.
32 citations
TL;DR: In this article, a method is proposed for calculating the variation in fraction liquid with distance in the mushy zone as an aid to determining the effect of alloy additions on solidification cracking susceptibility.
Abstract: A method is proposed for calculating the variation in fraction liquid with distance in the mushy zone as an aid to determining the effect of alloy additions on solidification cracking susceptibility. The model combines the general liquidus equation of a multicomponent system, solute redistribution relations, and temperature gradient information. Calculations are presented for a range of niobium bearing superalloys and the results were found to reveal important relations between alloy composition, variation in fraction liquid with distance in the mushy zone, and cracking susceptibility as measured by the Varestraint test. In particular, the results directly show that the addition of carbon to these alloys is generally beneficial because it reduces the size of the crack susceptible mushy zone and limits the amount of terminal liquid available for the low temperature L → γ + Laves reaction. The modelling results and experimental data are also used to describe the influence of other alloy additions.
TL;DR: In this paper, inclusion formation and microstructure development in autogenous laser and electron beam welds made on a submerged arc weld deposit were investigated, and the measured inclusion characteristics were compared with calcu lations obtained using an inclusion model.
Abstract: Inclusion formation and microstructure development in autogenous laser and electron beam welds made on a submerged arc weld deposit were investigated. Oxygen loss from the submerged arc weld metal deposit to the atmosphere occurred during electron and laser beam welding owing to the low pressure and helium shielding, respectively. Rapid weld cooling rates and changes in oxygen concentration resulted in different inclusion characteristics in these welds. The measured inclusion characteristics were compared with calcu lations obtained using an inclusion model. Acicular ferrite and bainitic microstructures were observed in electron beam welds, and predominantly martensitic microstructures were observed in laser welds.
TL;DR: In this article, a model for oxide inclusion formation in low alloy steel welds is described with a model as a function of weld metal composition and process parameters, coupled with numerical heat transfer and fluid flow models to extend the model to a wide range of welding process conditions.
Abstract: Oxide inclusion formation in low alloy steel welds is described with a model as a function of weld metal composition and process parameters. The model was developed by coupling thermodynamic and kinetic considerations. Thermodynamic calculations considered the effect of the alloying elements and kinetic equations allowed, describing oxide formation during weld cooling. The model showed that weld cooling rate influences the inclusion characteristics and therefore must be taken into consideration. This inclusion model is capable of predicting the composition, size, number density, and oxidation sequence of inclusions and was verified with published data. The inclusion model was coupled with numerical heat transfer and fluid flow models to extend the model to a wide range of welding process conditions.
TL;DR: In this paper, a neural network (NN) arc sensor is proposed that estimates the wire extension and the arc length by using measurements of both voltage and current, and from the output of the NN, the gap and the deviation of the oscillation center of the torch from the groove center are estimated.
Abstract: Full penetration control of the weld pool in the first layer of a single side multilayer weldment is important to obtain a good quality weld For this purpose, a new method, the switchback welding method, is proposed to achieve a stable back bead A welding torch not only weaves along the groove, but also moves back and forth Also, a neural network (NN) arc sensor is proposed that estimates the wire extension and the arc length by using measurements of both voltage and current Moreover, from the output of the NN, the gap and the error (deviation) of the oscillation centre of the torch from the groove centre are estimated Training data are constructed from experimental results, and performance of the NN arc sensor is examined using test data Seam tracking is carried out via the output of the NN arc sensors: a good tracking result is obtained
TL;DR: In this article, the weldability and mechanical properties of weldments made with Inconel filler metals I-52 and I-82 in the welding of 690 Alloy Alloy were investigated.
Abstract: This work investigated the weldability and mechanical properties of weldments made with Inconel filler metals I-52 and I-82 in the welding of Inconel alloy 690. Gas tungsten arc welding was used with different multipass sequences. The microstructures of the fusion and heat affected zones were examined and weldment properties were compared by tensile, hardness, and impact tests. Fracture surfaces were examined by scanning electron microscopy. Experimental results indicate that the subgrain structure near the fusion zone centreline was dominated by equiaxed dendrites in I-82 weldments but by columnar dendrites in I-52 weldments. In addition, the I-82 weldments had a finer subgrain structure near the fusion zone centreline and smaller cellular spacing near the fusion line than I-52 weldments. Mechanical test results demonstrate that the I-82 weldments had higher tensile strength (622–630 MPa) with rupture occurring in the base metal. In comparison, the I-52 weldments had lower tensile strength (568–5...
TL;DR: In this paper, the chemistry of the phases on the surface of inclusions found in steel welds was identified to enable a better understanding of their role in the formation of acicular ferrite.
Abstract: The main goal of the present study was to identify the chemistry of the phases on the surface of inclusions found in steel welds, to enable a better understanding of their role in the formation of acicular ferrite. Transmission electron microscopy and parallel electron energy loss spectrum imaging of specimens prepared by ultramicrotomy have been used to characterise inclusions found in C–Mn welds having different titanium concentrations. The results indicate that, for a weld containing 28 ppm titanium, which is the tough est weld studied, a phase comprising MnTi2O4 is present on the surface of the inclusions. As the concentration of titanium in the weld is increased to 120 ppm, the MnTi2O4 phase is found more towards the centre of the inclusions. It is partially enveloped by a slag of MnO . SiO2 . The presence of TiO, often cited as a phase promoting the formation of acicular ferrite, was found only in the specimen that contained 410 ppm titanium. Thermodynamic calculations using databases for ox...
TL;DR: In this paper, a three-dimensional computer model based on the control volume method has been developed to predict the temperature distribution in the heat affected zone (HAZ) and in the base plate region of the bead on plate welds, using the weld parameters as input data to the computer model.
Abstract: Welding is a highly reliable and efficient metal joining process. Manual metal arc (MMA) welding is very widely used in industry. The temperature distribution that occurs during welding affects the material microstructure, hardness, and the residual stresses present in the material after welding. In the present work, the temperature distribution during bead on plate welding using MMA welding was experimentally determined for AISI type 304 stainless steel plates and low carbon steel plates of thickness 6 and 12 mm. A three-dimensional computer model based on the control volume method has been developed to predict the temperature distribution in the heat affected zone (HAZ) and in the base plate region of the bead on plate welds, using the weld parameters as input data to the computer model. In this computer model, the heat energy used to melt the electrode is considered as a separate heat flux term and the remaining heat supplied by the welding arc is considered as another heat flux term. A good match between the experimental results and the theoretical predictions was obtained. Using the computer model, the time taken to cool from 800 to 500°C in the coarse grained HAZ (close to the fusion line) of low carbon steel specimens was calculated. From this cooling time and the chemical composition of the material, the maximum hardness in the coarse grained HAZ was predicted. Microhardness measurement in the same region of the welded plates was carried out. The experimentally measured values and predicted results match closely.
TL;DR: In this paper, the effect of nitrogen on the fracture toughness of a weld metal was evaluated by the small punch (SP) test, which showed that a small amount of σ in the weld metal led to a marked decrease in the SP energy.
Abstract: Duplex stainless steels were gas tungsten arc welded without filler material in various Ar–N2 mixed gas atmospheres. Weld metals having different nitrogen contents were annealed at 900–1300 K to examine the single effect of nitrogen on the σ transformation. Nitrogen content of the weld metal did not influence the nose temperature and the time for σ initiation in time–temperature–precipitation diagrams for σ, but did decrease the σ content after annealing for long times. These results were correlated with the nitrogen content and microstructure of the weld metals. The effect of σ on the fracture toughness of the weld metal was evaluated by the small punch (SP) test. A small amount of σ in the weld metal led to a marked decrease in the SP energy.
TL;DR: In this paper, an analytical penetration model for electron beam welding is presented, based on a combination of the moving line source solution and the solution for a cylindrical cavity moving through a plate of finite thickness.
Abstract: An analytical penetration model for electron beam welding is presented, based on a combination of the moving line source solution and the solution for a cylindrical cavity moving through a plate of finite thickness The input parameters are the net beam power, welding speed, keyhole wall temperature, and diameter of the electron beam from which the penetration depth can be calculated for a range of base materials, such as stainless steels, titanium grade 2, and aluminium alloy AA 5052 It is concluded that the penetration model is sufficiently comprehensive and relevant to be used as a predictive tool in ordinary production welding and some possible applications are briefly outlined
TL;DR: In this paper, a mathematical model for the behavior and interaction of power source, electrode extension, welding arc, and welding joint geometry is applied to simulation of seam tracking signals from high speed rotating electrodes in gas metal arc welding of carbon steel.
Abstract: A mathematical model for the behaviour and interaction of power source, electrode extension, welding arc, and welding joint geometry is applied to simulation of seam tracking signals from high speed rotating electrodes in gas metal arc welding of carbon steel. Sensor signals from a tilted electrode approaching internal and external fillet corners are analysed, as well as the frequency dependence of signal amplitude from a perpendicular electrode. The simulations are compared with experimental results from other references showing good agreement. The current signals are stronger than predicted from static arc characteristics, suggesting important dynamic effects in the behaviour of the electrode extension.
TL;DR: In this article, a mathematical model has been constructed to predict the electrode face diameter at various stages of electrode life using carbon imprint tests at 200 weld intervals throughout the life tests, and excellent agreement between the experimental results and the model predictions has been achieved.
Abstract: A mathematical model has been constructed to predict the electrode face diameter at various stages of electrode life. The model relates the electrode face evolution process to electrode design and welding parameters such as welding current, electrode force, etc. It requires a minimum amount of experimental data to determine the numerical constant in the model, which characterises electrode wear rate. To validate the model, constant welding current electrode life test data were used. These data were derived from earlier electrode life tests on six different galvannealed steels. The electrode face diameter was continuously recorded by carbon imprint tests at 200 weld intervals throughout the life tests. Excellent agreement between the experimental results and the model predictions has been achieved. Potential applications of the model in selecting electrode design and optimising welding schedules are also discussed.
TL;DR: In this article, the microstructural condition of 17-4-PH stainless steel was investigated in terms of room temperature tensile properties and the combined effects of prior micro-structural conditions, heat input during welding, and post-weld heat treatment procedures.
Abstract: Post-weld heat treatment (PWHT) procedures and heat input during welding of 17–4PH stainless steel, using matching chemistry consumables, have been optimised in relation to its microstructural condition before welding based on room temperature tensile properties. The 17–4PH stainless steel was welded in two different prior microstructural conditions, namely, condition A (solution treated) and condition H1150 (overaged), using three different heat inputs of 0·27, 0·48, and 0·72 kJ mm-1, and post-weld heat treated to condition H900 (aged) or condition H1150 (over aged), using different heat treatment procedures. Room temperature tensile tests were carried out to study the combined effects of prior microstructural condition, heat input during welding, and PWHT procedures.
TL;DR: In this paper, the influence of different additives on the physical behavior of the welding arc was investigated and it was found that the addition of SiO2 resulted in a voltage increase in the range 1-3 V, depending on arc length, welding current, and travel speed.
Abstract: This paper concerns a novel approach to through the arc position sensing, which is based on the influence that certain additives have on the physical behaviour of the welding arc. The changes in the physical behaviour are reflected by changes in arc parameters, in particular arc voltage, which can be monitored during the welding process. In the first part of the paper the results of bead on plate experiments aimed at determining the influence of different additives on arc voltage are presented. Of the different additives considered, SiO2 is found to have the most pronounced effect. It appears that addition of SiO2 results in a voltage increase in the range 1–3 V, depending on arc length, welding current, and travel speed. The observed effect is ascribed to arc contraction and arc trailing. The influence of SiO2 on the weld bead geometry and the mechanical properties of the weld was also determined. It appears that the addition of SiO2 results in enhanced weld penetration, presumably as a result of...
TL;DR: In this article, an electrical circuit was developed to model the behavior of gas metal arc welding, incorporating results from a free burning arc model to describe the arc and a second order differential equation to describe one-dimensional energy conservation in the welding anode.
Abstract: An electrical circuit was developed to model the behaviour of gas metal arc welding. The model incorporates results from a one-dimensional free burning arc model to describe the arc and a second order differential equation to describe one-dimensional energy conservation in the welding anode. Commercial circuit analy sis software was used to solve the circuit model. Predictions have been compared with experimental data for short circuit transfer mode as well as spray. Predictions agree well with experimental results. The model provides a fast and useful technique to simulate the gas metal arc welding process. In short circuit transfer mode, the model predicts that chaotic phenomena are occurring.
TL;DR: In this article, the effects of adding different quantities of Nb (0·1, 1·03, 2·49, and 3·35 wt-%) to the flux of electrodes used in welding Inconel alloy 690 on the microstructure, mechanical properties, and corrosion behaviour of the resulting weldments were investigated.
Abstract: The present work investigates the effects of adding different quantities of Nb (0·1, 1·03, 2·49, and 3·35 wt-%) to the flux of electrodes used in welding Inconel alloy 690 on the microstructure, mechanical properties, and corrosion behaviour of the resulting weldments. Inconel filler metal I–52 coated with flux was used as the welding electrode. Weldments were butt welded using a manual shielded metal arc welding process. The experimental results indicated that the subgrain structure of the fusion zone was primarily dendritic. Niobium was depleted at the dendritic cores and enriched in the interdendritic regions. A small heat affected zone with typical coarse grains, which subsequently formed ghost grain boundaries, was present. With increasing Nb, the welds tended to show a finer subgrain structure and smaller dendritic spacing. Niobium rich segregants in the form of small particles formed in interdendritic spaces, providing the sites for microvoid formation by rupture. Correspondingly, the tensi...
TL;DR: In this article, the effect of thermal cycles on the ferrite content in austenitic stainless steel weld metal was investigated, and the results indicated that the peak temperature, cooling rate, and number of thermal cycle cycles have a significant effect on the amount of retained ferrite.
Abstract: The properties of austenitic stainless steel weld metals are strongly influenced by the duplex structure of austenite and ferrite. The objective of the present study was to investigate the effect of thermal cycles on the ferrite content in austenitic stainless steel weld metal, and to explore the ferrite–austenite solid state transformation of austenitic stainless steel weld metal. The results indicate that the peak temperature, cooling rate, and number of thermal cycles have a significant effect on ferrite content in the austenitic stainless steel weld. As the cooling rate increases, or the number of thermal cycles decreases, the amount of retained ferrite is increased at room temperature. New δ ferrite phase can be formed if the reheating peak temperature is above the optimum γ solvus temperature of austenitic stainless steel, and this new δ ferrite can be retained under rapid cooling conditions.
TL;DR: In this paper, a model of the melting process was established based on the physical properties of the wire and the energy flow in the MIG process, which was used to study the influence of the different types of energy transfer to the wire.
Abstract: Current and wire feedrate are coupled in a complicated manner in the metal inert gas (MIG) welding process. To investigate this interaction, a model of the melting process was established. The model is based on the physical properties of the wire and the energy flow in the MIG process. This model was used to study the influence of the different types of energy transfer to the wire. The contact resistance, stickout length, current, and anodic heat all influence the melting rate of the wire. This knowledge could be used to control the MIG process. In the present case, measurements of the current and wire feedrate can be taken to obtain information on the physical status of the process. Control of the process is possible with this information.
TL;DR: In this paper, it was shown that, from the viewpoint of wetting, h-BN and aluminium are an ideal combination for joining and, even more so, for the manufacture of a metal matrix composite.
Abstract: To assist in selection of suitable wetting materials and control of wetting in various situations, previous results for ceramic–aluminium systems have been readdressed. Wetting systems can be categorised into three types (A, B, and C), characterised by original wettability and equilibrium wettability. In pure systems at 1373 K, AlN–Al and Si3 N4–Al are categorised as system A, a non-wetting system, and Al2O3–Al as system C, a wetting system. However, h-BN–Al, graphite–Al, MgO–Al, and SiC–Al belong to system B, changing from a non-wetting to a wetting system through interfacial reactions. From the present results, it was found that the contact angle for h-BN is far lower than the contact angles for typical ceramics. In fact, the contact angle decreased to 0° in phase IV (equilibrium phase) at and above 1273 K. This indicates that, from the viewpoint of wetting, h-BN and aluminium are an ideal combination for joining and, even more so, for the manufacture of a metal matrix composite. To demon strat...
TL;DR: In this paper, the authors compared the fatigue crack growth behavior of two weld metals deposited by shielded metal arc welding and flux cored arc welding (FCAW) processes in a vertical pulsator with a frequency of 30 Hz under constant amplitude loading (stress ratio R = 0).
Abstract: The fatigue crack growth behaviours of two weld metals deposited by shielded metal arc welding (SMAW) and flux cored arc welding (FCAW) processes have been compared. Load carrying cruciform joints, with a lack of penetration (LOP) defect, were fabricated from high strength, quenched and tempered steel of ASTM 517 ‘F’ grade. Fatigue crack growth experiments were carried out in a vertical pulsator (Schenck 200 kN capacity) with a frequency of 30 Hz under constant amplitude loading (stress ratio R = 0). It was found that the fatigue crack growth resistance of the weld metal deposited by the SMAW process is superior, compared to the weld metal deposited by the FCAW process. The high heat input involved in the FCAW process probably contributes to the changes in weld metal properties, which result in a change in fatigue crack growth behaviour.
TL;DR: In this article, a practical method to predict the heat affected zone (HAZ) hardness distribution was studied by considering the effects of prior austenite grain size and tempering on hardenability.
Abstract: A practical method to predict the heat affected zone (HAZ) hardness distribution was studied by considering the effects of prior austenite grain size and tempering on hardenability. For conventionally rolled and thermomechanically processed steels (400–490 MPa grade steels), the hardness distribution between the fusion and Ac3 lines can be fairly well predicted by introducing the effect of grain size into the maximum HAZ hardness prediction method of Yurioka et al. For a quenched and tempered steel with boron addition (780 MPa grade steel), as the maximum hardness is obtained a small distance away from the fusion line, the present method cannot adequately predict its HAZ hardness. Hardness at the Ac1 line for thermomechanically processed and quenched and tempered steels can be predicted with the present method, in which the parameter introduced by Inoue has been used to estimate the effect of tempering.