Groove Weld Research Articles

Effect of Welding Groove and Electrode Variation to the Tensile Strength and Macrostructure on 304 Stainless Steel and AISI 1045 Dissimilar Welding Joint Using SMAW Process

AISI 1045 and 304 stainless steel are widely used in automotive and industrial fields However, both of these steels have their own advantages and disadvantages. AISI 1045 is not resistant to corrosion but has good wear resistance and low price. Meanwhile, the 304 stainless steel provides good corrosion resistance and mechanical properties but is costly. Their combination is able to provide a good property and reduce the costs. Thus, in order to combine these two metals, shield metal arc welding is carried out using welding groove and electrode variation. The groove variations used were double bevel, V, and double V-groove, additionally, the electrode variations used were E6013 and E7016. Then, the welding results were characterized using the tensile strength and macrostructure analysis. The results revealed that the specimen using E7016 electrode for the double V-groove resulted in the highest tensile test results the value of 270.48 MPa yield strength, 411.49 MPa tensile strength, and 19.81% elongation. The macrostructure analysis showed that the specimens using E7016 electrode gave a narrow HAZ that led to higher mechanical properties.

A study on shrinkage residual stresses, microstructure and mechanical properties of ASS thick pipe welded by GMAW process

In this investigation, AISI 304LN austenitic stainless steel pipes having 25 mm thickness and 300 mm inner diameter with conventional and narrow groove were welded by continuous current gas metal arc welding (GMAW) and pulse current gas metal arc welding (P-GMAW) process. A gas tungsten arc welding (GTAW) process was used for the welding of the root pass. Microstructural study was carried out in fusion zone (FZ) and heat-affected zone (HAZ). A favourable microstructure characteristic was observed in the P-GMAW process. The study of transverse shrinkage and shrinkage stresses were done on the conventional groove with GMAW and P-GMAW process and narrow groove by P-GMAW process. It was found that narrow groove weld design with controlled welding parameters can reduce 45% shrinkage as compare to conventional groove, similarly 30% reduction in shrinkage stress can be achieved. The tensile properties were observed to increased, such as yield strength was improved from 260 MPa to 310 MPa and ultimate strength was improved from 510 MPa to 550 MPa in the case of narrow groove weld by the P-GMAW process.

Effects of Shear Tabs and High-Strength Bolts in Seismic Performance of Steel Moment Connections

A shear tab and high-strength bolts are often used to connect a steel H-beam to a column. The design demand and capacity of these elements vary from one standard to the other. To investigate the effect, this study applied a finite element method (FEM) to develop models for two steel moment connections and validated the effectiveness by test data. The connections were characteristic of bolted-web-and-welded-flange details. The FEM models were then used to study the design of shear tabs and high-strength bolts in accordance with the U.S. and Japan standards and compared to the Taiwan practice. The result showed a small difference in the peak loads of the connections. However, the U.S. direct welded flange connection had flange buckling and strength degradation at a relatively smaller drift. The connection had a thinner shear tab and fewer high-strength bolts. The other two connections had very similar design results and loading responses. The increase in shear-tab thickness reduced the stress concentration and fracture potential of the connections. It is, therefore, recommended to design a shear tab with moment capacity greater than the beam web. This will reduce the stress concentration of the base metal surrounding the beam-flange groove welds, increasing the connection ductility.

Detection of weld groove edge based on multilayer convolution neural network

To detect the weld groove edge interfered by noise, a lightweight multilayer convolution neural network is designed. The network can extract multi-layer features, which improve the resolution of weld groove edge position detection and have strong anti-interference ability. The position of weld groove edge is recognized and located by generating prior box region. The global detection and location of weld groove edge is transformed into confidence prediction and location coordinate value regression in local prior box region, which ensures the accuracy and robustness. The training data set covers different interference noise and groove deformation to improve the generalization ability of the network under different interference conditions. The experiments show that the designed network has good detection accuracy under the condition of strong interference, with an average error of 0.238 mm and a maximum error of 0.702 mm. The processing time is 0.09 s, which shows a good application prospect in field welding.

Study on Proper Welding Condition for Ultranarrow Gap Submerged Arc Welding

ABSTRACT Submerged arc welding (SAW) is widely used for butt welding of thick plates in large steel structures because of its high deposition rate and high weld quality. With a thickness of 150 mm or more, multilayer welding is required, and it takes a lot of time to finish build-up. Narrow gap welding with 1° to 3° of groove angle is an effective process to reduce the welding time. Recently, ultra-narrow gap welding with approximately 0° of groove angle has been studied. However, ultra-narrow gap SAW is hardly applied because of its risk of welding defects such as lack of fusion and undercut. In this study, the influence of distance L between the welding torch and groove wall on the welding defect with ultra-narrow gap SAW was clarified. Undercut is caused by the arc gouging effect and excessive melt of the groove wall. The relationship between lack of fusion and the weld shape was elucidated. The model for judging the lack of fusion defined by the heat input to groove H G and the distance squared between the heat source and the corner of the groove bottom r 2 was established, which were calculated by the heat input Q, bead width W B and cross sectional area of the deposited metal A R. With the model, appropriate range of L for each welding condition was determined.

Residual stress distribution in thick double-V butt welds with varying groove configuration, restraints and mechanical tensioning

This paper aims to investigate the effect of different weld groove configurations on the residual stresses dispersed in 40 mm thick multipass high strength low alloy (HSLA) steel butt-welds. Two welded joints having double-V type groove geometry were prepared, one of which had an equal double-V groove, and the other had an unequal double-V groove appearance. The locked-in residual stresses present in the weld zone and heat-affected zone (HAZ) were evaluated using both computational and experimental approaches. Furthermore, the effect of restrained condition on the trend of residual stresses of the equal double-V groove weld was analyzed using computational modeling technique with varying weld pass sequence. Lastly, a feasibility study was conducted on the implementation of mechanical tensioning technique to mitigate the weld-induced residual stresses in thick multipass butt-welded joints. The findings show that using an unequal-V groove joint can effectively reduce residual stress levels in the bottom half of the weld. A restrained welding condition with a single directional weld pass sequence can adversely impact the intensity of residual stresses across the weldment. The transverse residual stress levels can be reduced in the weld zone and its vicinity by an amount equal to the corresponding applied mechanical lateral tensioning load.

Laser Scanning and Parametrization of Weld Grooves with Reflective Surfaces.

This paper presents a novel weld groove parametrization algorithm, which is developed specifically for weld grooves in typical stub and butt joints between large tubular elements. The procedure is based on random sample consensus (RANSAC) with additionally proposed correction steps, including a corner correction step for grooves with narrow root weld, and an iterative error elimination step for improving the initially obtained data fit. The problem of curved groove sides (due to the pipe geometry) is attributed and solved. In addition, the procedure detects and eliminates several types of data noise due to laser line reflections. The performance of the procedure is studied experimentally using small-scale test objects, which have been ground using typical industrial power tools to achieve a realistic level of reflections. The execution times and data fit errors of the proposed procedure are compared to a procedure based on a more conventional RANSAC approach for line segment detection.

Characterization of inhomogeneous microstructure and mechanical property in an ultra-thick duplex stainless steel welding joint

Ultra-thick duplex stainless steel welding plates are widely used in various industries. However, one of the significant concerns is the inhomogeneous microstructure and mechanical properties along the thickness, which reduces welding efficiency and degrade service performance. In this study, a 55 mm thick duplex stainless steel welding joint with an X-type weld groove was prepared to study the variation of microstructure and mechanical properties along the through-thickness direction by both the miniature tensile specimen and cross-weld tensile specimen. The correlation between the microstructure and mechanical property was also studied. The results showed that the weld metal was characterized by abundant columnar grains with decreasing austenite content from surface to mid-thickness. Besides, the total fraction of low angle grain boundaries increased more than one-fold, while the total fraction of high angle grain boundaries decreased from 48.03% to 4.52% with increasing depth to the mid-thickness. Furthermore, substantial substructured grains and recrystallized grains were dominated in the weld metal and base metal. Along the thickness direction, the mechanical strength almost decreased and the elongation of welding joint increased with the increasing distance from the surface. Microhardness had a similar trend to that of strength, which all can be attributed to the variation of austenite content and grain boundary character distribution. Along the transverse direction, weld metal had the highest strength of 597.67 MPa, followed by the heat-affected zone of 549.42 MPa and base metal of 510.20 MPa, while the trend of elongation was opposite to that of strength. The microhardness distribution was not consistent with that of strength and had a maximum at the heat-affected zone.

Research on the effect of weld groove on the quality and stability of laser-MAG hybrid welding in horizontal position

Research on the effect of weld groove on the quality and stability of laser-MAG hybrid welding in horizontal position

Recent Advances in the Prediction of Weld Residual Stress and Distortion - Part 2

Weld residual stress can contribute to the reduction of structure lifetime and accelerate the formation of fatigue cracks, brittle fractures, or stress corrosion cracking. Distortion can have a significant impact on the dimensional ac-curacy of assembly, structure strength, and fabrication cost. In the past two decades, there have been many significant and exciting developments in the prediction and mitigation of weld residual stress and distortion. This paper reviews the recent advances in mitigation techniques that have been applied in the structure design, manufacturing, and postweld stages. The techniques used in the structure design stage include selecting the type of weld joint and weld groove, using balanced welding, determining appropriate plate thickness and stiffener spacing, and considering distortion compensation. Mitigation techniques used in the manufacturing stage include welding sequence optimization, reducing welding heating input, selecting low-transformation-temperature filler metals, prebending, precambering, constraints, trailing and stationary cooling, in-processing rolling, transient thermal tensioning, and additional heat sources. Postweld mitigation techniques include postweld heating and mechanical treatment. Finally, the remaining challenges and new development needs were discussed to guide future development in the field of mitigating weld residual stress and distortion.

Seismic behavior of double-HSS links for eccentrically braced frames

This study experimentally and analytically investigates an innovative double-HSS link (DHL) used as the active link in eccentrically braced frames (EBFs). Hollow structural sections (HSS) are mechanically efficient and are used in resisting compression, torsion, and bending. Their high torsional rigidity generally eliminates lateral-torsional buckling (LTB). As a result, the plastic rotational capacity and strength degradation rate are mainly governed by flange local buckling (FLB) and web local buckling (WLB). The proposed configuration consists of a double-HSS connected to braces or columns through a center gusset plate secured by flare-bevel groove welds. The advantages of the proposed configurations are: (1) They effectively reduce the width-thickness ratios (b/t) of the flanges by using two HSSs with much shorter flanges, which considerably increases the compactness thereby enabling a large rotational capacity. (2) They provide simple and practical connection details between the link and braces or columns. (3) Typically, double-HSS sections have an e/(Mp/Vp) ratio much larger than that of wide-flange sections due to the fact that double-HSS sections have four webs which significantly increase the shear capacity. Consequently, a DHL can yield in flexure even with a length similar to that of a wide-flange shear yielding link. This in turn eliminates the need for web stiffeners. (4) The welding requirement for DHLs is less than that of the conventional shear links since no stiffeners are required. (5) The overstrength factor due to strain hardening produced by flexural yielding links is generally less than that produced by shear yielding links leading to more economical designs for the elastic portion of the frame, and (6) the iteration design process is minimized by balancing the link length and rotational demand because of a single flexural yielding mode. Furthermore, experimental and analytical results indicated that the novel DHLs can sustain larger plastic rotations and meet AISC 341′s acceptance criterion for shear yielding links. In addition, DHLs can be potentially used in D-braced EBFs with links attached to columns because the link-to-column connection of DHL remains essentially elastic. DHLs can also be used as a replaceable link which is attached to the beam and column through bolted end plates.

Globular-to-Spray Transition in Cold Wire Gas Metal Arc Welding

The electrical current required for a transition from globular to spray droplet transfer during gas metal arc welding (GMAW) is determined by the specified wire feed speed in the case of constant-voltage power supplies. Generally, in narrow groove welding, spray transfer is avoided, be-cause this transfer mode can severely erode the groove sidewalls. This work compared the globular-to-spray transition mechanism in cold wire gas metal arc welding (CW-GMAW) vs. standard GMAW. Synchronized high-speed imaging with current and voltage samplings were used to characterize the arc dynamics for different cold wire mass feed rates. Subsequently, the droplet frequency and diameter were estimated, and the parameters for a globular-to-spray transition were assessed. The results suggest that the transition to spray occurs in CW-GMAW at a lower current than in the standard GMAW process. The reason for this difference appears to be linked to an enhanced magnetic pinch force, which is mainly responsible for metal transfer in higher welding current conditions.

Effects of groove configuration and buttering layer on the through-thickness residual stress distribution in dissimilar welds

Dissimilar metal welds (DMW) of ferritic to austenitic stainless steel are broadly used in steam generators working in power generation industries. Frequent failure of DMWs from the heat-affected zone (HAZ) of the ferritic part necessitates structural integrity assessment of the DMWs in order to determine and extend the lifetime of these components. In this regard, typical DMWs of SA516–309L–304L and SA516–309L/308L–304L attributed to domestic reactors were fabricated under different welding conditions. The effects of conventional and narrow weld groove configurations, buttering layer, and varying buttering layer width on the through-thickness residual stress fields in the DMWs were investigated experimentally and with the help of numerical simulations. Results show that the narrow groove weld is beneficial in reducing the residual stresses in the weld zone. Incorporating an additional buttering layer in the narrow groove joint further reduced the residual stresses across the weld joint. A 6 mm thick buttering layer was found to be competent enough to minimize the residual stresses dispersed across the weld cross-section.

Numerical investigation of heat flux distribution on the welding groove face in magnetic oscillation arc narrow gap GTAW

Obtaining uniform penetration on welding groove faces is one urgent problem in oscillation arc narrow gap welding; however, the heat flux distribution on the groove face under the deflected welding arc is difficult to investigate by the experimental method. In this article, a unified three-dimensional model is developed to study the heat flux distribution on groove faces. The model includes the electrode, welding arc, workpiece, and their coupling. The plasma arc profile, heat flux characteristics, and weld pool formation were simulated. Based on the simulation results, the following conclusions were contained. The deflecting degree of the welding arc axis is increased with the increasing of extra magnetic-field intensity, and this leads to the change of the distribution of conduction heat flux and electric heat flux. At the groove bottom, both heat fluxes move to one side, and their distribution shape changes from circular to elliptical. At the sidewall, the distribution shape of conduction heat flux is triangular, and that of electrical heat flux is elliptical. The maximum value of heat flux density decreased, and the affected area was increased with the associate of the extra magnetic field. The simulation welding bead was in agreement with the experimental result.

Evaluation of through-thickness residual stresses and microstructure in SA516 Gr. 70 steel welds

The critical working condition of nuclear power plant equipment necessitates meticulous determination of the welding process and parameters. In this work, some major influential factors of welding were investigated to observe their effects on the through-thickness residual stress distribution in multipass pressure vessel steel welds. In this regard, experiments were conducted to find the characteristics of residual stresses dispersed in SA516 Grade 70 steel welds of different groove geometries with distinct welding conditions. Three-dimensional finite element models of the weldments were developed considering a moving heat source with temperature-dependent material properties to simulate the welding thermal cycles and corresponding residual stress fields. Effects of weld groove geometry, number of weld passes, external constraints, and preheating on the through-thickness residual stress fields were studied. Additional attention was given to the evaluation of the heterogeneous microstructure and microhardness across the weld cross-section associated with their weld thermal history. Finally, the evolution of the through-thickness residual stresses attributed to subsequent weld passes was elaborated.

The effect of ship replating welding process on floating conditions against strength value

Ship replating is one of the important things in the process of ship maintenance. Ship replating can be done during docking and floating. The cooling rate of the welding process gave different effects on the mechanical properties of the material when the welding process is in a floating position and docking position. This research uses four variations in the distance between the weld groove lines and the water lines which were 30 mm, 60 mm, 100 mm, and 130 mm. This research also uses four variations in water temperature were 25°C, 28°C, 30°C and 32°C. The strength value of the variations will be compared to the strength value of dock welding. The results of tensile testing showed that there was a decrease in strength value at each increment of the water line spacing with weld groove lines and water temperature variations. Based on this research, welding in a floating condition with a minimum distance waterline and weld groove line of 30 mm, and the temperature of water between 25°C - 32°C can be applied in the field, because the strength value for all variations on this research satisfies by BKI (Biro Klasifikasi Indonesia) standards.

Mechanical properties and microstructure of multi-pass butt weld of plates made of Al-Mg-Zr alloy sparingly doped with scandium

Aluminum alloys doped with scandium represent a new generation of high-performance alloys that have numerous advantages compared to high-strength aluminum alloys. However, the cost of such alloys is quite high. Thus, scientists have been searching for new alloys sparingly doped with Sc that are suitable for industrial use. The current research aims to study the mechanical properties and microstructure of a multi-pass butt-welded joint of plates made of 1580 alloy of the Al-Mg-Zr system sparingly doped with Sc 0.1 wt%, depending on the shape of a weld groove and the chemical composition of the filler wire. Welding of plates with a thickness of 34.5 mm with X-groove and K-groove was performed by the TIG method in manual mode with filler wires from aluminum alloys. Good weldability and hot crack resistance of 1580 alloy providing ultimate strength of welded joints at the level of 0.84–0.93 of the ultimate strength of the base metal were established. The peculiarity of the thermal cycles of multi-pass welding affects the structure formation. The formed coarse-crystalline structure of the weld from 1580 filler wire leads to reduced mechanical properties of the welded joints, compared to the welded joints obtained with the use of 1561 filler wire. The analysis of the macro- and microstructure of the welded joints is given. The results of SEM and EDS studies of welds are presented.

Simulated stress induced sensitization of HAZ in multipass weld of 304LN austenitic stainless steel

Stress induced sensitization on heat affected zone (HAZ) of 304 LN austenitic stainless steel was studied using the thermo mechanical simulator (Gleeble 3800). The study was carried out using the weld thermal cycle and residual stresses, observed during pulse gas metal arc welding (P-GMAW) of 28 mm conventional groove weld. Layer wise study of weld seam deposition was done to understand the characteristic of stresses and thermal behavior on HAZ created by its adjacent weld seam during welding. The degree of sensitization, as a function of stress-type (tensile or compressive) and its magnitude under the thermal behavior of multi-pass heating and reheating in HAZ, has been studied through observations on changes in microstructure, electrochemical properties and variation in hardness of the matrix. It was observed that irrespective of its tensile or compressive nature, the increase in magnitude of residual stresses appreciably enhances the sensitization of the matrix by formation of Cr 23 C 6 precipitate as confirmed by high-resolution transmission electron microscopy (HRTEM) analysis. Also the study includes widening of HAZ grain boundary as well as increase of degree of sensitization (electrochemical studies) and hardness.

Mechanical properties and microstructural characteristics of rotating arc-gas metal arc welded carbon steel joints

Abstract The main problem associated with high thickness carbon steel plate's narrow range or “V” groove welding in conventional welding processes is the sagging of the molten pool due to gravity, which in turn leads to defects formation and deteriorates mechanical properties. This problem could be overcome by the rotating arc gas metal arc welding (RA-GMAW) technique. This investigation aims to evaluate mechanical properties and metallurgical characteristics of high thickness IS2062 Gr-B carbon steel joints welded by RA-GMAW technique. The experimental results show that RA-GMAW joint exhibited higher (598 MPa) tensile strength, higher hardness (220 HV) at weld metal region, and lower impact toughness (137 J) than the unwelded base metal. This is due to the presence of fine acicular ferrite and widmanstatten ferrite matrix mixed with fine lamellar pearlite microstructure in the weld metal region.

A Study on Bending Strength of Solid Steel Column Joints by Partial Penetration Groove Weld

A Study on Bending Strength of Solid Steel Column Joints by Partial Penetration Groove Weld