Transverse Weld Research Articles

A mechanism analysis of transverse weld cracks of marine thick steel plate

A mechanism analysis of transverse weld cracks of marine thick steel plate

Effective Weld Properties for Hollow Structural Section T-Connections under Branch In-Plane Bending

The 2010 AISC Specification for Structural Steel Buildings has expanded the scope in Chapter K, "Design of HSS and Box Member Connections,"� to include a Section K4, "Welds of Plates and Branches to Rectangular HSS."� An experimental program was undertaken to test various unreinforced HSS-to-HSS 90° T-connections subject to branch in-plane bending moment with the objective of determining the effectiveness of the welded joint. Twelve unique test specimens were designed to be weld-critical, and the results from the full-scale tests revealed that the current equation for the effective elastic section modulus for in-plane bending, Sip, given in Table K4.1 of AISC 360-10, is very conservative. A modification to the current requirement that limits the effective width of the transverse weld elements is proposed, resulting in a safe but more economical weld design method for HSS-to-HSS T-connections subject to branch bending moment. By reanalyzing the data of prior weld-critical tests on HSS-to-HSS T- and X- (cross-) connections subject to branch axial loading, it is shown that the proposed new weld effective length recommendation is applicable to these connections as well. It is also concluded that the fillet weld directional strength enhancement factor, (1.00 + 0.50sin1.5θ), should not be used for strength calculations of welded joints to square and rectangular HSS, with the proposed revision, when the effective length method is used.

A unified method for the design of steel beam‐columns

AbstractIn Eurocode 3, Part 1‐1 [1] two methods are given for the design of beam‐columns. They have been criticized for their complexity. Furthermore, internal plastic redistribution of stresses of class 3 cross‐sections is not utilized in the code. These shortcomings were resolved in proposal for amended rules in [5], however, the procedures for beam‐columns are still complicated and difficult to understand.An approximate method for the design of beam‐columns was proposed 1968 in [6] which was addressed in the Commentary to the Swedish regulations for steel structures [10] and used in Sweden since then [11]. It was accepted also in Eurocode 9 for aluminium [4], where it is especially convenient to allow for softening of the material at local transverse welds, see [9]. The method is here proposed to be included also in Eurocode 3.In this paper the resistance of class 3 cross‐sections is discussed and the unified method for beam‐columns is presented. Four worked examples are presented, three of them on rather complicated structures, to show the capability to treat such structures as well.

Effect of Punch Profile Radius on Springback in V-Bending of Tailor Welded Blanks Welded in Transverse Direction

Tailor welded blank (TWB) is an advancement in the field of sheet metal forming in which multiple blanks are welded together to create a single blank prior to forming process. Springback behaviour of TWBs in bending is complex due to thickness or material combination. In this research, the effect of punch profile radius on the springback of transversely welded strips has been investigated in V-bending operation with included bend angle of 90° and using punches with three different punch profile radii of 7.5, 10and 12.5 mm. TWBs were prepared by laser welding of interstitial-free steel blanks with a thickness combination of 0.6 and 1.2mm. The Tensile properties of parent materials and tailored blanks were evaluated by Tension test as per ASTM-E8M standard. The bend samples with transverse weld line were prepared to a size of 20X150mm to ensure plane strain bending. Finite element (FE) simulations were performed using Abaqus and were found to be in good agreement with the experimental results.

HARDNESS AND TENSILE BEHAVIOR OF FRICTION STIR WELDED ALUMINUM AA6351 ALLOY

Friction Stir Welding (FSW) is a solid state welding process gaining more applications in various industries due to better quality of the joint as it has no effect on parent metal. In FSW process a non consumable rotating welding tool is used to generate frictional heat between tool and abutting surface of work piece and plastic dissipation of energy to accomplish the weld. Being a solid state joining process, friction stir welding process offers various advantages like low distortion, absence of melt related defects, high joint strength etc. as compared to other conventional fusion welding techniques.Experiments were conducted on 6 mm thickness Aluminum AA6351-T4, commercially available plates. The seplates are joined by FSW along the rolling direction (longitudinal weld orientation) and across the rolling direction (transverse weld orientation). The hardness and tensile strength results of the weldments are presented. Results show superior mechanical properties for the joints with plates along the rolling direction as compared with the joints obtained by across the rolling direction.DOI: http://dx.doi.org/10.3329/jme.v44i1.19494

Cyclic performance of flange-plate connection to box column with finger shaped plate

The objective of using the flange plate connection as one of the most popular indirect connections to the built-up box column is to avoid using long plates. In deep beams, the need to provide sufficient length to fillet welds necessitates using of long flange plates, which may cause brittle failure due to increasing the bending moments at the face of the column. In the present study, configuring the top flange plate with a finger slot shape type is proposed in order to diminish length of the flange plates. In the proposed configuration, the longitudinal fillet weld was used in flange plates in addition to the transverse fillet and slot weld in the top and bottom flange plates, respectively; in order to provide the required strength for welds. Two full-scale specimens fabricated based on the proposed design methodology were subjected to the cyclic loading. The study results indicated that the flange plate connection with a suggested modified configuration could be prequalified for use in the special moment frames. In a parametric analytical study, the best arrangement of the longitudinal as well as the transverse fillet weld in a top flange plate was proposed for flange plate connections.

Modeling the Formation of Transverse Weld during Billet-on-Billet Extrusion.

A comprehensive mathematical model of the hot extrusion process for aluminum alloys has been developed and validated. The plasticity module was developed using a commercial finite element package, DEFORM-2D, a transient Lagrangian model which couples the thermal and deformation phenomena. Validation of the model against industrial data indicated that it gave excellent predictions of the pressure during extrusion. The finite element predictions of the velocity fields were post-processed to calculate the thickness of the surface cladding as one billet is fed in after another through the die (i.e., the transverse weld). The mathematical model was then used to assess the effect a change in feeder dimensions would have on the shape, thickness and extent of the transverse weld during extrusion. Experimental measurements for different combinations of billet materials show that the model is able to accurately predict the transverse weld shape as well as the clad surface layer to thicknesses of 50 μm. The transverse weld is significantly affected by the feeder geometry shape, but the effects of ram speed, billet material and temperature on the transverse weld dimensions are negligible.

Weldability of HAYNES 282 superalloy after long-term thermal exposure

HAYNES ® 282 ® alloy is a wrought gamma-prime (γ') strengthened Ni-base superalloy that was developed for high-temperature structural applications, especially those in aero- and land-based gas turbine engines. The 282 alloy exhibits excellent creep strength and thermal stability in the 649 to 927 ∘C temperature range, and was specifically designed for improved fabricability relative to other Ni-base superalloys. When welded in the annealed condition, 282 alloy exhibits excellent weldability for a γ'-strengthened alloy. To provide an estimate of its weldability and weld repairability after service exposure, welding experiments were conducted on 282 alloy after long-term thermal exposure (LTTE). Welds were successfully completed on the LTTE material and transverse weld tensile properties were determined. To evaluate susceptibility to heat-affected zone (HAZ) liquation cracking during welding, Gleeble ® hot-ductility tests were performed on the LTTE material. The experimental results were complemented by microstructure characterization and thermodynamic calculations. The capability of weld repair and rejuvenation of 282 alloy components in the LTTE condition was demonstrated.

Effect of transverse speed of the tool on microstructure and mechanical properties in dissimilar butt friction stir welding of al5083–copper sheets

Article history: Received September 20, 2013 Received in Revised form October, 14, 2013 Accepted 27 February 2014 Available online 12 March 2014 In this paper, butt joining of Al5083 to commercially pure copper is investigated by friction stir welding method. The effects of transverse welding speed of the tool on the mechanical properties and microstructure of the joint were studied, experimentally. By examining different circumstances, changes in the joint strength were studied and optimized in term of transverse speed. Based on the obtained results, welding speed can improve or reduce the joint strength and an optimum value can be found for the welding speed. Welded Joint that was conducted at the rotation speed of 800 RPM and tool traverse speed of 60 mm min had the highest tensile strength (i.e. about 98% of the weak base metal). Intermetallic compounds were formed in the stir zone and XRD results indicated that Al4Cu9 and Al2Cu were the intermetallic compounds in the stir zone. Micro-cracks formed around the intimatelic particles were observed in the section of joint. © 2014 Growing Science Ltd. All rights reserved.

Non-Destructive Detection of Weld Seams in Extruded Aluminum Profiles

The present study focuses on the feasibility of non-destructive testing methods for the detection of transverse and longitudinal weld seams in extruded aluminum alloys. Two extrusion trials using billet on billet extrusion with a porthole die producing both types of weld seams were conducted. First, two billets of different types of alloy, AlMgSi1 (EN AW-6082) and AlZn4.5Mg1 (EN AW-7020), were extruded. In a second trial, two billets of AlZn4.5Mg1 were processed. The produced profiles were then tested by non-destructive testing using a tactile eddy current sensor as well as an encasing sensor at room temperature. The measured signals of both sensors were then evaluated and compared. Microstructural analyses have been carried out to correlate the occurrence of transverse and longitudinal weld seams with the results of the non-destructive testing.

Numerical modelling of the material flow during extrusion of aluminium alloys and transverse weld formation

A comprehensive numerical model of the hot extrusion process for aluminium alloys has been developed and validated. Reflecting the complex thermomechanical changes effected in the alloys during extrusion, the model incorporated heat flow and plastic deformation during extrusion. This paper presents the overall numerical development of a hot extrusion process for AA3003 and validation of the numerical model, by comparison to industrial data. The plasticity module was developed using a commercial finite element package, DEFORM®, a 2-D transient Lagrangian model which couples the thermal and deformation phenomena and is able to predict the temperature, strain rate and strain distribution in the billet/extrudate at any position in the container and die. A new algorithm using MATLAB was also developed so that details of the material flow and formation of the transverse weld and how it is affected by the feeder geometry could be quantified. Validation of the DEFORM model and the MATLAB algorithm of the material flow against industrial data indicated that it gave excellent predictions of the pressure and temperature history during extrusion as well as material flow effects such as surface cladding as one billet is fed in after another through the die. The results indicated that the die feeder design has a significant effect on the transverse weld formation with tapered dies showing lower transverse weld lengths compared to regular feeder plates.

Shear Strength and Failure Angle Analysis of Fillet Welds Based on Structural Stress Approach

With conventional shear stress formula given in AWS B4.0, huge difference of strength between longitudinal and transverse fillet welds exists, and different failure angle of two type welds could not be interpreted. In this paper, a mesh-insensitive structural stress based shear strength definition is presented for correlating weldment test data obtained from longitudinal and transverse fillet welds in literature. Finite element model were created according to the geometry of specimens, and shear stress at different cut plane of weld were calculated. Failure angle could be interpreted reasonably for two type fillet welds, and discrepancies in shear strength between transverse and longitudinal shear tests can now be reconciled, resulting in a single shear strength value regardless of specimen types and loading conditions with this proposed approach.

Research on Welding Deformation of Thick Plate Duralumin Alloy under A-TIG

Using A-TIG to welding thick plate duralumin alloy and designing rationally welding processing for Y groove butt plates welding of duralumin alloy. Using repeated measurements of dot to get transverse and vertical welding deformation under different current of A-TIG after welding. This paper analyzed the influence of different current on welding deformation and the features of A-TIG welding deformation. The result showed that transverse deformation was the uniformity along weld direction but was not uniform along weld vertical direction. Transverse deformation was larger when it was nearer to weld. Vertical deformation of middle position of weld was smaller than the part of arc starting and arc suppression. The result also showed that the deformation increased as the current increased.

Influence of initial distortion on the structural stress in 3 mm thick stiffened panels

This paper investigates the effect of initial distortion on the structural stress in 3mm thick stiffened panels. The influence of initial distortion shape as well as magnitude is studied under axial tension and compression using geometrically non-linear finite element analysis. Different levels of structures are analyzed starting from the plate strips to an actual panel in order to understand how the structural response of thin initially distorted panel builds up. This way the difference between having initial distortion in one or two directions as well as the effect of boundary conditions becomes visible. The results reveal high non-linearity in the behavior of plate strip models and relatively linear behavior of actual plates and panel models in typical fatigue relevant ranges. This is due to support that the actual structures get from having initial distortion in two directions and from surrounding structures. In case of panels the most important effect on structural stresses near the transverse butt weld is the shape of the initial distortion. The second important is the magnitude of initial distortion and significantly less relevant is the straightening effect, i.e. decrease in structural to nominal stress ratio under loading.

Development of a highly efficient hot-wire laser hybrid process for narrow-gap welding—welding phenomena and their adequate conditions

The purpose of this work is to develop hot-wire laser welding for narrow-gap joints. Test pieces of ASTM A 304 stainless steel with a gap width of 3 mm were used. With welding by tentative filler rod made of Inconel 600 alloy, melting phenomena of the molten pool and the weld bead formation during welding were investigated by in situ observation using a high-speed camera. Variations in the main welding parameters such as wire current, wire feeding position, laser irradiation angle, and wire feeding angle were investigated to determine appropriate conditions. Experiments showed that under the optimum welding conditions, hot-wire laser welding was able to produce complete weld deposition with very low dilution of the base metal. An experiment on laser beam reflection indicated that the laser beam reflected from the molten pool was a crucial phenomenon to explain the formation of the weld bead, especially in terms of melting the side groove wall of the base metal. Welding parameters as mentioned above significantly affected weld quality. Furthermore, in the case of welding with filler wire ER NiCrCoMo-1, the Vickers hardness distribution along the transverse welding direction was examined to evaluate weld properties and the bonding strength at the fusion interface was examined in a tensile test, and the results showed that there was no great difference in the hardness profile throughout the cross section of the weld plate. Additionally, metallurgical examination of the fracture surface revealed the rupture occurred at the weld metal, probably because the bonding at the fusion interface was stronger than the weld metal. Therefore, the development of laser welding with hot wire can advance the multi-pass weld for an ultra-narrow-gap joint.

Oxide distribution and microstructure in welding zones from porthole die extrusion

The oxide distribution and microstructure in longitudinal and transverse welding zones during the billet-to-billet extrusion process through porthole die were adequately investigated by means of finite element method, scanning electron microscopy and optical microscopy. The results indicate that the oxides exist at the interface between the matrix and transverse welding zone rather than longitudinal welding seam. The longitudinal welding zone reveals a darker band including the largest grain with irregular shape due to the abnormal grain growth under the heavy shear deformation and high temperature. The transverse welding zone consists of equiaxed recrystallized grains which are a little finer than those in the longitudinal welding seam.

Mechanical properties and fatigue crack growth rates in friction stir welded nugget of 2198-T8 Al–Li alloy joints

A 2.0mm thick Al–Li alloy 2198-T8 plate is welded by friction stir welding in this work. Four dog-bone type samples are designed to use and measure stress–strain curves and mechanical properties. M(T) samples with transverse weld in the center are designed. Fatigue tests under different R ratio loads are performed on the welded samples with crack growing in the welded nugget and parent material samples. Fatigue crack growth rates in these welded nuggets are obtained and compared. It is shown that there is no peculiar yielding process in the stress–strain curve of the welded nugget compared with the parent material. Yield strength and tensile strength have a “U” shape through the weld zone and a lower value in the weld zone while the elongation is in reverse. Unlike the parent material, fatigue crack growth rates in the welded nugget are not sensitive to R ratios. Based on Kres, finite element models are built and the crack closure method is used to calculate the effect of residual stress. Redistributions of residual stress with crack growth are taken into account. Fracture surfaces are investigated to summarize the fracture feature of the welded nugget under fatigue load.

Structure of titanium alloy/austenitic steel welds formed by pressure welding with intermediate coatings

The structure of welds of titanium alloy PT-3V and austenitic steel 08Kh18N10T obtained by vacuum diffusion welding with the use of different intermediate coatings is studied. To create a process for depositing intermediate coatings and diffusion welding, batches of laboratory test bars with transverse weld are fabricated. Materials for the intermediate coatings and modes for solid-phase welding are developed for the test pieces. Metallographic and microscopic x-ray spectrum studies are performed. The use of intermediate coatings is shown to be a promising approach.

Estimation of Fatigue Life of Laser Welded AISI304 Stainless Steel T-Joint Based on Experiments and Recommendations in Design Codes

In this paper the fatigue behavior of laser welded T-joints of stainless steel AISI304 is investigated experimentally. In the fatigue experiments 36 specimens with a sheet thickness of 1 mm are exposed to one-dimensional cyclic loading. Three different types of specimens are adopted. Three groups of specimens are used, two of these are non-welded and the third is welded with a transverse welding (T-Joint). The 13 laser welded specimens are cut out with a milling cutter. The non-welded specimens are divided in 13 specimens cut out with a milling cutter and 10 specimens cut out by a plasma cutter. The non-welded specimens are used to study the influence of heat and surface effects on the fatigue life. The fatigue life from the experiments is compared to fatigue life calculated from the guidelines in the standards DNV-RP-C203 and EUROCODE 3 EN-1993-1-9. Insignificant differences in fatigue life of the welded and non-welded specimens are observed in the experiments and the largest difference is found in the High Cycle Fatigue (HCF) area. The specimens show a lower fatigue life compared to DNV-RP-C203 and EUROCODE 3 EN-1993-1-9 when the specimens are exposed to less than 4.0 1E06 cycles. Therefore, we conclude that the fatigue life assessment according to the mentioned standards is not satisfactory and reliable.

Effect of weld morphology on mechanical response and failure of friction stir welds in a naturally aged aluminium alloy

Friction stir butt welds in 6063-T4 aluminium alloy were obtained using square and two tapered tool pin profiles. Tensile tests at 0°, 45°, and 90° to the weld line, hardness contours in the weld cross-section, temperatures in the heat affected zones, cross-sectional macrographs, transmission electron micrographs, and X-ray diffraction studies were used to characterize the welds. In transverse weld specimen, tunnel defects appearing at higher weld speeds for tapered pin profiles, were found to result in mechanical instabilities, i.e. sharp drops in load–displacement curves, much before macroscopic necking occured. Further, in comparison to the base metal, a marked reduction in ductility was observed even in transverse specimen with defect free welds. Hardness contours in the weld cross-section suggest that loss in ductility is due to significant softening in heat affected zone on the retreating side. Transmission electron microscopy images demonstrate that while recovery and overaging are responsible for softening in the heat affected zone, grain size refinement from dynamic recrystallization is responsible for strengthening of the weld nugget zone. X-ray diffraction studies in the three weld zones: weld nugget zone, heat affected zone, and the base metal corroborate these findings. A weld zone model, for use in forming simulations on friction stir welded plates of naturally aged aluminium alloys, was proposed based on mechanical characterization tests. The model was validated using finite element analysis.