Showing papers on "Filler metal published in 2006"

Hybrid adaptive layer manufacturing: An Intelligent art of direct metal rapid tooling process

Abstract: A direct metal rapid tool making process, hybrid-layered manufacturing (HLM), was developed for building metallic dies and molds. This unique methodology has a numerical controlled system that integrates the TransPulse Synergic Metal Inert Gas (MIG)/Metal Active Gas (MAG) welding process for near-net layer deposition and Computer Numerical Control (CNC) milling process for net shaping. A customized software program was made to calculate the required adaptive slice thickness for the deposition of the filler metal with welding process as successive layers from the lowest to the topmost layer direction and to generate the required NC codes for machining from the top to the bottom layer direction of the deposited metallic layers for attaining the required contour profile shape. To implement this proposed process, a low-cost three-axis manipulator was fabricated with stepper motor divers in open-loop control and integrated with the weld machine. Adequate isolation to protect the motion control electronics from welding spike was incorporated. Synchronization of this two-step processing of each layer, yielding near-net deposition with welding process and near-net shaping with CNC milling operation offers a new accelerator way of building metal tools and dies.

Experimental study on welding characteristics of CO2 laser TIG hybrid welding process

Abstract: The experiments of CO2 laser TIG paraxial hybrid welding with 4 mm thick AISI 321 stainless steel sheet have been performed. The arc images and welding characteristics have been investigated with different energy ratios between laser and arc. The experimental results indicate that the hybrid welding is similar to laser welding and has also two welding mechanisms: deep penetration welding and heat conduction welding. Because of the effect of keyhole induced by laser, the arc root can be stabilised and compressed, and the current density and the penetration depth are all increased significantly, which show the characteristics of deep penetration welding. However, when the current is increased to a critical value, the laser induced keyhole disappears and the arc expands obviously, which decreases the penetration depth, so that the welding mechanism has been changed from deep penetration welding to heat conduction welding. Furthermore, the effects of distance between laser beam and electrode, pulsed l...

Multimaterial car body design: challenge for welding and joining

Abstract: High safety and low weight are requested for modern automobiles. Both demands are met best by tailored application of different materials. Multimaterial car body design is a challenge for joining and welding.

Microstructural evolution during transient liquid phase bonding of Inconel 617 using Ni–Si–B filler metal

Abstract: The influence of process parameters on microstructural characteristics of transient liquid phase (TLP) bonded Inconel 617 alloy was investigated. Experiments were carried out at 1065 °C using nickel based filler metal (Ni–4.5% Si–3% B) with B as the melting point depressant (MPD) element. Two different thickness of interlayer and various holding times were employed. The influence of these processing parameters on the characteristics of the joint area particularly size, morphology and composition of precipitates was investigated. The presence of MoB, Mo 2 B, M 23 C 6 , TiC, M 23 (B, C) 6 and Ni 3 B precipitates in the diffusion layer and Ni 3 B, Ni 3 Si and Ni 5 Si 2 precipitates in the interlayer at the interface between the base metal and interlayer were demonstrated using electron back scattered diffraction (EBSD), energy dispersive spectrometry (EDS) and TEM.

Cold-Metal-Transfer Welding Process and Welding Installation

Abstract: The invention relates to a cold metal transfer welding process, in which the welding process is defined by the cyclic alternation of an arc phase (36) and a short-circuit phase (39) According to the invention, during an arc phase (36), a welding rod (13) is displaced towards the workpiece (16) until it makes contact with the latter (16) and during the short-circuit phase (39) the welding rod displacement is reversed and the welding rod (13) is then moved away from the workpiece (16) The welding current (I) and/or the welding voltage (U) are controlled during the arc phase (36) in such a way that the welding rod (13) melts, forming a droplet and that during the short-circuit phase (39) a breaking of the short-circuit is suppressed by means of the welding current (I) The invention also relates to a welding installation for carrying out said welding method The aim of the invention is to achieve optimal welding results using the smallest possible number of settings To achieve this, a displacement frequency (40) of the welding rod (13) is set as a welding parameter by means of a control organ, said frequency being used to define the number of arc phases (36) and short-circuit phases (39) per second, and at least one additional welding parameter is set A control unit (4) determines, sets and controls all other welding parameters that are required to achieve the predefined displacement frequency (40)

Effects of pulse level of Nd-YAG laser on tensile properties and formability of laser weldments in automotive aluminum alloys

Abstract: Tensile properties and formability are important parameters in many applications. Being a lightweight material, aluminum is increasingly employed in the fabrication of automotive body panels. This study performs butt welding without filler metal on two frequently used automotive body panel aluminum alloys, 5754-O and 6022-T4E29. Welding is conducted using a Nd-YAG laser with a rectangular wave form having various pulse levels (ΔP) but a constant mean power of 1.5 kW. For both alloys, the results indicate that the travel speed required to achieve a successful butt joint increases as ΔP decreases. For a constant pulse level, the travel speed required for the higher Mg content 5754-O alloy (2.9 wt.% Mg) is approximately 2.5 times that of the lower Mg content 6022-T4E29 alloy (0.61 wt.% Mg). Additionally, it is shown that the tensile strength, percentage elongation and formability of both alloy weldments increase with decreasing ΔP level. In the 5754-O alloy, these trends are attributed primarily to the occurrence of magnesium evaporation during the welding process, microstructure refining, and porosity reduction in the resultant welds. However, for 6022-T4E29, the evaporation of Mg is not significant, and consequently, the variation in porosity is not great. These results are caused by a lower Mg content in the base metal. Therefore, the enhancement of the mechanical properties observed in the weldments is a result of a refinement of the weld microstructure.

New CMT arc welding process – welding of steel to aluminium dissimilar metals and welding of super-thin aluminium sheets

Abstract: (2006). New CMT arc welding process – welding of steel to aluminium dissimilar metals and welding of super-thin aluminium sheets. Welding International: Vol. 20, No. 6, pp. 440-445.

Suppressing type IV failure via modification of heat affected zone microstructures using high boron content in 9Cr heat resistant steel welded joints

Abstract: Creep rupture strength at 923 K and microstructural evolution of welded joints have been investigated for high boron–low nitrogen–9Cr heat resistant steels developed at the National Institute for Materials Science (Japan). Welded joints were prepared from plates containing 47–180 ppm boron using gas tungsten arc welding and Inconel type filler metal, and showed superior creep properties to those of welded joints of conventional high chromium steels such as P92 and P122. No type IV failure was observed in the boron steel welded joints. A large grained microstructure was observed in the heat affected zone heated to Ac 3 (Ac 3 HAZ) during welding, whereas the grains are refined at the same location in conventional steel welded joints. The simulated Ac 3 HAZ structures of the boron steels have a creep life almost equal to that of the base metal. Large grained HAZ microstructures and stabilisation of M23C6 precipitates are probable reasons for suppression of type IV failure and improved creep resistanc...

Effect of shielding gas mixture on gas metal arc welding of HSLA steel using solid and flux-cored wires

Abstract: In this work, gas metal arc welding of high strength-low alloy (HSLA) steel with solid- and flux-cored arc welding wires using different shielding gas compositions was performed. The composition of filler wire and shielding gas in gas metal arc welds of HSLA steel determines the inclusion characteristics, microstructure and mechanical properties. Thus, acceptable weld metal properties in HSLA steel using gas metal arc welding (GMAW) process could be achieved with the proper combination of filler wire and shielding gas composition.

Microcracking in multipass weld metal of alloy 690 Part 1 - Microcracking susceptibility in reheated weld metal

Abstract: Microcracking behaviour in the gas tungsten arc multipass weld metal of alloy 690 was investigated. The majority of microcracks occurred within about 300 μm from the fusion line of the subsequent weld bead and propagated along the solidification boundaries in the multipass weld metal. The morphology of the crack surface indicated the characteristic texture of ductility dip cracking. The microcracking susceptibility of the reheated weld metal was evaluated via the spot Varestraint test using three different filler metals having varying contents of impurity elements such as P and S. Microcracking occurring in the spot Varestraint tests consisted predominantly of ductility dip cracking, with a small amount of liquation cracking. The ductility dip cracking temperature range was about 1350–1600 K in the weld metal FF1, and narrowed in the order of weld metals FF1>FF3>FF5. The ductility dip cracking susceptibility was reduced with decreasing contents of impurity elements in the filler metal. It was conc...

Infrared brazing of Ti-6Al-4V and 17-4 PH stainless steel with a nickel barrier layer

Abstract: Infrared brazing of Ti-6Al-4V and 17-4 PH stainless steel using the BAg-8 filler metal was performed in this study. A nickel barrier layer 10 µm thick was introduced on the 17-4 PH stainless steel before infrared brazing. For the specimen that was infrared brazed at 800 °C and 850 °C for less than 300 seconds, the Ni layer served as an effective barrier layer to prevent the formation of Ti-Fe intermetallics. Experimental results show that the average shear strength of the joint can be greatly improved for the specimen by Ni plating. Comparing the specimens with and without electroless-plated Ni film, the former has no Ti-Fe intermetallic compound, but interfacial CuNiTi and NiPTi phases are observed in the latter. The fractured location of the joint after the shear test is changed from the interfacial TiFe (without Ni plating) into the TiCu reaction layer (with Ni plating). The plated Ni layer is consumed for the specimen that was infrared brazed at 880 °C for 300 seconds, and its bonding strength is impaired. Consequently, a lower brazing temperature and/or time are still preferred even though a plated Ni barrier layer is applied.

A New Laser-Arc Hybrid Welding Technique Based on Energy Conservation

Abstract: Aiming at the problem of energy loss in the process of welding at present, a new hybrid welding technique that low powered laser (about 400 W) combined with arc was put forward. Taking magnesium alloys as objects, it was found that the new technique had many advantages such as high welding speed, deep penetration and high quality welded joint comparing with that welded by laser or arc alone. Besides, the mechanical properties of the welded joint were improved remarkably. Comparing with high powered laser (about 2000 W)-arc hybrid welding, the laser used in the new technique was about 400 W, which was about 1 /5 of that of the former, so the welding costs could be reduced markedly, while a great deal of energy was saved. In the research of arc behaviors, a new hybrid mechanism was proposed, in which the ability of arc to discharge was improved mainly because the laser pulse acted on the negative arc (electrode was positive and the specimen was negative) during the hybrid welding.

Physical Phenomena and Porosity Prevention Mechanism in Laser-Arc Hybrid Welding

Abstract: Hybrid welding of stainless steels or aluminium alloys was performed with the heat sources of YAG laser and TIG, or YAG laser and MIG, respectively. The effects of welding conditions and melt flows on penetration depth, geometry and porosity formation were investigated with the X-ray transmission real-time observation method. Melt flows on penetration depth and geometry were consequently confirmed. Concerning porosity suppression, in TIG-YAG hybrid welding of stainless steel, no formation of bubbles was attributed to the absence of pores. On the other hand, disappearance of bubbles from the concave molten pool surface due to the arc pressure played an important role in reducing porosity in YAG-MIG hybrid welding of aluminium alloys at high arc currents.

MIG Welding Guide

Abstract: Part 1 Technologies: The MIG welding process Equipment for MIG welding Shielding gases in MIG welding Consumables in MIG welding Flux cored arc welding Pulsed MIG welding MIG brazing. Part 2 Quality and safety issues: Improving productivity in MIG/MAG welding Assessing weld quality in MIG welding Occupational health and safety in MIG welding Reducing costs in MIG welding. Part 3 Applications: MIG welding of uncoated and surface coated steel MIG welding of stainless steel MIG welding of aluminium and aluminium alloys Robotic equipment for MIG welding Optimising the use of robotic MIG welding Automotive applications of robotic MIG welding Heavy vehicle applications of robotic MIG welding.

System and methodology for zero-gap welding

Abstract: A method for welding includes providing a pair of substrates with no gap between them. The welding process uses lasers that are moveable through a locus of points relative to the substrates and each other to weld the substrate together. The moveable lasers assist in controlling a formation of a weld keyhole that assists in expelling gases that develop during the welding process.

Effects of laser brazing parameters on microstructure and properties of TiNi shape memory alloy and stainless steel joint

Abstract: Laser brazing has been applied for joining TiNi shape memory alloy (SMA) and stainless steel (SS) using the silver-based filler metal with composition of 52%Ag, 22%Cu, 18%Zn and 8%Sn (wt.%) and effects of laser brazing parameters has been investigated. The filler metal has good wettability on both TiNi SMA and SS. The brazing seam metal consists of α-Ag solid solution, α′-Cu solid solution surrounded by the α-Ag and eutectic structures. Heat affected zones (HAZs) of TiNi SMA and SS are comprised of B2 and B ′ 19 phases and austenite phase, respectively. Increasing laser output power and brazing time resulted in the grain coarsening and reducing the microhardness value in the HAZs. The laser output power and brazing time have effects on the superelasticity (SE) and shape memory effect (SME) of the TiNi SMA HAZ. With increasing laser output power and brazing time from 50 W/10 s to 70 W/20 s, the residual strain (ɛu) at room temperature in the HAZ increased from 0.37% to 2.22% and the shape recovery rate (ψ) at 100 °C decreased from 91.6% to 62.1%. The deterioration of SE and SME in TiNi SMA HAZ could be attributed to the coarse-grained structures. It is favourable to decrease laser output power and brazing time for improving both SE and SME of TiNi SMA HAZ.

Recent developments in repair welding technologies in Japan

Abstract: Developments in some difficult repair welding technologies in Japan during the past decade are reviewed. The topics covered include the repair welding of bridges in service, the temper bead method which makes it possible to omit post-weld heat treatment (PWHT) of repaired pressure vessels, the seal welding of a reactor vessel in which stress corrosion cracks were detected, low heat input repair welding of neutron irradiated stainless steel and nickel based alloys, the prevention of solidification cracking in repair welding of aged heat resistant cast steels, the development of welding materials for the mending of single crystal nickel based superalloy turbine blades, underwater repair welding of nuclear reactors, the reduction of residual stresses in repair welding, and an ultrasonic testing method for nickel based weld metals. The local PWHT of creep resistant ferritic steel tubes is also reviewed.

Microcracking in multipass weld metal of alloy 690 Part 3 – Prevention of microcracking in reheated weld metal by addition of La to filler metal

Abstract: The effect of addition of La to a filler metal on microcracking (ductility dip cracking) in the multipass weld metal of alloy 690 was investigated with the aim of improving its microcracking susceptibility. The susceptibility to ductility dip cracking in the reheated weld metal could be greatly improved by adding 0·01–0·02 wt-%La to the weld metal. Conversely, excessive La addition to the weld metal led to liquation and solidification cracking in the weld metal. Hot ductility of the weld metal at the cracking temperature was greatly improved by adding 0·01–0·02 wt-%La to the weld metal, implying that the ductility dip cracking susceptibility was decreased as a result of the desegregation of impurity elements of P and S to grain boundaries due to the scavenging effect of La. The liquation and solidification cracking resulting from excessive addition of La to the weld metal is attributed to the formation of liquefiable Ni–La intermetallic compound. A multipass welding test confirmed that microcracks...

Laser micro welding of copper and aluminum

Abstract: Aluminum combines comparably good thermal and electrical properties with a low price and a low material weight. These properties make aluminum a promising alternative to copper for a large number of electronic applications, especially when manufacturing high volume components. However, a main obstacle for a wide use of this material is the lack of a reliable joining process for the interconnection of copper and aluminum. The reasons for this are a large misalignment in the physical properties and even more a poor metallurgical affinity of both materials that cause high crack sensitivity and the formation of brittle intermetallic phases during fusion welding. This paper presents investigations on laser micro welding of copper and aluminum with the objective to eliminate brittle intermetallic phases in the welding structure. For these purposes a combination of spot welding, a proper beam offset and special filler material are applied. The effect of silver, nickel and tin filler materials in the form of thin foils and coatings in a thickness range 3-100 μm has been investigated. Use of silver and tin filler materials yields to a considerable improvement of the static and dynamic mechanical stability of welded joints. The analysis of the weld microstructure shows that an application even of small amounts of suitable filler materials helps to avoid critical, very brittle intermetallic phases on the interface between copper and solidified melt in the welded joints.

MIG Brazing of Galvanized Thin Sheet Joints for Automotive Industry

Abstract: MIG welding of zinc-coated thin plates in the automotive industry leads to major issues, mainly zinc evaporation followed by a decrease of corrosion resistance, as well as residual strains and stresses difficult to minimize. The use of a lower heat input technique for joining galvanized steels would bring significant benefit, if the final overall mechanical properties of the joints are adequate for the application. The use of MIG brazing (MIGB) with the recently commercialized alloyed copper-based filler metal is an alternative worth considering. The present paper addresses the MIGB processes, describing the influence of the different shielding gases and the process parameters on the mechanical, corrosion, and metallurgical properties of the joint, when lower heat input procedures are targeted. The paper describes the influence of the gases on the mechanical properties of the brazed joint, both in normal conditions after joining and after corrosion in a salt water environment. Microstructural features of the different zones are discussed. Results of corrosion and tensile tests are presented and interpreted.

Process for repairing turbine engine components

Abstract: A process for repairing a component includes the steps of placing a piece of refractory metal material (16) over an area (12) of component to be repaired; depositing a repair filler metal (18) material proximate to the piece of refractory metal material (16) in an amount sufficient to repair the component; subjecting the repair filler material (18) to a welding treatment without directly heating the piece of refractory metal material (16); flowing the repair filler material (18) within the area (12); and casting the repair filler material (18).

Advanced welding processes : technologies and process control

Abstract: An introduction to welding Advanced process development trends Welding power source technology Filler materials for arc welding Gases for advanced welding processes Advanced gas tungsten arc welding (GTAW) Gas metal arc welding (GMAW) High energy density processes Narrow-gap welding techniques Monitoring and control of welding processes Welding automation and robotics.