Arc stability and melting characteristics of welding wire for use with 2219 aluminum alloy plate
Arc stability and melting characteristics of welding wire for arc welding of 2219 aluminum alloy plate
ALUMINUM ALLOY↗
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Device for preventing high voltage arcing in electron beam welding Patent
Development of device to prevent high voltage arcing in electron beam welding
Hanchey, K. K.↗
Nondestructive ultrasonic characterization of a triple-weld-bead wire arc additively manufactured ER70S-6 S-curved wall
Understanding build-scale microstructural variation in wire arc additive manufacturing (WAAM) of low-carbon steels is essential for ensuring consistent structure–property relationships throughout large components. Conventional destructive characterization techniques, such as scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), are time-intensive and limited to localized regions, making comprehensive evaluation of large WAAM structures challenging. In this study, a nondestructive ultrasonic approach was employed to characterize a 252 mm tall ER70S-6 S-curved WAAM wall produced using a triple-bead deposition strategy. Optical and SEM analysis revealed a repeating dual-region microstructure consisting of uniform polygonal ferrite at melt pool centers and heterogeneous ferrite with coarse and fine grains near melt pool boundaries, attributed to cyclic thermal conditions. Longitudinal ultrasonic backscatter imaging was used to evaluate the continuity of this periodicity along the full build height. The ultrasonic response exhibited a consistent repeating pattern that correlated with the observed layer-wise microstructural variation. X-ray computed tomography confirmed the absence of detectable porosity, indicating that ultrasonic contrast is primarily governed by grain morphology. Overall, the results indicate that longitudinal backscatter ultrasound is a promising nondestructive characterization technique for validating microstructural variations along the s-curved WAAM wall, with significant potential for microstructure optimization and process control.
36 MATERIALS SCIENCE↗
Fluid Flow Phenomena during Welding
MOLTEN WELD POOLS are dynamic. Liquid in the weld pool in acted on by several strong forces, which can result in high-velocity fluid motion. Fluid flow velocities exceeding 1 m/s (3.3 ft/s) have been observed in gas tungsten arc (GTA) welds under ordinary welding conditions, and higher velocities have been measured in submerged arc welds. Fluid flow is important because it affects weld shape and is related to the formation of a variety of weld defects. Moving liquid transports heat and often dominates heat transport in the weld pool. Because heat transport by mass flow depends on the direction and speed of fluid motion, weld pool shape can differ dramatically from that predicted by conductive heat flow. Temperature gradients are also altered by fluid flow, which can affect weld microstructure. A number of defects in GTA welds have been attributed to fluid flow or changes in fluid flow, including lack of penetration, top bead roughness, humped beads, finger penetration, and undercutting. Instabilities in the liquid film around the keyhole in electron beam and laser welds are responsible for the uneven penetration (spiking) characteristic of these types of welds.
36 MATERIALS SCIENCE↗
Self-clamping arc light reflector for welding torch
This invention is directed to a coaxial extending metal mirror reflector attached to the electrode housing or gas cup on a welding torch. An electric welding torch with an internal viewing system for robotic welding is provded with an annular arc light reflector to reflect light from the arc back onto the workpiece. The reflector has a vertical split or gap in its surrounding wall to permit the adjacent wall ends forming the split to be sprung open slightly to permit the reflector to be removed or slipped onto the torch housing or gas cup. The upper opening of the reflector is slightly smaller than the torch housing or gas cup and therefore, when placed on the torch housing or gas cup has that springiness to cause it to clamp tightly on the housing or gas cup. The split or gap also serves to permit the feed of weld wire through to the weld area,
Gordon, Stephen S.↗
MPTA Overview
Presentation discusses Micro Plasma Transfer Arc (MPTA) welding. It was introduced in 1960, and has been used for blade refurbishment for jet engines since 1980. It is compared with Gas Tungsten Arc Welding. MPTA welding reduces the heat input to perform the weld. It uses controlled filler material, and it is easy to use.
Weeks, Jack↗
Arc-starting aid for GTA welding
Three-in-one handtool combining arc-gap gage, electrode tip sander, and electrode projection gate, effectively improves initiation on gas tungsten arc (GTA), automatic skate-welding machines. Device effects ease in polishing electrode tips and setting exactly initial arc gap before each weld pass.
Whiffen, E. L.↗
Welding procedures improves quality of welds, offers other advantages
An improved procedure for arc spot welding uses the SIGMA /Submerged Inert Gas Metallic Arc/ method. This has resulted in welds of higher quality than are obtainable by conventional meansc
Source record↗
Non-Intrusive Load Monitoring of EBW Processes A Second Study [Slides]
The Objective is to Determine if induced off-nominal welding disturbances: (1) Beam arc out (weld on high vapor pressure aluminum plate); (2) Pulsed beam voltage; (3) Pulsed beam current; and (4) Pulsed beam focus current can be observed in the input power to the high-voltage cabinet powering the EB gun, ie Non-Instrusive Load Monitoring (NILM).
36 MATERIALS SCIENCE↗
Welding Rustproof Steels
The following experimental results will perhaps increase the knowledge of the process of welding rustproof steels. The experiments were made with two chrome-steel sheets and with two chrome-steel-nickel sheets having the composition shown in Table I.
STEELS, STAINLESS - ETCHING↗
Analysis And Control System For Automated Welding
Automated variable-polarity plasma arc (VPPA) welding apparatus operates under electronic supervision by welding analysis and control system. System performs all major monitoring and controlling functions. It acquires, analyzes, and displays weld-quality data in real time and adjusts process parameters accordingly. Also records pertinent data for use in post-weld analysis and documentation of quality. System includes optoelectronic sensors and data processors that provide feedback control of welding process.
Powell, Bradley W.↗
Development of strain gages for use to 1311 K (1900 F)
A high temperature electric resistance strain gage system was developed and evaluated to 1366 K (2000 F) for periods of at least one hour. Wire fabricated from a special high temperature strain gage alloy (BCL-3), was used to fabricate the gages. Various joining techniques (NASA butt welding, pulse arc, plasma needle arc, and dc parallel gap welding) were investigated for joining gage filaments to each other, gage filaments to lead-tab ribbons, and lead-tab ribbons to lead wires. The effectiveness of a clad-wire concept as a means of minimizing apparent strain of BCL-3 strain gages was investigated by sputtering platinum coatings of varying thicknesses on wire samples and establishing the optimum coating thickness--in terms of minimum resistivity changes with temperature. Finally, the moisture-proofing effectiveness of barrier coatings subjected to elevated temperatures was studied, and one commercial barrier coating (BLH Barrier H Waterproofing) was evaluated.
Lemcoe, M. M.↗
Advanced Welding Applications
Some of the applications of advanced welding techniques are shown in this poster presentation. Included are brief explanations of the use on the Ares I and Ares V launch vehicle and on the Space Shuttle Launch vehicle. Also included are microstructural views from four advanced welding techniques: Variable Polarity Plasma Arc (VPPA) weld (fusion), self-reacting friction stir welding (SR-FSW), conventional FSW, and Tube Socket Weld (TSW) on aluminum.
Ding, Robert J.↗
Automated Welding System
Fully automated variable-polarity plasma arc VPPA welding system developed at Marshall Space Flight Center. System eliminates defects caused by human error. Integrates many sensors with mathematical model of the weld and computer-controlled welding equipment. Sensors provide real-time information on geometry of weld bead, location of weld joint, and wire-feed entry. Mathematical model relates geometry of weld to critical parameters of welding process.
Bayless, E. O.↗
The keyhole region in VPPA welds
The morphology and properties of the Variable Polarity Plasma Arc (VPPA) weld composite zone are intimately related to the physical processes associated with the keyhole. The effects of microsegregation and transient weld stress on macrosegregation in the weld tool are examined. In addition the electrical character of straight and reverse polarity portions of the arc cycle were characterized. The results of the former study indicate that alloy 2219 is weldable because large liquid volumes are available during latter stages of weld solidification. Strains in the pool region, acting in conjunction with weld microsegregation can produce macrosegregation great enough to produce radiographic contrast effects in welds. Mechanisms of surface copper enrichment were identified. The latter study has demonstrated that increased heat is delivered to workpieces if the reverse polarity proportion of the weld cycle is increased. Current in the straight polarity portion of the welding cycle increased as the reverse cycle proportion increased. Voltage during reverse polarity segments is large.
Walsh, Daniel W.↗
Transition of creep damage region in dissimilar welds between Inconel 740H Ni-based superalloy and P92 ferritic/martensitic steel
Highlights: • The fresh martensite formed in P92-sided CGHAZ during PWHT due to high Ni content. • Transition from type I to type IV cracking was observed with increasing temperature. • Creep damaged area changed depending on the dominant creep mechanism. • The transition value of Larson-Miller parameter would be within 25,063–26,168. - Abstract: Characterization of microstructures and creep fracture characteristics of dissimilar welds between Ni-based Inconel 740H superalloy and ferritic/martensitic P92 steel has been investigated. The welds were produced by shielded metal arc (SMA) welding process with the AWS A5.11 Class ENiCrFe-3 filler metal, commonly known as Inconel 182 superalloy. Postweld heat treatment (PWHT) at 760 °C for 4 h was conducted to temper the martensite in heat-affected zone (HAZ) of P92 and to form γ′ strengthener in Inconel 740H. The deposited Inconel 182 austenitic weld metal had a columnar microstructure, and grew epitaxially from the Inconel 740H base metal. The weld interface between P92 and weld metal was characterized by the discrete line with a minimal inter-diffusion, where the fresh untempered martensite was found to be formed during PWHT due to higher Ni contents diffused from Inconel 182 into P92. The P92 base metal and Inconel 182 weld metal displayed low hardness values (~240 Hv), and the sharp hardness increase was detected at coarse-grained HAZ of P92 while the hardness minimum occurred at the fine-grained HAZ (FGHAZ). Fracture location after creep was found to shift from the P92-sided fusion line to the FGHAZ of P92 with increasing creep temperature. The carbon migration from the P92 into the weld metal was not significant at lower creep temperature (600 °C), where the crack initiation at the P92-sided fusion line appeared to be related with a significant strain incompatibility across the fusion line. At both 650 °C and 700 °C where diffusion-controlled creep was more pronounced, the type IV cracking was observed. This may be attributed to the strain localization at the weak grain boundaries of FGHAZ due to the smaller grain size as well as the lack of grain boundary strengthening by carbides.
36 MATERIALS SCIENCE↗
Welding of Stainless Materials
It would appear that welds in some stainless steels, heat-treated in some practicable way, will probably be found to have all the resistance to corrosion that is required for aircraft. Certainly these structures are not subjected to the severe conditions that are found in chemical plants.
WELDING↗
Methodology for Estimating Thermal and Neutron Embrittlement of Austenitic Stainless Steel Welds During Service in Light Water Reactors
The effect of thermal aging on the degradation of fracture toughness and Charpy-impact properties of austenitic stainless steel (SS) welds has been characterized at reactor temperatures. The solidification behavior and the distribution and morphology of the ferrite phase in SS welds are described. Thermal aging of the welds results in moderate decreases in Charpy-impact strength and fracture toughness. The upper-shelf Charpy-impact energy of aged welds decreases by 50–80 J/cm2. The decrease in fracture toughness J-R curve, or JIc is relatively small. Thermal aging has minimal effect on the tensile strength. The fracture properties of SS welds are insensitive to filler metal; the welding process has a significant effect. The large variability in the data makes it difficult to establish the effect of the welding process on fracture properties of SS welds. Consequently, the approach used for evaluating thermal and neutron embrittlement of austenitic SS welds relies on establishing a lower-bound fracture toughness J-R curve for unaged and aged, and non-irradiated and irradiated, SS welds. The existing fracture toughness J-R curve data for SS welds have been reviewed and evaluated to define lower-bound J-R curve for submerged arc (SA)/shielded metal arc (SMA)/manual metal arc (MMA) welds and gas tungsten arc (GTA)/tungsten inert gas (TIG) welds in the unaged and aged conditions. At reactor temperatures, the fracture toughness of GTA/TIG welds is a factor of about 2.3 higher than that of SA/SMA/MMA welds. Thermal aging decreases the fracture toughness by about 20%. The potential combined effects of thermal and neutron embrittlement of austenitic SS welds are also described. Lower-bound curves are presented that define the change in coefficient C and exponent n of the power-law J-R curve and the JIc value for SS welds as a function of neutron dose. The potential effects of reactor coolant environment on the fracture toughness of austenitic SS welds are also discussed.
Chopra, O. K.↗