Weld Filler Research Articles

Study of Underwater Laser Welding Repair Technology

IHI developed underwater welding process by using YAG laser and qualified the process to repair a thin wall stainless steel tank in a power plant in Japan. Important features of YAG laser welding are less welding distortion, and a small heat-affected zone (HAZ) due to the smaller heat input and higher cooling rate than with other conventional welding methods. In this study, we have conducted underwater laser welding of Ni-base alloy and stainless clad materials, such as Alloy 600 and E-309L / E-308L clad materials. Alloy 690 was selected as weld filler metal for a corrosion resistant overlay to prevent corrosion attack by the service environment. Welding trials were conducted on the surface of flat plates with simulated surface cracks, and the trial welds were assessed for soundness of welding. The preliminary results of the trial welds by using high power laser diode, and comparison between YAG laser and high power LD are reported.

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

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 Ac3 (Ac3 HAZ) during welding, whereas the grains are refined at the same location in conventional steel welded joints. The simulated Ac3 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 resistance of the boron steel welded joints.

Gas tungsten-arc filler welding of AZ31 magnesium alloy

Optical microscopy and scanning electron microscopy (SEM) were used to examine the microstructure and fracture of AZ31 magnesium alloy joint welded by automatic gas tungsten-arc filler (GTAF) welding process with AZ61 wire. More endeavors have been put on investigating the effect of filler wire on microstructure and performance of welded joint. The result showed that the grain size in heat-affected zone (HAZ) of GTAF welded joint holds significant variety compared with that of GTA welded joint (without filler wire). The modification of microstructure in HAZ has changed the fracture location as well as the ultimate tensile strength (UTS) of joint in tensile test.

Microstructure of butt laser joints of aluminium alloy 6056 sheets with an AS12 filler

Butt joints of 1·6 mm thick sheets of Al–Mg–Si–Cu alloy 6056 in the T4 temper have been produced using a 3 kW Nd:YAG laser with an Al–12 wt-%Si filler wire. The fusion zone consists of a very fine dendritic structure (DAS=5 μm) with a grain size of 100 μm. Its composition is controlled by the ratio between the welding speed and filler wire speed. The interdendritic space is rich in all alloying elements and contains several complex phases. The dendrite interior still contains sufficient solute to enable precipitation hardening during a post-welding heat treatment. The grain boundaries of the base material close to the weld nugget appear to be affected by liquation during the welding process, with spatial extension controlled by the welding speed.The microstructure of the heat affected zone is characterised by GP zone dissolution. The resulting hardness decrease can be fully recovered by a T6 or T78 post-welding heat treatment. The comparatively lower hardness of the fusion zone can also be improved by precipitation hardening during a post-welding heat treatment.

Investigations on the use of Nitrogen Shielding Gas in Welding and its Influence on the Hot Crack Behaviour of High-Temperature Resistant Fully Austenitic Ni- and Fe-Base Alloys

Due to their excellent high-temperature behaviour and corrosion-resistance properties, as well as to their equally good high-temperature strength and long time strength, high-temperature resistant fully austenitic Ni-base alloys are widely employed in industrial branches for especially demanding and exacting use. The outspoken tendency of the weld metal to hot cracking, however, considerably restricts the outstanding working-life properties of this group of materials. In our research project is investigated systematically the metallurgical effect of nitrogen for avoidance of hot cracks in fully austenitic weld metal. As objects of the investigation, were selected hot-crack sensitive fully austenitic high-temperature Ni- and Fe-base alloys (alloy 602 CA, alloy 601 H, alloy 617, alloy 690, alloy 800), which were processed with GTAW and pulsed GMAW procedures under the use of suitable weld filler materials as applied in practical use. The element nitrogen was added as gaseous component with the weld shielding gas. The hot-crack behaviour of the base metals and of the welds was evaluated by the Programmed Deformation Rate-Test. As results of the hot cracking tests, the positive effect of nitrogen was shown at first and foremost only with the primary carbide containing Ni-base alloy 602 CA and slightly with alloy 601 H. The reasons for this effect are metallurgical. Starting from the presented results and the experience meanwhile gained in practice in matched arc welding the high-temperature resistant Ni-base alloy 602 CA, nitrogen additions between 1 and 3 % for the GTAW process and between 5 and 12% for the pulsed GMAW process are recommended.

Review: Corrosion and cracking of weldable 13 wt-%Cr martensitic stainless steels for application in the oil and gas industry

A critical review of the literature has been undertaken to establish the current state of knowledge and understanding of the corrosion and stress corrosion cracking (SCC) of 13 wt-%Cr martensitic stainless steels for applications in the oil and gas industry. Corrosion data for 13%Cr martensitic stainless steels are critically evaluated to establish the conditions in which the various steels are in the active state, pitting or passive state. There is evidence that as welded specimens have poorer pitting resistance at ambient temperatures than at elevated temperatures owing to the formation of an oxidised layer, perhaps depleted in chromium. Data for hydrogen uptake and diffusivity in 13%Cr steels are reviewed. The results suggest that incorporation of Mo in the steel reduces the subsurface hydrogen content when the steel is in the active state, suggesting repressed dissolution kinetics. The data in the literature on SCC of modified 13%Cr steels indicate that increasing the temperature at pH values where pitting is the precursor to cracking decreases the susceptibility to sulphide stress cracking. Whilst a matching weld filler would be expected to be more susceptible to hydrogen embrittlement because of a higher hardness of the weld metal relative to the duplex stainless steel filler, there is limited evidence to suggest that welds with matching fillers are more resistant to cracking than welds with duplex fillers. The heat affected zone of a duplex weld appears to be more susceptible to pitting than for a matching filler. Evidence of intergranular SCC from the root of a girth weld at 110°C has been obtained but is eliminated by post-weld heat treatment. Nevertheless, this is an important observation and needs further investigation.

ALCOTEC WELD FILLER WIRE 5183

Abstract Alcotec Weld filler wire 5183 is a non-heat-treatable aluminum welding wire whose principal alloying elements are magnesium, manganese, and chromium. It is similar to the European wire AlMg4.5Mn. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on joining. Filing Code: AL-384. Producer or source: AlcoTec Wire Corporation.

ALCOTEC WELD FILLER WIRE 4145

Abstract AlcoTec weld filler wire 4145 is a general-purpose high-silicon-containing wire for both welding and brazing. The alloy is often used instead of 2319 for welding higher-strength alloys because of its low melting temperature and high fluidity. This datasheet provides information on composition and physical properties. It also includes information on joining. Filing Code: AL-383. Producer or source: AlcoTec Wire Corporation.

Gas tungsten arc welding of vanadium alloys with impurity control

Gas tungsten arc welding in vanadium alloys is controlled by interstitial impurities. Techniques have been developed to weld V–4Cr–4Ti in a high-purity argon atmosphere resulting in a DBTT of −20 °C. The atmosphere was controlled by a Zr–Al getter which is activated at high temperature to obtain a clean surface then cooled and allowed to absorb hydrogen and oxygen impurities. Through the use of low-oxygen base metal and high-purity weld filler wire, a DBTT of −145 °C was obtained. Experiments using electron beam welding have shown that grain size also has an important effect on weld ductility. Introduction of nitrogen and yttrium has been used to study their effect on grain size. Using a combination of atmosphere control, alloy purity control, and grain size control, it is anticipated that V–Cr–Ti alloys will be weldable in field conditions.

ALCOTEC WELD FILLER WIRE 2319

Abstract Alcotec weld filler wire 2319 is a heat treatable wire. The principal alloying elements are copper, manganese, vanadium, zirconium, and titanium. Weld filler wire 2319 was developed primarily for aircraft structural components to weld the high-strength age-hardenable wrought alloy 2219. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on joining. Filing Code: AL-382. Producer or source: AlcoTec Wire Corporation.

ALCOTEC WELD FILLER WIRE 4047

Abstract AlcoTec weld filler wire 4047 is a general-purpose high silicon containing wire for both welding and brazing. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on joining. Filing Code: AL-381. Producer or source: AlcoTec Wire Corporation.

ALCOTEC WELD FILLER WIRE 4043

Abstract AlcoTec weld filler wire 4043 is a general-purpose high-silicon-containing wire for both welding and brazing. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on joining. Filing Code: AL-380. Producer or source: AlcoTec Wire Corporation.

ALCOTEC WELD FILLER WIRE 5654

Abstract AlcoTec Weld Filler Wire 5654 is a nonheatable wire with moderate high-strength capabilities. The principal alloying elements are magnesium, manganese, chromium, and titanium. This datasheet provides information on composition, physical properties, and shear strength. It also includes information on corrosion resistance as well as joining. Filing Code: AL-379. Producer or source: AlcoTec Wire Corporation.

In Situ Repair Welding of Steam Turbine Shroud for Replacing a Cracked Blade

A root-cracked blade in a high-pressure steam turbine of a nuclear power plant had to be replaced with a new blade by cutting the shroud to remove the cracked blade. This necessitated in situ welding of a new shroud piece with the existing shroud after the blade replacement. The in situ welding of the shroud, a 12% Cr martensitic stainless steel with tempered martensite microstructure, was carried out using gastungsten arc welding and 316L austenitic stainless steel filler metal followed by localized postweld heat treatment at 873 K for 1 h using a specially designed electrical resistance-heating furnace. Mock-up trials were carried out to ensure that sound welds could be made under the constraints present during the in situ repair welding operation. In situ metallography of the repair weld after postweld heat treatment confirmed the adequate tempering of the martensitic structure in the heat-affected zone. Metallurgical investigations carried out in the laboratory on a shroud test-piece that had been welded using the same procedure as employed in the field confirmed the success of the in situ repair operation. The alternate option available was replacing the cracked blade and the shroud piece to which it is riveted with a new one, reducing the height of all the blades attached to the shroud by machining, riveting the blades with reduced height to the new shroud, and, finally, dynamic balancing of the entire turbine after completion of the repair. This option is both time-consuming and expensive. Hence, the successful completion of this repair welding resulted in enormous savings both in terms of reducing the downtime of the plant and the cost of the repair. The turbine has been put back into service and has been operating satisfactorily since December 2000.

ALCOTEC WELD FILLER WIRE 5556

Abstract AlcoTec Weld Filler Wire 5556 is a non-heat-treatable wire with very high strength capabilities. The principal alloying elements are magnesium, manganese, chromium, and titanium. This datasheet provides information on composition, physical properties, tensile properties, and shear strength. It also includes information on corrosion resistance as well as joining. Filing Code: AL-378. Producer or source: AlcoTec Wire Corporation.

Some Aspects on Weldability of Aluminium-Lithium Alloy

The effect of welding conditions, technique and filler wire type have been studied to understand their effect on the size and width of nondendritic equiaxed grain of GTA weld in alloy 1441-T8. The microstructure of all the welds exhibited a fusion boundary equiaxed zone (EQZ). In addition to heat input, filler wire type and welding technique are found to have considerable effect on the grain size and width of EQZ.

Analysis of residual stresses and distortions in T-joint fillet welds

T-joint fillet welds are extensively used in ship engineering and bridge structures. Localized heating from the welding process and subsequent rapid cooling induce tensile residual stress near the toe of the T-joint in fillet welds. Welding produces thermal stresses that cause structural distortions, which influence the buckling strength of the welded structures. This study describes the thermal elasto-plastic analysis using finite element techniques to analyse the thermomechanical behaviour and evaluate the residual stresses and angular distortions of the T-joint in fillet welds. Furthermore, this work employs the technique of element birth and death to simulate the weld filler variation with time in T-joint fillet welds. Also discussed are the effects of flange thickness, welding penetration depth, and restraint condition of welding on the residual stresses and distortions.

Fracture Toughness Requirements for ASME Section VIII Vessels for Temperatures Colder Than 77K

Earlier research work conducted at MIT and NIST indicated that CVN specimens with an initial temperature at or near 4K (−452°F) actually fracture at temperatures significantly above 4K due to adiabatic heating. As a result of this work, ASTM E-23 test method on CVN testing was revised to incorporate a restriction that CVN tests are valid only at 77K (−320°F) and warmer. ASME requested PVRC to assess the above CVN issue and provide an appropriate recommendation for the Code change or for a further Code change, if needed for vessels with MDMT colder than 77K. PVRC formed a Task Group under the Committee on Failure Modes. The TG undertook a program which included a review of the existing data and an experimental program to develop new KIcJ data at 4K and 77K and CVN data at 77K. In the experimental program, a total of four 1-in-thick weldments were prepared from SA 240, Type 304 stainless steel plate using the SMAW process and E316L-15 electrodes. The electrodes purchased permitted the preparation of the weldments with four progressively higher levels of ferrite. The PVRC data and existing data were utilized in developing the recommendations to ASME. The recommendations are: use CVN tests (with 316L S.S. weld filler metal with FN⩽5) at 77K with increased acceptance criterion of 21 mils lateral expansion; for welds not meeting the foregoing requirements, use ASTM E1820 JIc tests at MDMT and the acceptance criterion for KIcJ has been set at 120 ksi√in. This paper presents the test data, analysis and technical basis for the PVRC recommendations to ASME.

Subsurface properties of laser peened 6061–T6 Al weldments

A high power Q switched laser system has been used to laser shock process or ‘laser peen’ heat affected zones in a welded 6061–T6 aluminium alloy specimen. The effect of laser peening on hardness and elastic modulus versus depth and location with respect to the weld centre of the 6061–T6 specimen with 5083 and 5356 weld filler alloys has been analysed. Two laser energy densities, 100 and 200 J cm-2, with water as a containment layer, were used to laser peen the metal specimen. In addition to increasing the hardness of the metal the treatment also affected the elastic modulus, and the affected depth varied with respect to the distance from the weld centre.

HAYNES 230-W FILLER WIRE

Abstract Haynes 230-W Filler Wire is a specially formulated welding filler metal designed for the fabrication of Haynes 230 alloy (see Alloy Digest Ni-320, August 1985). This datasheet provides information on composition, physical properties, elasticity, and bend strength. It also includes information on joining. Filing Code: Ni-558. Producer or source: Haynes International Inc.