Manuel Marya

Steel-to-Aluminum Joining by Control of Interface Microstructures - Laser-Roll Bonding and Magnetic Pulse Welding -

Laser-roll bonding and magnetic pulse welding are two relatively new processes that greatly minimize problems of metallurgical incompatibilities between dissimilar metals and alloys. These two processes, though technologically apart and invented for components with distinct geometries, utilize to various extents high pressures to facilitate rapid and localized interfacial heating and create reliable joints. In this paper, relations between process parameters, microstructures, and properties are discussed for aluminum-to-steel joints made by laser-roll bonding and magnetic pulse welding.

A Brief Review of Challenges & Technologies to Weld Dissimilar Metals in Two Industries: The Upstream Oil & Gas and the Automotive

In both Oil & Gas (OG) and automotive industries, welding is an essential part of fabrication routes and the challenges in welding metallic materials are frequently similar. Processes that are fast, robust, and therefore tolerate variations in process parameters (including operators for manual processes) and materials (i.e. compositions and properties) are important to reproduce high weld quality and facilitate non-destructive examinations (NDE). New grades of high-strength alloys, required to be weldable by common processes and preferably without post-weld heat treatments, are not only needed by both industries, but dissimilar-metal welding is also becoming unavoidable, thereby demanding for novel processes with either low heat inputs or high-energy densities. In this paper, technologies for dissimilar-metal welding are examined in reference with both OG and automotive applications.

Microstructures and Mechanical Properties of an Artificially-Aged Al-Mg-Ga Alloy

The microstructures of an Al-Mg-Ga cast alloy have been investigated to fundamentally understand its hardening response during heat-treatment. In as-cast, solution heat-treated, and aged conditions, the alloy is characterized by having a variety of metallurgical phases with unique morphologies and chemical compositions. Micro-hardness indentations subsequent to artificial aging between 50°C and 300°C revealed that the investigated Al-Mg-Ga alloy is capable of Vickers hardness values in excess of 180, therefore demonstrating a remarkably elevated age hardening behavior relative to conventional aluminum alloys. SEM and TEM observations, coupled with DSC analysis with several aging conditions, revealed that hardening is induced by submicron platelet precipitates having the length, width, and density that depend largely on the alloy aging conditions.

Transition Microstructures and Properties in the Laser Additive Manufacturing Repair of Monel K-500 (UNS N05500) and Toughmet 3AT (UNS C72900)

The laser powder-fed additive manufacturing (AM) of Alloy 625 (UNS N06625) on two heat-treatable, high-strength, and copper-rich alloys, such as Monel K-500 (UNS N05500) and Toughmet 3AT (UNS C72900), has been investigated to determine the suitability of AM for the repair of high-value oilfield parts requiring good machinability, magnetic transparency, anti-galling resistance, and general corrosion resistance. In contrast to conventional laser cladding, AM deposition rates can be greatly reduced to minimize thermal effects, chemical dilution, and number of powder-fed deposits, while still producing a top surface that fully meets Alloy 625 specification. This paper presents and discusses test results from microstructural analyses, chemical composition, electron-backscatter diffraction (EBSD), and microhardness indentation measurements on both Monel K-500 and Toughmet 3AT.

Surface Property Enhancement of UNS N07718 and G41400 by Ultrasonic Impact Treatment

Ultrasonic impact treatment is a relatively new surface modification process that may be potentially applied to impart compressive residual stresses onto oilfield parts experiencing wear, fatigue, and possibly environmentally-assisted cracking. Through severe plastic deformation, ultrasonic impact treatment is herein investigated to surface harden two oilfield alloys, UNS N07718, a premium alloy with satisfactory oilfield performance but occasionally lacking surface hardness and abrasive wear resistance, and UNS G41400, a comparatively low-cost alloy restricted by its corrosion fatigue limit in oilfield rotating equipment. For comparison purposes, the two studied alloys were ultrasonic impact treated under identical conditions and carefully selected to exhibit similar yield strengths (900 MPa). Results from microstructural examinations, micro-hardness indentations, and residual stress measurements all indicate that ultrasonically treated surfaces exhibit superior properties that create opportunities for implementing this new surface modification process in selected oilfield applications.

Comparative Performance of Three High-Strength Ni-Cr-Mo Alloys in Oilfield Simulated H2S Environment

Three Ni-Cr-Mo alloys with 140ksi minimum yield strength, namely 625Plus, 718, and 945X were tested in selected sour environments to evaluate and rank their environmentally-assisted cracking susceptibility. The testing revealed that none of the alloys, stressed to 90% of their actual yield point, cracked as a result of an agressive 30-day NACE level VII-modified environment (401 ± 9 oF, 500 psia H2S, 500 psia CO2 and 151,700 mg/liter chlorides). In a complementary attempt to rank the alloy cracking susceptiblity, quasi-static strain rate (SSR) tests per NACE TM0198-2004 were conducted in a modified H2S-saturated NACE TM0177 Solution A. Following a critical analysis of parameters such as time-to-failure (TTF), percentage reduction in ductility (%ε), percentage reduction of cross-sectional area (% RA) and fractomicrographs, 625Plus was confirmed to outperform its counterparts while some evidence of hydrogen embrittlement was found on 945X.

Advanced Degradable Alloys for Multi-Stage Fracturing Applications

New aluminum alloys with unique mechanical and electrochemical properties have been developed in response to a strong demand for new technologies tailored to the expanding hydrocarbon multi-stage fracturing market. The novel alloys disclosed in this paper purposely possess an augmented degradability in water-based oilfield fluids, an unusually high hardness and high compressive strength following proper processing while withstanding thermal aging in wellbore environments. In highlighting major findings from years of research in developing new alloys, this paper overviews major characteristics of these novel alloys from microstructural development, processing, mechanical properties, and electrochemical response in oilfield fluids such as salinated water (brine), acids, and cross-linked fracturing fluids.

Microstructural Features and Age Hardening in an Al-Mg-Ga Sacrificial Anode Alloy

Novel aluminum alloys enriched with magnesium and gallium alloys have recently found oilfield applications owning to unique combination of mechanical & electrochemical properties. In this investigation, the microstructural evolution and artificial ageing response of a cast Al-Mg-Ga alloy have been investigated. In as-cast and solution & aged heat-treat conditions, the novel alloy is shown to exhibit a variety of metallurgical phases with profoundly unusual morphologies. Hardness surveys, conducted on specimens aged between 100 °C and 300 °C also demonstrated the alloy was not only surprisingly thermally-stable, but also able to age harden greatly, consistently exhibiting Vickers hardness numbers in excess of 180 following 100-to-120 °C ageing cycles. In the aged alloys, complementary x-ray examinations revealed a number of binary intermetallic phases (e.g., Mg5Ga2, Mg2Ga5, MgGa2, and Mg2Al3) that were found to be partly or fully responsible for the significant age-hardening observed in this novel alloy.