Murray W. Mahoney's research while affiliated with Midway College and other places
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Publications (51)
In the present work, a thick-sectioned multilayered steel structure was fabricated by multipass friction stir welding on A516 Grade 70 steel. Tensile strength of the multilayered samples was comparable to that of the base metal. Failure was located in the base metal when a defect-free sample was tested. Charpy impact toughness was higher in the sti...
Friction stir welding (FSW) has recently attracted attention as an alternative construction process for gas/oil transportation applications due to advantages compared to fusion welding techniques. A significant advantage is the ability of FSW to weld the entire or nearly the entire wall thickness in a single pass, while fusion welding requires mult...
Friction stir welding (FSW) has recently attracted attention as an alternative construction process for gas/oil transportation applications due to advantages compared to fusion welding techniques. A significant advantage is the ability of FSW to weld the entire or nearly the entire wall thickness in a single pass, while fusion welding requires mult...
A multilayered multipass friction stir weld (MMFSW) on ASTM A572 Grade 50
steel was characterized to understand its potential application for thicksection structures.
The 15mmthick section was fabricated by stacking three steel plates and then
friction stir welding the plates together in a total of five passes. The unique butt/lap
joint configu...
Friction stir welding (FSW) offers both economic and technical advantages over conventional fusion welding practices for welding line-pipe. For offshore line-pipe construction, the economic savings has been shown to be considerable, approaching a calculated 25%. Offshore pipe is relatively small diameter but heavy wall compared to onshore pipe. One...
Friction Stir Welding (FSW) is being investigated as a method to fabricate a partial penetration closure weld of the steel vessel of a copper-coated used fuel container. The hemi-head is made of A516 Grade 70 steel and the cylinder body is made of A106 Grade C steel. In this initial feasibility study, the objective is to use FSW to demonstrate the...
Multilayered multipass friction stir welding (MM-FSW) makes it possible to use FSW to fabricate thick-section structures. In this work, MM-FSW was demonstrated on a high strength low alloy steel; ASTM A572 Grade 50. Three steel plates with thicknesses of 0.18'', 0.18'', 0.24'' respectively were stacked and friction stir welded together to form a 0....
Microstructures and mechanical property changes associated with Friction Stir Processing (FSP) of HY-80 steel both dry and under seawater were examined. FSP on HY-80 plates employed a PCBN / tungsten rhenium tool operating at 400 rpm and 2 ipm. Microstructural characterization of the as-received HY-80 plate emphasized the differences in the distrib...
The oxide dispersion strengthened steel MA956 was friction stir welded using eight different rotational speed/translational speed combinations using a polycrystalline cubic boron nitride tool. Weld parameter conditions with high thermal input produced defect-free, full penetration welds. Electron backscatter diffraction showed a significant increas...
In prior FSW studies, consistent full penetration in pipeline steel has proved to be a difficult goal when using a portable FSW system capable of operation in the field [1]. In a previous study, metallography, mechanical testing (tensile and Charpy impact), and workmanship testing (root bend) demonstrated that full penetration can be achieved throu...
Microstructures and mechanical property changes associated with Friction Stir Processing (FSP) of HY-80 steel both dry and under seawater were examined. FSP on HY-80 plates employed a PCBN / tungsten rhenium tool operating at 400 rpm and 2 ipm. Micro structural characterization of the as-received HY-80 plate emphasized the differences in the distri...
Multilayered multipass friction stir welding (MM-FSW) makes it possible to use FSW to fabricate thick-section structures. In this work, MM-FSW was demonstrated on a high strength low alloy steel; ASTM A572 Grade 50. Three steel plates with thicknesses of 0.18", 0.18", 0.24" respectively were stacked and friction stir welded together to form a 0.6"...
Recent advances in FSW tool material and design will facilitate numerous applications of this solid-state joining technology to steels. A single W-Re-CBN tool was used to conduct a series of bead-on-plate FSW traverses, approximately 1.5m in total length, on 6.3mm thick plates of a hardenable alloy steel. The first series of traverses involved vari...
Objective Background Experimental Procedures Results Conclusions
As Friction Stir Welding (FSW) broadens its applications, the need for portable equipment has arisen. Minimizing both loads and torque is necessary to fabricate a truly versatile and portable FSW system. In order to do this, a tool study was performed to find the minimum loads needed to make a defect free weld in order to minimize the weight and lo...
Friction stir welding (FSW) is a solid state joining process providing many advantages over typical arc welding processes. Although initially developed for low melting point materials such as aluminum alloys, recent developments in tool materials have enabled FSW to be applied to higher melting temperature materials such as alloys of steel and stai...
The microstructural and mechanical property evolution of friction stir welded 7050-T7651 and 7075-T651 Al alloys were examined as a function of room temperature (natural) aging for up to 67,920 h. During the range of aging times studied, transverse tensile strengths continuously increased, and are still increasing, with improvements of 24% and 29%...
The stir zone (SZ) temperature cycle was measured during the friction stir processing (FSP) of NiAl bronze plates. The FSP
was conducted using a tool design with a smooth concave shoulder and a 12.7-mm step-spiral pin. Temperature sensing was accomplished
using sheathed thermocouples embedded in the tool path within the plates, while simultaneous o...
Friction stir welding (FSW) offers many potential benefits including reduced distortion, lower cost, no harmful airborne emissions, semi-automated, etc. Although initially developed for Al alloys, considerable work now has been completed to explore the ability of FSW to weld relatively thin (6 mm) ferrous alloys including many alloys of interest to...
Friction stir welding (FSW) has a broad field of applications in the aerospace, auto, oil and gas drilling, oil pipelines, shipyard, and nuclear industries. For ferrous alloys, FSW tool material development is at the heart of the advancement of this novel joining technique. Polycrystalline cubic boron nitride (PCBN) materials, produced via high pre...
Friction stir processing (FSP) was conducted on a wrought plate of AA2099 to refine and homogenize the microstructure and
enhance the through-thickness ductility and fracture resistance. Optical microscopy (OM), orientation imaging microscopy (OIM),
and transmission electron microscopy (TEM) methods were employed to evaluate microstructure and micr...
Our objective is to demonstrate a practical approach for friction stir welding (FSW) of "T" joints in long lengths of HSLA-65 steel. Friction stir welding of HSLA-65 steel offers challenges but achieving a defect-free weld in a "T" joint geometry in HSLA-65 steel is even more challenging. In addition to producing a sound weld nugget, the "T" fillet...
Friction stir processing (FSP) of cast NiAl bronze has resulted in significant increases in properties including more than doubling the yield greater that 40 percent increase in the threshold fatigue life; all achieved while increasing ductility. These and other strength, greater than a 60 percent increase in tensile strength, and property improvem...
Friction stir processing (FSP) produced local microstructural refinement in cast Ni Al Bronze. The refined microstructure quality was evaluated with mechanical property characterization using monotonic tension and fatigue testing as a function of FSP raster patterns. Modifying the cast NiAl bronze with FSP resulted in a 140 - 172 % increase in yiel...
Friction stir processing (FSP) is used locally to modify the microstructure and thus mechanical properties of 5083-H321/5356
aluminum gas metal arc welds (GMAWs). Four specimen approaches were examined: as-arc welded, weld toe FSP (with arc weld on
either the advancing or the retreating side of tool), and weld crown FSP. Microstructures within the...
Friction stir welding (FSW) as an alternative to brazing can be used for fabricating microwave waveguide structures. The FSW fabrication process is described, and the transmission and reflection of the straight sections of aluminum K-band waveguide made by FSW and brazing are compared. The section made by FSW exhibits 0.04 dB lower transmission and...
Friction-stir processing (FSP) was used to modify surface microstructures, to enhance the bending of thick-plate 6061-T6 and
7050-T7451 aluminum alloys. Plates were bent at room temperature into a V-shaped die, to various angles. Bending performance
in the friction-stir-processed plates was significantly better than that in the base plates, where p...
Friction-stir processing (FSP) is an emerging surface-engineering technology that can locally eliminate casting defects and refine microstructures, thereby improving strength and ductility, increase fatigue and corrosion resistance, enhance formability, and improve wear resistance. The technology involves plunging a rotating (100-1200 RPM), non-con...
The effect of friction stir processing on the superplastic behavior of extruded Al-4Mg-1Zr was examined at 350 °C to 600 °C
and at initial strain rates of 1×10−3 to 1 s−1. A combination of a fine grain size of 1.5 μm and high-angle grain boundaries in the friction stir-processed (FSP) alloy led to considerably enhanced superplastic ductility,
much-...
High melting temperature materials, including steels, stainless steels, and nickel base alloys, are used extensively in the oil and gas industry for structural components, tubular products and many other applications. The selection of a material for a given application is driven by the service and safety requirements. The service requirements for t...
Superplasticity was investigated in friction stir processed A356 alloy at temperatures of 470–570 °C and initial strain rates of 3×10−4–1×10−1 s−1. Maximum superplastic elongation of 650% was obtained at 530 °C and an initial strain rate of 1×10−3 s−1 where a maximum strain rate sensitivity of 0.45 was observed.
Since the invention of Friction Stir Welding (FSW) in 1991, an increasing number of successful applications have been found for this unique solid-state welding technique. More recently, attention has been given to utilizing the mechanics of friction stirring to thermo-mechanically modify the microstructure of aluminum alloys to create or enhance su...
Friction stir processing (FSP) is being developed as a metal working tool to heal casting defects and modify microstructures in a cast NiAl bronze (NAB) alloy for the purpose of substantially increasing mechanical properties. The initial microstructural evolution and resultant mechanical properties for the variety of microstructures created by FSP...
Friction stir processing (FSP) is a new solid state processing technique for microstructural modification in metallic materials. FSP has been applied to cast aluminum alloy A356 plates to modify the microstructure to enhance mechanical properties. FSP broke up and dispersed the coarse acicular Si particles creating a uniform distribution of Si part...
Al–4Mg–1Zr extruded bar was subjected to friction stir processing (FSP), resulting in generation of a fine microstructure of 1.5 μm grain size. Superplastic deformation behavior of FSP Al–4Mg–1Zr alloy was investigated in strain rate range of 1×10−3 to 1 s−1 and temperature range of 350–550°C and compared with that of as-rolled one. It is indicated...
The grain structure, dislocation density and second phase particles in various regions including the dynamically recrystallized zone (DXZ), thermo-mechanically affected zone (TMAZ), and heat affected zone (HAZ) of a friction stir weld aluminum alloy 7050-T651 were investigated and compared with the unaffected base metal. The various regions were st...
Friction stir processing (FSP) can be used to locally tailor the microstructure to enhance specific properties. In this work, FSP has been applied to cast aluminum plates to modify the microstructure to improve mechanical properties. The influence of FSP parameters on microstructural changes and microstructure-mechanical property correlations is de...
Diffusion bonding/superplastic forming (DB/SPF) is an established fabrication technology for titanium aerospace components. However, DB cannot be applied easily to aluminum alloys because of tenacious surface oxides. Friction stir welding may eliminate this problem and allow fabrication of multi-sheet structures via friction stir welding/SPF.
Commercial 7075Al rolled plates were subjected to friction stir processing (FSP) with different processing parameters, resulting in two fine-grained 7075Al alloys with a grain size of 3.8 and 7.5 μm. Heat treatment at 490 °C for 1 h showed that the fine grain microstructures were stable at high temperatures. Superplastic investigations in the tempe...
Superplasticity is achieved in thick section aluminum alloys using a unique thermo-mechanical metal working process based on the friction stir welding process. The process offers the potential to form complex shaped parts at a higher strain rate and in section thicknesses not possible using conventional superplasticity processing.
Friction stir (FS) processing of nanophase aluminum alloys led to high strength, approximately 650 MPa with good ductility above 10%. Improvements in ductility were due to a significantly improved homogenization of the microstructure during FS processing. The FSP technique is amenable to produce ductile, very high specific strength aluminum alloys,...
Friction stir processing is a new thermo-mechanical processing technique that leads to a microstructure amenable for high strain rate superplasticity in commercial aluminum alloys. Friction stirring produces a combination of very fine grain size and high grain boundary misorientation angles. Preliminary results on a 7075 Al demonstrate high strain...
This work demonstrates friction stir processing as a thermomechanical process to create a fine grain microstructure in 7050 T7651 Al resulting in high strain rate (>10-3), thick section (>5mm) superplasticity. Elements of process control and microstructural evolution are characterized. Superplastic behavior is illustrated as a function of test cond...
Friction stir welding (FSW) and friction stir processing (FSP) produce a fine grained 'nugget' region. The microstructural refinement and uniformity depends on processing parameters and tool design. During post-processing at high temperatures, friction stir processed 7050 and 2519 aluminum alloys show abnormal grain growth not reported previously....
Friction stir welding (FSW) is a solid state joining technique. This makes it an attractive joining method for aluminum alloys and composites produced by a powder metallurgy route. In this study, the mechanical behavior of both a powder metallurgy monolithic aluminum alloy and composite were evaluated, i.e., IN 9052 and 7093 Al-SiC. Mini-tensile sp...
In this paper, the authors report the first results using friction stir processing (FSP). In the last ten years, a new technique of Friction Stir Welding (FSW) has emerged as an exciting solid state joining technique for aluminum alloys. This technique, developed by The Welding Institute (TWI), involves traversing a rotating tool that produces inte...
Metallic materials may be joined utilizing a friction stir processing technique. The friction stir processing technique utilizes a shaped, rotating tool to move material from one side of the joint to be welded to the other without liquefying the base material.
Citations
... Compared to the studies mentioned above in which two superimposed and welded sheets were investigated, an FSW joint made of three superimposed steel sheets was investigated in [13] to understand the effect of the direction of the tool rotation on the joint quality, especially in terms of the formation of hooking defects [14]. Three ultrathin aluminum alloy sheets, each having a thickness of 0.254 mm [15], were superimposed and welded by using micro friction stir welding before being experimentally tested. ...
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... The welded joint's tensile strength was about 62% of the base metal at conditions of 630 rpm and 1 mm/s as rotational speed and travel speed respectively. The FSW of Stainless-steel pipes was considered in [14] while Hattingh et al. [15] investigated the semiautomatic FSW of Aluminum 6082 tubes. AA6063 pipes butt joints were considered for studying the effect of rotational and traverse speed by Ismail et al. [16]. ...
... Friction stir welding (FSW), which is a solid state joining process, have been considered to be a promising way to weld ODS alloys [6]. The related work concerning the FSW of high-Cr ODS steels has shown that the microstructural evolution in the joint is characterized and dominated by the continuous dynamic recrystallization (CDRX) [9][10][11]. The CDRX is activated and promoted by the mechanical force imposed by the stir tool. ...
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... Due to its excellent weldability, this steel finds extensive use in the fabrication of steam generating plants, superheater tubes, piping, pressure vessels, storage tanks and low-pressure heat exchanger. ASTM A 516 grade 70 steel is often used for boilers [1]. ...
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... Moreover, this material possesses low toughness due to which brittle failure occurs. However, these tools are very hard, have high melting point, good strength at high temperature and lower coefficient of thermal expansion [267,273]. On comparing PCBN and WC, it can be said that PCBN is a much harder material, while WC has comparatively good fracture toughness. Rai et al. [267] reported that these materials possess lower coefficient of thermal expansion with approximately identical thermal conductivity. ...
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... He added Mg to increase strength through solid solution and improve strain-hardening ability. [13] experiment dwelled on superplastic forming response in AA7075 aluminum at approximately 516 o C in a 5-mm thick aluminum alloy. [1] produced an alloy having 4 % zinc by weight and varied composition of Magnesium by weight, [3] experimented on three different Al-Cu alloys of 3,6 and 9 w.t.% Cu and tested both mechanically and chemically. ...
... Hardness of such materials are in the range 30-34 GPa, depending on the amount of cBN in the composite. 1 Cubic boron nitride materials could also be produced through a so-called "catalytic approach" from hexagonal boron nitride (hBN), using Mg or Li as catalysts. In this process, low melting temperature eutectics are thought to form and to facilitate cBN nucleation and crystal growth through dissolution-reprecipitation mechanism. ...
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... Çeliklerin sürtünme karıştırma kaynağı esnasında mikroyapıda oluşan kalıntı gerilmeler ve çarpılma sınırlıdır ve düşük ısı girdisi sayesinde ısı etkisi altındaki bölgede tane büyümesi en düşük seviyede tutulmaktadır [7][8][9]. Son yıllarda bazı araştırmacılar sürtünme karıştırma kaynağının çevre dostu oluşu, enerji verimliliği ve metalürjik avantajlarından dolayı yüksek mukavemetli çeliklerin birleştirilebildiği üzerine çalışmalar yapmaktadır [10,11]. ...
... Mishra et al [6,8] reported the optimum superplastic strain rate to be 10 -2 s -1 at 490 °C achieved in FS processed AA 7075 sheet. Also Mahoney et al [9] presented friction stir processing as a thermo-mechanical process to create a fine grain microstructure in thick section ...
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... As stated above, reports in the literature regarding the presence or presence of various zones in the vicinity of the weld are ambiguous. According to Mishra and Mahoney [16], the history of the FSW nomenclature was as follows. Early in the development of FSW, the term TMAZ referred to the region between the SZ and the HAZ. ...
