Abdullah Qaban

Bio: Abdullah Qaban is an academic researcher from City University London. The author has contributed to research in topics: Grain boundary & Twip. The author has an hindex of 4, co-authored 13 publications receiving 64 citations.

Current research and development status of dissimilar materials laser welding of titanium and its alloys

Abstract: Since its inception, laser beam welding as a high-quality fusion joining process has ascertained itself as an established and state of art technology exhibiting tremendous growth in a broad range of industries. This article provides a current state of understanding and detailed review of laser welding of titanium (Ti) alloys with corresponding dissimilar counterparts including steel, aluminium, magnesium, nickel, niobium, copper, etc. Particular emphasis is placed on the influence of critical processing parameters on the metallurgical features, tensile strength, hardness variation, percentage elongation and residual stress. Process modifications to improve dissimilar laser weldability by virtue of techniques such as laser offsetting, split beam, welding-brazing, hybrid welding and materials modifications by means of the introduction of single or multiple interlayers, fillers and pre-cut grooves are exploited. Detailed and comprehensive investigations on the phenomena governing the formation and distribution of the intermetallic phase, material flow mechanisms, their relations with laser parameters and their corresponding impact on the microstructural, geometrical and mechanical aspects of the welds are thoroughly examined. The critical issues related to the evolution of defects and the corresponding remedial measures applied are explored and the characteristics of fracture features reported in the literature are summarised in thematic tables. The purpose of this review is tantamount to emphasise the benefits and the growing trend of laser welding of Ti alloys in the academic sector to better exploit the process in the industry so that the applications are explored to a greater extent.

A comprehensive assessment of laser welding of biomedical devices and implant materials: recent research, development and applications

Abstract: This review comprehensively covers the research accomplished in the field of laser welding of biomedical devices and implant materials. Laser welding technology in the recent past has been ...

Hot ductility of high Al TWIP steels containing Nb and Nb-V

Abstract: The hot ductility of B-Ti-Nb-high Al (1.5%Al) containing TWIP steels having Ti/N ratios mainly in excess of 3.4/1 was obtained. After soaking at 1250°C, the tensile specimens were cooled at 12 or 60°C min−1 to the test temperature and then strained to failure at 3 × 10−3 s−1. Ductility was always good (reduction of area >40%), independent of Ti/N ratio or cooling rate. The good ductility is due to B segregation strengthening the grain boundaries and the low S level (0.005%S) limiting the volume fraction of MnS inclusions and restricting AlN precipitation to the matrix. Increasing the cooling rate, higher N levels and Nb resulted in a small improvement in ductility. An addition of V to the Nb-containing steels caused a slight deterioration in the hot ductility.

Understanding the high temperature side of the hot ductility curve for steels

Abstract: The study tests the validity of the tensile hot ductility test for assessing cracking during the straightening operation. Steels with a thin film of deformation induced ferrite (DIF) or fully auste...

The effect of Al and Nb contents, cooling rate and rolling condition on the microstructure and corrosion behaviour of HSLA steel

Abstract: The effect of the addition of aluminium and niobium, and processing conditions, including cooling rate and rolling condition, on the corrosion behaviour of HSLA steel in 10 wt% sulfuric acid environment has been investigated The experimental procedures included electrochemical corrosion techniques using potentiodynamic and electrochemical impedance spectroscopy, as well as weight loss method The microstructure was examined using optical and scanning electron microscopes in order to investigate the effect of the microstructural features on the corrosion behaviour Surface films were evaluated by X-ray photoelectron spectroscopy (XPS) to identify the corrosion products formed on the surface The results showed that increasing the Al content enhanced the corrosion resistance through obstructing pitting attack on the surface by the refinement of grain boundary carbides and the formation of a protective passive layer rich in carbide and oxide compounds The combination of both Al and Nb promoted the corrosion resistance further, by enriching the passive layer with Nb and higher levels of carbide and oxide compounds, despite the presence of martensite and grain size refinement by niobium carbonitride (NbCN) Increasing the cooling rate reduced the corrosion resistance due to the refinement of grain size, giving a higher density of grain boundaries that act as active sites, besides increasing the level of carbide distribution in the microstructure Controlled rolling offered higher corrosion resistance than hot rolling, independent of the composition, because of the absence of martensite, the presence of low-angle boundary and the refinement of grain boundary carbides provided by controlled rolling

Autogenous Fiber Laser Welding of 316L Austenitic and 2304 Lean Duplex Stainless Steels

Abstract: This study presents results of experimental tests on quality of dissimilar welded joints between 316L austenitic and 2304 lean duplex stainless steels, welded without ceramic backing. Fiber laser welded butt joints at a thickness of 8 mm were subjected to non-destructive testing (visual and penetrant), destructive testing (static tensile test, bending test, and microhardness measurements) and structure observations (macro- and microscopic examinations, SEM, element distribution characteristics, and ferrite content measurements). Non-destructive tests and metallographic examinations showed that the welded joints meet the acceptance criteria for B level in accordance with EN ISO 13919–1 standard. Also the results of the destructive tests confirmed the high quality of the joints: specimens were fractured in base material with lower strength—316L austenitic stainless steel and a 180° bending angle was obtained confirming the high plasticity of the joints. Microscopic examination, SEM and EDS analysis showed the distribution of alloying elements in joints. The microhardness of the autogenous weld metal was higher by about 20 HV0.2 than that of the lean duplex steel. Ferrite content in the root was about 37% higher than in the face of the weld. The Schaeffler phase diagram was used to predict the phase composition of the welded joints and sufficient compliance with the magnetic method was found. The presented procedure can be used for welding of 316L–2304 stainless steels dissimilar welded joints of 8 mm thickness without ceramic backing.

Laser Dissimilar Welding of AISI 430F and AISI 304 Stainless Steels.

Abstract: A dissimilar autogenous laser welded joint of AISI 430F (X12CrMoS17) martensitic stainless steel and AISI 304 (X5CrNi18-10) austenitic stainless steel was manufactured. The welded joint was examined by non-destructive visual testing and destructive testing by macro- and microscopic examination and hardness measurements. With reference to the ISO 13919-1 standard the welded joint was characterized by C level, due to the gas pores detected. Microscopic observations of AISI 430F steel revealed a mixture of ferrite and carbides with many type II sulfide inclusions. Detailed analysis showed that they were Cr-rich manganese sulfides. AISI 304 steel was characterized by the expected austenitic microstructure with banded δ-ferrite. Martensitic microstructure with fine, globular sulfide inclusions was observed in the weld metal. The hardness in the heat-affected zone was increased in the martensitic steel in relation to the base metal and decreased in the austenitic steel. The hardness range in the weld metal, caused by chemical inhomogeneity, was 184–416 HV0.3.

Investigation of Coatings, Corrosion and Wear Characteristics of Machined Biomaterials through Hydroxyapatite Mixed-EDM Process: A Review.

Abstract: Together, 316L steel, magnesium-alloy, Ni-Ti, titanium-alloy, and cobalt-alloy are commonly employed biomaterials for biomedical applications due to their excellent mechanical characteristics and resistance to corrosion, even though at times they can be incompatible with the body. This is attributed to their poor biofunction, whereby they tend to release contaminants from their attenuated surfaces. Coating of the surface is therefore required to mitigate the release of contaminants. The coating of biomaterials can be achieved through either physical or chemical deposition techniques. However, a newly developed manufacturing process, known as powder mixed-electro discharge machining (PM-EDM), is enabling these biomaterials to be concurrently machined and coated. Thermoelectrical processes allow the migration and removal of the materials from the machined surface caused by melting and chemical reactions during the machining. Hydroxyapatite powder (HAp), yielding Ca, P, and O, is widely used to form biocompatible coatings. The HAp added-EDM process has been reported to significantly improve the coating properties, corrosion, and wear resistance, and biofunctions of biomaterials. This article extensively explores the current development of bio-coatings and the wear and corrosion characteristics of biomaterials through the HAp mixed-EDM process, including the importance of these for biomaterial performance. This review presents a comparative analysis of machined surface properties using the existing deposition methods and the EDM technique employing HAp. The dominance of the process factors over the performance is discussed thoroughly. This study also discusses challenges and areas for future research.

A comprehensive assessment of laser welding of biomedical devices and implant materials: recent research, development and applications

Abstract: This review comprehensively covers the research accomplished in the field of laser welding of biomedical devices and implant materials. Laser welding technology in the recent past has been ...