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The paper aims to present new technique to fusion the glasses, by using the microwaves as thermal source to put the materials in fusion state. Microwaves are high frequency electromagnetic waves (usually 2.45 GHz) produced by specific generator usually known as magnetron. The interaction between the microwaves and different classes of materials produces the heating of the materials. The paper shortly presents the results of exhaustive study on the behaviour of the glasses which are exposed to the microwaves in order to weld them. [ABSTRACT FROM AUTHOR]

The paper deals with the seismic behaviour of column bases and beam-to-column joints made with high strength steel tubular columns subject to seismic loading. A test programme was carried out at the University of Trento with the aim of evaluating the seismic performance of these joints under monotonic, cyclic and random loads. With these load protocols, it was possible to assess the activation and location of plastic hinges and the stiffness and resistance of beam-to-column joints and column bases, as well as to quantify the ductility behaviour of some joint components. The cyclic tests were performed by employing a standard loading protocol and the random tests utilised displacements provided by Finite Element based simulations of a five-storey steel-concrete composite building subject to seismic loading. The paper reports and describes experimental tests on both beam-to-column joint and column bases. [ABSTRACT FROM AUTHOR]

The chemical process industries use a variety of equipment which sometimes requires the use of clad plates. These clad plates use carbon or low-alloy steel for the main structural or pressure-containing load bearing requirements and are clad on one side with a corrosion resistant material. These plates can be bonded through either high temperature roll bonding or by explosion cladding. After the cladding process a heat treatment is required to stress relieve the carbon or low-alloy steel and is required by either application requirements or by design code (such as ASME). Heat treating the clad plates will have an effect on the corrosion resistant clad layer and needs to also be considered. This paper will focus on the heat treat requirements of various substrate materials and how these impact nickel alloys used for the corrosion resistant clad layers. The use of standard laboratory corrosion tests to verify the corrosion resistance of the clad layer after heat treating is also reviewed here [ABSTRACT FROM AUTHOR]

In this paper, we propose a J-groove dissimilar weld crack visualization system based on ultrasonic propagation imaging (UPI) technology. A full-scale control rod drive mechanism (CRDM) assembly specimen was fabricated to verify the proposed system. An ultrasonic sensor was contacted at one point of the inner surface of the reactor vessel head part of the CRDM assembly. Q-switched laser beams were scanned to generate ultrasonic waves around the weld bead. The localization and sizing of the crack were possible by ultrasonic wave propagation imaging. Furthermore, ultrasonic spectral imaging unveiled frequency components of damage-induced waves, while wavelet-transformed ultrasonic propagation imaging enhanced damage visibility by generating a wave propagation video focused on the frequency component of the damage-induced waves. Dual-directional anomalous wave propagation imaging with adjacent wave subtraction was also developed to enhance the crack visibility regardless of crack orientation and wave propagation direction. In conclusion, the full-scale specimen test demonstrated that the multiple damage visualization tools are very effective in the visualization of J-groove dissimilar weld cracks. [ABSTRACT FROM AUTHOR]

The synergistic effects of niobium and molybdenum in lowering austenite-to-ferrite transformation temperatures have been known for approximately 45 years. The benefits have been widely exploited in linepipe steels since 1971 when 485 MPa (X70) linepipe produced by IPSCO [1] was installed in Canada in the TransCanada and Novacorp gas transmission systems. At that time the steels were cast as semi-killed ingots and had inferior transverse Charpy properties due to the presence of MnS and silicate inclusions. Other applications have been found in hot-rolled long products [2] and Nippon Steel's HT80 quenched and tempered plate [3,4], As linepipe yield strengths have increased to X80, X100 and above, and carbon contents have been reduced to 0.03-0.06 percent, the Nb-Mo combination has become indispensable for producing economical steels when used in combination with chromium, copper and nickel. This paper provides a brief chronology o f the adoption of Nb-Mo and Nb-Mo-B alloying since the mid 1960s. [ABSTRACT FROM AUTHOR]

The developments of steel structures aim at light and slender constructions. Therefore, high-strength steels with good welding characteristics and a high ductility, aside from higher strength, have been developed by the steel industry. With increasing strength of the steel, the loads which have to be transferred in the welded connections are also growing. In building constructions, fillet and partial penetration connections are commonly used. When using high-strength steels, it is very important to ensure strength, as well as sufficient ductility and toughness of these welded connections, in order to allow for the necessary redistribution of stresses and internal forces. The use of high-strength steels can bring significant savings in terms of material consumption, weight, transportation and fabrication costs. Beside the savings due to the reduced material consumption, advantages result from the smaller construction weight and a faster fabrication by reduction of the weld thickness. However, especially for high-strength steel grades S460 and S690, the benefit of saving of material cannot be used, due to the present restrictive design rules. Therefore, the aim of this research project, realized by four partners, was the development of appropriate and modern construction and design rules, as well as manufacturing principles, in order to achieve an economical use of high-strength fine grained steels. This paper presents the results of a research project, investigating the strength and ductility of fillet welded connections of high-strength steels S460 and S690, by means of experimental and numerical analyses. Experimental and numerical investigations of the load bearing capacity and safety against brittle fracture at lap joints with longitudinal fillet welds, cruciform joints with transverse fillet welds and butt joints with partial penetration double-V-groove welds of high-strength steels S460M/ML and S690Q/QL have been carried out. Numerical investigations in terms of welding simulation and measurements of residual stresses have been performed, in order to identify the local microstructure, hardness, residual stresses and strength in the weld profile. These results support the assessment of strength and ductility of welded connections. Based on the investigations, recommendations for the design of welded connections of high-strength steels, in terms of load bearing capacity and safety against brittle fracture, as well as manufacturing principles, were derived. The results of the research project thus contribute significantly to an optimized use of high-strength steel in welded constructions. [ABSTRACT FROM AUTHOR]

Within the last years, the beneficial effect of boron addition in order to increase the creep strength of martensitic 9-12 % Cr steels has been widely investigated and demonstrated. Several boron-strengthened alloys are the outcome of an intensive European research activity within the scientific framework of COST. Tire most promising alloy for castings with a targeted application temperature of 650 °C for use in future ultra-super critical steam power plants is a modified 0.1C-9Cr-1.5Mo steel with the addition of approximately 110 ppm boron. For joining of this advanced steel grade, new "chemically matching" welding consumables have to be developed to provide similar creep strength in the weld. Within this paper, the development of an advanced flux-cored wire with a good "out of position weldability" - based on a rutile slag system is presented. The work discusses the optimization of the chemical composition of the filler, the influence of various post-weld heat treatments on short term mechanical properties, first results of creep tests and results of thick section welds. The boron content of the consumable was optimized to achieve highest creep strength combined with acceptable toughness and lowest hot cracking sensitivity. For a butt weld of a 34 mm-thick casting, the optimum welding parameters and layer sequence were determined. A post-weld heat treatment consisting of stress relieving twice at 730 °C for 12 h seemed to be the best compromise between applicability in the manufacturing of large turbine casings and achievement of acceptable weld toughness. [ABSTRACT FROM AUTHOR]

This paper will present the experimental and numerical investigation on the fatigue crack failure at the root of the enhanced partial joint penetration welds in the circular hollow section X-joint specimens subjected to constant - amplitude brace in-plane bending actions. The enhanced partial joint penetration welds, which include a portion of the brace wall as the inherent "back-plate" for the welds, reduce the workmanship requirement on the welding procedure and improve the quality control of the welded joint. This study compares the fatigue crack developments observed at both the weld toe and the weld root in three large-scale X-joint specimens with different post-weld surface treatments. Root cracking does not take place in as-welded tubular X-joint specimens, of which the fatigue life depends on the weld toe failure. In specimens with post-weld grinding treatments to enhance fatigue resistance of the material near the weld toe, however, the finite-length root face triggers the initiation and propagation of fatigue cracks with an applied number of cycles more than that required to initiate a toe crack in the same tubular X-joint. Ultimate strength testing of specimens with large fatigue cracks, and post-test sectioning, reveals that fatigue failure weld-toe fatigue cracks remain more critical than the root cracks. [ABSTRACT FROM AUTHOR]

A unique study of structural and chemical analysis of crystalline phases in developed agglomerated fluxes was carried out. Thirty-two fluxes were developed by using a mixture of oxides, halides, carbonates, silicates, and ferroalloys for submerged arc welding. The present paper focuses on only ten (out of thirty-two) fluxes which were analyzed by X-ray diffraction (XRD) to know the different types of oxides formed and changed in oxidation number of metallic centers after sintering process at around 850 °C. To know the effect of temperature over phase transformation and melting of different compounds, differential thermal analysis (DTA) was carried out from 1000 to 1400 °C. This study aims to know the quantity of ions present (percentage) and melting behavior of developed agglomerated fluxes for submerged arc welding process. [ABSTRACT FROM AUTHOR]

Due to their good corrosion resistance in high-temperature and wet corrosive environments, nickel-based alloys are widely used as construction materials in the chemical industry, as well as in offshore applications and other energy and environmental technologies. Their outstanding corrosion performance, however, is often accompanied by a limited weldability due to a high hot cracking sensitivity. This paper presents a comparative overview of the hot cracking susceptibility of iron and nickel-based alloys type 1.4958 (alloy 800 H), 2.4663 (alloy 617), 2.4816 (alloy 600 H), 2.4856 (alloy 625) and 2.4605 (alloy 59). Hot cracking tests are performed by PVR test (deformation crack test), using GTA-welded externally loaded specimens to rank the hot cracking sensitivity of the base metals. In order to gain further knowledge regarding formation and propagation of the hot cracks, optical microscopy and EDX-analyses were performed. In addition to a ranking of materials and processes, interim results regarding the crack types and the metallurgical causes of cracking are discussed. [ABSTRACT FROM AUTHOR]

This paper describes recent developments in the welding of thermoplastics, including laser welding of microfluidic devices and friction stir welding of fibre-reinforced plastics. It also describes new developments in the assessment of welds in thermoplastics, including the long-term mechanical testing and phased array ultrasonic inspection of welded joints in polyethylene pipes. [ABSTRACT FROM AUTHOR]

This paper deals with a newly developed pretreatment for TIG arc welding to improve weld penetration. As a pre-treatment, a small oxidized region was produced on the surface of stainless steel plates by laser irradiation using oxygen gas prior to travelling TIG arc. Tlte effect of the pre-treatment (espe-cially named LA pre-treatment) on the TIG weld penetration was evaluated. It was found that the pre-treated region extremely smaller than the weld could make the TIG weld penetration deeper at lower welding speeds. [ABSTRACT FROM AUTHOR]