Search results

The purpose of this paper is to optimize the gas metal arc welding (GMAW) process input parameters simultaneously considering the multiple output variables (bead width (BW), bead height (BH) and depth of penetration (DP)).

Grey‐based Taguchi approach was used for designing the experiment, L27 orthogonal array was used which composed of three levels and 27 rows, which means that 27 experiments were carried out. Design of experiments was selected based on a four welding parameters with three levels each. The selected welding parameters for this paper are gas flow rate, voltage, travel speed and wire feed rate. The bead‐on‐plate welding trials are carried out on AISI 904L super austenitic stainless steel (SASS) sheets and evaluate the shape of the fusion zone depends upon a number of input parameters.

Bead‐on‐plate welding of 904L SASS sheet is successfully performed (without any cracks and discontinuity) by GMAW process and the bead profiles are measured. The predicted bead profiles have the better DP and lower BH and BW. It is found that the optimized setting values are improving the response values by 10 per cent.

The optimal welding conditions are identified in order to increase the productivity and minimize the total operating cost. The process input parameters effect is determined under the optimal welding combinations.

Friction welding (FW) is a solid state joining process. Super austenitic stainless steel is the preferable material for high corrosion resistance requirements. These steels are relatively cheaper than austenitic stainless steel and it is expensive than nickel base super alloys for such applications. The purpose of this paper is to deal with the optimization of the FW parameters of super austenitic stainless steel using artificial neural network (ANN) simulation and particle swarm optimization (PSO).

The FW experiments were conducted based on Taguchi L-18 orthogonal array. In FW, rotational speed, friction pressure, upsetting pressure and burn-off length are the important parameters which determine the strength of the weld joints. The FW trials were carried out on a FW machine and the welding time was recorded for each welding trial from the computerized control unit of the welding machine. The left partially deformed zone (L.PDZ) and right partially deformed zone (R.PDZ) were identified from the macrostructure and their values are considered for the output variables. The tensile test was carried out, and the yield strength and tensile strength of the joints were determined and their fracture surfaces were analyzed through scanning electron microscope (SEM).

The tensile test was carried out, and the yield strength and tensile strength of the joints were determined and their fracture surfaces were analyzed through SEM. An ANN was designed to predict the weld time, L.PDZ, R.PDZ and tensile strength of the joints accurately with respect to the corresponding input parameters. Finally, the FW parameters were optimized using PSO technique.

There is no limitations, difficult weld by fusion welding process material can easily weld by FW process.

The research work described in the paper is original.

Properties of the parts manufactured by selective laser melting (SLM) depend strongly on the each single laser‐melted track and each single layer, as well as the strength of the connections between them. The purpose of this paper to establish links between the principal SLM parameters (laser power density, scanning speed, layer thickness), properties of the powder and geometrical characteristics of single tracks. This study will provide a theoretical and technical basis for production of parts from metal powders.

This paper discusses the SLM parameters affecting on geometrical characteristics of the synthesized single tracks. Granulomorphometric characteristics of powders were studied in detail. A Greco‐Latin square design was used to control geometrical characteristics of the tracks. Analysis of variance (ANOVA) permitted to establish a statistically significant influence of the SLM process parameters on geometry of the single laser‐melted track.

The behavior of individual tracks and their geometric characteristics depend on the process parameters, and physical‐chemical and granulomorphometrical properties of the powder. Each powder shows peculiar behavior in the process of single track formation. For stainless steel grade 904L powders with different particle size it was found that the most influencing parameter is the laser power (the following values were applied: 25, 37.5, 50 W), and then, in order of decreasing importance, are the powder layer thickness (60, 90, 120 μm), the scanning speed (0.05, 0.10, 0.15 m/s), and, finally, the particle size.

The proposed hierarchy of the process parameters is a new systematic study presented by the authors, developed for selective laser melting. Obtained data can be used in surface structuring and micro‐manufacturing characterized by a small number of layers within a part and, thus, sensible to the geometric dimensions and shape of the individual tracks.

The resistance to stress corrosion cracking of austenitic stainless steels has been investigated and discussed with respect to the influence of molybdenum.

The presence of excess quantities of phosphoric acid in a process stream led to severe corrosion in a Type 316L stainless steel (T316L S.S.) reactor and in associated piping. The pipes were steam‐jacketed and the reactor was heated with Dowtherm. Laboratory tests, which were carried out using 75% phosphoric acid at temperatures of 200° and 250°C, confirmed the high corrosion rates on T316L S.S. and determined the rates for thirty‐nine other metals and alloys. Copper alloys (particularly cupro‐nickels) and high nickel alloys (particularly Ni‐28Mo) demonstrated much better resistance than T316L S.S, as did the following pure metals: platinum, tantalum, molybdenum and silver. Ferrous alloys, zirconium, lead, titanium and aluminium were found to have extremely high corrosion rates.

Cabot Corporation of Boston has purchased the Aurora plc bar plant at Openshaw, Manchester. Cabot plans to reopen the facility this month with the creation of 30 jobs to produce a range of specialist alloys.

The purpose of this paper is to investigate interface characterization of CO₂ laser welded AISI 304 austenitic stainless steel and AISI 1010 low carbon steel couple. Laser welding experiments were carried under argon and helium atmospheres at 2000, 2250 and 2500 W heat inputs and 200‐300 cm/min welding speeds.

The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy, SEM, EDS and X‐Ray analysis. The tensile strength of the welded joints was measured.

The result of this study indicated that the width of welding zone and HAZ became much thinner depending on the increased welding speed. On the other hand, this width widened depending on the increased heat input. Tensile strength values also confirmed this result. The best properties were observed at the specimens welded under helium atmosphere, at 2500 W heat input and at 200 cm/min welding speed.

There are many reports which deal with the shape and solidification structure of the fusion zone of laser beam welds in relation to different laser parameters. However, the effect of all influencing factors of laser welding has up to now not been extensively researched. Much work is required for understanding the combined effect of laser parameters on the shape and microstructure of the fusion zone. This paper, therefore, is concerned with laser power, welding speed, defocusing distance and type of shielding gas and their effects on the fusion zone shape and final solidification structure of some stainless steels.

Considers the advantages of highly alloyed stainless steel such as duplex stainless steels or nickel‐based alloys in highly corrosive environments. Looks at corrosion rates for alloys in acetic acid and presents results of tests on the influence of contaminants in the acid. Gives practical applications. Concludes that duplex stainless steels demonstrate higher corrosion resistance than austenitic stainless steels and are often comparable to nickel base alloys.