scispace - formally typeset
Search or ask a question
Author

Daniel Seferian

Bio: Daniel Seferian is an academic researcher. The author has contributed to research in topics: Welding. The author has an hindex of 1, co-authored 1 publications receiving 32 citations.
Topics: Welding

Papers
More filters
Book
01 Jan 1962

32 citations


Cited by
More filters
Journal Article
TL;DR: In this paper, the effects of process variables and heat input on various metallurgical aspects, namely, the widths of the HAZ, weld interface, and grain growth and grain refinement regions, were investigated.
Abstract: A B S T RAC T. In submerged arc welding (SAW), selecting appropriate values for process variables is essential in order to control heat-affected zone (HAZ) dimensions and get the required bead size and quality. Also, conditions must be selected that will ensure a predictable and reproducible weld bead, which is critical for obtaining high quality. In this investigation, mathematical models were developed to study the effects of process variables and heat input on various metallurgical aspects, namely, the widths of the HAZ, weld interface, and grain growth and grain refinement regions of the HAZ. The color metallography technique and response surface methodology were also used. Direct and interaction effects of the process variables and heat input on the characteristics of the HAZ were presented in graphical forms. The study revealed: 1) heat input and wire feed rate have a positive effect, but welding speed has a negative effect on all HAZ characteristics; 2) width of grain growth and grain refinement zones increased and weld interface decreased with an increase in arc voltage; and 3) width of HAZ is maximum (about 2.2 mm) when wire-feed rate and welding speed are at their minimum limits.

85 citations

Journal ArticleDOI
TL;DR: In this article, a model capable of describing the thermal cycles occurring in multipass welds was developed which was used to investigate theoretically the effect of interpass temperature, welding current and Ac3 temperature on the fraction of weld microstructure which becomes reaustenitised during fabrication.
Abstract: A model has been developed which is capable of describing the thermal cycles occurring in multipass welds. The method involves a calculation of the size and shape of the single bead-on-plate weld. The isotherms beneath the weld centre-line are estimated using an analytical solution for the problem of heat-flow into a thick plate. The volume of metal deposited per unit length of weld, i.e. the reinforcement, is then assumed to adopt the shape of a spherical cap on the surface of the plate. For multipass welds, the model applies the heat-flow equations as each bead is deposited. The model has been calibrated for a 214Cr1Mo multipass weld of a type commonly used for joining steam-pipes in a modern steam-generating power plant. The method has been used to investigate theoretically the effect of interpass temperature, welding current and Ac3 temperature on the fraction of weld microstructure which becomes reaustenitised during fabrication of the weldment. Where possible, the results are rationalised by comparison with experimental observations.

72 citations

Journal ArticleDOI
TL;DR: In this paper, the grain structures in two dimensional GTA welds of a number of commercial aluminum alloys have been studied in order to clarify the mechanisms of grain refinement in welds.
Abstract: The grain structures in two dimensional GTA welds of a number of commercial aluminum alloys have been studied in order to clarify the mechanisms of grain refinement in welds. At low welding speeds and heat inputs the structures were either axial (continuous grains along the weld centerline) or stray (intermittent new grains). At higher speeds and heat inputs the structures were generally either columnar to the weld centerline, or contained some equiaxed grains at the center. Regression analyses indicated that both stray grains and equiaxed grains were favored by increased titanium content. In several alloys, titanium-rich compounds, and in one alloy, zirconium-rich compounds were found at the centers of dendrites. It is concluded that both stray and equiaxed grains originate by heterogeneous nucleation, with possible secondary effects due to constitutional undercooling.

61 citations

Journal ArticleDOI
TL;DR: In this paper, the structural changes taking place in a commercial AISI Type 310 steel at temperatures in the range 650° to 950°C have been examined for times of up to 900 hours by means of optical metallographic techniques.

29 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of auxiliary preheating of the solid filler wire in mechanized gas metal arc welding (GMAW) process (by using a specially designed torch to preheat the filler wire independently, before its emergence from the torch) on the quality of the as-welded single layer stainless steel overlays was investigated.
Abstract: Weld cladding is a process for producing surfaces with good corrosion resistant properties by means of depositing/laying of stainless steels on low-carbon steel components with an objective of achieving maximum economy and enhanced life. The aim of the work presented here was to investigate the effect of auxiliary preheating of the solid filler wire in mechanized gas metal arc welding (GMAW) process (by using a specially designed torch to preheat the filler wire independently, before its emergence from the torch) on the quality of the as-welded single layer stainless steel overlays. External preheating of the filler wire resulted in greater contribution of arc energy by resistive heating due to which significant drop in the main welding current values and hence low dilution levels were observed. Metallurgical aspects of the as welded overlays such as chemistry, ferrite content, and modes of solidification were studied to evaluate their suitability for service and it was found that claddings obtained through the preheating arrangement, besides higher ferrite content, possessed higher content of chromium, nickel, and molybdenum and lower content of carbon as compared to conventional GMAW claddings, thereby giving overlays with superior mechanical and corrosion resistance properties. The findings of this study not only establish the technical superiority of the new process, but also, owing to its productivity-enhanced features, justify its use for low-cost surfacing applications.

15 citations