Spray Welding Research Articles

A model for prediction of fume formation rate in gas metal arc welding (GMAW), globular and spray modes, DC electrode positive.

Prediction of fume formation rate during metal arc welding and the composition of the fume are of interest to occupational hygienists concerned with risk assessment and to manufacturers of welding consumables. A model for GMAW (DC electrode positive) is described based on the welder determined process parameters (current, wire feed rate and wire composition), on the surface area of molten metal in the arc and on the partial vapour pressures of the component metals of the alloy wire. The model is applicable to globular and spray welding transfer modes but not to dip mode. Metal evaporation from a droplet is evaluated for short time increments and total evaporation obtained by summation over the life of the droplet. The contribution of fume derived from the weld pool and spatter (particles of metal ejected from the arc) is discussed, as are limitations of the model. Calculated droplet temperatures are similar to values determined by other workers. A degree of relationship between predicted and measured fume formation rates is demonstrated but the model does not at this stage provide a reliable predictive tool.

Cavitation erosion of flame spray weld coating of nickel-base alloy powder

Cavitation erosion of flame spray weld coating of nickel-base alloy powder

Cavitation erosion of flame spray weld coating of nickel-base alloy powder

The cavitation erosion of flame spray weld coating of five kinds of commercial nickel alloy powder was investigated by using a vibratory cavitation apparatus. For comparison a plain carbon steel and a stainless steel were also studied. The result showed that the cavitation erosion resistance of the flame spray weld coating of the nickel alloys was strongly related to the degree of solution hardening of the matrix and the quantity, fineness and dispersivity of the second phase (compound).

Thermal spraying and powder spray welding processes for the hardfacing of grey cast iron

Grey cast iron has many fields of application in which wear may be a problem. This requires the replacement of castings or where possible their reclamation. Application of hardfaced coatings to parts or components most subjected to breakdown through wear extends their working lifetime. The choice of alloy, spraying processes and operating technique are all important if grey cast iron is to be hardfaced successfully. This paper reports the results of a practical investigation into the potential assessment of thermal spraying (TS) and powder spray welding (PSW) processes for the hardfacing of grey cast iron to resist abrasive wear.

Effect of flame spraying welding on fatigue life of carbon steel: Yu, W., Yuan, J. and Liu, M. Hanjie Xuebao (Trans. China Weld. Inst.) Sept. 1988 9, (3), 171–187 (in Chinese)

The determination of the transverse cracking which occurs during the fatigue of cross-ply materials with two different fibres (T300 or T400) has been undertaken. The study includes an experimental part and a theoretical part containing both an analytical and a numerical approach for modelling the observed stiffness reduction.In particular, this paper gives improved solutions to the well known modified shear lag analysis, due to Garrett and Bailey, concerning the stress distributions in the cross-ply composite after transverse cracking. These methods have been used in a fatigue context to model transverse-ply crack development. The difference between the theoretical model and the experimental results—especially for the T300-based composite—enables an evaluation to be made of the stiffness reduction due to fibre failure in the 0° plies.It is thought that this last mechanism is activated by the extension in two directions of the stress concentration zones existing in the region of the transverse-ply crack tip: along the fibres by delamination and across the 0° layer by rupture of fibres.

Plasma metal coating of finely divided carbides for spray deposition and weld facing

Plasma metal coating of finely divided carbides for spray deposition and weld facing