This article presents the results of studies into the effects of flux oxide slags on the mechanism of the formation of weld beads on the CrNi18-10 stainless steel during A-TIG welding. The results obtained make it possible to determine the effects of some thermophysical properties of individual flux oxides formed at the edges of the weld pool slags on the peculiarities of the formation of the weld pool during the A-TIG welding of the CrNi18-10 stainless steel and their influences on the weld bead geometries. Also, the authors of the present article propose a hypothesis about the active mechanisms of flux oxides in the formation of the weld beads during A-TIG welding.
The analysis of residual stresses or distortion of welded structures requires a welding structure analysis. This kind of analysis incorporates some specifics compared to other FEM-simulations. Apart from the definition of geometry (mesh) and clamps, the welding structure analysis requires the definition of heat sources, trajectories and time schedules. The heat source applies the heat in the model according to the welding process. An equivalent heat source is used which needs to be calibrated for tests or predictively calculated from a welding process analysis. The trajectories describe the path of the moving welding heat source in the simulation model. Most welding heat sources are not rotational symmetric. Their trajectories require a path to define the local origin of the heat sources and a reference line to define the orientation of the heat source. Welding is a transient process where the time schedule of the actions welding time, intermediate time has an impact on the result. The process plan defines the welding time schedule and has to be considered in the simulation model.
The utilisation of high-strength fine-grained structural steels for applications in steel construction, vehicle construction and pipeline construction is increasing continuously. In addition to the substantial weight savings by reducing the wall thicknesses, the resource consumption and thus the production costs can be reduced considerably by utilising these steels in welded structures. One problem resulting from the use of a submerged arc welding process for such applications is the danger of hydrogen input, particularly due to the use of the welding fluxes. In this study, the decrease in the hydrogen input into the weld metal of high-strength fine-grained structural steels was investigated by using a submerged arc welding process in a pulsemodulated form of direct current. In this respect, it was possible to observe that the cavity is not formed up to its final size due to the constant change between a pulse condition and a basic condition within the basic phase. This results in a smaller cavity volume with a lower partial hydrogen pressure on average and thus also in a reduction in the contact area to hydrogen sources. Rezime Koriscenje finozrnih konstrukcionih celika povisene cvrstoce za celicne konstrukcije, konstrukcije vozila i cevovoda kontinualno raste. Dodatno, osnovna usteda na težini, smanjenjem debljine zida, potrosnje resursa i cak proizvodnih troskova može se znacajno smanjiti koriscenjem ovih celika u zavarenim konstrukcijama. Jedan problem koji može da se javi pri koriscenju postupka zavarivanja pod praskom za takve primene je opasnost od unosa vodonika, posebno zbog koriscenja praskova za zavarivanje. U ovoj studiji se istražuje smanjenje unosa vodonika u metal sava finozrnih konstrukcionih celika povisene cvrstoce koriscenjem postupka zavarivanja pod zastitom praska u impulsno-modulovanom obliku jednosmerne struje. Sa tog stanovista moguce je postici to da se ne stvaraju supljine njihove konacne velicine usled konstantne promene između pulzirajucih uslova i baznih uslova. Ovo rezultuje u manjoj zapremini sa nižim parcijalnim pritiskom vodonika od srednje vrednosti uz redukciju kontaktne povrsine izvora vodonika.
Fillet welds are one of the most commonly used weld joints but one of the most difficult to weld consistently. This paper presents a technique using Artificial Neural Networks (ANN) to identify the key Gas Metal Arc Welding (GMAW) fillet weld parameters and interactions that impact on the resultant geometry, when using a metal cored wire. The input parameters to the model were current, voltage, travel speed; gun angle and travel angle and the outputs of the model were penetration and leg length. The model was in good agreement with experimental data collected and the subsequent sensitivity analysis showed that current was the most influential parameter in determining penetration and that travel speed, followed closely by current and voltage were most influential in determining the leg length. The paper also concludes that a ‘pushing’ travel angle is preferred when trying to control the resultant geometry mainly because both the resultant leg length and penetration appear to be less sensitive to changes in heat input.
Long-time exposure to welding fumes is supposed to be responsible for lung disease in some cases [1]. Whether welding fume exposure leads to an impairment of human health seems to be dependent on various factors like fume concentrations, ventilation of the workshops [2, 3], use of personal protection equipment [4-6] and presence of co-factors like cigarette smoking [7]. From different epidemiological and toxicological studies, it is also known that ultrafine particles which are produced by many thermal processes such as welding are able to induce inflammatory processes not only in the lung but also systemically [8-15], thus inducing not only lung injury but also impairment of the cardiovascular system. However, it seems to be evident that health effects of welding fumes also depend on the nature of the fumes, on welding techniques and on base and filler materials. In order to improve the prevention of welding-related diseases, it would be helpful to have better knowledge about the relationship between the potential to induce lung diseases and those welding-related factors (welding techniques and materials).
The aim of Cost Sensitivity Modelling (CSM) is to analyse the relevance of input data in weld cost or production investment calculations, and to show through different calculations how the final result is influenced by variations in input data in order to find the most important cost/profitability determining parameters. Today’s welding production systems are complex installations both in terms of technology, day-to-day operation, maintenance and investment. This is evident with processes such as Tandem-MAG and Laser-hybrid MAG welding. During the past decades, the profitability of investment is more in focus than, for example, production cost per m weld length or produced unit. CSM can be applied in conventional weld cost calculations (cost/m produced weld) or in complex investment calculations. In this paper both cases are analysed to demonstrate the usefulness of the method. Two crucial questions arise as a consequence of CSM: how accurate is the input data used and which cost factor(s) are of prime importance? It is shown, for example, that deposition rate is not the only important cost determining factor in sophisticated welding systems. CSM identifies other factors which must be controlled in order to keep deviations in profitability from target value within acceptable limits. Implementation time in a new investment is one such factor.
