The objective of the present paper is to propose a global model for describing heat flow in arc welding, aiming the understanding of the phenomena involved. The attempt is to fill out a gap of knowledge which has been generated between the application of simplified analytical models (not totally realistic) and numerical models (that disguises the physics of the phenomena). Initially, a physic-oriented description of the reasons for welding arc voltage drop is presented. This description is based on the heat generation and its losses to maintain the balance between deionization and reionization, in contrast to the approach that the arc is comparable to an electrical resistor. Following, a descriptive model of the thermal subsistence of the arc is proposed to describe the heat transference from the arc to the plate. Then, a second descriptive model is proposed to explain how the heat enters, diffuses and leaves the workpiece during welding. Sequentially, it is discussed how the application of these two models in a global way allows to understand that not all the heat flow from the arc to the plate will affect the cooling rate of the heated parts. A proposal for applying the term Effective Heat Input to mean the heat parameter which is important to be determined in welding is put forward.
Heat input; heat flow in welding; models
