It is well known, that the arc column has the shape of the truncated cone, the larger base of which is on the product regardless of polarity. However, the reason for the expansion of the arc column at the surface of the product has not yet been established. Therefore, we need to determine the processes that contribute to the expansion of the column at the surface of the product.
Let us first consider the schemes shown in Fig. 1, in case is the «product» is the non-melting plate.
In order to understand the metallurgical properties of the metals, first of all, it is necessary to describe some properties of particles that form all types of matter. These basic particles, which together form solid, liquid and gaseous substances, are called «atoms». One of the main properties of atoms is that in certain temperature ranges they form substances having the ordered structure. This is because certain forces begin to act on atoms that are at the certain distance from each other. These forces attract and at the same time repel atoms from each other. Thus, these opposing forces keep individual atoms at certain «initial» positions with respect to Continue reading →
The impurities are important in the polymorphous transformations. The nature of the influence of impurities is related to their solubility in the metal. If the impurity does not dissolve in the solid metal, the polymorphic transformation in the alloys is similar, as we described earlier. In this case, as for pure metal, it is possible to indicate a certain equilibrium temperature of both modifications, which does not depend on the composition of the alloy.
In Fig. 1, the condition diagram of the double system which component A has a polymorphic point (То) above the eutectic temperature is provided, and the Continue reading →
This test group is designed to assess the quality of the metal structure and the non-existence of defects in it. The non-existence of defects monitoring is usually used during the certification of welding technologies and welders. After welding on the control sheet material, the samples are cut from it, which are subjected to the control for the non-existence of defects, which makes it possible to identify possible violations in the structure of the weld metal.
For the destructive non-existence of defects monitoring, three main types of tests are used: the bend test, the breakdown test of the welded joint specimen with two notches along the weld and the breakdown test of the corner sample. The deficiency can also be checked by means of non-destructive testing, for which Continue reading →
The value of Wи for each atom cannot be precisely calculated. However, if we assume that the quantity Wи and depends linearly on T, then its value can be calculated by the formula
Wи =(Ui/Ti)*T,
where Ti — the temperature at which almost all the atoms in the plasma are ionized, for example, when the degree of ionization reaches 0.95.
The Ui/Ti ratio for each class of atoms constantly and can be denoted by с, then the formula can be written as
Wi = Ui – cТ,
where с — the coefficient constant for each substance.
