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WELDING TECHNOLOGIES
AND EQUIPMENT

Table 2. MIG and A-MIG welding modes

Type of Diameter of Distance to Wire feed Welding Voltage Welding Shielding
electrode an electrode, the plate, speed, m / speed, cm current gas (argon),
mm mm min / min strength, A l / min

G 19 L Si 1,0 12 7 50 20 - 21 140 - 160 16
(1.4316)

takes place [11, 12].
The instrumental microscope was used to
check the morphology of the weld (Fig. 2), which
is characterized by the penetration depth (P), the
width of the weld (L), the height of the bulge (h)
and the coefficients of penetration (Kp = P / L) and
bulge (Kh = L / h).
The degree of influence of the thermodynamic
and physicochemical properties of oxides on the
morphology of stainless steel welds was evaluated
using the determination coefficient R2. The
coefficient of determination is in the range 0 <R2
<1 and denotes the strength of the linear correlation
between the properties of oxides and morphology
welds (the ratio of the depth of penetration to the
width of the weld - P / L). Moreover, a value of R2
from 0.81 to 1.0 indicates a very strong correlation,
from 0.49 to 0.81 – at strong correlativity, from
0.25 to 0.49 - to variables that can be considered Fig. 2. Scheme of the weld obtained MIG welding.
moderately correlated, from 0.09 to 0.25 indicate a

low correlation and less 0.09 do not have any (linear) correlation [8].
RESULTS AND DISCUSSION
Macro photographs of cross-sections of welds of stainless steel CrNi 18-10 with a thickness
of 4 mm, made by welding according to conventional technology (MIG) and using gas-powder
mixture (A-MIG) are shown in Fig. 3.
As a result of studying macro sections of welds obtained during A-MIG welding using oxide
compounds as powders, and comparison of these welds with welds obtained using standard
MIG welding technology, it was revealed that an increase in penetration depth is observed when
using all oxides except MgO by 10 – 70 %. By the degree of their influence on increasing the
penetration depth, they can be arranged in the following series: SiO2, CaZrO3, TiO2, Fe2O3,
Co3O4, Al2O3, Cr2O3, WO3, BaZrO3. In addition, all oxides except CaZrO3 contribute to the
expansion of welds by 25 - 90% in the following sequence: Fe2O3, SiO2, WO3, Co3O4, BaZrO3,
MgO, TiO2, Al2O3, Cr2O3.
The values of the coefficients of penetration (Кр) and convexity (Kh) of welds made by
welding according to conventional technology (MIG) and using a gas-powder mixture (A-MIG)
are shown in Fig. 4. These values of the melt and bulge coefficients were used to study the
effect of the physicochemical properties of oxides on the morphology of welds.
Figure 5 shows graphs of the dependences of the melt penetration (Кр) and bulge
(Кh) of welds on the melting temperature of oxides (Tmo). A high correlation dependence is
observed between the melt penetration coefficient (Кр) and the bulge (Кh) of welds and the
melting temperature of oxides (Tmo) (see Fig. 5). According to this dependence, the value
of Kp increases slightly with increasing melting temperature of the oxides, and the value of
Kh decreases sharply. This effect suggests that when A-MIG is used for welding oxides with a
melting point up to 2000 °C, stainless steel welds have the most favorable morphology. From a
technological point of view, a narrow and high seam adversely affects the fatigue properties of

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