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WELDING TECHNOLOGIES
AND EQUIPMENT
It should be noted that these
results indicate a close relationship
penetration coefficient (Kp) and bulge coefficient (Kh)
between the melting and boiling points
of the metal being welded and the
oxides used in A-MIG welding.
A high correlation dependence is
observed between the melt coefficient
(Kp), the convexity coefficient (Kh) of
the joints and the temperature interval
(Tbo - Tmo) (see Fig. 7). According
to the graph presented in Fig. 7, the
value of Kp is maximum at 800 °C, and
for Kh at this value of the temperature
range it is minimal. This indicates the
greatest efficiency of the action of
oxide melting point (Tmo °C) oxides on the morphology of welds
Fig. 5. The dependence of the coefficient of penetration (Кр) and the at values of the temperature interval
coefficient of bulge (Kh) on CrNi 18-10 stainless steel from the melting (Tbo - Tmo) between 600o and 1000o
temperature of oxides (Tmo), used in the form of a gas-powder mixture within the framework of the accepted
during welding A-MIG.
. welding conditions.
In accordance with the results
obtained, individual flux-oxides most effectively affect the morphology of welds of CrNi18-10
steel during MIG welding, subject to the following conditions:
600° ≥ (Tbo - Tmo) ≤ 1000°.
As the research results (Fig. 8) show, the magnitude of the surface tension of oxide
melts plays an important role in the formation of welds of the steel under study. The curves
of the coefficients of penetration (Kp) and convexity (Kh) on the surface tension (σ) of five
oxides (SiO2, WO3, Fe2O3, TiO2, Al2O3 and MgO, no information on surface tension for melts
of the oxides Cr2O3, Co3O4, BaZrO3
and CaZrO3 was found ) showed a high
correlation between these parameters.
Figure 8 shows a graph of the
dependence of the morphology of the
welds on the surface tension (σ) of these
oxides, according to which an increase penetration coefficient (Kp) and bulge coefficient (Kh)
in the surface tension contributes to a
narrowing of the width of the weld (L) and
an increase in the convexity of the weld
(h). This indicates that an increase in the
surface tension of the oxides worsens the
interfacial tension between the molten oxide boiling point (Tbo °C)
and solid metal and leads to the formation Fig. 6. The dependence of the coefficient of penetration (Кр) and
of a narrow seam with high gain and the coefficient of bulge (Kh) on CrNi 18-10 stainless steel from
impairs the mechanical and technological the boiling point of the oxides (Tbo), used in the form of a gas-
powder mixture during welding A-MIG.
properties of the welded joint.
Studying the effect of surface tension on the melt penetration coefficient (Kp) and weld
bulge (Kh) revealed a high correlation between these indicators (Fig. 8), which showed an
improvement in weld bulge formation with a surface tension of oxides in the range of 200-300
mJ / m2.
Thus, the best results in MIG welding using oxides are achieved with a surface tension of
less than 300 mJ / m2 (σ <300 mJ / m2).
Within the framework of this project, studies were also carried out to study the influence
of the thermodynamic properties of compounds used as powders for gas-powder mixtures on
the formation of stainless steel welds made by MIG welding.
One of the important thermodynamic properties of compounds is the enthalpy of their
formation (ΔHo 298). The results of studies of the influence of the enthalpy of oxide formation
on the formation of welds of CrNi18-10 stainless steel during A-MIG welding are presented in
Fig. 9.

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