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6.2. STUDY OF INFLUENCE OF PHYSICAL AND CHEMICAL PROPERTIES OF OXIDES FLUXES ON THE WELD FORMATION DURIN MIG WELDING OF STAINLESS STEEL
Saidov Rustam Мannapovich, PhD, senior research of the Institute of Material science, SPA «Physics-Sun» Academy of Science of Uzbekistan, e-mail: [email protected]
Mario Kusch, Dr.-Ing., Department of Manufacturing and Welding Engineering, Chemnitz University of Technology, Germany, e-mail: [email protected]
Peter Mayr, Professor, Dr., Department of Manufacturing and Welding Engineering, Chemnitz University of Technology, Germany, e-mail: [email protected]
Kevin Hoefer, Dipl.-Ing., Department of Manufacturing and Welding Engineering, Chemnitz University of Technology, Germany, e-mail: [email protected]
Gafurov Bakhadir Khafizovich, Leader research of the Institute of Material science, SPA «Physics-Sun» Academy of Science of Uzbekistan, e-mail: [email protected]
Atabaev Ilkhom Gafurovich, Professor, Director of the Institute of Material science, SPA «Physics-Sun» Academy of Science of Uzbekistan, e-mail: [email protected]
Akhadov Jobir Zamirovich, PhD, senior research of the Institute of Material science, SPA «Physics-Sun» Academy of Science of Uzbekistan and International Solar Energy Institute, e-mail: [email protected]
Komilova Durdona Rustamovna, senior research of the Institute of Material science, SPA «Physics-Sun» Academy of Science of Uzbekistan, e-mail: [email protected]
Mukhitdinov Zayniddin Salokhitdinovich, Scientist of the Institute of Material science, SPA «Physics-Sun» Academy of Science of Uzbekistan, e-mail: [email protected]
Huang Yong, Dr., Head of Laboratory of Lanzhou University of Technology, China, e-mail: [email protected]
Abstract: This article presents the results of research on the effect of physical and chemical properties of chemical compounds used in the gas-powder mixture for their feeding to the welding zone during MIG welding. The results obtained allowed to determine the influence of the thermodynamic and physical-chemical properties of individual oxides used in the gas-powder mixture, to the morphology of the welded joints and to identify recommendations for the selection of oxides compounds based on optimal physical and chemical properties that ensure to obtain the qualitative welded joint for A-MIG welding of the stainless steels.
Index terms: physical and mechanical properties of chemical compounds, gas-powder mixture, feeder, MIG welding.
ИССЛЕДОВАНИЕ ВЛИЯНИЯ ФИЗИКО-МЕХАНИЧЕСКИХ СВОЙСТВ ХИМИЧЕСКИХ СОЕДИНЕНИЙ НА ХАРАКТЕР ИХ РАСПЫЛЕНИЯ ИЗ ДОЗАТОРА ПРИ СВАРКЕ В ИНЕРТНЫХ ГАЗАХ
Саидов Рустам Маннапович, канд. техн. наук, старший научный сотрудник. Институт материаловедения НПО «Физика-Солнце» Академия Наук Республики Узбекистан, e-mail: [email protected]
Марио Куш, Др.-Инж., Департамент производство и сварочной техники, Хемницкий технологический университет, Германия, e-mail: [email protected]
Петер Майр, Профессор, Др., Департамент производство и сварочной техники, Хемницкий технологический университет, Германия, e-mail: [email protected]
Кевин Хоефер, Инж., Департамент производство и сварочной техники, Хемницкий технологический университет, Германия, e-mail: [email protected]
Гафуров Бахадыр Хафизович, канд. техн. наук, ведущий научный сотрудник. Институт материаловедения НПО «Физика-Солнце» Академия Наук Республики Узбекистан, e-mail: [email protected]
Атабаев Ильхом Гафурович, профессор, директор Института материаловедения НПО «Физика-Солнце» Академия Наук Республики Узбекистан, e-mail: [email protected]
Ахадов Жобир Замирович, канд. техн. наук, старший научный сотрудник. Институт материаловедения НПО «Физика-Солнце» Академия Наук Республики Узбекистан; Международный институт Солнечной энергии, e-mail: [email protected]
Комилова Дурдона Рустамовна, младший научный сотрудник. Институт материаловедения НПО «Физика-Солнце» Академия Наук Республики Узбекистан, e-mail: [email protected]
STUDY OF INFLUENCE OF PHYSICAL AND CHEMICAL PROPERTIES OF OXIDES FLUXES ON THE WELD FORMATION DURIN MIG WELDING OF STAINLESS STEEL
Saidov R. М., M. Kusch, P. Mayr, K. Hoefer, Gafurov B. Kh., Atabaev I. G., Akhadov J. Z., Komilova D. R., Mukhitdinov Z. S., Huang Yong
Мухитдинов Зайниддин Салохитдинович, сотрудник. Институт материаловедения НПО «Физика-Солнце» Академия Наук Республики Узбекистан, e-mail: [email protected]
Хуанг Йонг, Др., Заведующий лабораторией. Ланжоунский Технологический Университет, КНР, e-mail: [email protected]
Аннотация: В настоящей статье приведены результаты исследований по изучению влияния физико-механических свойств химических соединений, используемых в газопорошковых смесях для их дозированной подачи в зону сварки при сварке в инертных газах. Полученные результаты исследований позволили определить влияние физико-механических свойств химических соединений, используемых в газопорошковых смесях, на характер их распыления из дозатора и выявить рекомендации к подбору химических соединений на основе оптимальных физико-механических свойств, которые обеспечивали бы оптимальное распыление газопорошковых смесей из дозаторов при сварке в среде инертных газов.
Ключевые слова: Физико-механические свойства химических соединений, газопорошковые смеси, дозатор, сварка в среде инертных газов.
INTRODUCTION
One of the common ways of stainless steel joining is semiautomatic electrode wire in the inert gas (argon) environment (MIG). Stainless steel welding by this way provides high productivity and good quality of the bead. The main advantages of the MIG welding process are high productivity and good quality of the bead. High productivity can be classified with time loss of electrode change, as well as this method allows to use high welding current.
Disadvantages of this method are the presence of the gas balloon and limited usage of it in the open air. Also during welding in the pure inert gas in despite of good protection of welding zone from ambient air impact, welding bead morphology deteriorates, and arc becomes unstable.
This method of welding with using flux-cored wire will allow correcting these defects. However the defects of usage of flux-cored wire are the formation of high quantity of slag and high price of flux-cored wire.
These problems probably can be solved with using common melting wire and special powders [1-3] instead of flux-cored wire that will be applied on the welding edges by paste with brush or aerosol can.
Although these methods disadvantage are the labor intensity process increase, irregular thickness and width (applying by brush), high consumption of powder and welding process automation difficulty.
More effective and economical way of usage these powders by welding in the environment of shielding gas are the method of special powders supply as gas-powder mixture [4-6], which can be obtained by feeder [7] as a result of mixing shielding gas with powder. Gas-powder mixture in feeder goes directly to the zone of welding arc.
However, it has not been studied yet the influence of physical-chemical properties of chemical compound, that can be used in gas-powder mixtures, for the size and form of weld bead pro
duced with MIG welding with feeder. Also it is not developed the recommendations to the chemical joint selection based on optimal physical-chemical properties, which will provide qualitative weld joint by MIG welding with usage gas-powder mixtures spraying to the zone of welding by feeder.
The purpose of these investigations are the study of influence of physical-chemical properties of chemical compounds, which are used in gas-powder mixtures and identify the optimal requirements by its basis to the indicated properties to produce qualitative welded joints with MIG welding in the inert gas environment.
EXPERIMENTAL PROCEDURE
The research on influence thermodynamic and physical-chemical properties of powder mixtures to the morphology of welded joints produced with MIG welding of the stainless steel plates CrNi1810 of thickness in 4 mm and size in 60x150 mm. Chemical composition of steel CrNi1810 is shown in table 1.
Table 1
Chemical composition of steel CrNi18-10 [according to norms DIN EN 10088-3]
C Si Mn P S N Cr Ni
<0,07 <1,0 <2,0 <0,045 <0,015 <0,11 17,0-19,5 8,0-10,5
As a chemical composition to research the influence on physical-chemical properties to the morphology of welded joints with MIG welding for the stainless steels, it was used oxide powders (MgO, SiO2, Fe2O3, Cr2O3, TiO2, Co3O4, WO3, Al2O3 CaZrO3 u BaZrO3) with granulomere size composition < 100 mkm, which widely used in the flux composition for the welding of stainless steels.
Gas-powder mixture has been obtained in the device for continuous dosed feeding of gas-powder mixture to the zone of welding (feeder), developed by authors of the current work [7].
The device for preparation and dozed feeding of gas-powder mixtures is shown in Fig. 1.
Type of electrode Diameter of electrode, mm Interval to plates, mm Wire feed speed, m/min Welding speed, cm/min Voltage, B Welding current intensity, A Shielding gas (Argon), l/min
G 19 9 L Si (1.4316) 1,0 12 7 50 2021 140-160 16
- Melting temperature (Tmo), oC;
- Boiling temperature (Tbo), oC;
- Boiling and Melting temperature difference (Tbo-Tmo), o;
- Enthalpy of formation (AH°298), kJ/mol;
- Surface tension (a), mJ/m2.
It also investigated the influence of oxygen content in oxides (O2, % mass) to the peculiarities of the stainless steel weld bead formation.
Data of physical-chemical properties of oxides used in research of its influence to the stainless steel CrNi18-10 weld bead formation has been taken from well known database [9] and information from manual [10].
Regarding cobalt oxide (II, III) Co3O4 it was used the data of the properties to the cobalt oxide (II) CoO due to the temperature high than 900oC there is a reaction 2 Co3O4 = 6 CoO + O2 [11, 12].
Instrumental microscope was used to test the morphology of the weld bead (Fig. 2), which characterizes the penetration depth (P), bead width (W), convexity (h) and melting and (Kp=P/W) and convexity (Kh=W/h) factors.
Fig. 1. Device for preparation and dozed feeding of gas-powder 1 - funnel-shaped feeder tank; 2 - screw auger; 3 - mixing chamber.
Circuit diagram of pushing screw feeder is shown in Figure 1. The necessary quantity of flux is pouring to the funnel shaped feeder tank 1. Screw feeder 2 is placing in the bottom part of the tank, which brings in rotation by drive motor with smooth control of screw speed. By effect of the screw the flux is pouring to the transport channel feeder and fills the space between screw coils. During rotation of feed screw the portion of flux shifting along screw and feeding to the mixing chamber of the mixer 3, where it is mixing with process gas stream (argon, helium and etc.) and in the suspension pose it goes to the welding zone. Gas goes to the feeder under pressure of 3.68 MPa of argon consumption in 16 litre/min, but the quantity of flux powder coming to the arc zone by the fixed speed of welding (50 cm/min), it consist on average 1,8 gr/min.
Automatic MIG and A-MIG welding conducted by the welding robot «Romat 310» with placed feeder above the torch with the welding mode shown in Figure 2.
Table 2
Modes of MIG and A-MIG welding
As thermodynamic and physical-chemical properties of oxides have been studied the below mentioned properties:
Fig. 2. Diagram of welding bead produced with MIG welding.
The influence degree of thermodynamic and physical-chemical properties of oxides to the morphology of the stainless steel weld bead was estimated with the help of determination coefficient R2. Determination coefficient is on the range 0<R2<1 and it expresses the linear correlation intensity between oxides properties and morphology of the weld bead (relation of the penetration depth to the bead width - P/L). Herewith the size R2 from 0,81 to 1,0 indicated very high correlation, but from 0,25 to 0,49 indicates alternative, which can be considered as moderately correlated, and from 0,09 to 0,25 shows low correlation and less than 0,09 has no (linear) correlation [8].
RESULTS AND DISCUSSIONS
Macrographs of transverse section of the stainless steel CrNi18-10 weld bead with thickness in 4 mm produced with conventional technology (MIG) welding and using gas-powder mixture (A-MIG) shown in Fig. 3.
As a result of micrographs research of weld bead produced with A-MIG welding with using oxides compound as powders and comparison of these beads with beads produced with conventional technology MIG welding, it is observed that penetration depth increase occurred while using all oxides instead of MgO to 10-70%. Due to the influence degree to the increase of penetration depth, we can put them by the following order: SiO2, CaZrO3, TiO2, Fe2O3, Co3O4, Al2O3, Cr2O3, WO3, BaZrO3. As well as all other oxides except CaZrO3 facilitate to the weld bead widening up to 25-90% by the following order: Fe2O3,SiO2,
WO3, Co3O4, BaZrO3, MgO, TiO2, Al2O3, Cr2O3.
STUDY OF INFLUENCE OF PHYSICAL AND CHEMICAL PROPERTIES OF OXIDES FLUXES ON THE WELD FORMATION DURIN MIG WELDING OF STAINLESS STEEL
Saidov R. М., M. Kusch, P. Mayr, K. Hoefer, Gafurov B. Kh., Atabaev I. G., Akhadov J. Z., Komilova D. R., Mukhitdinov Z. S., Huang Yong
4,28 mm
■J!
3
3 -
Ee3 loca
5,34 mm
jaSnpra E
W >5r . CM
Cr2O3
7,07 mm
3 3
SiO2
TiO2
WO3
Co3O4
6,51 mm
.¿IIHä E
I v f
'W-4
Al2O3 CaZrO3 BaZrO3
Fig. 3. The view of transverse sections of the stainless steel CrNi18-10 weld bead with thickness in 4 mm produced with conventional technology (MIG) and using gas-powder mixture (A-MIG).
Melting (Kp) and convexity (Kh) factors value of the weld bead produced with conventional technology (MIG) and using gas-powder mixture (A_MIG) are shown in Fig. 4. These values of melting and convexity factors have been used at the research of physical-chemical properties of oxides influence on the morphology of the weld bead.
Fig. 4. Values of melting (Kp) and convexity (Kh) factors of the stainless steel CrNi18-10 of weld bead with thickness in 4 mm produced with conventional welding (MIG) and using gas-powder mixture (A-MIG).
Fig. 5. Dependency of melting (Kp) and convexity (Kh) factors of stainless steel CrNi18-10 beads from melting temperature of oxides (Tmo) using as a gas-powder mixture with A- MIG welding.
Fig. 5 shows the diagram of the dependency of melting (Kp) and convexity (Kh) factors of beads with melting temperature of oxides (Tmo). High correlation dependency is observed between melting (Kp) and convexity (Kh) factors (shown in Fig. 5). According to its dependency Kp is slightly increases with temperature increase of melting oxides, but value Kh is sharply falls. This effect shows that
with the usage of A-MIG welding of oxides with melting temperature to 2000°C , stainless steel weld bead have the more favorable morphology. With technological point of view the narrow and high beads negatively affect to the weld joint tiredness properties. That's why according to the obtained results for these indicators the more favorable effect can be seen in width and magnification of beads by oxides having melting temperature with higher melting temperature of the welding metal (1450oC).
Hereby, the more effective oxides used as fluxes by MIG welding of the steel CrNi18-10 are the oxides with melting temperature (Tmo) in the range of melting temperature (Tmm) and 2000°C with the following conditions:
Tmm < Tmo < 2000°C Research results of the influence of oxides boiling temperature (Tbo) on the morphology of the stainless steel CrNi18-10 weld beads are shown (Fig. 6) the diagram of the dependency of the weld bead morphology. High correlation dependency can be seen between convexity (Kh) factor of beads and boiling temperature of oxides (Tho). Polynomial Approximating Curve of this dependency has descending character, which indicates to the decrease of convexity character with oxide boiling temperature increase.
Accordingly the more effective oxides used as fluxes by MIG welding of steel CrNi18-10 are the oxides with boiling temperature of oxides (Tbo), which should meet the following conditions: Tbm < Tbo < 3000°C It should be noted, that these results evidence with tight relation between melting and boiling temperatures of the melting metal and oxides produced with A-MIG welding.
High correlation dependency can be observed between melting (Kp) and convexity (Kh) factors of the bead and temperature interval (Tbo-Tmo) (Fig. 7). According to the diagram presented in Fig. 7 the content Kp is maximum at 800°C, but for Кh is minimum by this temperature interval. It gives evidence of more effectiveness of oxides action to the morphology of beads by the temperature intervals (Tbo-Tmo) between 600°C and 1000°C in the framework of the accepted welding mode.
According to the obtained results individual fluxes-oxides are more effectively effects to the morphology of the stainless steel CrNi18-10 weld bead by MIG welding by the following conditions: 600oC > (Tbo-Tmo) ^ 1000oC
Boiling point of oxides {TfcJJnc
Fig. 6. The dependency of the melting (Kp) and convexity (Kh) factors of beads to the stainless steels CrNi18-10 from boiling temperature of oxides (Tto), used as a gas-powder mixtures with A-MIG welding.
& is
¡LJ = 0,521
Khl ■
[ a
■ i pK^i
Kp -PiW Kh-W
RJ = 0,410
Fig. 7. Dependency of the melting (Kp) and convexity (Kh) factors of beads to the stainless steel CrNi18-10 from melting temperature of oxides (Tbo-Tmo), used as gas-powder mixtures with A-MIG welding.
i I. w .i
j C «J
..Kh □ Kp-PiW Kh-VWh
□
\
** RJ = 0,647
i kP RJ = 0,546
------- r-4---
TejiBlo n surface of ox i ae s (0) h m J.'mz
Fig. 8. Dependency of the melting (Kp) and convexity (Kh) factors of beads to the stainless steel CrNi18-10 from surface tension of oxides (a), used as gas-powder mixture with A-MIG welding.
1 1
Kp -PftV Ki-,' Jh 0,581
i' ■
Kh RJ = 3,537
Kp A.....
3 —
U0U 1WJU im, kj/mol
Fig. 9. Dependency of melting (Kp) and convexity (Kh) factors of beads to the stainless steel CrNi18-10 from enthalpy oxide formation (AH°298), used as gas-powder mixture by A-MIG welding.
As research results show (Fig. 8) the important role in formation of weld beads on investigating steels plays the dimension of the surface tension of oxide melts.
Curve dependency of melting (Kp) and convexity (Kh) factors from dimension of surface tension (a) of five oxides (SiO2, WO3, Fe2O3, TiO2, Al2O3 u MgO, information of the surface tension to the oxide melts Cr2O3, Co3O4, BaZrO3 u CaZrO3 has not observed) showed to the high correlation between indicated parameters.
STUDY OF INFLUENCE OF PHYSICAL AND CHEMICAL PROPERTIES OF OXIDES FLUXES ON THE WELD FORMATION DURIN MIG WELDING OF STAINLESS STEEL
Saidov R. М., M. Kusch, P. Mayr, K. Hoefer, Gafurov B. Kh., Atabaev I. G., Akhadov J. Z., Komilova D. R., Mukhitdinov Z. S., Huang Yong
Fig. 8 shows the diagram of the weld bead morphology dependency from the dimension of the surface tension (a) of the indicated oxides, in accordance with surface tension increase results to the weld bead constriction (W) and weld convexity raise (h). It shows, that increase of surface tension of oxides deteriorate interfacial tension between penetration and hard metal, leads to the formation of narrow bead with high magnification and worsens of mechanical-technological properties of weld joint.
Study on the influence of the surface tension increase to the melting (Kp) and convexity (Kh) factors of weld bead observed high correlation between these indicators (Fig. 8), which showed the improvement the bead convexity morphology by dimension of surface tension of oxides in its range of value 200-300 mJ/m2.
Thereby, best results with MIG welding by using oxides will be produced by dimension of surface tension less than 300 mJ/m (a<300 mJ/m2).
In the framework of the current project it were conducted also investigations by study on influence of thermodynamic properties of joints used as powders for gas-powder mixtures on morphology of stainless steel weld bead produced with MIG welding.
One of the important thermodynamic properties of joints is enthalpy of its formation (AH°298). Results of researches on influence of enthalpy oxides formation to the morphology of stainless steels CrNi18-10 weld beads with A-MIG welding are shown in Fig. 9.
In diagram of dependence is observed by high correlation relation between enthalpy formations of oxides (AH°298) and melting (Kp) and convexity (Kh) factors of weld beads (Fig. 9).
In accordance with obtained results the best formation of bead surface (Kh) assured with MIG welding of oxides with enthalpy of formation in the interval from -800 kJ/mol to -1000 kJ/mol.
of oxide fluxes for its effective reaction to produce the qualitative weld beads.
In accordance with the obtained requirements to physical-chemical properties of fluxes-oxides in the framework of the current work it was developed new composition of fluxes type SST-13MIG. In the table 3 presented physical-chemical properties of this flux, determined by diagram the oxides status and calculation method.
Table 3
Physical-chemical properties of flux SST-13MIG
Grade of flux Tm, oC Tb, oC Tb - Tm, 0 a, mJ/m2 ÛH 298, kJ/mol
SST-13MIG 1785 2650 865 255 - 850
Welding tests of new flux produced with TIG welding on plates of stainless steel CrNi18-10 with thickness in 4 mm, which produced by welding regime indicated in table 2.
In Fig. 11 and 12 presented the photos of weld beads cross sections obtained with conventional MIG and A-MIG welding of plates of stainless steels CrNi18-10 with thickness in 4 mm with using of new flux SST-13MIG.
Due to the results of welding tests the weld beads produced with new flux SST-13MIG have full penetration in all thickness of plates and comparing with beads produced with welding without flux its penetration depth increases to 130% (shown in Fig. 12 and Table 4).
4,28 mm
# V
Fig. 11. Macro section of weld bead produced with MIG welding of steel CrNi18-10.
5,01 mm
■
. o
Fig. 10. Dependency of melting (Kp) and convexity (Kh) factors of beads on the stainless steels CrNi18-10 from oxygen content in oxides (O2), used as
gas-powder mixtures during A-MIG welding. Besides, in the framework of the current work it were conducted works on studying the influence of oxygen content in oxides for weld bead formation of investigating stainless steels with A-MIG welding. Study on influence of oxygen content in oxides to the morphology of weld bead with A-MIG welding of the stainless steel CrNi18-10 showed the low correlation dependency between oxygen content in oxides (02), melting (Kp) and convexity (Kh) factors of weld beads (Fig. 10).
Obtained results showed the oxygen content in oxides (02) influences to the dimension of penetration bead depth (P) and convexity height (h), which indicates to the maximum beads penetration with oxygen content in oxides about 30 u 40%.
Thereby obtained results allow to determine the requirements to the physical-chemical properties of oxides, used as a fluxes with MIG welding by following it we can select the optimal composition
- . - . <■■, r
Fig. 12. Macro section of weld bead produced with A-MIG welding of steel CrNi18-10 with flux SST-13MIG.
Table 4
Sizes of the weld bead produced with MIG and A-MIG welding of steel CrNi18-10 with using new flux SST-13MIG
Welding method Grade of flux Width of bead (W), mm Convexity height of bead (h), mm Penetration depth (P), mm Kp Kh
MIG Without flux 4,28 2,12 0,86 0,20 2,02
A-MIG SST-13MIG 5,01 3,05 1,99 0,40 1,64
CONCLUSIONS
1. It were conducted the researches on influence of thermodynamic and physical-chemical properties of powder mixtures for weld bead formation with A-MIG welding of the stainless steels, which allowed to determine the dependency of weld bead formation of thermodynamic and physical-chemical properties of oxide joints as melting temperature (Tmo), boiling temperature
(Tbo), temperature interval (Tbo-Tmo), surface tension (a) and joint formation enthalpy (AHo298). It is observed that the main indicators of indicated oxides properties favorably affecting to the qualitative formation of welded joints, which are as follows:
a) Melting temperature of oxides (Tmo) should be in the melting temperature range (Tmm) and 2000оС, i.e. The following condition is met: Tmm <Tmo <2000oC;
b) Boiling temperature of oxides (Tbo) must satisfy the following conditions: Tbm <Tbo <3000oC;
c) Temperature interval between boiling and melting of oxides (Tbo-Tmo) must be in temperature range from 600° to 800°, that means it is implementing the following: 600o > (Tbo-Tmo ) < 1000°;
d) Surface tension of joints is providing the best results with MIG welding using oxides reached by dimension not less 300 mJ/m2;
e) Oxides formation enthalpy (ДИ°298) positively effecting to the formation of weld bead in range from 800 kJ/mol to -1000 kJ/mol
Also it is identified the oxygen content in oxide (О2) influences to the convexity height (h) and penetration depth of bead (Р) and optimal oxygen content in oxides corresponds 30-40%.
2. In the basis on determined requirements to thermodynamic and physic-chemical properties of oxide fluxes for A-MIG welding of the stainless steels as an example of the steel CrNi18-10 developed new composition of fluxes containing of oxide joints mixtures, which will allow to get the weld bead with penetration depth to 130% comparing with beads produces with conventional MIG welding at the same welding parameters.
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12. Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. p. 1520.
ОТЗЫВ
В статье приведены результаты исследований по изучению влияния физико-механических свойств химических соединений, используемых в газопорошковых смесях для их дозированной подачи в зону сварки при сварке в инертных газах. Полученные результаты исследований позволили определить влияние физико-механических свойств химических соединений, используемых в газопорошковых смесях, на характер их распыление из дозатора и выявить рекомендации к подбору химических соединений на основе оптимальных физико-механических свойств, которые обеспечивали бы оптимальное распыление газопорошковых смесей из дозаторов при сварке в среде инертных газов.
Известно, что главными достоинствами процесса сварки электродной проволокой в среде инертного (аргона) газа (МИГ) являются высокая производительность и высокое качество сварного шва. Высокая производительность объясняется отсутствием потерь времени на смену электрода, а также тем, что этот способ позволяет использовать высокий ток сварки.
Недостатком этого способа является наличие газового баллона и ограниченное использование на открытом воздухе. Также, при сварке в чистом инертном газе, несмотря на хорошую защиту сварочной зоны от воздействия окружающего воздуха, формирование сварного шва ухудшается, а дуга становится нестабильной.
Применение порошковой проволоки при этом способе сварки позволяет успешно устранить эти недостатки. Однако недостатками использования порошковой проволоки является образование большого количества шлаков и высокая стоимость порошковой проволоки.
В статье приведены результаты исследовании по изучению влияния физико-механических свойств химических соединений, используемых в газопорошковых смесях и выявление на их основе оптимальных требований к указанным свойствам для получения качественных сварных соединений при дуговой сварке в среде инертных газов.
Исследование влияния физико-механических свойств порошковых смесей на характер их распыления из шнекового дозатора проводилось на новой модернизированной конструкции устройства для непрерывной дозированной подачи газопорошковой смеси в зону сварки нержавеющих сталей. Исследования истечения порошковых смесей из дозатора проводились при различных скоростях вращения шнека и расходах инертного газа (аргона), подаваемого в дозатор, установленный на роботизированную установку для аргонодуговой сварки.
В качестве химических соединений для исследования физико-механических свойств порошковых смесей и их влияние на характер распыления из дозатора при аргонодуговой сварке нержавеющих сталей использовались порошки оксидов и фторидов (MgO, SiO2, TiO2, CaZrO3, WO3, Al2O3, Na3AlF6, CaF2 и MgF2) с различными гранулометрическими составами (от 25 до 100-150 мкм), которые применяются в составах флюсов для сварки нержавеющих сталей.
В результате проведенных исследований установлено требования к физико-механическим свойствам газопорошковых смесей, соблюдение которых будет способствовать получению наиболее эффективного действия этих смесей при горячей обработке нержавеющих сталей.
Выявлены основные рекомендации к физико-механическим свойствам порошков соединений для их использования в газопорошковой смеси для сварки, которые обеспечивают лучшее распыление порошков из дозатора.
Работа выполнена на высоком научно-техническом уровне и может быть опубликована в журнале «Computational nanotechnology».
Рецензент:
Заведующий лаборатории №1
НПО «Физика-Солнце» АН РУз,
доктор технических наук
Рахимов Р.Х.
