On the Calculation of the Chemical Composition of Deposited Metal in Automatic Welding or Surfacing

I. G. Lyapichev

(Presented by Prof. A. N. Dobrovidov, Doctor of Technical Sciences)

Soviet scientists K. V. Lyubavsky, I. I. Frumin, K. K. Khrenov, and others have made a major contribution to the study and introduction of automatic welding and surfacing of high-alloy steels.

One of the conditions hindering the broader introduction of automatic surfacing of high-alloy tool steels and wear-resistant alloys is the insufficient development of methods for calculating the chemical composition of the deposited metal.

The introduction of alloying elements into the deposited metal is possible by the following methods:

1) by means of a special electrode wire,
2) by means of a flux with a mechanical addition of ferroalloys,
3) by means of a ceramic unfused flux,
4) by means of a bar or paste made from ferroalloys.

The first method of alloying, owing to the insufficient reserve of alloying elements in the electrode wire and the dilution of the pool by 60–70% with the base metal—low-carbon steel—does not ensure, in single-layer surfacing, a bead composition close, for example, to steels P9, Kh12, G13, etc.

This method is used only in multilayer surfacing [1, 2, 3].

The second method of alloying, because of segregation by size and weight of the grains of flux and ferroalloys, does not ensure a uniform composition of the deposited metal (bead) [1, 2]. Therefore, this method of alloying has not gained industrial application.

The third method of introducing alloying elements was proposed by K. K. Khrenov. This method provides increased alloying of the first layer of deposited metal even when using low-carbon welding wire [4]. However, with fluctuations in the line voltage, which are inevitable under production conditions, obtaining a constant bead composition becomes difficult [1, 2].

The fourth method is characterized by concentrating the required quantity of ferroalloys in the surfacing zone (on the surface of the base metal) in the form of a paste [5] or a bar of ferroalloys, instead of uniformly distributing the ferroalloys in the flux, as is done in the third method. This method makes it possible to obtain the highest alloying (up to 30–40%) of the deposited metal. However, the use of paste is associated with a number of technological difficulties: filling the groove for surfacing with paste; the need for subsequent drying of the workpiece with the applied paste. Storage of the paste is difficult (it “sets” and hardens), as is its use in surfacing flat workpieces (toolholders for cutters, knives for assembled milling cutters ...

and so on), when preparation for surfacing may be absent. Dosing the paste according to the preparation profile cannot provide the required accuracy and, consequently, constancy of the chemical composition.

The alloying of the deposited metal by means of ferroalloy bars, proposed by us in 1951, is free of these shortcomings. In this case the influence of fluctuations in the mains voltage on the chemical composition of the deposited metal is considerably weaker than with other methods of alloying.

Method for Calculating the Composition of Alloying Ceramic or Unfused Fluxes and Fluxes with a Mechanical Addition of Ferroalloys

Alloying unfused fluxes and fluxes with a mechanical addition of ferroalloys consist of slag-forming and alloying components. When the deposited metal is insufficiently deoxidized, or when there is a large burn-off of alloying elements, deoxidizers are introduced into the flux composition.

A method for calculating an alloying unfused flux, or a flux with a mechanical addition of ferroalloys, has not yet been developed. The quantity of ferroalloys that must be introduced into the slag-forming part of the flux is determined by a series of experimental surfacings. The composition thus found for the alloying flux ensures the required composition of the bead while the experimental surfacing conditions are maintained. A change in even one parameter of the surfacing conditions \((I_0, U_0, V_{\mathrm{sv}}, V_{\mathrm{el}}, U_{\mathrm{mains}})\) causes a disturbance in the ratio of the amounts of molten flux, base metal, and electrode metal and, consequently, a change in the chemical composition of the deposit.

There is no universal composition of an alloying unfused flux or of a standard flux with a mechanical addition of ferroalloys.

The ferroalloys introduced must alloy the molten base and electrode metal. It is assumed here that the base metal is carbon or low-alloy steel and that the electrode is low-carbon wire of grade Sv-08. Therefore, as a first approximation, independently of the composition of the slag-forming base of the welding flux, the quantity of ferroalloys introduced may be calculated from the weight per unit length of the bead of deposited metal. In doing so, the amount lost by burn-off due to the unavoidable oxidation of ferroalloys remains unaccounted for, as does another portion of them that remains unused in the solidified slag crust.

The quantity of ferroalloys found for alloying the deposited metal must be distributed in such a quantity of slag-forming components as will make it possible, after surfacing, to obtain the calculated composition of the bead. For this it is necessary that, during surfacing, such an amount of the alloying unfused flux be melted as will ensure the introduction of the calculated quantity of ferroalloys. In addition, the introduction of ferroalloys into the flux must not, in comparison with the experimental surfacings, lead to a change in the cross-sectional area of the deposited metal that was adopted for determining the amount of ferroalloys to be introduced.

To solve these questions, the following assumptions were made:

1. The introduction of the calculated quantity of ferroalloys—a high-melting constituent—into the slag-forming part of the flux reduces only the degree of its overheating. However, this does not lead to a change in the quantity of molten flux despite the change in its composition and, consequently, in the heat of fusion. The rapidity of the surfacing process, the considerable overheating of the flux in the zone of the arc column, and the insufficient heat transfer from the overheated to the cold layers weaken the dependence between the heat of fusion of the components and the quantity of molten flux.

When the arc power per unit length is maintained, the amount of molten “slag-forming” ceramic flux, made only from protective slag-forming components, remains constant in comparison with the amount of alloying unmelted flux composed of the same slag-forming components and ferroalloys. It should be noted that the consumption of alloying unmelted flux cannot be determined from the weight of the slag crust: during melting of the flux, its ferroalloys pass into the bead;

1. when the arc power per unit length is maintained, the amount of molten base and electrode metal deposited both under a “slag-forming” ceramic flux (made only from slag-forming components) and under an alloying unmelted flux composed of the same slag-forming components and ferroalloys remains constant.

These assumptions were confirmed by numerous experiments.

The calculation of the composition of a ceramic unmelted alloying flux, or a flux with a mechanical addition of ferroalloys, is carried out in the following sequence:

1. the slag-forming base of the alloying flux is selected in advance and a “slag-forming” flux is prepared. Such a flux is subject to the general requirements for all welding fluxes. An additional requirement is the need to ensure the least oxidation of the alloying elements that, after calculation, will be introduced into the composition of this “slag-forming” flux;

2. according to the drawing of the part to be surfaced or of the cutting part of the tool, the surfacing conditions are determined in order to create the required cross-sectional area of the deposited layer—the future wear-resistant working part of the component or the cutting part of the tool. The surfacing conditions may be determined from the data given in [2];

3. at the selected conditions, an experimental surfacing of blanks of components or cutting tools is carried out with low-carbon welding wire under the “slag-forming” flux;

4. the cross-sectional area of the bead and the consumption of flux per 100 g of deposited metal are determined. A chemical analysis of the deposited metal is performed;

5. by the formula given below, the amount of ferroalloys required for alloying 100 g of deposited metal is calculated;

6. from the flux consumption data (item 4) and the required amount of ferroalloys (item 5), the charge for the unmelted ceramic flux is prepared. The granulation of the finished ceramic alloying flux, as well as of the “slag-forming” flux, must be the same.

The amount of ferroalloy \(Q\) g whose introduction into \(A\) g of deposited metal will ensure in it a content of \(a\%\) of the element is recommended to be determined by the formula:

\[ Q=\frac{100+k}{100}\,A\,\frac{a}{b}, \tag{1} \]

where \(b\) is the content of the element in the ferroalloy, in %,

\(k\) is a coefficient accounting for burn-off and other losses, in %.

If \(c\%\) of the element is introduced in addition to the ferroalloy—for example, by slag-forming components, electrode metal, or base metal—then in the formula, instead of “\(a\)” one should substitute “\(a-c\).”

We prepared unmelted “slag-forming” fluxes (Table 1). Flux No. 1 differs from Kosmachev’s flux I. G. [5] by the absence in it of three percent ferroaluminum and two percent ferrotitanium.

This is explained by the absence of any noticeable influence of these on the composition and structure of the bead. Apparently, aluminum and titanium burn out prematurely outside

within the limits of the welding pool. Flux No. 2 is made from crushed fused flux AN-348-A and has a higher acidity than flux No. 1. It may be assumed that flux No. 2 will retain the high technological properties of the fused flux.

Table 1

The components of flux No. 1 were mixed after crushing and screening through a sieve with 1600 openings/cm². After liquid glass was added, the mixture was dried at a temperature of 250°. Subsequent crushing completes the manufacture of the unfused flux. According to the study by I. G. Kosmachev [5], the normal fineness of a flux is considered to be the granulation of the residue on a sieve with 400 openings/cm².

Our experiments showed that such fineness does not ensure normal arc burning when surfacing high-carbon steels and alloys. For example, when surfacing high-speed steel, gas blowouts are observed. When surfacing low-carbon steel, blowouts are observed less often. In this connection, the grain size of the unfused flux used for surfacing high-carbon steels was increased to 1–2 mm in cross section. The flux layer when surfacing high-speed steel was increased to 6–7 cm, instead of 3–4 cm when welding or surfacing low-carbon steel.

When surfacing high-speed steel with a content of 0.9–1.4% C, strong gas bubbling forms in the spaces between the flux grains. Evidently, this is the result of intensive carbon burn-off, the content of which in high-speed steel is 4–6 times higher than in structural steels.

Crushing the flux lengthens the spaces between the flux grains and reduces their cross section. This increases the resistance to the escape of gases. The increased gas evolution during surfacing of high-speed steel leads to an increase in the velocity of gas motion in the arc zone. The gases do not have time to cool sufficiently while passing through a flux layer 3–4 cm high. This leads to ignition of the gases on the surface of the flux, which is facilitated by the high content of carbon monoxide in them.

Ignition causes additional local melting of the flux and enlarges the channels through which the gases break through. The main mass of arc gases rushes into these channels, despite the considerable distance of up to 130–160 mm between the blowout opening and the place where the arc is burning.

With an increased flux layer (6–7 cm), the gases have time to cool. They sometimes burn out on the surface of the flux with a calm bluish flame without forming a blowout. It should be noted that an increase in arc length promotes gas blowout.

The gas permeability of the flux when surfacing high-speed steel is an important factor. It is necessary to use porous, pumice-like or

coarse-grained fused fluxes. When unfused fluxes are used, their grain size should be not less than 1–2 mm in cross section.

The authors of a recently published work [6] recommend increasing the grain size of ceramic flux.

Surfacing operations were carried out under fluxes No. 1, 2 and AN-348-A on TS-17 tractors (constant electrode feed rate) and ADS-1000 tractors (adjustable electrode feed rate) at a mains voltage of 208–210 V. Low-carbon electrode wire of grade SV08 was used.

The surfacing was performed on specimens measuring \(18 \times 18 \times 370\) mm made of steel 3, obtained after planing bars measuring \(20 \times 20 \times 370\) mm. There was no rust on the surface of the specimens. To prevent spreading of the deposited metal, graphite molds were used.

Surfacing conditions:

\[ \begin{array}{ll} \text{TS-17} & \begin{array}{lll} I_d = 600\ \text{A}; & U_d = 45\ \text{V}; & V_e = 40\ \text{m/h}.\\ V_{sv}=20\ \text{m/h}; & \varnothing_e = 4\ \text{mm}. & \end{array} \\[1em] \text{ADS-1000} & \begin{array}{lll} I_d = 600\ \text{A}; & U_d = 42\ \text{V}. & \\ V_{sv}=20\ \text{m/h}; & \varnothing_e = 4\ \text{mm}. & \end{array} \end{array} \]

Each surfacing operation was repeated on three specimens. The measurement results are presented in Table 2.

Table 2

On the basis of the consumption data for slag-forming fluxes No. 1 and 2 (Table 2) and the required amount of ferroalloys, alloying unfused fluxes No. 1 and 2 were prepared.

For example, to obtain deposited high-speed steel containing 1.2% C, 9.5% W, 4.6% Cr, 2.7% V, and 1.7% Mo, for alloying 100 g of deposited metal it is necessary to use 14.3 g of ferrotungsten (70% W, 0.8% C), 9 g of ferrochrome (52.2% Cr, 6.02% C), 7.5 g of ferrovanadium (38.8% V, 0.52% C), 3 g of ferromolybdenum (59.9% Mo), and 19 g of cast iron based on U12 steel (4.81% C).

Melting of U12 steel scrap was carried out on a high-frequency generator AZ-43 at a voltage of 8–9 kilovolts and 2.5–3 amperes of anode current, with the frequency lowered by additionally introducing banks of air capacitors. A crucible made from a mixture of 80% quartz sand and 20% refractory clay was inserted into the inductor of the installation. The capacity of the crucible was 1.5–2 kg of steel.

Carburization of the steel was carried out with powdered graphite. The melt was protected with cullet from window glass.

We do not know the data on burn-off of alloying elements during automatic surfacing of high-speed steel. As a guide, we adopted: for chromium 6–8%, vanadium 4–6%, tungsten 3–4%, carbon 20–30%, molyb-

by 1–2%. In addition, from the above-mentioned mixture of ferroalloys, bars measuring \(6 \times 16 \times 50\) mm and weighing 26 g each were made (the technology of their manufacture is described below).

To determine the effect of fluctuations in the line voltage on the chemical composition of the deposited metal, at line voltages \(U_{\text{line}} = 200 \div 210\) and 220 V, under alloying fluxes Nos. 1 and 2 and under flux AN-348-A over bars of ferroalloys placed on the workpieces, surfacing was carried out under the above-mentioned conditions for the tractors TS-17 and ADS-1000. Each surfacing run was repeated on three workpieces measuring \(18 \times 18 \times 370\) mm, made of St. 3 steel.

Chemical analysis for carbon, tungsten, and vanadium was performed on one specimen at the beginning, middle, and end of the deposited bead (Table 3). On the second and third workpieces, in these same places, a control analysis for carbon and tungsten was performed. Fluctuations in the composition of the beginning and middle of the bead on the three holders in all cases did not exceed \(\pm 3\text{–}4\%\) for carbon and \(\pm 2\text{–}3\%\) for tungsten. Only the composition of the ends of beads deposited over ferroalloy bars under flux AN-348-A has an increased scatter¹. Additional experiments showed that this scatter depends on the moment at which the arc is broken relative to the end of the ferroalloy bar. Switching off the welding current at the moment when the vertical axis of the electrode coincides with the end of the bar causes 8–12 mm of it to remain. A later breaking of the arc leads to additional melting of the base and electrode metal and, consequently, to dilution of the bath.

To obtain the same chemical composition at the end and in the middle of the bead, it is necessary to meter the arc-burning time (for example, by means of a time relay), so as to be able to determine precisely the moment at which the welding circuit is broken.

A comparison of the compositions of the middles of the beads at \(U_{\text{line}} = 210\) V shows that surfacing on TS-17 and ADS-1000 over ferroalloy bars agrees best with the calculated composition. This occurs because of the complete melting of the ferroalloy bar and confirms the correctness of the assumptions underlying the calculation of the composition of a ferroalloy bar.

The discrepancy between the composition of the beginning and the middle of a single bead, for any method of alloying, is the result of the unsteady process of arc burning during the first 1–2 seconds after its striking. This leads to an increased local consumption of flux at the beginning of surfacing. Therefore the beginning of the bead has an increased content of elements if surfacing is performed under alloying flux No. 1 or 2. It should be noted that the composition of the beginning of a bead deposited on TS-17 has a higher content of elements than in surfacing on ADS-1000. This occurs because of the longer duration of arc stabilization on TS-17, owing to the absence of forced regulation of the electrode feed rate, which is characteristic of the electrical circuit of the ADS-1000.

The end of surfacing is also a point at which the established arc-burning condition is disturbed. Along the contour of the “last” pool, the depth of penetration of the base metal decreases. When the “Stop 1” button is pressed, the feed of the electrode wire ceases, but the welding current is not switched off. The arc continues to burn until self-extinction. This increases the alloying of the end of the bead when surfacing under fluxes Nos. 1 and 2.

When surfacing under flux AN-348-A over ferroalloy bars, the alloying of the end of the bead in this case, on the contrary, decreases.

The smallest change in the composition of the bead when the line voltage is changed from 200 to 220 V is observed when surfacing over ferroalloy bars—

Table 3

Note: 1. The place where chips were taken for chemical analysis, “beginning of bead,” was located at a distance of 25 mm from the beginning of the bead; “end of bead”—at a distance of 35–40 mm from the end of the bead. The chips were taken with a cutter or drill fitted with a VK8 plate. Before chips were taken for chemical analysis, the deposited metal was not annealed, but underwent only high-temperature tempering at \(750 \div 800^\circ\).

alloys on the TS-17 tractor. The use of the ADS-1000 tractor under these conditions produces a greater change in the composition of the bead.

The weak influence of fluctuations in the line voltage on the composition of the bead when surfacing over ferroalloy bars on the TS-17 is explained by the fact that the tractor has an electrode feed speed independent of the line voltage. This ensures a constant quantity of molten electrode metal. A constant quantity of alloying elements is ensured because the ferroalloy bar is always melted completely, regardless of fluctuations in the line voltage. A change in the amount of molten flux does not cause substantial fluctuation in the composition of the bead, since alloying is carried out by the ferroalloy bar. Only the third component of the bead composition—the proportion of base metal—undergoes a change.

When the line voltage drops, the TS-17 tractor, owing to the need to melt a constant amount of electrode metal, establishes a new mode with a reduced arc voltage and a practically unchanged welding current.

Despite the overall decrease in arc power when the line voltage drops, the amount of molten base metal changes only slightly. This occurs because the arc column is immersed in the base metal, which increases the proportion of heat expended on melting the base metal.

Our experiments agree with the theoretical investigations of welding equipment by I. L. Brinberg [7]. The experiments performed show the possibility of using welding heads with a constant electrode feed speed for surfacing high-speed steel when the line voltage fluctuates within the range \(210 \pm 10\) V. If the head is adjusted at the highest line voltage and only a decrease in it is anticipated, the ferroalloy bar must be calculated according to the lower limit of the content of elements in the steel. A voltage drop will reduce the amount of molten base metal and will cause an increase in the alloying level of the bead.

It should be noted that the permissible fluctuations, according to GOST, in the content of elements in steel R18 reach 8.5–25%, and in steel R9—11.8–30%.

Heads with a regulated electrode feed speed (ADS-1000), when the line voltage drops, establish a new mode with an unchanged arc voltage and a reduced welding current. The latter leads to a decrease in the molten electrode and base metal. The amount of molten flux decreases only slightly. The composition of the deposited metal changes more strongly than when using heads with an independent, constant electrode feed speed. This is explained by the unfavorable reaction of the ADS-1000 to fluctuations in the line voltage, which leads to a change in the technologically important parameter of the mode (welding current) and to the preservation of the secondary one (arc voltage).

Equipping heads with a constant electrode feed speed with primary-voltage stabilizers will increase their value when carrying out surfacing work.

Analysis of the deposited metal over the height of the section shows the absence of zonal segregation (Table 4).

Table 4

This means that the deposited metal over the entire cross section is equivalent to the deposited part of the component or the cutting part of the tool.

Method for Calculating the Composition of a Bar Made of Ferroalloys

The composition of the deposited metal depends on the amount of molten ferroalloys in the bar, of base metal, electrode metal, and flux. The calculation of the composition of a bar made of ferroalloys must be carried out as a function of the surfacing conditions and the composition of the flux. Fluctuation of the surfacing conditions leads to a change in the amount of molten base and electrode metal and to a change in the composition of the bead.

These requirements are not fully satisfied by the method for calculating the composition of an alloying paste proposed by I. G. Kosmachev [5]. In this method, a high (more than 30%) reserve of alloying elements is provided without regard to their burn-off. The paste dosage is determined as a function of the cross-sectional area of the grooves for surfacing. There is no connection with the surfacing conditions and the grade of flux. Use of the calculation method is difficult when complex or carbonaceous ferroalloys are employed.

The method we propose is based on the assumption that the cross-sectional area of the bead, at constant linear arc power, does not depend on its chemical composition. The cross-sectional area of the bead when surfacing over bars and without them will be the same. When surfacing over bars, the amount of molten base low-carbon metal must decrease in accordance with the weight of the ferroalloy bar.

A change in the chemical composition of the deposited metal, and consequently in the heat of melting, will lead only to a change in the degree of superheating of the weld-pool metal. However, this does not lead to a corresponding fluctuation in the cross-sectional area of the bead because of insufficient heat transfer from the liquid to the solid metal.

To determine the influence of the density and chemical composition of the bar on the cross-sectional area of the bead, the following experiments were carried out. From chips of steels 3 and R18 and from mixtures of ferroalloys of various compositions, bars of different density but of identical weight—26 g—were made on a press, with dimensions \(6 \div 8 \times 16 \times 50\) mm; plates \(4 \times 16 \times 50\) mm were made from steel 3; and plates \(3.6 \times 16 \times 50\) mm, weighing 26 g each, were made from steel R18. Surfacing was carried out with a TS-17 tractor on \(18 \times 18 \times 370\) mm blanks of steel 3 under the following conditions: \(I_{\mathrm{e}} = 600\) A, \(U_{\mathrm{a}} = 45\) V, \(\varnothing_{\mathrm{e}} = 4\) mm, line voltage \(U = 208\text{–}210\) V, \(V_{\mathrm{e}} = 40\) m/h, \(V_{\mathrm{sv}} = 20\) m/h, under AN-348-A flux, using pressed bars, plates, and also without them, i.e., directly on the blanks. Measurements of the cross-sectional area of the beads showed no dependence of it on the chemical composition and density of the alloying addition (bar or plate). The bead cross section when surfacing over a plate and chips of steel 3 was \(1.19\text{–}1.23\ \text{cm}^2\); over a plate and chips of R18, \(1.14\ \text{cm}^2\); and over a mixture of ferroalloys, \(1.09\ \text{cm}^2\). If the different specific gravity of the deposited metal is taken into account, it turns out that the weight of the molten base and electrode metal is constant and does not depend on the bead composition. In conclusion, we carried out the following experiments.

In the TS-17 tractor, set to the above conditions, the low-carbon welding wire Sv. 08 was replaced by 4 mm diameter silver-steel wire made of steels R9 and R18. Blanks of steels R9 and R18 served as the base metal. No disturbance of the stability of the surfacing process was observed. The cross-sectional area of the deposited metal was \(1.18 \div 1.24\ \text{cm}^2\).

We recommend calculating the composition of a bar made of ferroalloys in the following sequence:

1. The welding flux is selected in advance. As experience has shown, high-manganese fluxes of the AN-348-A type can be used successfully. The physicochemical characteristics of alloying metal deposited using ferroalloy bars ensure the high quality of deposited high-speed steel and only slight burn-off of alloying elements.

2. According to the drawing of the part to be surfaced, or of the cutting portion of the tool, a surfacing regime is specified that provides the required cross section of the deposited metal.

3. Trial surfacing is carried out on a blank of the part or tool with low-carbon welding wire under the selected regimes.

4. The cross-sectional area is measured and the linear weight of the bead is determined.

5. If the bead cross section satisfies item 2, then, by formula (1), the composition of the ferroalloy bar for alloying the deposited metal to the required level is calculated.

6. The ferroalloy bar is manufactured in a press mold. The dimensions of the bar are established as follows: the length of the bar must ensure the linear feed of the ferroalloys. The width of the bar is taken as 2 mm less than the width of the deposited-metal bead (item 4). After the bar has been made, it is placed on the surface of the part to be surfaced or of the cutting-tool blank. Then surfacing is carried out under the previously selected regimes (item 1). The melting bar alloys the weld pool.

To prevent lack of fusion, the linear weight of the bar must not exceed 80% of the linear weight of the bead obtained in surfacing with low-carbon wire (item 4).

Alloying the deposited metal with ferroalloy bars opens up a broad possibility for using briquettes made from chips of alloy steels. In this case a considerable saving of ferroalloys is achieved.

The use of briquettes made from chips of special steels for alloying deposited metal is based on the fact that, for each automatic surfacing regime, there is a maximum quantity of ferroalloys (in grams) that can be introduced per unit length of deposited metal. If this quantity is exceeded, lack of fusion is observed. For example, this occurred when ferroalloys were fed at 9.2 g/cm during surfacing under the above-mentioned regimes (welding current 600 A, electrode-wire diameter 4 mm).

From the ratio of the cross-sectional area of the deposited metal to the consumption of electrode wire, it can be determined that, in the composition of the deposited metal under the specified regime, the fraction of electrode metal reaches only 20%.

By increasing the quantity of ferroalloys introduced, the depth of penetration of the base metal can be reduced to 1–1.5 mm. This will reduce dilution of the weld pool with the low-carbon steel of the part or tool blank. The fraction of base metal in the weld pool will decrease to 15–20%. As a result, the deposited metal will consist, to the extent of 35–40%, of unalloyed base and electrode metal. This makes it possible, for example, to obtain deposited metal whose chemical composition is close to that of type R9 steel if a briquette made of chips of R18 steel is used. With a linear weight of the bar of chips from R18 steel of 6.5–7 g/cm, when surfacing under the specified regimes with AN-348-A flux on the TS-17 tractor, we obtained the following composition of deposited metal: 0.46% C; 0.84% Mn; 0.70% Si; 10.02 W; 1.82% Cr and 0.54% V. The reduced content of chromium, vanadium, and carbon can be compensated by adding ferroalloys and cast iron. The results

results of such complex alloying with chips and ferroalloys are given in Table 5.

Table 5

In alloying the deposited metal with chips and ferroalloys, we used 40 g of R18 steel chips, 4.4 g of ferrochrome, 4.8 g of ferrovanadium, and 26 g of cast iron based on R18 steel waste. Such replacement of a ferroalloy bar consisting of 14.3 g of ferrotungsten, 9.0 g of ferrochrome, and 6.75 g of ferrovanadium saves 100% of the ferrotungsten, 51% of the ferrochrome, and 30% of the ferrovanadium. The use of additions of chips of high-chromium steel of the Kh12 type will lead to a greater saving of ferrochrome.

Further work should broaden the field of application of alloyed-steel chips both in the form of briquettes and for the manufacture of alloying ceramic fluxes. The use of special surfacing regimes that ensure minimum penetration of the base metal, as well as equipment with a nonconsumable (graphite, tungsten) electrode, will considerably increase the concentration of alloying elements in the welding pool.

At present, at the Tomsk Plant of Cutting Tools, holder of the Order of the Red Banner of Labor, surfacing of tools is being introduced with the use of both ferroalloys and high-speed-steel chips.

Briquetting of the chips is carried out on a hammer or friction press (180 t).

Alloying with ferroalloy bars was also used by us to obtain experimental deposits of high-speed steel of the R9 type, additionally alloyed with carbon, vanadium, titanium, and tungsten.

To determine the required fineness of the ferroalloys (granulation), the bars were made from their powders passing through sieves with hole diameters of 0.5—1—2 mm.

After the ferroalloys were mixed in the dry state, the mixture was slightly moistened with liquid glass previously diluted with 50–60% water. After this, repeated mixing was carried out.

The moistened mixture is poured into the press mold. The mixture may be charged either by measuring container or by weighing. Pressing is carried out at a low pressure—8–10 kg/cm².

Experience has shown that a certain nonuniformity of the linear dosing of ferroalloys in the bar may be tolerated: in practice, it is not reflected in the chemical composition of the deposited metal along the length of the bead. The chemical composition of the bead is equalized owing to the vigorous stirring of the metal in the welding pool. The welding pool combines regions with different concentrations into one “mixing” reservoir.

Ferroalloy fineness down to 2 mm does not affect the technological properties of the flux or the homogeneity of the chemical composition of the deposited metal.

When surfacing high-speed steel using ferroalloy bars under AN-348-A flux, the loss of alloying elements reaches the following values: for chromium—2.5%, for vanadium 2.1%. Molybdenum and tungsten practi-

they practically do not oxidize. The loss of elements was determined on the basis of chemical analysis of the slag crust after surfacing high-speed steel of the R9 type.

The main advantage of surfacing with bars made of ferroalloys, in comparison with surfacing under alloying ceramic fluxes, lies in the possibility of obtaining a highly alloyed composition (up to 30–40%) of the deposited metal in the first bead, that is, in single-layer surfacing. In this case it is possible to use any automatic-welding conditions that provide the largest cross section of deposited metal. Considerable melting of the base metal when using conditions with high welding-current densities is not an obstacle to the introduction of this surfacing method. On the contrary, it makes it possible to increase the degree of alloying of the surfacing, since the linear weight of a ferroalloy bar is directly dependent on the amount of melted base metal.

When alloying the deposited metal with ceramic flux, the calculated composition of the deposited metal can be obtained only in the second or third layer of metal [1, 2, 3].

The transfer of alloying elements from the ceramic flux into the deposited metal does not exceed 60% because of considerable losses of ferroalloys with the slag crust and by oxidation.

Losses of alloying elements during surfacing with bars made of ferroalloys do not exceed 2–3%.

If one takes into account that the technology of manufacturing bars from ferroalloys and that of ceramic flux are approximately the same, then in single-pass surfacing of beads of high-alloy steel with a large cross-sectional area, alloying with bars has obvious advantages.

Conclusions

1. A method has been developed for calculating the chemical composition of deposited metal when alloying it with bars made of ferroalloys and with ceramic fluxes.

2. The expediency has been demonstrated of alloying deposited metal with bars made of ferroalloys or with chips of alloy steel when surfacing beads with a large cross-sectional area. It is recommended that surfacing be carried out on welding equipment with a constant electrode-feed speed.

Literature

1. Frumin I. I. Alloying of deposited metal in welding under flux. Avtomaticheskaya svarka, No. 1 (22), 1952.

2. Automatic electroslag welding. Mashgiz, 1953.

3. Polodnya I. K. Automatic surfacing of a layer of high-chromium wear-resistant steel. Avtomaticheskaya svarka, No. 4, 1953.

4. Khrenov K. K. Ceramic unfused fluxes for automatic arc welding. Collection of reports of the Scientific and Technical Conference of Welders. Mashgiz, 1953.

5. Kosmachev I. G. Automatic surfacing of a multi-blade tool. Mashgiz, 1952.

6. Khrenov K. K.; Kushnerev D. M. Ceramic fluxes for welding. Mashgiz, 1954.

7. Brinberg I. L. Modern equipment for welding under flux. TsNIITMASH. Book 14. Problems in the theory of welding processes. Mashgiz, 1948.

1. Table 3 gives the results of experiments for which the operating procedure already predetermined scatter. ↩