DE2713020C2 - Process for producing layered composite metal materials - Google Patents

Description

25th

The invention relates to a method for producing layered composite metal materials as described in the preamble of claim 1 specified genus. Such a process is already known from US Pat. No. 3,695,337.

In this known method, metallic layer materials are produced in such a way that a Kemmatcrial with a polyfluoroethylene coating (polytetrafluoroethylene, Polychlorotrifluoroethylene and its derivatives) is coated, whereupon the coated Core material is poured around with a second molten material.

This known method is disadvantageous in that the known coating in the area of the melt level of the second molten material thermally decomposed with the formation of halogen-containing decomposition products, with the help of which an oxidation of the Core surfaces is prevented by oxygen contained in the mold.

However, it has been found that producing non-oxidizing Gases in the area of the core surfaces are insufficient to impair the core surface and thus to prevent the quality of the composite material produced. Investigation of material inclusions in the area of the interface between core and cladding show that these are oxidic materials that floated as foam on the melt surface. Inclusions of this type arise when the steel melt reacts with air and / or with the refractory lining of the melting vessel. To such To prevent inclusions, the familiar formation of a protective coating is sufficient Thermally decomposed non-oxidizing gases, not from. In particular, it is important to prevent floating Oxide particles get into the area of the interface between the core and cladding.

Another disadvantage of the known Polyttralluoräthylen-Bcschichtungen consists in the fact that these b5 decompose with the formation of a black smoke, without to ignite. This smoke development is however In no way conducive to keeping the mentioned interface free from oxygen and oxidic impurities.

Another disadvantage of the known process arises from the fact that it is in an aqueous or alcoholic dispersion must be used because of the lack of a suitable solvent. As a result, the coating after application must be dried and fired, in which there is a risk of cracks appearing lies. In addition, coatings of the type mentioned do not have excellent adhesive properties.

From GB-PS 1 289639 it is known in the production of layered metal materials to form a suitable protective layer on the metal substrate and the Thoroughly clean the surface of the substrate before applying the coating.

The invention is based on the object of providing a method of the type known from US Pat. No. 3,695,337 form that as a result of an improved protective layer formation the number of inclusions in the area the mentioned boundary layer can be reduced.

This object is achieved with a method of the type specified in the preamble of claim 1 by the features specified in the characterizing part of claim 1.

De; With the help of the invention achievable technical progress is primarily to be seen in the fact that a Halogen-free coating material is used, which is thermally with particularly vigorous gas development decomposed. This ensures that there are no oxidic inclusions at the interface between the core material and the cladding layer can set. It is also made by the lively Gas evolution, the partial pressure of oxygen in the mold greatly reduced, whereby the risk of oxidation is reduced. In contrast to the known polyfluoroethene coatings Ignite the coating layer materials according to the invention at the beginning of the encapsulation with the second melt, wherein the Oxidation process takes place with strong flame formation. The vigorous evolution of gas ensures that the the presence of oxygen of the access to the core material surface is practically completely denied and that this oxygen is washed away together with any particles which may lead to foam formation will.

Another advantage of the method according to the invention results from the fact that the coating to be applied can be applied in dissolved form, so that the layer thickness and the viscosity of the coating Can be adjusted effortlessly. This also creates a special drying and baking process superfluous, which prevents the risk of drying cracks in the coating material.

According to a preferred embodiment of the invention, the coating material is in a thickness of Applied 100 ^ to 3000 µm.

The invention is explained in more detail below with the aid of exemplary embodiments and with reference to the drawing explained. In this shows

1 shows a schematic explanation of the casting production of a sheathed composite metal block,

Figs. 2Λ and 2B are a side view and a sectional view, respectively of the coated composite metal block. which is produced with the aid of the procedure explained in FIG became.

Fig. 3 is a schematic sectional view showing a

represents other casting production of the sheathed cut metal block,

Fig. 4 is a graph showing the relationship between the shear strength and the ratio the area provided with entrained foam in the clad sheet shows which is made of the encased Laminated metal block has been manufactured,

Fig. 5 is a graphical diagram showing a relationship between the distance from the mold wall to the Surface of the core material and the ascent rate of the melt, as this results in the Occurrence of defects in the solidified metal layer is influenced, and

Fig. 6 is a graph showing the relationship between the ascent rate and the ratio the area exhibiting entrained foam.

By performing the method of the invention in the case where an oxide film is present on the surface of a steel core material, it is necessary, this oxide film beforehand by sandblasting, grinding, sanding, etching or the like. To remove the To improve the binding ability of the composite metal block to be formed in the subsequent operation. aside from that the bonding capacity can be improved by making parallel rectangular grooves, triangular grooves, Circular grooves or other bumps are formed in the surface of the core material after the Oxide film has been removed to remove the interface between the core surface and the Enlarge melt. Then an organic one consisting primarily of carbon and hydrogen becomes Cloth is applied to the surface of the core material so as to form a coating film having a thickness from 50 μm to 3000 μm, preferably 100 μm to 3000 μm arises.

In the interests of considerably weakening the foam inclusions and reducing them sufficiently the partial pressure of oxygen inside the mold the required amount of organic substance required for gas evolution through sufficient thickness of the Coating film can be guaranteed. In this context, reference is made to the test results that that the thickness of the coating film is within a range of 50 μΐπ to 3000 μιη, preferably should be from 100 μm to 3000 μm. Is the thickness of the coating film less than 50μιτι, so evaporated or the coating film burns even before the melt comes close to the core material or the same touches, in addition, the amount of gas generated is only so small that the oxide film and the casting foam are included in the composite block, which in turn increases the bond or bondability at the interface between the core material and the cladding or cladding metal. If the coating film exceeds a thickness of 3000 μm, the binding behavior remains unaffected, so that another application of the organic matter would be an uneconomical waste. For this reason, it is important that the thickness of the coating film in a range from 50 μm to 3000 μm and preferably from 100 μm to 3000 μm. It is also in the interest of maintaining a sufficiently low partial pressure of oxygen in the The atmosphere inside the mold is advantageous, the oxygen content of the coating film is so low as possible, eliminating the use of carbohydrates such as molasses and the like as organic matter is unsuitable.

In forming the coating film, it is necessary that those composed primarily of carbon and Hydrogen existing organic substance is dissolved in a solvent to a suitable viscosity and have suitable adhesiveness if necessary. The organic substance is sprayed on, Dipping or the like applied to the surface of the core material and then allowed to stand at room temperature or heated to a suitable temperature,

around a solid or semi-solid coating film form whose thickness is within the range defined above.

In addition, the coating film can be formed by mixing the organic substance with powdery

Granules of a substance that has a stronger oxygen affinity than iron. Such substances are Aluminum, magnesium, CaSi, silicon, titanium, zirconium, Magnesium-aluminum alloy, calcium-silicon-aluminum alloy, Calcium-silicon-barium-

Aluminum alloy, iron-silicon alloy, Fe-Si-Mg alloy, Fe-Si-Ca alloy, Fe-Si-Al alloy, Fe-Ti alloy and dg;!. As can also be seen from the following examples, by using of such substances the binding properties

the interface between the core material and the solidified metal layer is improved compared to the cases where the organic matter was used alone. To explain this process it is assumed that that the large amount of FeO containing foam components, which have penetrated into the interface due to the interaction of the organic substance with the additives is reduced in order to change the morphology and the composition of the inclusions.

According to the invention, a synthetic resin is used as an organic

Used substance that consists primarily of carbon and hydrogen. Phenolic resin, amino resin, epoxy resin, polyamide resin, acrylic resin, polyester resin and vinyl acetate resin are mentioned as examples.
The use of a synthetic resin is particularly advantageous because the viscosity and adhesiveness can be easily adjusted with the aid of a solvent and the solidification rate can be increased so that the thickness of the coating film can be adjusted and easily made larger. There are various methods of applying or applying the organic matter. For example, the organic substance can be sprayed using a spray gun, the organic substance can be applied using a brush, or the organic substance can be applied by immersing the core material in a solution thereof. In any case, the function of the coating film remains unchanged as long as the thickness is always the same. In general, it should be noted that the coating film can be peeled off from the core material if it is subjected to mechanical impact when the core material is placed in the mold. Accordingly, however, the coating film is prevented from peeling off due to its high mechanical strength and excellent adhesiveness to the core material. In addition, the coating film made of synthetic resin is found to be thermally stable. Thus, the coating film made of epoxy resin is for example up to a temperature of etv, .i 120 ⁰ C stable, whereby there is no risk that the coating film evaporates or burns and thus disappeared from the surface of the core material when the core material during the casting of it -

is warmed. This also ensures that the coating film is still present when the core material dips into the surface of the melt and this can cause the oxidation reaction and entrapment of foam in the surface of the core material can be prevented. It is advantageous not to allow air to enter into the mold during casting. This means that the entry of an oxygen-containing medium into the Form is prevented and that the oxygen particle pressure inside the form is at a low level can be held. Of course, it is advantageous that the partial pressure of oxygen inside the mold is reduced still further by the fact that the atmosphere inside the mold by an inert or reducing Gas is replaced before and / or during the casting process.

To increase the output, it is proposed that the upper end of the core material be in a range of 5 cm to 30 cm away from a given position depending on the bottom of the composite metal block in the shape to be arranged, which in other words means that the lower end of the core material 5 cm to 30 cm above the bottom surface of the casting mold. It is also proposed that the mold up to a height of at least 5 cm above the top of the molten metal core material to fill.

As can be seen in FIGS. 2A and 2B, in the layered metal block usually solidified in the Layer 3 of the cladding material increases the head shrinkage or pores 8 are present, which are arranged above the upper end of the core material 1. aside from that cracks 9 are often observed in the solidified metal which are in contact with the corners of the core material stand. In addition, an area 10 that has gone into solution is formed on the bottom of the core material where there is the core approaches the casting head of the casting channel 5. Is the distance between the final melting surface and the The upper end of the core material is shorter, so the head shrinkage pores 8 and / or the cracks 9 extend through the solidified layer so that access routes are created, through which air penetrates to the core material. which in turn has the consequence. that the interface between Core material and the solidified layer is oxidized by means of the Lull, as a result of which an insufficient bond is achieved and an interlaminar separation can be observed during the final rolling. On the other hand, is the Distance between the final melting surface and the upper end of the core material is too large, so the lost Section of the final product increases considerably. which reduces the yield. For these reasons, the Agstand should not be less than 5 cm, with best results being achieved when the distance is within Holding member 6 and the solidified layer 3 penetrates. However, the cross-sectional area of this area is considerable less than the cross-sectional area of the core material, with the consequence that the air penetration depth is low and the tendency of the product to separate due to oxidation is low.

The distance between the lower end of the core material placed in the mold and the upper one Surface of the team, d. H. the length of the solidified cladding metal layer from the lower end of the core material, should be within a range of 5 cm to 30 cm. If the length is shorter than 5 cm, then Cracks 9 formed in the solidified layer, which allow the penetration of air to the core metal, whereby the interface between the core metal and the solidified layer is oxidized. Also that will be in solution Gone area 10 is larger, which results in a reduction in output. On the other hand, it is the length more than 30 cm, the discarded or lost portions of the product increase, which in turn increases Means deterioration in yield.

It has been experimentally confirmed that the deterioration in the yield can not be ignored due to the dissolved portion, when the degree of superheating of the melt 80 ° C with respect to the liquidus temperature of the core material (Tj ⁰ ₁ C ') exceeds. Frequently, the block is not produced when the superheating degree was more than 100 ⁰ C to use.

If the degree of overheating of the melt is high with regard to the liquidus temperature of the melt (T '{ "C). Cracks are also formed in the head area and in the foot area of the block produced and the interface between the core material and the solidified layer is oxidized by the air, which penetrates through the cracks in the subsequent hot deformation, whereby the interlaminar bond is considerably deteriorated.This tendency has been confirmed experimentally to the extent that it is clearly manifested when the degree of overheating from (P ₁ ) exceeds 100 ° C.

On the other hand, is the superheat degree in terms of Tj; low, the crusts are formed on the melt surface, with the result that the good contact between the melt and the surface of the core material is lost and that at the same time an increased entrapment of foam can be observed, which is associated with a reduction in the interlaminar bonding properties . It has been experimentally confirmed that a deterioration in the interlaminar bonding properties occurs when the degree of overheating in terms of Tj; is less than 40 ° C. the deterioration in the binding properties is clearly evident when the degree of overheating

r-iüijCruCiTl: ~ _rt - ..ir-

a gate can be provided around the head shrinkage pores to avoid, which depends on the type of melt or the casting conditions, and im In the present case, better results can be achieved by pouring the melt with the aid of a riser will. Is the distance between the final melting surface and the upper end of the core material less than 5 cm. so in any case it is difficult to prevent the oxidation of the interface between the nuclear materials and to prevent the solidified layer completely.

There is a possibility that the core material 1 near the area connected to the holding member 6 is oxidized by the air which escapes from the interface between the clogging of this space by solidifying melt during casting has a relationship between a middle space (d). an ascending rate of the melt (r) and a height (H) of the ingot were found to be an important factor. In other words, it has been found that a composite metal block suitable for the production of layered composite metal-metal materials can be produced by maintaining conditions which satisfy the following equations when the melt is poured with a normal degree of superheating:

Applies to the rate of ascent
(r) 0.0125 // + 0.011> r ^
so applies

(I>

29.08 // - 10001-413
4.154 // "1Qo"

whereas with an ascent rate of

6.67> rg0.0125 // + 0.011 applies </ £ 4.

This relationship is particularly advantageous in the manufacture of layered metal materials with a low cladding ratio apply.

If the above relationships are observed in order to obtain a dense solidified layer from the melt without clogging To generate, the rate of rise of the melt during casting becomes significant Factor that influences the interlaminar bonding properties of the layered metal material produced. If the rate of ascent is high, the surface of the melt is in lively motion, what often leads to foam floating on the melt / surface with the surface of the core material comes into contact and is included in this. This with vigorous movement of the enamel surface increased risk stands in the way of efforts to include the casting foam in the interface with Help prevent a vigorous gas evolution reaction caused by evaporation and / or thermal Decomposition of the oxidation film is brought about, which covers the surface of the core material. The upper limit of the melt ascent rate should preferably not be above 1.8 cm, sec., as shown in the following examples.

On the other hand, if the rate of rise of the melt is slow, the protective coating which the The surface of the core material is exposed to the radiant heat emanating from the melt surface, plus that heat comes from the core material by conduction, which is already is in the melt, reaches the coating film. As a result, the film evaporates or

thermally decomposes and burns, even if it is located far above the melt surface. on in this way, the antioxidant protection effect of the coating is no longer present when the surface of the core material comes into contact with the surface of the melt. Is the rate of ascent the Melt is low, so crusts form on the surface of the melt, which is the contact between the melt and affect the surface of the core material

ίο and an inclusion of foam in the interface support financially. Accordingly, there is a lower limit to the rate of rise of the melt. This lower one The limit is advantageously not less than 0.5 cm / sec., As can be seen from the following examples.

As already mentioned, the rate of ascent of the melt should be within a range of 0.5 cm / sec. up to 1.8 cm / sec. "if a dense layered metal block with excellent interlaminar Binding properties should be generated without clogging processes.

It has been found that the interlaminar binding intensity of the coated by processing the Layered metal blocks obtained production product is first achieved in that an overall reduction ratio (Thickness of the ingot / thickness of the blank manufactured as an intermediate product) of not less than 1.5 when rolling out the block to form the blank is adhered to.

example 1

A non-killed steel with a cross-sectional area of 25 95 cm ² was used as the core material, and a material mentioned in Table 1 below was applied thereon as a coating having the thickness shown in Table 1. After placing the core material in a mold having a cross-sectional area of 55 × 110 cm ² , a high carbon steel was poured into the mold to produce a laminated metal block. The ingot was then rolled out into a slab or blank and subjected to further hot working until a

Table 1

Occurrence (%) of defects in 4 mm thick clad sheets (using an ultrasonic defect detector) Thickness of the coating

materials (μΐη) 20 40 60 100 500 1000 2000 4000

Coating agents

Γ »1 1 DD
riiciiui-ΓΐΛί /. 100 46 16 13th 5 Amino resin 95 32 20th 8th 5 Epoxy resin 80 39 19th 5 3 Epoxy resin + Al powder 81 30th 16 3 1 Epoxy resin + CaSi powder according to Yep Industry standard No. 1 *) 75 32 10 3 2 Polyamide resin 93 38 18th 10 6th Acrylic resin 84 35 15th 7th 4th Melamine resin 95 37 17th 6th 4th Polyester resin £ 8 33 13th 9 4th Polyester resin + Al powder 80 29 15th 7th 2 Vinyl resin 96 41 18th 11th 7th Vinyl resin + Al powder 90 25th 17th 10 3 Vinyl resin + CaSi powder according to Yep Industry standard No. 1 *) 85 31 15th 7th 3

4th 3 5 3 2 3 1 2 2 2 1 3 , 1 2 3 1 2 2 4th 3 3 3 2 2 3 1 2 1 1 3 2 4th i 1 3

*) Powder content 20-30% by weight.

ίο

clad sheet 4 mm thick was obtained. The occurrence of low binding intensity at the interface Defects between the core material and the poured melt were detected with the help of an ultrasonic detector examined on samples that had been cut out of the clad sheet metal. The on Test results obtained from a large number of blocks are summarized in Table 1 below.

As can be seen from the results summarized in Table 1, with thick dimensions of the coating film of 20μηι or 40 μΐη the occurrence errors more frequently, whereas the occurrence of errors with a coating thickness of 4000 μm does not occur shows significant difference compared to a coating film with a thickness of 2000 μm. Will Aluminum powder or CaSi powder according to Japanese Industrial Standard No. 1 as a substance with strong Oxygen affinity to the coating material in one Amount of 20 to 30 percent by weight added, so it has been found that there is a tendency for further reduction the frequency of errors is present.

Example 2

(1) A piece of metal was attached to an upper portion of a low carbon steel billet for holding purposes 0.12% carbon, 0.40% manganese and traces of silicon with a size of 20 cm (thickness) χ 100 cm (width) χ 200 cm (height) was welded on as the core material and then one made of epoxy resin and aluminum paste existing silver paint applied to the perimeter of the assembly to form a coating film with a thickness to form from about 400 to 800 μm. That achieved in this way Core material was placed in the middle of a mold for blocks measuring 50cm (thickness) χ 110 cm (width) χ 230 cm (height) arranged in such a way that the height of the top of the core material could be changed on five levels. Then became a high carbon steel melt with 0.63% carbon, 0.27% silicon, 0.65% manganese in the mold poured to a predetermined height from the top of the core material so that in the following

ίο Table 2 assembled layered metal blocks A to E were achieved. These ingots were made into slabs or with a given total reduction ratio Blanks rolled out. After cutting off the head and foot sections with a length of 10 cm, the Slabs or blanks rolled out warm to strip material with a thickness of 7 mm. This tape material was trimmed, trimmed and inspected. Upon inspection, the interlaminar Separation properties and the plating ratio are investigated using the test results compiled in Table 2 were determined.

As can be seen from the results compiled in Table 2, block A has a low product yield due to the deviation from the predetermined plating ratio and the block C also shows a low product yield due to the interlaminar separation or separation of the cladding layers, whereas blocks B, D and E lead to satisfactory product yields.

(2) Two low carbon steels (C: 0.12%, Si: traces, Mn: 0.4%) each having a size of 18 cm (thickness) χ 100 cm (width) 195 cm (height) using magnesia powder as

Table 2

block distance between Amount of final Total reduction Spreading at Spreading at product Floor area of the melting surface tion ratio Sinker rollers Hot rolling spread Shape and core above the top when rolling (%) and trimming (%) material (cm) End of core to the board (%) matcrials (cm) A. 3 10 2.6 94 81 63 B. 7th 10 2.6 95 82 95 C. 10 4th 2.6 94 82 60 D. 10 7th 2.4 95 81 96 E. 10 7th 1.8 93 81 91 F. 15th 15th 1.6 80 90 89 G 15th 15th 1.45 79 91 53 blackboard 2 (continued) block Total- Remarks Application

48

} B. 74 L. C. 46 ν f
t D. 74 E. 69 F. 64 G 38

10 cm long sections were cut at the top and bottom of the board. the

Plating ratio deviation is often caused.

Head and foot sections 10 cm long were removed from the board.

Head and foot sections were removed from the board over a length of 10 cm.

The interlaminar separation failure is often caused.

Foot and head sections were removed from the board to a length of 10 cm.

Foot and head sections were removed from the board over a length of 10 cm.

Foot and head sections were cut from the board to a length of 15 cm.

Head and foot sections were cut from the board to a length of 15 cm.

The interlaminar separation failure is often caused.

Separator arranged on top of one another and on the circumference and also on the bottom surface with a so-called "Chilier" welded, which consisted of the low carbon steel with the same composition, as shown with the aid of reference numeral 12 in FIG. 3. This became a core material with a Size of 36cm (thickness) χ 100cm (width) χ 200cm (Height) made. The core material produced in this way was treated and in the manner already described processed into two layer blocks F and G. These Blocks were rolled into blanks. After having taken sections of 15 cm length from both sides had been, the sinkers were separated from each other in the center line and then warm to strip material rolled out to a thickness of 7 mm. The production yield of the tape material was as described above examined in one inspection step and the results are also summarized in Table 2. As can be seen from the results contained in Table 2, the product yield of block G is due to the interlaminar separation low, which is why the total reduction ratio when rolling out the block to Plate is 1.54, whereas the block F has a satisfactory product yield, since its overall deformation ratio 1.6.

Example 3

(1) Two high-carbon steel sheets, each with a cross-sectional shape of 5.5 χ 200cm ² , were placed on top of one another using magnesium oxide powder as a separator and welded on the circumference and on the bottom surface with a so-called »chiller«, which consisted of a carbon steel of the same composition, as shown in Fig 3 specified. After a core material was prepared in this way, a synthetic resin made of epoxy resin was applied to the entire surface of the core material so as to obtain a coating film having a thickness of 300 to 700 µm. After the core material had been placed in the center of a casting mold with a cross-sectional area of 80 χ 210 cm ² , a melt of a steel capable of withstanding high stresses was poured around the core material, using different rates of ascent of the melt, ranging from 0, 67 to 1.67cm / sec. lay. The layered metal blocks obtained in this way were rolled out with a total deformation ratio of 2.7 to form blanks. After the two ends of the board were cut off with the aid of a gas burner, the board was separated in its middle. The block K mentioned in the following table 3 had been considerably dissolved in the bottom area of the core material including the so-called "chiller" during casting, because the degree of overheating in relation to the liquidus temperature of the core was 110 ° C., which is why a given cladding ratio cannot be achieved and also as a result of the penetration of the melt into the contact surface of the core material, a separation of the board was no longer possible. For this reason the block was discarded. The other blanks made from blocks H, I and J according to Table 3 were separated and hot-rolled to obtain flat billets with a thickness of 12.7 mm. The samples taken from these flat billets were then tested for shear strength at break in accordance with US Standard ASTM A-264. In addition, the transverse section of the test specimen was examined with the aid of a microscope, the ratio of the area covered with enclosed foam being determined according to a ruler analysis. A relationship between the thus determined shear strength at break and the ratio of enclosed foam area is graphically illustrated in FIG. If, according to FIG. 4, the ratio of the area provided with enclosed foam is not more than 5%, the shear strength at break is more than about 30 kg / mm ² and there is generally a sliding break. In contrast, if the ratio of scum entrapped area is more than 5%, the shear strength decreases at break and a separation break is caused. Accordingly, sufficient interlaminar bonding intensity is produced by limiting the ratio of the enclosed foam area to not more than 5%.

Table 3 shows the mean values of the shear strength at Fraction and the ratio of the enclosed foam area in the blocks from blocks H, 1 and J, with different degrees of overheating indicated for the billets are.

(2) A core material composed of two non-killed steels was placed in a mold and then a melt of a high tensile steel was made in that already described Way poured into the mold to make a layered metal block. That block became one Blank rolled out. After both ends were cut off with the help of a gas burner, the circuit board was separated along the middle of their thickness dimension. The separate sinkers were used to achieve a flat billet hot rolled to a thickness of 38 mm. The shear rupture strength and the proportion of those with foam inclusions The provided area was applied to a sample of the material in the same manner as described above and as a result it was found that the relation shown in Fig. 4 is also quantitatively in this case is confirmed and that the shear rupture strength

Plate 3

block Ascent rate Overheating in Overheating in Shear strength Proportion of foam age of Regarding the Liqui Relation to the liquidus speed (kg / mm ² ) inclusions Melt (m / min) dust temperature T'i temperature r _s ' - send area (%) ( ⁰ C) ( ⁰ C) H 0.8 16 58 25th 15th I. 0.5 35 77 34 4th J 0.6 43 85 39 0.3 K 0.6 68 110 Discarded due to loss of solution

13th 27 13 020 14th Share of with Foam inclusions Plate 4 Rate of ascent Resistant to breakage provided area block age of Overheating against Overheating against speed (kg. mm ² ) Melt (m / min) above the liquidus above the liquidus 0.4 temperature ( ⁰ C) temperature ( ⁰ C) 0.2 0.7 the melt of the core 38 5 1. 0.6 50 34 37 28 M. 0.7 73 57 33 N 0.8 95 79 25th O 103 87

decreases if the proportion of area provided with foam inclusions is more than 5%. In the following Table 4 shows the mean values of the shear rupture strengths and the area fractions provided with foam inclusions compiled, whereby the results were obtained on flat billets, which were obtained from the blocks L, M, N and O were achieved at different degrees of superheat.

As can be seen from Tables 3 and 4, there is a suitable casting temperature T for producing a layered metal block having improved interlaminar bonding properties within one defined the following equation Area:

for given values for d and H.

For the purpose of examining the question of whether the critical condition illustrated in FIG. 5 of the occurrence of errors is influenced by the compositions of the core metal and the melt, a melt became one low-carbon killed steel around the core material of high tensile steel under the same conditions potted as described above, and as a result, the film shown in FIG. 5 critical condition shown essentially confirmed in this case too. The critical condition can be expressed by the following equation To be defined.

In the above equation, the expression Γ {: denotes a lower value between T \ and Tlf.

Example 4

A core material was prepared by applying paint made of epoxy resin to the surface of unkilled steel plates of various thicknesses and heights so as to form a coating film having a thickness of about 300 to 700 μm. The core material was then placed in the middle of three molds, which had capacities of 7 t (150 cm high), 9 t (230 cm high) and 18 t (280 cm high), respectively. The core material was arranged in the casting mold in such a way that an average distance (d) between the mold wall and the surface of the core material in the range from 3.5 to 9 cm was maintained. A melt of a high-carbon steel was then poured into the casting mold around the core material at various rates of ascent in order to produce laminated metal blocks. These blocks were rolled into blanks, which were hot rolled into strip materials with a thickness of 9 mm. The samples were taken out of the strip materials in blocks, and defects in the surface layer of the high carbon steel were detected by a penetration defect detector to obtain the results shown in FIG. In the figure mentioned, the symbols ο, Π and Δ, which only have contours, designate the error-free blocks, while the symbols ·, ■ and A, which are shown in area coloring, designate the blocks with errors. When examining blanks manufactured under the same conditions as defective strip materials, it was found that the defects were due to a loose structure and / or voids which had arisen as a result of insufficient supply of melt in the cladding metal, in other words on an incorrect choice of the rate of ascent

d>

29.08 // - 10Ot-413
4.154 // - 106

Where: 0.0125 // + 0.011> ι! 0.33.
Applies: 6.67> r SO ₁ Ol 25 // + 0.011,
then i / S4 applies.

In the above equations, d (cm) denotes a distance or space between the mold wall and the surface of the core material, r (cm / sec.) Denotes a rate of rise of the melt in said space or distance, and H (cm) denotes a block height.

Example 5

Two sheets or plates made of boiled steel with a cross-sectional area of 23 × 90 cm ² and 28 × 130 cm ² , respectively, were coated with a paint made of epoxy resin to form a coating film with a thickness of 300 to 700 μm. The coated material was then placed in two GuO molds, the cross-sectional areas of which were 60 120 cm ² (for the production of 9 ton blocks) and 80 150 cm (for the production of 23 ton blocks). Then, a melt was cast of a high carbon steel at a temperature from 1540 to 156o C ⁰ under different advancement speeds of the melt to produce metal layer blocks. These laminated metal blocks were rolled into blanks at a total reduction ratio of 3.0 and then hot rolled into strip material with a thickness of 7 mm.

The samples taken from the tape materials were microscopic on their cross-sectional areas investigated, the proportion or the ratio of the enclosed foam area according to a Ruler analysis was determined. The change in the proportion (ratio) of enclosed foam build-up

t> 5 facing area depending on the rate of rise is shown in FIG. In addition, the shear strength wedge of the strip material in the at Example 3 determined manner described, wherein in the wc-

Δ. Ι ι -

senile a qualitative agreement with the results plotted in FIG. 4 was achieved. From it it is found that the shear strength wedge decreases when the proportion (the ratio) of the enclosed foam-exhibiting Area is more than 5%. It thus follows that in order to achieve an improved bond and thus a rate of ascent to achieve a satisfactorily high interlaminar breaking strength of the melt from 0.5 to 1.8 cm / sec. be respected should, as can be seen from FIG.

The one achievable with the aid of the method according to the invention compared to the method according to US Pat. No. 3,695,337 technical progress results from the following.

Comparative test report

A block of killed steel with 0.09% carbon. 0.31% manganese. 0.009% phosphorus and 0.026% sulfur were subdivided into 5 test specimens with the designations ABC D and E, each test specimen having the dimensions 210 × 830 × 2000 mm and serving as the core material. The test specimens were subjected to the following coating procedures: Test specimen A: According to US Pat. No. 3,695,337, 5.4 kg of an aqueous dispersion of polytetrafluoroethylene were brushed onto test specimen A until a coating film with a thickness of 200 to 400 μm was obtained. The coating was ^{dried at 70 °} C. for ^{20 minutes and baked at 400 °} C. for 30 minutes, after which it was cooled to room temperature. Test specimen B: According to the teaching of the application proposal, 4.4 kg of epoxy resin were brushed onto test specimen B and the applied coating dried for 24 hours at room temperature to form a coating with a thickness of 200 to 400 μm. Test specimen C: According to the teaching of the application proposal, 5.0 kg of polyester resin were brushed onto the test specimen and the applied coating dried for 24 hours at room temperature to form a coating with a thickness of 200

up to 450 μm.

Test specimen D: According to the teaching of the application proposal, 4.5 kg of phenolic resin were used brushed onto the specimen D and the applied coating

dried for 24 hours at room temperature to form a coating with a thickness of 250 to 400 μm.

is specimen E: According to the teaching of the registration proposal 4.5 kg of acrylic hair were brushed onto test specimen E, whereupon the coating dried at room temperature for 24 hours to form a coating 200 in thickness to form 400 μπι.

Each of the test pieces A to E was placed in the center of a mold for 7t block. Then became a Melt of a high carbon steel with 0.85% carbon, 0.25% silicon, 0.43% manganese, 0.018% Phosphorus and 0.004% sulfur with a rise rate of 80 to 110 cm / min in the rising cast around the Test specimen cast in order to achieve a metallic composite material. Next up were the Layer blocks A to E rolled out warm to strip materials with a thickness of 7 mm. From the tape materials A to E head, middle and foot samples (based on the starting block) were taken and under the Microscope examined. The area occupied by inclusions was determined, leading to the following Results resulted in:

It can be seen from the above experimental results that the percentage of inclusions is the same Area with the aid of the invention can be reduced considerably from the results obtained by following the teaching of US-PS 3695 337 were determined. This means that with the help of the invention a more intense one Material connection (interlaminar bond strength) is achievable than according to the known teaching.

block mil inclusions To do this, 4 hours provided area (%) foot Middle- Head- Middle- section wc r ι section iibschniti A. 7.2 6.2 U.S. Patent 3,695,337 2.4 4.1 0.7 0.4 B. 0.3 0.2 1.2 0.7 C. 0.5 0.3 0.8 0.6 D. 0.6 0.4 0.8 0.8 E. 1.4 0.3 (according to the invention) itt drawings

Claims (2)

Patent claims: 1. Process for producing layered composite metal materials, in which a thermally decomposable coating material is applied to the oxide-free surface of a metallic core material becomes and a molten metal of the same or different composition in the rising Casting around the ι ο coated core material arranged in a mold is cast, whereupon the layered metal block produced in this way is further processed by rolling or forging, thereby characterized in that one of the phenolic resin, amino resin, epoxy resin, Selected organic group consisting of polyamide resin, acrylic resin, polyester resin and vinyl acetate resin Substance is applied with a layer thickness of 50 to 3000 μm. 2. The method according to claim 1, characterized in that the coating material in a Thickness from 100 to 3000pm is applied.