JPH03219014A - Production of cast iron clad steel excellent in damping characteristic - Google Patents

Abstract

PURPOSE:To produce a cast iron clad steel excellent in damping characteristic, weldability, etc., by laminating flaked graphite cast iron and a steel stock, heating the resulting clad iron and steel slab up to a specific temp., and then carrying out rolling while specifying finishing temp. and rolling reduction, respectively. CONSTITUTION:Flaked graphite cast iron and a steel stock are laminated, and the resulting clad iron and steel slab is heated to 900-1140 deg.C. Subsequently, this clad iron and steel slab is rolled under the conditions of >=750 deg.C finishing temp. and 15-50% rolling reduction. By this method, the cast iron clad steel stock excellent in toughness and weldability as well as in damping characteristic can be produced with superior productivity.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing cast iron clad steel material that has excellent vibration damping properties that suppress vibration and noise, and also has excellent weldability and formability. .

[Background Art] In recent years, research has been carried out on increasing the added value of steel materials, and as one of these studies, cast iron clad steel materials, which are a combination of cast iron and steel materials, have been developed.

In other words, cast iron cladding combines the characteristics of cast iron, such as corrosion resistance, vibration damping, and wear resistance, with the characteristics of steel materials, such as high strength, high toughness, weldability, and good workability. Steel materials and methods of manufacturing the same have been developed. For example, (1) A method for producing a land steel with good strength and toughness as described in JP-A-61-245985, in which a cladding of steel and cast iron is heated to 950 to 1100°C and rolled at 800°C or higher.

■Cast iron with Cχ+Siz/3≧3,0χ is sandwiched between steel plates from both sides, and the thickness of the steel plate on one side is 5z or more in total thickness ratio, which has excellent vibration damping characteristics as described in JP-A-62-6983. Composite steel plate.

(2) A cast iron clad steel plate with excellent corrosion resistance and toughness, described in JP-A-63-230332, which uses a steel plate as a core material and has a cast iron plate bonded to at least one side thereof.

(2) A cast iron clad plate with excellent vibration damping properties as described in JP-A-62-164531, which is made of spheroidal graphite cast iron (JIS G 5502) as a core material and steel as a bonding material on the front and back surfaces, and is hot rolled and crimped.

etc. are disclosed.

[Problems to be Solved by the Invention] The method (2) above is aimed at producing a rad steel plate with good strength and toughness, and is not aimed at imparting vibration damping properties. In addition, as stated in the text, the composite steel plate mentioned above is only a hot-rolled plate with a rolling reduction ratio of 8.3 for the cladding made of ordinary cast iron and steel, and the internal wear value R' = 0.8
10-'' to 3
) Even compared to the internal wear value Ω-1≧15×10-” of a single unit, the damping performance is considerably inferior, and it is impractical.

The cast iron clad steel plate of item (1) has excellent corrosion resistance and toughness, but as with item (2), vibration damping properties are not the objective.

In addition, the cast iron clad plate mentioned in (1) above has spheroidal graphite cast iron as its core material, and flake graphite cast iron (also referred to as rat cast iron), which has better vibration damping properties than spheroidal graphite cast iron (for example, Takashi Sugimoto Ni-iron) steel,
14 (1974), p. 127)).

The present invention is based on the actual situation based on the background of the prior art described above. (1) Establishment of a method for manufacturing a cast iron clad steel material with good vibration damping properties using a cladding made of flaky graphite cast iron and steel material.

■ Establishment of a rolling method that does not cause cracking or flaking of cast iron.

■ Establishment of a rolling method that does not cause cracks on the front, back, left and right edges.

It is an object of the present invention to provide a method for manufacturing cast iron clad steel materials with good vibration damping properties.

[Means for Solving the Problems] In order to achieve the above objects, the present invention provides (1) 900 composite iron and steel slabs constructed by laminating flake graphite cast iron and steel materials.
After heating to a temperature range of ~1140℃, finishing temperature 750℃
A first method for manufacturing cast iron clad steel materials with excellent vibration damping properties, which is characterized by rolling at a temperature of 15 to 50% at a temperature of 15% to 50%.
As a means of
The second method is a method for manufacturing cast iron clad steel materials with excellent vibration damping properties, which is characterized in that after heating to a temperature range of 3) Steel materials are laminated on the front and back sides of flake graphite cast iron with a thickness ratio of 70% or more to make a laminated steel material, the front, left and right ends of the laminated steel material are covered with the steel materials, and the steel materials are welded to produce composite steel. After heating the composite steel piece to a temperature range of 900 to 1140°C, the rolling reduction rate is 15 to 50 at a finishing temperature of 750°C or higher.
The third method is a method for manufacturing a cast iron clad steel material with excellent vibration damping properties, which is characterized by rolling a cast iron clad steel material of 50%.

[Effects] Each effect that led to the establishment of the above means will be explained below based on the findings obtained through experiments and studies by the present inventors.

The composition of the steel material does not need to be specific, but the formability of cast iron,
In order to complement weldability, toughness, etc., it is desirable to use a steel material that itself has excellent properties, and the use of stainless steel in order to obtain corrosion resistance, aesthetic appearance, etc. will hinder the implementation of the present invention. I found out that there is no.

In addition, in order to share high vibration damping properties with cast iron, it is necessary to use flake graphite cast iron, which has the highest vibration damping properties among cast irons.
Composite steel slabs can also be made by, for example, using casting, injecting molten iron into continuous casting slabs or steel ingot molds, or by laminating the steel slabs and then welding the surrounding areas. Furthermore, we have learned that many methods are used, such as a welding method using a strip electrode using explosive bonding, submerged arc welding, electrogas welding, electroslag welding, and other welding methods.

In addition, if the chemical composition of the steel to be selected and the dimensions, thickness, and thickness ratio of the composite steel slab are selected, the thickness ratio of the flake graphite cast iron and the steel material will remain unchanged after rolling, so the final We learned that it is necessary to determine the thickness ratio between the two in advance depending on the use and purpose of the product.

As a result of the above studies, the present inventors have developed flaky graphite cast iron with excellent vibration damping properties and corrosion resistance, and steel with excellent toughness, weldability, and formability. By rolling a three-layer cast iron clad steel material with one layer of cast iron or steel in the middle layer under appropriate rolling conditions, a cast iron clad steel material with excellent vibration damping properties and formability can be obtained. I found it.

The chemical components of the materials used at this time are shown in Table 1.

The inventors have developed flake graphite cast iron A and ordinary steel B shown in Table 1.
A-82 layers (each 10 mm, total 20 mm), A-
3 layers of B-A and B-A-8 (each 10 ml, total 30
++m) composite steel pieces were created, and further experiments and studies were conducted to establish manufacturing conditions for cast iron clad steel materials that are low cost, have high vibration damping properties, and have good weldability and toughness.

Table 1 (wt%) (Note) Steel A: Flaky graphite cast iron Steel B: Structural steel As a result, the heating temperature of the composite steel slab is: ■ The melting point of flaky graphite cast iron is approximately 1150°C, ■ Flake graphite cast iron is 900
It has been found that at heating temperatures below .degree. C., deformation resistance increases and cracks are likely to occur during rolling, and that the heating temperature must be 900.degree. C. to 1140.degree.

It has also been found that if the finishing temperature is not higher than 750°C, cracks will occur as the rolling temperature decreases.

Based on these findings, composite steel slabs were heated to 1100''C and then rolled at various reduction rates.

The test results are shown in Figures 1 and 2.

The present inventors have determined from these figures that at a reduction rate of 50% or less, the loss coefficient η is 0.02 or more (internal wear rate Q-1≧0.0
2) ,vE)≧IQI(gf −a+(10m+s
It was learned that a cast iron clad steel material with good vibration damping properties and toughness can be obtained.

Note that the loss coefficient η of common steel was 0.001.

The loss coefficient η is the vibration energy S decay rate per cycle when vibration is excited in the material and then is allowed to freely decay by 2π.
It is defined as the value divided by (π: Pi), and the internal wear value g-
The value is equal to 1.

It has been found that when the rolling reduction exceeds 50χ, not only does the interface between the graphite in the cast iron and the base metal peel off significantly, but also cracks occur in the base metal, resulting in deterioration of both toughness and vibration damping properties.

Furthermore, it is considered that a vibration damping steel plate that can be put to practical use must have a loss coefficient η of at least 20 times that of an ordinary steel plate.

In order to obtain such high vibration damping properties in cast iron clad steel plates, the present inventors conducted various experiments and studies and obtained the results shown in Figure 3.

Based on this figure, the inventors used flake graphite cast iron, which has the highest vibration damping properties among cast irons, and set the thickness ratio of flake graphite cast iron to 70χ.
If it is increased above, the loss coefficient η is approximately 0.03 or more (approximately 30 times or more compared to the loss coefficient η-0,001 of ordinary steel plate)
I learned that it is possible to obtain

In addition, flake graphite cast iron is prone to cracking due to rolling, but according to the experiments and studies of the present inventors, it is possible to use the casting method at the casting stage, the explosion bonding method by laminating the steel slabs at the stage, or the method of welding the surrounding area. In addition, as shown in Fig. 4 (1), (2), (3), and (4), the ends of the steel plates 2 on the front and back layers are bent back and forth and left and right within a range equivalent to the thickness of the cast iron forming the intermediate layer. After coating flaky graphite cast iron l, the front and back steel plates 2 are welded to form a composite steel piece, and when rolled at a rolling reduction of 15% or more and 5oz or less, poor crimping or edge cracking occurs as shown in Figure 5. It was found that this can be suppressed.

In addition, it was found that this method also improves the delamination phenomenon that tends to occur due to sudden changes in the rolling edge in the rolling direction head and continuous parts, and also reduces the minimum rolling reduction required for complete crimping. did.

According to the combination of the above composite cast iron billet production method, the reduction rate is 1
It was learned that a damping cast iron clad steel plate with perfect crimping and no edge cracking can be obtained at 5 to 50Z.

In addition, after rolling, accelerated cooling is performed to improve toughness and strength, and post-rolling heat treatment is performed to stabilize and ensure important mechanical properties for the intended use of the product, such as skewering, annealing, quenching and tempering. Furthermore, it has been found that the treatment of cast iron before the lamination work can be utilized because it promotes the formation of the functions and effects of the present invention without hindering it.

Having obtained the above-mentioned knowledge, the present inventors have established a method for economically producing cast iron clad steel materials with excellent vibration damping properties using flaky graphite cast iron, and have achieved the objects of the present invention. It is.

[Example] Table 2 shows the chemical compositions of the test cast irons and steel plates used in the invention examples and comparative examples, and Table 3 shows the manufacturing conditions and obtained properties of each steel material. After rolling, several types of specimens were subjected to accelerated cooling, accelerated cooling tempering, and reheating quenching and tempering.

As is clear from the table, in perfumes 1 to 17 of the present invention examples, cast iron clad steel materials with good vibration damping properties were obtained.

Further, perfume preparation 1 which is an example of the second and third means of the present invention
Nos. 2 to 17 had better damping properties.

Incidentally, in perfumes 15 to 17, which are examples of the third means of the present invention, there is no cracking at the front, rear, right and left ends of the laminated steel material during rolling, and it is possible to avoid a decrease in yield due to cutting and removal of the cracks. done.

In contrast to these inventive examples, Comparative Examples 19, 23, 26, and 27.32, in which the rolling reduction rate was outside the upper limit of the range of the present invention, had cracks in the cast iron; In case of Kaori No. 33, peeling occurred between the eyebrows due to poor crimping, and a sound steel material could not be obtained.

In addition, in Comparative Examples 20, 22, 25, and 31 whose finishing temperature did not satisfy the range of the present invention, cracks occurred in the cast iron.

In Comparative Examples 18, 24, and 30, in which the heating temperature exceeded the upper limit of the range of the present invention, the cast iron melted, and a clad steel material with a sound crimp surface could not be obtained.

Furthermore, in Comparative Examples 21, 28, and 29, in which the heating temperature was lower than the lower limit of the range of the present invention, cracks occurred in the cast iron.

Furthermore, the comparative perfume 34 using spheroidal graphite cast iron without using the flaky graphite cast iron limited in the present invention had a loss coefficient η of 0.011, which was poor in damping performance.

As is clear from these examples, a composite steel piece made of flaky graphite cast iron and steel is heated to a temperature range of 900 to 1140°C.
After heating, the finishing temperature is 750℃ or higher and the reduction rate is 15 to 50.
% rolling, we were able to obtain a cast iron clad steel material with excellent vibration damping properties.

In addition, although the required level of vibration damping property, that is, the loss coefficient η, varies somewhat depending on the purpose of use of the steel material, by setting the cast iron thickness ratio in the present invention to 70z or more, a higher η≧0.03 can be achieved.
We were able to produce a clad steel plate with vibration damping properties.

Furthermore, when rolling a composite steel piece with cast iron and steel laminated and welded at the edges, cracks tend to occur at the front, rear, left and right edges of the steel, so it is necessary to cut and remove the cracked parts. Although it is necessary, by covering the end portions with the steel material according to the present invention, the disadvantages thereof can be avoided, and an economically efficient manufacturing method has been obtained.

[Effects of the Invention] As described above, according to the present invention, a cast iron clad steel material made of flake graphite cast iron and ordinary steel or special steel and having excellent vibration damping properties, as well as excellent toughness and weldability, can be manufactured at low cost and with high productivity. This will have an extremely large effect on industrial fields involved in creating a quiet living environment.

[Brief explanation of drawings]

Figure 1 shows the relationship between vibration damping properties and rolling reduction of the cast iron clad steel material of the present invention, Figure 2 shows the relationship between the toughness and rolling reduction of the cast iron clad steel material of the present invention, and Figure 3 shows the relationship between the toughness and rolling reduction of the cast iron clad steel material of the present invention. The relationship between the cast iron thickness ratio and the loss coefficient η of the clad steel plate is shown, FIG. 4 is a cross-sectional view showing the covering state of flaky graphite cast iron with the steel plate of the present invention, and FIG. 5 is the rolling reduction ratio of the cast iron clad steel plate of the present invention. The relationship between occurrence of rolling cracks is shown in relation to the manufacturing method of composite steel slabs.

Claims (3)

[Claims] (1) A composite steel piece made by laminating flaky graphite cast iron and steel is heated to a temperature range of 900 to 1140°C, and then rolled at a finishing temperature of 750°C or higher and a rolling reduction of 15 to 50%. A method for manufacturing cast iron clad steel materials with excellent vibration damping properties. (2) Composite steel pieces made by laminating steel materials on the front and back sides of flake graphite cast iron with a thickness ratio of 70% or more at 900-1140℃
A method for manufacturing a cast iron clad steel material with excellent vibration damping properties, which comprises heating to a temperature range of 100° C. and then rolling at a rolling reduction of 15 to 50% at a finishing temperature of 750° C. or higher. (3) Steel materials are laminated on the front and back sides of flake graphite cast iron with a thickness ratio of 70% or more to make a laminated steel material, the front, left and right ends of the laminated steel material are covered with the steel materials, and the steel materials are welded to form a composite. After heating the composite steel slab to a temperature range of 900 to 1140°C, the rolling reduction rate is 15 to 50 at a finishing temperature of 750°C or higher.
A method for manufacturing a cast iron clad steel material with excellent vibration damping properties, which is characterized by rolling a cast iron clad steel material of 50%.