JPH07216507A - Alloy type high damping steel plate excellent in weldability and workability - Google Patents

Abstract

PURPOSE:To obtain an alloy type high damping steel plate excellent in weldability and workability at a low cost suitable for industrial material for public welfare. CONSTITUTION:A layer A is composed of a steel having a composition consisting of, by weight, 0.0005-0.0800% C, 0.005-0.060% Si, 0.05-1.50% Mn, 0.003-0.2% P, 0.005-0.060% S, 0.01-0.10% Al, 0.0010-0.0500% N, and the balance iron with inevitable impurities. A layer B is composed of an iron alloy consisting of 0.1-5.0% C, 0.01-6.00% Si, 0.1-1.6% Mn, 0.01-0.60% P, 0.005-0.012% S, and the balance iron with inevitable impurities. The high damping steel plate can be produced so that it has a multilayer structure by a casting process and so that a structure of A-B-A in a plate thickness direction is provided and the ratio of the thickness of the layer B to the whole plate thickness after solidification becomes 4-60%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloy type vibration damping steel plate having excellent weldability and workability, which is used as a structural material for general processing such as automobiles and building materials.

[0002]

2. Description of the Related Art Steel sheets used for automobiles and building materials are
Since it undergoes press working and bending, it is required to have excellent workability. Therefore, it is said that those steel sheets need to have low yield strength, high elongation, and high Rankford value. On the other hand, from the viewpoint of weight reduction, it is desirable that the tensile strength be as high as possible. Moreover, since those steel plates are often assembled into a structure by welding,
Excellent weldability is also required.

On the other hand, in recent years, noise and vibration have become a social problem as pollution due to the development of transportation facilities and the approach of houses to factories. Also, noise and vibration have been created in the workplace for the purpose of improving the working environment. It tends to regulate vibration. In response to such a trend, it is required to add vibration damping performance to a metal material that is a noise source or a vibration source and to improve the vibration damping performance.

From such a background, there has been a need for a steel sheet which is excellent in press workability and bending workability, has high vibration damping property, and can be welded.

Several proposals have been made for such steel sheets.

For example, Japanese Examined Patent Publication No. 45-35662 discloses a composite vibration-damping steel sheet having a three-layer structure in which a viscoelastic intermediate layer made of a viscoelastic resin is sandwiched between two metal layers. This resin composite type damping steel plate is used for automobile oil pans, engine covers, hopper chute parts,
It is used as a stopper for transportation equipment, a vibration reduction member for home electric appliances and other metal working machines, and a structural member for precision machinery where vibration prevention is desired.

The Cu-Al-Ni type alloy described in "Iron and Steel", No. 60 (1974) No. 14, page 2203, is a twin type vibration damping alloy having high vibration damping performance and high strength. It has been known since ancient times. Damping alloys are generally classified into composite type, ferromagnetic type, dislocation type, twin type, and others. Among them, twin type damping alloys are considered to be metal materials that have both damping performance and strength characteristics. .

"Material Science" Vol. 15 (1978) 24
Cast iron described on pages 5 to 249 has long been known as a metal material having a vibration absorbing ability. Cast iron has high strength,
It can withstand a high temperature of at least 400 ° C to 500 ° C and is inexpensive.

[0009]

However, the above-mentioned resin composite type vibration-damping steel sheet begins to deteriorate when the viscoelastic intermediate layer exceeds about 100 ° C., and therefore, heat resistance and strength are particularly required like those of automobile exhaust system members. It cannot be used for various purposes. Also,
Twin type vibration damping alloys have not been put to practical use in consumer products because they are extremely expensive and almost impossible to process. Cast iron is also generally poor in workability and is not suitable for steel plates. There is also the problem that welding is completely impossible.

Therefore, it is an object of the present invention to provide a vibration-damping steel plate having both weldability, workability, and vibration-damping property at a low cost suitable for a commercial industrial material.

[0011]

The present invention is based on C, in weight percent.
: 0.0005 to 0.0800%, Si: 0.005
~ 0.060%, Mn: 0.05-1.50%, P:
0.003-0.2%, S: 0.005-0.060
%, Al: 0.01 to 0.10%, N: 0.0010
.About.0.0500%, and if necessary, further Ti:
0.4% or less, Nb: 0.2% or less, Zr: 0.2% or less, B: 0.0080% or less, and at least one kind is included,
A layer of steel with the balance being iron and inevitable impurities, and C
: 0.1 to 5.0%, Si: 0.01 to 6.00%,
Mn: 0.1 to 1.6%, P: 0.01 to 0.60
%, S: 0.005 to 0.012%, and the balance being B and a layer of an iron alloy consisting of iron and unavoidable impurities.
It has a multi-layer structure manufactured by a casting method so as to have a structure in the thickness direction of B-A and a ratio of the thickness of the B layer to the total plate thickness after solidification is 4 to 60%. It is an alloy type vibration damping steel plate with excellent weldability and workability.

[0012]

According to the present invention, when the composition of the steel sheet surface layer and the inner layer is changed and the ratio of the surface layer in the steel sheet thickness direction is specified,
It is based on the fact that the surface layer has good weldability and workability, and the inner layer has excellent vibration damping properties, so that it is possible to achieve both weldability, workability, and vibration damping properties for the entire multilayer steel sheet.

The present invention will be described in detail below. All components are in weight%.

First, the components of the A layer which is the surface layer of the three-layer structure will be described.

When C content increases, weldability and workability deteriorate, so the upper limit of C is limited to 0.0800%. In order to improve workability, the lower the content, the better. However, if it is less than 0.0005%, the steelmaking cost becomes excessive and the vibration damping property deteriorates. Therefore, the lower limit is limited to 0.0005%.

If the Si content exceeds 0.06%, the weldability and workability deteriorate, so the upper limit is limited to 0.06%. The lower the content, the better, but 0.005
%, The steelmaking cost becomes excessive, so the lower limit is set to 0.
Limited to 005%.

When the content of Mn is less than 0.05%, hot brittleness occurs, and a steel sheet cannot be manufactured.
It is necessary to contain at least 05%. Further, Mn is an element that hardens steel, and the addition amount may be increased according to the required strength characteristics, but if the amount exceeds 1.50%, it hardens excessively, impairs workability, and weldability. Will also deteriorate, so
Limit the upper limit to 1.50%.

P is also an element for hardening the steel, and the addition amount may be increased according to the required strength characteristics, but if the amount exceeds 0.2%, it is excessively hardened and the workability is impaired,
Since the weldability also deteriorates, the upper limit is limited to 0.2%. For applications where weldability and workability are more important than strength characteristics, the lower the P content, the more preferable. However, if it is less than 0.003%, the steelmaking cost becomes excessive, so the lower limit is 0.00.
Limited to 3%.

If the content of S exceeds 0.06%, the weldability deteriorates and hot brittleness easily occurs, so the upper limit is set to 0.
It is limited to 06%. The lower the S content, the better,
If it is less than 0.005%, the steelmaking cost will be too high.
The lower limit is limited to 0.005%.

Al is necessary for deoxidation and also for ensuring workability, but when the content exceeds 0.10%, Al ₂ O
_The increase in the amount of ₃ type inclusions causes flange cracks during molding, and also increases the cost.
Limited to 0%. Further, if Al is less than 0.01%, the workability deteriorates, so the lower limit is limited to 0.01%.

N is a harmful unavoidable impurity element that causes aging. When it exceeds 0.0500%, workability deterioration such as stretcher strain occurs due to aging, and overhardening causes deterioration of workability. Therefore, the upper limit is limited to 0.0500%. The lower the N content, the more preferable, but if it is less than 0.0010%, the steelmaking cost becomes excessive, so the lower limit is limited to 0.0010%.

For applications requiring complicated press workability, it is effective to add one or more of Ti, Nb, Zr and B in addition to the above components.

Ti, Nb and Zr are all carbonitride forming elements and can fix the solid solution C and the solid solution N in the steel to improve the workability and the non-aging property. However,
If the amount of addition is large, the alloy cost becomes too large to achieve low cost. Therefore, Ti is 0.4% and Nb and Zr are 0.2%.

B is effective in improving the secondary workability. However, if the amount of addition is large, the alloy cost becomes excessive and the low cost is not achieved, so 0.0080% is made the upper limit.

Next, the component composition of the B layer which is the inner layer of the three-layer structure will be described.

C is the most important element for obtaining excellent vibration damping properties, and it is necessary to contain C in an amount of 0.1% or more. However, if it exceeds 5.0%, brittleness remarkably increases and welding becomes difficult, so the upper limit is limited to 5.0%. In order to achieve both excellent vibration damping and workability / weldability, 1.0 to 4.0
% Range is preferred.

Si is an important element next to C in order to obtain excellent vibration damping property, and it is necessary to contain Si in an amount of 0.01% or more. However, if it exceeds 6.00%, brittleness increases remarkably and welding becomes difficult, so the upper limit is limited to 6.00%. In order to achieve both excellent vibration damping and workability / weldability,
The range of 1.00 to 3.00% is preferable.

When the content of Mn is less than 0.1%, the vibration damping property deteriorates, hot brittleness occurs, and a steel sheet cannot be manufactured. Therefore, the lower limit is set to 0.1%. Content is 1.6
If it exceeds 0.1%, it becomes excessively hardened, the workability deteriorates, and welding becomes difficult, so the upper limit is limited to 1.6%.

If the content of P is less than 0.01%, the vibration damping property deteriorates and the strength as a structural material decreases, so the lower limit is limited to 0.01%. If the content exceeds 0.60%, the material is excessively hardened, workability deteriorates, and brittleness occurs, so the upper limit is limited to 0.60%.

When the content of S exceeds 0.12%, the vibration damping property deteriorates, hot brittleness occurs, and a steel sheet cannot be manufactured. Therefore, the upper limit is limited to 0.12%. The lower the S content, the more preferable, but if it is less than 0.005%, the steelmaking cost becomes excessive, so the lower limit is limited to 0.005%.

Next, the structures of the layers A and B will be described.

The A layer alone has good workability and a low cost like ordinary thin steel sheets, but is inferior in vibration damping property. Although the layer B alone has excellent vibration damping properties, it is difficult to process and welding is impossible. To achieve the object of the present invention, A layer and B layer are
It is necessary to manufacture it by the casting method so as to have a structure in the plate thickness direction of B-A. In the plate thickness direction structure of B-A-B and A-B, it is not possible to achieve both weldability / workability and vibration damping property, no matter how the ratios of both layers are combined. Further, in the case of the B-A-B plate thickness direction structure, the composition of the surface layer is significantly different from that of ordinary steel, so that there is a drawback that the type of plating is restricted when used as a base plate of a surface-treated steel plate.

As a method for producing a multi-layer steel sheet, there are a casting method, a hot rolling compression bonding method, an explosive bonding method and the like. As a result of examining these manufacturing methods, the state of characteristic change at the interface, and the fracture phenomenon from the interface during heavy working, in the multi-layer steel sheet produced by a method other than the casting method, characteristic change at the interface, that is, separation of components Since it was abrupt, it was easy to break from the interface during strong working. Therefore, in order to realize excellent workability, it is essential to limit the manufacturing method to the casting method.

Next, the thickness ratio of the A layer and the B layer will be described.

The thickness of the layer B must be 4% or more in terms of the total plate thickness in order to secure excellent vibration damping properties.
On the other hand, since the weldability and workability deteriorate as the thickness of the B layer increases, it is necessary to set it to 60% or less.

The steel sheet of the present invention can be used as it is cast, but in order to obtain particularly excellent workability, hot rolling, pickling, cold rolling, recrystallization annealing are performed as in the case of ordinary thin sheets. ,
It is desirable to perform temper rolling.

In the present invention, the hot rolling, cold rolling and annealing conditions are not particularly limited, but the hot rolling is preferably performed at a finishing temperature of 800 to 950 ° C. from the viewpoint of workability and productivity.
The winding temperature is preferably 500 to 750 ° C. from the viewpoint of workability and pickling property. The cold rolling is preferably performed at a reduction rate of 60 to 93%, and the annealing is preferably performed at a temperature of 600 to 900 ° C to ensure workability. Plating may be applied as needed. The type of plating does not matter.

[0038]

EXAMPLE A molten steel for layer A was adjusted to the components shown in Table 1 and molten steel for layer B was adjusted to the components shown in Table 2 to obtain a multi-layer slab by a two-nozzle casting method. No. For comparative example 7, a multi-layer steel slab was obtained by the hot rolling compression bonding method. The multilayer structure in the plate thickness direction was an ABA type, the thickness of the A layer was the same on both surface layers, and the ratio of the B layer thickness to the total thickness is shown in Table 3. These slabs and steel pieces were heated to 1200 ° C. for 4 hours, then made into a steel strip having a thickness of 4 mm at a finishing temperature of about 930 ° C. by a continuous hot rolling mill, wound at about 730 ° C., and pickled and cooled to 80%. Hot rolling, then 830
Continuous annealing was performed at 60 ° C. for 60 seconds, and temper rolling was further performed at 1%. After that, the characteristics were evaluated.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

Regarding the tensile properties, JIS No. 5 test pieces were sampled in the rolling direction, yield strength was 280 MPa or less, and tensile strength was 2
Those satisfying all the conditions of 60 MPa or more and the total elongation of 10% or more were evaluated as pass and indicated by ◯, and those other than that were evaluated as rejected and indicated by x. Further, the Erichsen test was carried out in accordance with JIS standard Z2247, and those having an Erichsen value of 8 mm or more were evaluated as passing and indicated by ◯, and those having an Erichsen value of less than 8 mm were evaluated as rejected and indicated by ×. The bending test is performed in accordance with JIS standard Z2248, and a value obtained by dividing the minimum bending radius by the plate thickness is 0.4 or less is evaluated as pass, and is indicated by ○, and a value exceeding it is evaluated as fail. X
Displayed in. Regarding the interfacial fracture resistance, the fracture morphology during tensile deformation was observed, and those with cracks from the interface and those with suspicious existence were judged to be unacceptable and displayed as ×, and those that do not exist at all were judged to be acceptable. And indicated by ○.

The weldability was determined by using a spot welder in a laboratory to prepare a shear tension joint at a splash generation limit current, and the tensile strength of which is commercially available solid solution strengthened type 400 with the same plate thickness.
85% of shear tensile joint strength of MPa-class high-strength cold-rolled steel sheet
The above-mentioned items were evaluated as passing and indicated by ◯, and those less than that were evaluated as rejected and indicated by ×.

With respect to the vibration damping property, a test piece having a width of 10 mm and a length of 60 mm was subjected to bending vibration, and the loss coefficient was measured by the free damping method. It was displayed, and those less than that were evaluated as unacceptable and displayed as x. The measurement of the vibration damping property was performed in two ways, that is, when the test piece temperature was room temperature and when the test piece temperature was 240 ± 10 ° C.

Table 4 shows the results of these characteristic evaluations.

[0046]

[Table 4]

No. 1-5 is an example of the present invention, the workability,
Excellent in weldability and vibration control. On the other hand, No. Nos. 6 and 7 are comparative examples. In No. 6, since the A layer satisfied the conditions of the present invention, weldability and workability were secured, but since the B layer deviated from the conditions of the present invention, the vibration damping property was poor. No. 7 is layer A, B
Since all the layers deviate from the conditions of the present invention, the weldability, workability, and vibration damping properties are inferior, and the interfacial fracture resistance is also poor because they are manufactured by the hot rolling compression bonding method instead of the casting method.

[0048]

INDUSTRIAL APPLICABILITY The present invention makes it possible to provide a vibration-damping steel plate that has both weldability, workability, and vibration-damping properties at a low cost suitable for industrial materials for consumer use.

Claims (2)

[Claims] 1. By weight%, C: 0.0005 to 0.0800%, Si: 0.005 to 0.060%, Mn: 0.05 to 1.50%, P: 0.003 to 0. 2%, S: 0.005-0.060%, Al: 0.01-0.10%, N: 0.0010-0.0500%, and the balance A of steel consisting of iron and unavoidable impurities Layer, C: 0.1 to 5.0%, Si: 0.01 to 6.00%, Mn: 0.1 to 1.6%, P: 0.01 to 0.60%, S: 0 B-layer of an iron alloy containing 0.005 to 0.012% and the balance iron and unavoidable impurities.
Welding characterized by having a multi-layer structure manufactured by a casting method so as to have a structure in the thickness direction of A and a ratio of the thickness of the B layer to the total plate thickness after solidification is 4 to 60%. Alloy type damping steel plate with excellent workability and workability. 2. The A layer contains, in addition to the chemical components, one or more of Ti: 0.4% or less, Nb: 0.2% or less, Zr: 0.2% or less, and B: 0.0080% or less. The alloy-type vibration-damping steel sheet having excellent weldability and workability according to claim 1, comprising: