JPH04180524A - Production of high damping steel sheet excellent in workability - Google Patents

Abstract

PURPOSE:To form an intergranular oxide layer at the surface part of a steel sheet, to allow microcrack to occur in this surface part, and to improve workability by subjecting a sheet of steel, in which respective contents of C, Si, Mn, Al, N, and Fe are specified, to annealing under the prescribed conditions and then to cold working. CONSTITUTION:A steel having a composition consisting of, by weight, <=0.25% C, 0.05-1.5% Si, 0.05-2.5% Mn, 0.003-0.075% Al, 0.003-0.012% N, and the balance Fe is refined. Annealing is applied to the sheet of this steel under the prescribed atmosphere to allow intergranular oxidation to proceed, by which an intergranular oxide layer is formed at the surface part. Further, cold working is applied to this sheet to allow microcrack to occur in the above intergranular oxide layer.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for producing vibration-damping steel sheets, and in particular to a method for producing vibration-damping steel sheets, and in particular, for improving the roughness of crystal grains during annealing treatment, which is carried out in an atmosphere adjusted to promote grain boundary oxidation. This invention relates to a new improvement for manufacturing vibration-damping steel plates that prevent granulation, have no surface roughness, and are excellent in workability at low cost on a production line that is almost the same as a normal thin steel plate production line.

(Conventional technology and its problems) Conventionally, methods have been adopted to suppress vibration and noise by using damping materials for various mechanical elements and structures, and the metals used for these damping materials Materials include 1, for example, Mn-Cu alloy 5 high Cr steel, graphite cast iron 4, and
Cladding or sandwiching with other viscoelastic materials is generally well known.

All of the above-mentioned metal materials have certain characteristics, but they are not ordinary materials, but are special materials, and their manufacture is extremely difficult and extremely expensive.

Therefore, instead of seeking damping performance from the viewpoint of improving the alloy composition or combining materials as described above, the present inventors
As disclosed in Japanese Patent Publication No. 34720, the grain boundary oxidation phenomenon after annealing treatment is used to generate network-like oxides at the grain boundaries, and then cold working such as roller leveling is performed. We are developing a manufacturing method for shaken steel plates.

In other words, this is a method in which a grain boundary oxidation layer is formed on the surface of the steel material by annealing the thin steel sheet in an atmosphere adjusted to promote grain boundary oxidation, and then cold working is performed. It is thought that the vibration damping effect is increased by causing further microcracks in the grain boundary oxidation layer formed on the surface portion due to this cold working.

(Problems to be Solved by the Invention) The above method for producing a damping steel plate had the following problems. That is, during the annealing treatment to form a grain boundary oxidation layer on the surface of the steel sheet, the crystal grains become coarse, which deteriorates the workability and the surface quality after working.

In addition, plating treatment is applied to vibration-damping steel plates for applications that require corrosion resistance and/or beauty, but in this case,
It had the disadvantage that the surface quality after plating was poor due to the coarsening of the crystal grains.

The present invention has been made to solve the above-mentioned problems, and in particular, by preventing coarsening of crystal grains during annealing treatment that forms a grain boundary oxidation layer on the surface of a steel sheet,
The purpose of this invention is to provide a method of manufacturing a damping steel plate with excellent workability.

(Means for Solving the Problems) The present inventors have conducted various studies to prevent coarsening of crystal grains during annealing treatment to form a grain boundary a (H layer) on the surface of a steel sheet. Limiting the content and further,
It has been found that the addition of Nb and Ti is effective.

(Structure of the invention) The present invention contains 1% by weight, C: 50.25%, Si: 0.0
5-165%, Mn: 0.05-2.5%, Al: 0
．． 003-0.075%, N: 0.003-0.012
%, with the remainder consisting of Fe and unavoidable impurities, is annealed in an atmosphere adjusted to allow grain boundary oxidation to proceed, thereby forming a grain boundary oxidation layer on the surface of the steel sheet. To provide a method for manufacturing a vibration-damping steel plate with excellent workability, which comprises forming a vibration-damping steel plate and further cold working to generate microcracks in a grain boundary oxidation layer.

The present invention also includes, in weight percent, C: 50.25%, Si: 0
．． 05-1.5%, Mn: 0.05-2.5%, A1
:0.003-0.075%.

N: 0.003-0.012%, Nb: 0.01-0.
A thin steel plate containing 20% Ti:O, 1 to 0.20% of O, and the remainder consisting of Fe and unavoidable impurities is placed in an atmosphere adjusted to conditions for grain boundary oxidation to proceed. A vibration-damping steel plate with excellent workability is obtained by annealing the steel plate to form a grain boundary oxidation layer on the surface of the steel plate, and further cold working to generate micro-cranks in the grain boundary oxide layer. Provide manufacturing method.

The present invention also provides that a grain boundary oxidation layer is formed on the surface of the steel sheet by annealing a thin sheet of any of the steels described above in an atmosphere adjusted to conditions that allow grain boundary oxidation to proceed, and Provided is a method for manufacturing a damping steel sheet with excellent workability, which comprises processing to generate microcracks in grain boundary oxidation layers, and then plating.

The present invention also provides a method for forming a grain boundary oxidation layer on the surface of the steel sheet by annealing the thin sheet of any of the above-mentioned steels in an atmosphere adjusted to conditions in which grain boundary oxidation progresses, and further plating. To provide a method for manufacturing a damping steel sheet with excellent workability, which comprises applying cold working to generate microcracks in grain boundary oxidation layers.

The present invention limits the Al content and N content of carbon steel, and also
By adding Nb, we produce vibration-damping steel sheets with fine crystal grains, excellent workability, and good surface texture by annealing in an atmosphere adjusted to conditions where grain boundary oxidation progresses. It is something.

Next, the constituent elements of the steel used in the method of the present invention and their addition amounts will be explained.

C is decarburized by annealing in an atmosphere adjusted to promote grain boundary oxidation, so there is no need to limit it in particular; however, if the amount of C is too large, hot rolling may occur.

Approximately 0.25 because the manufacturability in cold rolling deteriorates.
% is the upper limit.

Si is included in steel as a deoxidizing agent and is an effective element for improving strength. It is also an effective element for combining with oxygen to generate a grain boundary oxidation layer. The lower limit of is approximately 0.05%.

If it exceeds about 1.5%, the effect of forming a grain boundary oxidation layer will be saturated and the workability will deteriorate, so the upper limit was set at 1.5%.

An is an effective element as a deoxidizing agent, fixing impurity S as MnS, preventing hot embrittlement, and combining with oxygen to form a grain boundary oxidation layer. The lower limit for this is approximately 0.05%. On the other hand, approximately 2.5%
If it exceeds 2.5%, the effect of forming a grain boundary oxidation layer will be saturated and the workability will deteriorate, so the upper limit was set at 2.5%.

A1 is an element effective for fixing N as AIN.

If the AIN content is low, crystal grains will become coarse during annealing treatment under conditions adjusted to an atmosphere in which grain boundary oxidation progresses.

The lower limit of the amount of Al to prevent grains from becoming coarse is approximately 0.
．． It is 0.003%. When the amount of Al increases, the cleanliness of the steel deteriorates, surface defects occur, and the AIN becomes larger.
The effect of preventing coarsening of crystal grains is lost. Therefore, the upper limit is about 0.075%.

N precipitates as AIN, and the lower limit of the amount of N to prevent coarsening of crystal grains is about 0.003%. On the other hand, when the amount of N increases, workability deteriorates, and the upper limit is approximately 0.012%.
It is.

The basic composition of the steel used in the method of the present invention is as above and satisfactorily achieves the purpose, but it also contains Nb.

Selective addition of Ti also provides favorable results in preventing coarsening of crystal grains. Nb and Ti are elements that form fine carbonitrides and are effective in preventing coarsening of crystal grains.
．． 0.01% or more is required, and the effect is saturated at about 0.2%, so the lower limit was set to 0.010% and the upper limit was set to 0.2%.

In the method of the present invention, cold rolling for generating microcracks is preferably performed by passing the sheet through a roller leveler line, but the method is not limited thereto. Note 1
It is common knowledge for those skilled in the art to insert skin pass rolling at appropriate stages to improve the surface texture.

The plating is usually galvanized or aluminized. Zinc plating can be hot-dip plating or electrolytic plating, but is usually hot-dip plating. In the case of zinc plating, pretreatment for iron electrolytic plating is often performed. This pretreatment may be performed immediately before galvanizing, but cold working may also be performed during electrolytic iron plating. Although there is virtually no plating of expensive metals such as Ni on the steel sheet that is the object of the present invention, the plating metal may be a metal more expensive than iron.5 The plating thickness is [0 to 150 g/ m2
That's about it.

(Specific Disclosure of the Invention) The present invention will be specifically explained below using Examples and Comparative Examples, but the present invention is not limited by these Examples.

Example 1 and Comparative Examples Steel having the chemical composition shown in Table 1 is hot-rolled in a conventional manner to obtain a hot-rolled plate with a thickness of 3.5 mm, and then cold-rolled to obtain a cold-rolled plate with a thickness of 0.8+sm. And so. After that, the dew point was 50℃,
Open coil annealing was performed under annealing conditions of 800° C. for 20 hours to form grain boundary oxidation layers of about 55 μm on each side of the plate thickness. Next, these annealed plates were subjected to cold rolling with an elongation rate of 1%, and then passed through a roll leveler with a roll diameter of 291 m.

A specimen with a width of 16 m1I+ and a length of 220 mm was cut from these steel plates, and the loss coefficient (η) was determined by the oscillating bending vibration method.
was measured. The tensile test was conducted using a JIS 22201 No. 5 test piece. Processability tests were also conducted using the Erichsen test of JIS Z2247 and the conical cup test of JIS Z2249. The results are shown in Table 2.

As is clear from Table 2, Nα1,45. In a comparative example using a sample of Nα6, the loss coefficient (η) is good, but the crystal grains become coarser, so the strength (T, S, ), total elongation (T-EL), Erichsen value (Era) and It was found that the conical cup value (C, C, V) was low and the workability was poor. In addition, the processed area after the Erichsen test was noticeably rough.

On the other hand, NQ2-4. In the examples of the present invention using samples with Nα7 to 12, the loss coefficient (η) was good, and the strength, elongation, Er value, and C, C, and V showed good values, and the processed parts after the Erichsen test showed good values. No rough skin is observed.

A cold-rolled material with a chemical composition of Nα1 to 6 in Table 1 was heated at a dew point of 50°C.
The metal structure was observed after open coil annealing at an annealing temperature of 800°C and annealing time varied.

The results are shown in FIG. As is clear from FIG. 1, the comparative steels have Nα1, which has a low A1 content, and Nα5, which has a high AI content. It can be seen that the ferrite crystal grains become significantly coarser at Nα6. On the other hand, it can be seen that the coarsening of ferrite crystal grains does not occur in the present invention example using samples with N(12 to Nα4).The coarseness of the crystal grains is determined according to JIS
Number 5 or lower according to GO552.

Example 2 Using the open coil annealed materials of Nα1 and Nα3 obtained by the operation of Example 1, the coating amount was 3 ger on an electroplating line.
After applying iron plating of m2, a hot-dip Zn-plated steel sheet with a basis weight of 45 g/+i'' was obtained using hot-dip Zn plating equipment. After that, skin pass rolling with an elongation rate of 1% was performed, and then cracks were removed in the grain boundary oxidation layer. Roll diameter 29m5 to apply
The plate was passed through the + roll leveler line. The tensile test, workability and loss factor (η) measurements were carried out in the same manner as above. Table 3 shows the results.

As shown in Table 3, in the comparative example &1-1, the loss coefficient (η
) is good, but the workability is poor. Invention example Nα3
It can be seen that -1 has a high loss coefficient (η) and is also good in T-EL, Er value, C, C, and V.

Example 3 Na 1 with grain boundary oxidation layer produced by the operation of Example 1
and Nα3 samples were electroplated in the form of a line with a coating weight of 3 g/m
After applying 2 iron plating, the roll diameter is 29Ill! The plate was passed through a roll leveler (No. 1) to create cracks in the grain boundary oxidation layer. Thereafter, hot-dip Zn plating with a basis weight of 45g10+2 was applied, and skin pass rolling was performed with an elongation rate of 1%.

After that, we investigated its characteristics. The tensile test, workability, and loss factor (η) were measured using the same methods as described above. Fourth
The results are shown in the table.

According to Table 4, Ncil-2 of the comparative example is the loss coefficient (η)
is good, but processability is poor. Na 3 which is an example of the present invention
It can be seen that -2 has a high loss coefficient (η) and excellent workability.

(Effects of the Invention) As described above, according to the present invention, a vibration-damping steel plate with excellent workability can be produced without coarsening of ferrite crystal grains during annealing treatment to form a grain boundary oxidation layer on the surface of the steel plate. method can be provided.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between Al content and annealing time for ferrite grain structure. Figures 2 and 3
The figure is a photograph showing the metal surface structure of the comparative specimen and the invention specimen after the Erichsen test.

Claims (1)

[Claims] 1. In weight%, C: ≦0.25%, Si: 0.05-1
．． 5%, Mn: 0.05-2.5%, Al: 0.003
~0.075%, N: 0.003~0.012%, with the balance consisting of Fe and unavoidable impurities, is annealed in an atmosphere adjusted to promote grain boundary oxidation. A method for producing a damping steel sheet with excellent workability, which comprises forming a grain boundary oxidation layer on the surface of the steel sheet, and further cold working to generate microcracks in the grain boundary oxidation layer. 2. In weight%, C: ≦0.25%, Si: 0.05-1
．． 5%, Mn: 0.05-2.5%, Al: 0.003
~0.075%, N:0.003~0.012%, Nb
:0.01~0.20%, Ti:0.01~0.20%
By annealing a steel thin plate containing one or more of these, with the remainder consisting of Fe and unavoidable impurities in an atmosphere adjusted to conditions that allow grain boundary oxidation to proceed, A method for manufacturing a damping steel sheet with excellent workability, which comprises forming a grain boundary oxidation layer and further cold working to generate microcracks in the grain boundary oxidation layer. 3. Forming a grain boundary oxidation layer on the surface of the steel sheet by annealing the steel sheet according to claim 1 or 2 in an atmosphere adjusted to conditions that allow grain boundary oxidation to proceed, and further cooling. A method for producing a vibration-damping steel sheet with excellent workability, which involves performing a spacing process to generate microcracks in the grain boundary oxidation layer, and then applying plating. 4. The method according to claim 3, wherein iron electroplating is performed as a pretreatment before galvanizing. 5. The method according to claim 4, wherein the iron electroplating is performed before cold rolling. 6. Forming a grain boundary oxidation layer on the surface of the steel plate by annealing the steel thin plate according to claim 1 or 2 in an atmosphere adjusted to conditions in which grain boundary oxidation progresses, and further plating. A method for manufacturing a damping control plate with excellent workability, which comprises applying cold working to generate microcracks in the grain boundary oxidation layer. 7. The method according to claim 6, wherein iron electroplating is performed as a pretreatment before galvanizing. 8. The method according to any of the preceding claims, wherein the plating metal is zinc or aluminum. 9. The method according to claim 8, wherein the plating is zinc hot-dip plating.