JP5464572B2 - High strength steel plate for slide bearing - Google Patents

Description

  A plain bearing has a bimetallic configuration in which a bearing layer having good sliding properties is provided on a base metal. The present invention relates to a high-strength steel plate suitable as a material for the base metal.

A plain bearing used for an engine of an automobile or the like has a bearing layer having a good sliding property on a base metal. As the bearing layer, a Cu-Pb alloy, a copper alloy such as a Cu-Sn-Pb alloy, an aluminum alloy, or the like is used, and the bearing layer is manufactured by joining on a base metal by a method such as sintering or pressure welding. Of these, copper-lead-based alloys have been the mainstream for copper-based alloy bearing layers, but in recent years, replacement with lead-free copper-based alloys has been progressing from the viewpoint of environmental problems. Moreover, steel (carbon steel) is mainly used for the base metal. Carbon steel with a C content of about 0.1 to 0.2% is used as the steel material for the base metal. However, in recent years, the C amount has been further increased due to demands for higher engine output and smaller and lighter bearing devices. High strength steel has also been used.

JP-A-6-192774

However, in a bearing manufactured by sintering a copper-based alloy, if the C content of the steel sheet is large, there is a problem that the bearing layer is easily peeled off from the steel material after sintering. This mechanism is not clear. In order to strengthen the adhesion between the steel plate and the bearing layer, measures such as using a steel plate pre-plated with Cu or roughening the surface of the base metal before the sintering process are taken, There are many problems such as an increase in manufacturing costs due to an increase in processes.
This invention solves simultaneously the subject of the high intensity | strength of a base metal, and the adhesiveness of the steel material and copper-type sintered layer which are base metals.

  As a result of experiments conducted by appropriately changing the amount of C in the steel sheet, the present inventors controlled C ≦ 0.2% so that the adhesion to the copper-based sintered layer can be achieved without performing Cu pre-plating. Was found to be favorable. That is, in order to improve the adhesion between the steel plate of the base metal and the copper-based sintered layer, the C content of the steel plate is limited to 0.03 to 0.2%. Further, by adding Ti and Nb, a steel material having a lower C content than that of the conventional steel material can be obtained.

  By using the high-strength steel plate according to the present invention, it is possible to obtain a steel plate for a base metal of a slide bearing having excellent adhesion between the base metal and the sintered alloy layer without plating or roughening.

  The reason which prescribes | regulates the chemical component of the cold-rolled steel plate in this invention, its effect, and content is demonstrated. In the present invention, “%” means “% by weight”.

C: 0.03-0.20%
C is an element effective for ensuring material strength. Further, as a result of various studies on the adhesion between the steel sheet and the bearing layer, it was found that the adhesion after sintering and the C content of the steel sheet component are closely related. The factor that C impairs the adhesion between the steel sheet and the bearing layer is not necessarily clear, but in order to obtain good adhesion, the C content needs to be 0.20% or less. The lack of strength due to the limited amount of C added is compensated by the addition of alloy elements other than C, such as Ti and Nb, as will be described later.
The lower limit is 0.03%. If no more C is contained, the strength as a base metal is insufficient even when Ti and Nb are added.

Si: 1.5% or less An element effective for improving the strength by dissolving in the ferrite phase. However, if added in excess, the ductility decreases, so 1.5% is made the upper limit.

Mn: 1.0-2.0%
It is an effective component for improving strength. Excessive addition deteriorates moldability and weldability, so the upper limit is made 2.0%. In order to develop the strength as a base metal while limiting the C amount to 0.2% or less, addition of 1.0% or more is necessary, so the lower limit is set to 1.0%.

P: 0.05% or less Since the ductility is adversely affected, in applications where high workability is required, the addition amount of P is preferably low. However, since the strength is increased, it can be added in a range where the workability is not adversely affected for high strength applications. Therefore, the upper limit was made 0.05%.

N: 0.005% or less Since N is an impurity and impairs workability, it is limited to 0.005% or less. Moreover, regarding B to be described later, it is preferable to reduce N in the steel in order to secure an effective B amount.

Ti: 0.05-0.2%, Nb: 0.02-0.2%
In the present invention, as described above, it is an important element added to ensure high strength. All of them are precipitated as fine carbonitrides and are effective components for improving the strength and refining the metal structure. Further, since C is fixed as a carbide, it prevents the decarburization phenomenon during heat treatment during sintering of the bearing layer, and also suppresses the decrease in surface hardness. Therefore, the lower limit value of the addition amount is set to 0.05%.
If it is added excessively, not only will the effect be saturated, but it will lead to deterioration of the workability of the steel material and an increase in manufacturing cost, so the upper limit value is specified as 0.2%.

Cu: 0.01 to 0.3%
Cr: 0.01 to 0.3%
Mo: 0.01 to 0.3%
V: 0.01 to 0.3%
Both are selective elements in the present invention, and can be added as necessary. Any element is an effective component for improving the strength. However, the effect is not recognized if the addition amount is less than 0.01%. Moreover, when it adds abundantly, an effect will be saturated and toughness will deteriorate. In addition, the upper limit is limited to 0.3% because it causes a cost increase.

B: 0.0001 to 0.01%
B segregates at the grain boundaries to increase the interfacial bonding force and is effective in increasing the strength of the steel. The effect appears when 0.0001% or more is added. However, excessive addition causes formation of borides, inhibition of crystal grain growth, and deterioration of workability, so the upper limit is made 0.01%.
When B reacts with C and N in the steel to form BN, the effective amount of B that segregates at the grain boundaries and acts to increase the strength of the steel is reduced. Therefore, as the base steel, reduction of the effective B amount can be suppressed by reducing C and N or fixing C and N with Ti and Nb.

Steels having chemical components shown in Table 1 were melted by vacuum melting to produce ingots, and hot-rolled sheets were obtained through forging and hot rolling. After removing the scale of the hot-rolled sheet by pickling, a cold-rolled sheet having a thickness of 1.5 mm was obtained by cold rolling. The cold-rolled sheet subjected to annealing at _75% H ₂ -25% _N 2 mixed gas atmosphere 800 ° C., and a cold-rolled annealed sheet.
A powder of lead-free additive-based alloy (Cu-10% Sn) was applied on a cold-rolled annealed plate, and a sintering treatment was performed at 800 to 900 ° C. for 10 minutes in a reducing atmosphere. A bending test piece having a width of 30 × 100 mm in length was collected from the obtained composite plate, and a V-bending test was performed under the conditions of an indentation angle of 30 ° and an indentation tip R = 3 mm. The cross section in the bending portion longitudinal direction of the test piece after the V-bending test was observed with an optical microscope, the peeling length between the bearing layer and the steel sheet was measured, and the case where the peeling length was 3.0 mm or less was regarded as acceptable. The peeling length is the length of the steel sheet surface from which the bearing layer is missing.
FIG. 1 shows the test results. From FIG. 1, it was found that the peeling length decreased with a decrease in the C content of the steel sheet, and passed in the region where the C content ≦ 0.20%.

Steels having chemical components shown in Table 2 were produced in the same process and conditions as in Example 1, and JIS No. 5 tensile test specimens were collected and subjected to tensile tests. Moreover, the bending test similar to Example 1 was implemented, and the peeling length was measured.
The results of tensile strength and peel length are also shown in Table 2. The tensile strength was 400 MPa or more, and the peel length was 3.0 mm or less. The steel of the present invention is in the acceptable range for both tensile strength and peeling length. On the other hand, B1 and B2 have a C content of more than 0.20% and a very long separation length. Further, B3 does not have Ti and Nb amounts within the specified ranges, and the tensile strength does not reach 400 MPa.

Figure showing the relationship between C content and peeling length

Claims (3)

In mass%, C: 0.03 to 0.20%, Si: 1.5% or less, Mn: 1.0 to 3.0%, P: 0.05% or less, N: 0.005% or less, Ti: 0.05 to 0.2%, Nb: 0.02 to 0.2%, the balance is made of Fe and inevitable impurities, tensile strength is 400 MPa or more, peeling length (30 × length from composite plate) A 100 mm bending test piece is collected, and the length of the test piece in the longitudinal section of the bending part after the V bending test is performed under the conditions of an indentation angle of 30 ° and an indentation tip R = 3 mm) is 3.0 mm or less A high-strength steel sheet for slide bearings. Further, one or two of Cu: 0.01 to 0.30%, Cr: 0.01 to 0.30%, Mo: 0.01 to 0.30%, V: 0.01 to 0.30% The high-strength steel sheet for a sliding bearing according to claim 1 containing at least a seed. Furthermore, B: The high strength steel plate for plain bearings of Claim 1 or 2 containing 0.0001-0.01%.

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