JPS6214624B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to highly tough sliding members (materials and parts) that have good strength and toughness and also have excellent sliding lubricity. Traditionally, sliding materials have been used in equipment such as pumps and compressors that reciprocate a piston within a cylinder, lathes that reciprocate a tool post on a bed, and grinders that reciprocate a table on a base. machine tools, and tube expanders that fit multiple segments around the outer periphery of a tapered cone and move each segment forward and backward in the radial direction. Among these tube expanders, there are, for example, those having structures shown in FIGS. 1 and 2. In the figure, 1 is a steel pipe, 2 is a pull rod, 3 is a tapered cone with a regular polygonal cross section fitted on the outer periphery of the pull rod 2, and 4 is a male threaded portion 2a at the end of the pull rod 2.
This is a nut that is screwed into the cone 3 and holds the cone 3 through the ring 5. Then, an inverted T-shaped groove 3a is formed on each surface of the cone 3, as shown in FIG.
A T-shaped guide 6a fixed to the sliding surface side of the segment 6 is fitted into this inverted T-shaped groove 3a, and the segment 6 is aligned in the axial direction of the pull rod 2 on each surface of the cone 3 having a regular polygonal cross section. It is configured to be able to slide in the same direction. Further, 7 is an annular flange that abuts the ends of the segments 6, and 8 is a boom that supports the annular flange 7 and accommodates the pull rod 2. In the pipe expanding machine having such a configuration, the steel pipe 1 is disposed around the outer periphery of the segment 6 while the pull rod 2 is moved to the left in FIG. When the pressure cylinder is operated to move the pull rod 2 to the right in Figure 1, the cone 3 simultaneously moves to the right in Figure 1, but each segment 6 is prevented from moving in the above direction by the annular flange 7. Therefore, it moves in the radial direction and pushes the steel pipe 1 from the inside, thereby correcting the shape of the steel pipe 1 in the cross-sectional and longitudinal directions, adjusting dimensions, uniformly dispersing residual stress, etc. Thereafter, when the pressure cylinder is operated to move the pull rod 2 to the left in FIG. 1, each segment 6 moves in the centripetal direction, making it possible to take out the steel pipe 1. In this case, the surface on the outer periphery of each segment 6 where the steel pipe 1 is actually expanded is referred to as the effective expansion surface, and its longitudinal dimension L is referred to as the effective expansion length.
The feed pitch P per feed of the steel pipe 1 by a gripper cart (not shown) or the like is the effective pipe expansion length L.
It is normal to make it shorter. In such a pipe expanding machine, forward and backward operations are repeatedly performed by a pressurizing cylinder (not shown).
Frictional sliding is frequently repeated between the outer sliding surface 3b of the tapered cone 3 having a regular polygonal cross section and the inner sliding surface 6b of each segment 6. By the way, in this type of conventional tube expanding machine, the cone 3 is made of alloy cast iron, and the segment 6 is made of special cast steel, and the sliding lubricity between the two can be said to be quite good. Since this segment 6 is a casting, its mechanical strength is low, especially thick-walled steel pipe (e.g., t/D≧4%, X-65
There was a problem in that the segment 6 often cracked or broke during pipe expansion of pipes (grade), which could lead to a shutdown of the operation. Therefore, measures to prevent cracking or damage of such segments are mainly considered from the viewpoint of the shape of the segment and from the viewpoint of the material. It has been desired that sliding members have good sliding properties as well as excellent mechanical strength and toughness. This invention was made in order to solve the above-mentioned conventional problems, and the object is to obtain a sliding member that has high strength, high toughness, and excellent sliding characteristics, especially in terms of material. It is. By the way, the performance required of sliding members such as the above-mentioned segments is good sliding lubricity with mating materials such as cones, and at the same time, high strength and high toughness to prevent breakage. However, these properties are generally contradictory, and in the past, if a cast product was made with priority given to sliding lubricity, the mechanical strength would decrease, and The reality is that when changing from a cast product to a forged product, sliding lubricity generally decreases. Therefore, the present inventors have accumulated various experimental studies and have developed 1.5%C-12%Cr- as a member other than cast steel.
1.2%Mo-0.3%V-Fe system and 0.5%C-5%Cr
We conducted experiments by selecting alloy tool steels such as -Fe series, but these all have the problem of superior mechanical strength compared to cast steel products, but inferior sliding lubricity. As a result of our research, we have developed a sliding member that has good mechanical strength and toughness, as well as excellent sliding lubricity. That is, the sliding member according to the present invention has a weight percentage of
So, C: 0.6 to 1.2%, Si: 3% or less, Mn: 3% or less, Cr: 6 to 10%, Mo: 0.1 to 1.5%, V: 0.01 to
1%, and if necessary, to further improve wear resistance, Ni: 1.2% or less, Cu: 2% or less, W: 2% or less, Co: 2% or less, Nb: 2% or less. One or more of the following: B: 0.0005 to 0.1%, REM (rare earth element): 0.0005% to 0.3%, in order to improve hardenability.
In order to improve machinability during finishing after machining or forging, S: 0.2% or less, Pb: 0.4% or less, Se: 0.3% or less, Bi: 0.5%.
Hereinafter, it is characterized in that it contains one or more of Te: 0.3% or less and Ca: 0.0002 to 0.01%, respectively, and the remainder substantially consists of Fe. From the perspective of improving the mechanical strength and toughness of sliding members, the present inventors have conducted various studies based on conventional tool steel, focusing on the amount of giant carbides and sliding lubricity, and have determined the optimal composition range. I found out. In other words, in Fe-C-Cr-1%Mo steel, the C and Cr content increases in the number of primary carbides (hereinafter referred to as macrocarbides) of 10μ or more in the high-temperature tempering hardness (approximately 515°C) and the microscopic structure. When we investigated the effect of C content, we obtained the results shown in Figure 3.
By setting the Cr content to 0.6 to 1.2% and 6 to 10%, it is possible to improve mechanical strength and toughness, and at the same time improve sliding properties by the presence of appropriate giant carbides. I found out that it can be done.
The reason for limiting the range of each component of the sliding member of the present invention based on such knowledge will be explained below. C: 0.6-1.2% C is an element necessary for forming carbides that contribute to improving wear resistance, and is an element necessary to improve hardenability, increase the hardness of martensite, and obtain excellent strength. However, if it is less than 0.6%, the hardenability decreases, making it difficult to obtain the necessary hardness after quenching and tempering, and the ability to form carbides decreases, resulting in insufficient strength and wear resistance. %, large amounts of giant carbides are produced as shown in FIG. 3, which deteriorates the sliding properties and also deteriorates the toughness, so the range is set from 0.6 to 1.2%. Si: 3% or less Si acts as a deoxidizing agent and is an element that contributes to increasing the tempering resistance of martensite, but if it is too large, the toughness deteriorates, so the content should be 3% or less. Mn: 3% or less Mn acts as a deoxidizing and desulfurizing agent, improving the cleanliness of steel and contributing to good hardenability. It is set to 3% or less in order to generate austenite and reduce hardness after quenching and tempering. Cr: 6 to 12% Cr dissolves into the matrix during hardening to improve hardenability, forms Cr carbide, improves wear resistance, and improves oxidation resistance at the same time, but if it is less than 6%, If the amount of giant carbides produced is small and exceeds 12%, as shown in FIG. 3, there will be too many giant carbides, deteriorating sliding properties and toughness, so it is set in the range of 6 to 12%. Mo: 0.1 to 1.5% Mo is an effective element for forming a solid solution in the matrix during quenching, forming carbides, improving wear resistance as a sliding material, and increasing quenching and tempering resistance. For this purpose, it is necessary to contain 0.1% or more, but if it exceeds 1.5%, the toughness will deteriorate, so it should be in the range of 0.1 to 1.5%. V: 0.01-1% V is an element that prevents the coarsening of austenite crystal grains in the matrix and forms fine carbides, contributing to improving wear resistance and hardening resistance. Although it is necessary to contain V, it must be contained in an amount of 1% or less because too much V fixes effective C, and if it is too large, it will actually cause a decrease in hardness. Ni: 1.2% or less, Cu: 2% or less, W: 2% or less,
One or more of the following: Co: 2% or less, Nb: 2% or less Ni, Cu, W, Co, and Nb all contribute to strengthening the matrix and form carbides to improve wear resistance. However, if added in large amounts, hot workability and toughness will deteriorate, so it is appropriate to limit the content of each component to the above ranges. B: 0.0005-0.01%, REM (rare earth element):
One or more of 0.0005 to 0.3% B and REM are elements that contribute to improving hardenability, and are effective in improving toughness and preventing cracking and breakage, but when added in large amounts Since this impairs processability, it is appropriate to limit the range of each component above. S: 0.2% or less, Pb: 0.4% or less, Se: 0.3% or less, Bi: 0.5% or less, Te: 0.3% or less, Ca: 0.0002
~0.01% of one or more S, Pb, Se, Bi, Te, and Ca are all effective elements for improving machinability, and are effective for machining and plastic processing (forging, etc.) It improves the workability during the subsequent finishing process, but if the amount is too large, the hot workability and toughness are reduced, so it is appropriate to limit the content of each component to the above ranges. On the other hand, mating materials for the sliding member according to the present invention include ingot materials, forged materials, cast materials, sintered materials, sintered forged materials, etc. of metallic or non-metallic materials. For example, in the case of cast iron, The basic composition is C: 2.5-2.8%, Si: 1.6-1.8%, Mn: 1.0 in weight%.
~1.2%, with the balance preferably consisting essentially of Fe, with optional additions of Cr, Mo, Ni,
Those containing Cu, V, Co, and B are also desirable. It also shows good properties for ceramics and cermets. Further explanation will be given below based on examples. First, steel with the chemical composition shown in Table 1 (inventive material:
After melting No. 1 to 9, comparative material: No. 10 to 14),
Each was quenched and tempered under the conditions shown in Table 2, and the tempering hardness, impact value, bending test bending value, rotary bending fatigue test (10 ⁷ times) strength, and friction coefficient were examined. The results are shown below. Next, a contact surface pressure of 5 to 30
Kgf/ ^mm2 , friction speed; 30-100mm/sec, lubricating oil;
When sliding tests were conducted under mineral oil-based and oil-based conditions, the results of the friction coefficient and seizure surface pressure were shown in Table 2. Furthermore, when a tube expansion test was conducted using an actual machine under the conditions shown in Table 4, the results of the attractive force and seizing conditions shown in Table 2 were obtained.

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[Table] As is clear from the results shown in the above tables, inventive materials No. 1 and 2 both have excellent strength, toughness, and sliding lubricity.
In Nos. 3, 6, 7, and 9 containing Ni, Co, Nb, and Cu, better strength and toughness could be obtained. Furthermore, B, No. 4, 7, 8 with REM added,
In No. 9, the hardenability was improved, and improvements in strength and toughness were observed in the actual machine, and good wear resistance was obtained. In addition, No. 5 with added S, Pb, Ca, and Te,
Samples Nos. 6, 8, and 9 had good machinability when preparing test pieces. On the other hand, high C, high Cr, and high Co No.
No. 10, and No. 11 with high C and high Cr, had poor toughness, high friction coefficient, and low seizure pressure.
In addition, No. 12 with low C and low Cr had low strength, a large wear coefficient, and low seizure pressure. Furthermore, No. 13 to which Mo was not added and No. 14 to which V was not added had lower strength and toughness than the steel of the present invention. Also,
No. 15, which was made of cast iron, had both the friction coefficient and the seizure pressure at the same level as the material of the present invention. In other words, the material of the present invention was confirmed to exhibit sliding lubricity equivalent to that of cast iron, and was able to solve the problems of cast iron, such as low strength and low toughness. As explained above, the sliding member according to the present invention has good sliding lubricity as well as excellent mechanical strength and toughness. It has excellent sliding properties with other metal materials, as well as sintered bodies of non-metallic materials, surface treated bodies, etc., and is for segments that expand the pipe material from the inner side by sliding contact with the tapered cone. In addition to being suitable as a material for various applications, it has the remarkable effect of being suitable as a sliding material or sliding parts for various purposes.

[Brief explanation of the drawing]

Figures 1a and b are a cross-sectional explanatory view and a longitudinal cross-sectional view showing an example of the structure of a tube expander, respectively, and Figure 2 is an enlarged cross-sectional explanatory view showing the fitting part of the cone and segment of the tube expander in Figure 1. , Figure 3 shows Fe-C-Cr-1%Mo
It is a graph showing the influence of C and Cr contents on the high temperature tempering hardness and the number of giant carbides of steel.

Claims (1)

[Claims] 1% by weight, C: 0.6 to 1.2%, Si: 3% or less,
Mn: 3% or less, Cr: 6-10%, Mo: 0.1-1.5
%, V: 0.01 to 1%, the balance being Fe and unavoidably mixed impurities.A sliding member having good sliding lubricity and excellent mechanical strength and toughness. 2. A sliding member having good sliding lubricity and excellent mechanical strength and toughness according to claim 1, wherein the sliding member is a segment of a steel pipe expanding machine. 3 In weight%, C: 0.6 to 1.2%, Si: 3% or less,
Mn: 3% or less, Cr: 6-10%, Mo: 0.1-1.5
%, V: 0.01-1%, and B: 0.0005-0.01
%, REM: 1 or 2 of 0.0005-0.3%
1. A sliding member having good sliding lubricity and excellent mechanical strength and toughness, characterized in that the remaining part is Fe and impurities inevitably mixed in. 4. A sliding member having good sliding lubricity and excellent mechanical strength and toughness according to claim 3, wherein the sliding member is a segment of a steel pipe expanding machine. 5% by weight, C: 0.6 to 1.2%, Si: 3% or less,
Mn: 3% or less, Cr: 6-10%, Mo: 0.1-1.5
%, V: 0.01 to 1%, and S: 0.2% or less,
One or more of Pb: 0.4% or less, Se: 0.3% or less, Bi: 0.5% or less, Te: 0.3% or less, Ca: 0.0002 to 0.01%, the balance being Fe and unavoidably mixed impurities. A sliding member having good sliding lubricity and excellent mechanical strength and toughness. 6. A sliding member having good sliding lubricity and excellent mechanical strength and toughness according to claim 5, wherein the sliding member is a segment of a steel pipe expanding machine. 7 In weight%, C: 0.6 to 1.2%, Si: 3% or less,
Mn: 3% or less, Cr: 6-10%, Mo: 0.1-1.5
%, V: 0.01 to 1%, and Ni: 1.2% or less,
Cu: 2% or less, W: 2% or less, Co: 2% or less,
A sliding member with good sliding lubricity and excellent mechanical strength and toughness, characterized by consisting of one or more of Nb: 2% or less, the balance being Fe and impurities that are inevitably mixed in. . 8. A sliding member having good sliding lubricity and excellent mechanical strength and toughness according to claim 7, wherein the sliding member is a segment of a steel pipe expanding machine. 9% by weight, C: 0.6 to 1.2%, Si: 3% or less,
Mn: 3% or less, Cr: 6-10%, Mo: 0.1-1.5
%, V: 0.01-1%, and B: 0.0005-0.01
%, REM: 1 or 2 of 0.0005-0.3%
Species or higher, S: 0.2% or less, Pb: 0.4% or less,
Characterized by one or more of the following: Se: 0.3% or less, Bi: 0.5% or less, Te: 0.3% or less, Ca: 0.0002 to 0.01%, the balance being Fe and unavoidably mixed impurities. A sliding member with good sliding lubricity and excellent mechanical strength and toughness. 10. A sliding member having good sliding lubricity and excellent mechanical strength and toughness according to claim 9, wherein the sliding member is a segment of a steel pipe expanding machine. 11 Weight%: C: 0.6 to 1.2%, Si: 3% or less, Mn: 3% or less, Cr: 6 to 10%, Mo: 0.1 to
1.5%, V: 0.01~1%, and B: 0.0005~0.01
%, REM: 1 or 2 of 0.0005-0.3%
Seed or higher, Ni: 1.2% or less, Cu: 2% or less,
Good sliding lubricity characterized by one or more of W: 2% or less, Co: 2% or less, Nb: 2% or less, the balance being Fe and impurities that are inevitably mixed in. A sliding member with excellent mechanical strength and toughness. 12. A sliding member having good sliding lubricity and excellent mechanical strength and toughness according to claim 11, wherein the sliding member is a segment of a steel pipe expanding machine. 13 In weight%, C: 0.6 to 1.2%, Si: 3% or less, Mn: 3% or less, Cr: 6 to 10%, Mo: 0.1 to
1.5%, V: 0.01-1%, and S: 0.2% or less,
Pb: 0.4% or less, Se: 0.3% or less, Bi: 0.5% or less, Te: 0.3 or less, Ca: one or more of 0.0002 to 0.01%, and Ni: 1.2% or less,
Cu: 2% or less, W: 2% or less, Co: 2% or less,
A sliding member with good sliding lubricity and excellent mechanical strength and toughness, characterized by consisting of one or more of Nb: 2% or less, the balance being Fe and impurities that are inevitably mixed in. . 14. A sliding member having good sliding lubricity and excellent mechanical strength and toughness according to claim 13, wherein the sliding member is a segment of a steel pipe expanding machine. 15% by weight, C: 0.6 to 1.2%, Si: 3% or less, Mn: 3% or less, Cr: 6 to 10%, Mo: 0.1 to
1.5%, V: 0.01~1%, and B: 0.0005~0.01
%, REM: 1 or 2 of 0.0005-0.3%
Species or higher, S: 0.2% or less, Pb: 0.4% or less,
Se: 0.3% or less, Bi: 0.5% or less, Te: 0.3% or less, Ca: one or more of 0.0002 to 0.01%, further Ni: 1.2% or less, Cu: 2% or less,
Good sliding lubricity characterized by one or more of W: 2% or less, Co: 2% or less, Nb: 2% or less, the balance being Fe and impurities that are inevitably mixed in. A sliding member with excellent mechanical strength and toughness. 16. A sliding member having good sliding lubricity and excellent mechanical strength and toughness according to claim 15, wherein the sliding member is a segment of a steel pipe expanding machine.