JPH07316759A - Treatment for partially modifying copper material - Google Patents

Abstract

PURPOSE:To modify the mechanical properties and/or physical properties of the treated part in a copper material without deteriorating its characteristics as those of the copper material by irradiating a copper-base stock with high density heat energy and partially remelting and alloying the same. CONSTITUTION:The required part in a copper-base stock of copper, a copper alloy or the like is irradiated with high density heat energy such as an electron beam, a laser and TIG, and if required, the irradiated part is added with metallic elements for alloying. Thus, the copper-base stock is partially remelted and alloyed. Immediately after that, the heat source is moved, the heat in the melted part is absorbed into the peripheral low temp. part, and rapid solidification is executed. Thus, the structure of the irradiated part is refined, and its mechanical properties such as strength and wear resistance or its physical properties such as thermal conductivity and the coefficient of thermal expansion are modified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention, when using copper or a copper alloy (hereinafter referred to as a copper material) as a constituent member of a device or the like, only metallurgically metalizes only a portion requiring strength as a constituent element. The present invention relates to a method of strengthening mechanical and / or physical properties required therefor by subjecting to

[0002]

2. Description of the Related Art Conventionally, when a copper material is used as a component for a device or the like, a general-purpose metallurgical strengthening and reforming treatment such as carburizing and quenching in iron and steel is used to reinforce weak points caused by its softness. The law has not been developed. Therefore, even if abrasion resistance of only that part is required, such as in the sliding part, or if proof stress is required only on the contact surface of the gasket such as the seal part, use a hard alloy material for the entire member. ing.
In this case, however, the good heat and electrical conductivity peculiar to copper is sacrificed by using the alloy material.

Further, since a fastening material made of a copper material, which has a high strength like a steel bolt, has not been developed, a steel bolt is used for assembling the device. Therefore, due to the difference between the yield strength of the tightened copper material and the tensile strength of the steel bolt, the axial force of the bolt generated by the firm tightening reaching the plastic range of the member is The thread and the bolt seat surface are deformed. In order to prevent this deformation, a steel-made metal fitting that has been preliminarily formed into a screw shape may be inserted into the female thread to reinforce it, but repeated fitting and removal of screws causes deformation between the fitting and the base metal, and It causes an accident that deviates. In particular, when the temperature of the bolt fastening portion rises, a problem occurs due to a difference in thermal conductivity and thermal expansion coefficient between the object to be fastened and the bolt.
That is, the copper material fastened material with high thermal conductivity expands first,
The axial force of the steel bolt is increased, and the bolt seat surface of the soft object to be fastened is depressed. In this manner, when the temperature of the bolt seat surface is depressed and the temperature is lowered, the object to be fastened is contracted, and the depression becomes a gap, resulting in loosening of the fastening portion. This may cause the device to malfunction and damage the conductivity of heat and electricity, resulting in device failure.

[0004]

A steel bolt is used to assemble a device using a copper material as a constituent member by bolting, taking advantage of its original characteristic of good conductivity of heat and electricity. The current situation is that it must be done. At this time, it is not possible to ignore the problems caused by the difference in mechanical and physical properties between the copper-based material to be fastened and the steel-based bolt. In the present invention, in order to maintain the solidity and durability of the device without impairing the characteristics of the copper material, mechanical strength such as proof stress is imparted, and at the same time physical properties such as thermal conductivity and thermal expansion coefficient. Is also trying to modify. Although there are various problems to be solved, the modification is characterized in that the modification is applied only to the necessary parts so as not to impair the properties of the material.

That is, in a portion that receives a frictional force, such as a sliding portion of the device or a female screw portion that is repeatedly inserted and removed,
It is necessary to improve wear resistance.

[0006] It is necessary to improve the proof stress in a portion that is directly subjected to tightening stress, such as a female thread portion of a device assembly, a periphery of a screw hole, and a contact surface of a sealing gasket. Particularly in an apparatus that raises the temperature, in order to reduce the increase in the bolt axial force caused by the temperature rise, making the thermal conductivity and the thermal expansion coefficient of the copper material close to that of steel is also one method for solving the problem. It is also a feature of the present invention.

[0007]

In order to solve this problem, the present invention heats and remelts only the portion requiring modification from the surface of the material. At the same time as the material is remelted,
A metal element for alloying is added and fused to modify the matrix of the base material and modify by crystallizing an intermetallic compound. The alloy layer thus formed has a property different from that of the base material. By selecting the type and amount of the metal to be added and the shape of the fusion zone, only the required portion is converted into a composite material having the desired characteristics.

The present invention is characterized in that high-density heat energy, which is usually used for welding, such as electron beam, laser, TIG, etc. is used for the heat source for remelting. The use of high-density thermal energy in the present invention allows the remelting part to be only around the necessary part of the material, and even when a metal having a higher melting point than the copper material is added, it can be melted at the same time as the base material. This is because. Further, one of the features is that a so-called keyhole effect is utilized in which high-density thermal energy is made into a beam shape and is irradiated and melted from the surface of an object to be perforated. That is, the molten base material and the added metal are sufficiently stirred by utilizing the keyhole effect, and the components are uniformly distributed to form a stable alloy layer.

In the present invention, the heat source is moved immediately after the fusion of the base material and the additive metal in the fusion zone is completed. This is because the irradiation of excess energy should be refrained from, and the temperature around the fusion zone should not be raised as much as possible, and the heat of the fusion zone should be absorbed by the surrounding low temperature zone during solidification so that it should be solidified in a very short time. is there. By rapidly cooling and solidifying the remelted portion, solidification is performed without giving time to cause gravity segregation due to the difference in density of the component metals, and a uniform and fine structure can be obtained. The miniaturization of the rapidly solidified reformed portion contributes to strengthening by the crystallized intermetallic compound and particularly to the effect in terms of strength.

[0010]

[Function] A metal that forms a solid solution with copper for high alloying,
By adding a single substance or several types at the same time,
The solid solution can be modified. The α solid solution has a difference in thermal or electrical conductivity depending on the solid solution component, so that the added metal, the amount of crystallization and the treatment conditions can be determined according to the purpose of modification. For example, when a high alloy layer containing aluminum is formed around the seat surface portion against the lack of creep strength such as fatigue of the bolt seat surface, the hardness increases and the yield strength increases proportionately. Furthermore, the conductivity and expansion coefficient of the copper material with respect to heat are lowered to prevent accidents when the temperature is raised due to thermal expansion by approaching the steel material.

The metal element added in excess of the solid solution limit can be crystallized as an intermetallic compound combined with copper as a base material. This intermetallic compound is extremely hard, and when treated with a beam-shaped heat source so as to be uniformly distributed, a structure having high hardness and excellent wear resistance having hard particles only in necessary portions is formed. The structure thus hardened has excellent wear resistance and improved proof stress more than the solid solution of copper, and therefore has a favorable effect on the improvement of the durability of the device.

Further, the use of high-density thermal energy enables local melting while keeping the peripheral portion at a low temperature, and after fusion, it is rapidly solidified by self-cooling to realize a fine crystal structure.
The fine crystal structure thus obtained increases dislocations against deformation and contributes to a synergistic effect of improving mechanical strength such as proof stress and creep strength.

[0013]

EXAMPLE FIG. 1 is a schematic diagram in which a female thread portion (3) machined into an electrode using C1020 material is subjected to a modification treatment according to the present invention in order to prevent a decrease in heat and electric conductivity. Is. Conventionally, in order to secure the tightening force and prevent wear due to repeated bolt insertion / removal, SUS3 pre-formed into a screw shape.
A reinforcing metal fitting made of 04 was inserted. Although the mechanical strength was secured by inserting the reinforcing metal fittings, I was troubled by the problem that the metal fittings would slip out when the bolts were inserted and removed. In this method, since no consideration is given to thermal expansion, problems such as deformation occur between the reinforcing metal member and the base material. This embodiment has succeeded in improving the reliability of the screw portion because of integration without a reinforcing metal fitting, reducing the chance of failure occurrence due to heat consideration, and eliminating man-hours for inserting the reinforcing metal fitting.

In the construction of this product, the high-density heat energy obtained by the electron beam processing machine at the time of material processing is used to perform remelting processing at the time of material processing. That is,
A groove having a diameter of 10 mm and a depth of 1 mm is machined in a portion to be an M6 female screw, an aluminum wire having a diameter of 1 mm is press-fitted, and the periphery of the groove is remelted by an electron beam. For the remelting portion, heat input conditions are selected so that the diameter is 15 mm and the depth is 8 mm. In the case of this product, if the hardness of the modified portion was set to around HRB80, there were no problems such as fastening at the specified torque and abrasion due to bolt insertion / removal. The aluminum content of this reformed portion was 5%, and the thermal conductivity was 20% of the oxygen-free copper of the base material, which was close to the stainless steel of the fastening bolt. For this reason, a decrease in the thermal conductivity of the base material causes a delay in thermal expansion and is used in SUS30.
It approaches the expansion of 4 bolts, and the increase in stress caused by the difference in the coefficient of thermal expansion is reduced, so that the deformation of the internal thread portion is reduced. Further, in the modification by adding aluminum, the yield strength and creep strength are improved, the deformation occurring in the threads of the female thread portion is reduced, and the resistance to shear fracture occurring in the valley portion is also increased. Hardness and proof stress increase in proportion to aluminum content, and wear resistance also improves, but HRB
If the ratio is not 100 or less, the modified portion becomes so brittle that post-processing becomes impossible.

FIG. 2 shows the oxygen-free copper flange of a vacuum device utilizing the good thermal conductivity of copper material, and the modification treatment according to the present invention is applied to the periphery of the sealing edge portion (4) and the screw hole portion (5). It is a schematic diagram of what was done. In this embodiment, a gasket of C1020 material, which has been sufficiently softened, is used by being bitten into the edge of the flange which has been finished with an acute angle. In this case, the edge portion is intended to have a hardness difference of about HV100 with the gasket by adding nickel. In this modification, pure nickel wire is used as an additive. Modification with nickel improves hardness and
The coefficient of thermal expansion of the reformed portion is reduced by about 20% as compared with oxygen-free copper as a base material, and deformation due to thermal expansion is reduced. Further, a high alloy layer made of aluminum is formed in the peripheral portion of the screw hole, and a hardening and modifying treatment is performed so that the hardness becomes HV200, so that the compressive stress due to tightening has a proof strength. When the bolt used for fastening is made of SUS material, it is also effective in terms of thermal conductivity.

[0016]

Industrial Applicability The ability to use a soft copper material as a component for an apparatus without deteriorating the good heat and electric conductivity, which are the original characteristics of copper, is an academic development that requires temperature control. It has a remarkable effect on the devices used in the industrial field. In the modification treatment according to the present invention, the base material itself is modified, and it is possible to machine the portion after the treatment, which is a unique feature. In other words, the modification that takes heat into consideration improves the durability of the equipment due to the improvement of wear resistance due to hardening, and the improvement of the proof strength strengthens the parts where stress concentrates, such as the female screw part and bolt seating surface. Is possible. In particular, an integrated structure that does not use reinforcing metal fittings on the female thread makes fastening with bolts more reliable and makes accidents such as the removal of reinforcing metal fittings due to bolt insertion / removal completely unrelated, and simplification of the structure is It also has a great effect on production.

[Brief description of drawings]

[Fig. 1] Schematic diagram of installation on female threads

[Fig. 2] Schematic diagram of installation on the seal part

[Explanation of symbols]

 1 Base material 2 Modified part 3 Female thread part 4 Sealing edge part 5 Screw hole part

Claims (1)

[Claims] 1. A partial modification characterized by irradiating a copper-based material with high-density thermal energy to partially remelt / alloy it to modify the mechanical and / or physical properties of the treated part. Quality treatment method.