JP4156963B2 - Bonding method between sprayed layer and steel member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a method for joining a sprayed layer and a steel member.
[0002]
[Prior art]
Conventionally, in order to protect the surface of a steel member such as a mold, a technique for coating the steel member with a sprayed layer has been put into practical use (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-2002-241920 (page 3 to page 5, FIG. 2)
[0004]
FIG. 10 is a reprint of FIG. However, the code is reassigned. Reference numeral 101 denotes a substrate to be protected, 102 denotes a first sprayed layer, 103 denotes a second sprayed layer, 104 denotes a third sprayed layer, and 105 denotes an impregnation strengthening layer.
The substrate 101 to be protected is, for example, an iron material or an aluminum alloy (see Patent Document 1, paragraph number [0029] lines 3 and 4).
The first sprayed layer 102 is, for example, a NiCrAl heat-resistant alloy (see paragraph number [0032] lines 1 to 3 in the same paragraph).
[0005]
The second sprayed layer 103 is a MoB (molybdenum boride) -based composite sprayed material (see paragraph [0035], lines 1 and 2).
The third sprayed layer 104 is a composite sprayed material made of a ceramic powder / MoB powder mixture (see paragraph [0042] in the same paragraph).
The impregnated reinforcing layer 105 is formed by impregnating an organic silicon material solution and then baking (see paragraph [0054], lines 1 to 3).
[0006]
The technique of Patent Document 1 is that MoB is mixed, so that wear resistance and heat resistance are improved (for example, see paragraph numbers [0037] and [0046]).
[0007]
[Problems to be solved by the invention]
However, as a result of investigations by the present inventors, in the structure in which the thermal spray layer is merely laminated as in Patent Document 1, as a result of repeated use over a long period of time, separation between layers, particularly the first thermal spraying, occurs. It was found that delamination occurred between the layer 102 and the second sprayed layer 103. This mechanism is considered that the adhesion between the heat-resistant alloy constituting the first thermal spray layer 102 and the MoB-based composite thermal spray material constituting the second thermal spray layer 103 is relatively small, and cracks are generated from the adhesion. .
[0008]
Accordingly, an object of the present invention is to provide a technique capable of sufficiently bonding a thermal spray layer containing ceramics to a surface of a steel member and strongly joining the thermal spray layer to the steel member.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, claim 1 includes a quenching process in which a workpiece formed by processing a steel material into a desired shape is subjected to a quenching process, and ceramic powder and a self-processed surface on the workpiece that has been quenched. It consists of a thermal spraying process for spraying a mixed powder of soluble alloy powder and a tempering process in which the thermally sprayed work is subjected to multiple tempering treatments. This tempering process allows the sprayed layer to be metallurgically bonded to the work. It is the joining method of the thermal spray layer and steel member characterized.
[0010]
Since the self-fluxing alloy is employed, a diffusion bonding layer can be formed at the boundary surface between the sprayed layer and the steel member, and this diffusion bonding layer exhibits an effect of increasing the bonding strength between the sprayed layer and the steel member.
In addition, the self-fluxing alloy plays a role of appropriately dispersing the ceramic powder by performing tempering a plurality of times after thermal spraying.
Therefore, by adopting the self-fluxing alloy, it is possible to suppress the progress of cracks between the sprayed layers, increase the bonding strength between the sprayed layer and the steel member, and appropriately disperse the ceramic powder.
As a result, the life and durability of the workpiece can be dramatically improved.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
[0012]
FIG. 1 is a principle diagram of a quenching process according to the present invention. In the quenching process, a steel workpiece 15 is charged into a quenching furnace 10 and quenched at a temperature of 1000 ° C. to 1050 ° C. Specifically, the quenching furnace 10 includes a furnace body 11, a heating means 12, an atmosphere gas blowing means 13, and a gas discharge pipe 14, and a steel work 15 is charged into the furnace body 11. The atmosphere gas blowing means 13 is used to blow an inert gas such as argon gas into the furnace. At that time, the air in the furnace is discharged through the gas discharge pipe 14 to fill the furnace with the inert gas.
[0013]
Next, the inside of the furnace is raised to a predetermined temperature by the heating means 12 and kept at a high temperature for a predetermined time. Thereafter, the steel workpiece 15 is rapidly cooled. Oil cooling and blast cooling are appropriate for the rapid cooling treatment.
This completes the quenching process.
[0014]
FIG. 2 is a principle diagram of a thermal spraying process according to the present invention. In the thermal spraying process, a high-temperature fluid 21 (high-temperature gas or plasma jet) is fired from a spray gun 20 and the high-temperature fluid 21 is passed through a powder supply pipe 22 to ceramics. A mixed powder 23 obtained by mixing the powder and the self-fluxing alloy powder is supplied, and the mixed powder 23 is sprayed and laminated on the steel workpiece 15 while melting the mixed powder 23. The laminate is referred to as a sprayed layer 30.
[0015]
The steel workpiece 15 is, for example, a casting mold (JIS SKD61).
As the ceramic powder, a zirconia (ZrO ₂ ) ceramic powder, an alumina (Al ₂ O ₃ ) ceramic powder, a titania (TiO ₂ ) ceramic powder, or a silica (SiO ₂ ) ceramic powder can be adopted.
[0016]
The self-fluxing alloy is preferably a Ni—Cr—B—Si alloy, and its melting point is 980 ° C. to 1000 ° C. Ni-Cr-B-Si alloys include, for example, C: 0.69%, B: 3.28%, Si: 4.50%, Fe: 2.86%, Cr: 16.7%, Ni: It consists of a balance composition.
Thermal spraying is a technique in which ceramic powder or alloy powder is sprayed onto a steel member at high temperature and high speed, but in principle, fine gaps are generated. If a self-fluxing alloy powder is employed as the thermal spray material, the fine gaps can be reduced.
[0017]
FIG. 3 is an enlarged view of a part 3 in FIG. 2, and the thermal spray layer 30 is represented by ceramic powder 31 (... indicates a plurality, the same applies hereinafter) represented by a shaded ellipse, and a white ellipse. The self-fluxing alloy powders 32,...
[0018]
The thickness of the sprayed layer 30 is selected from the range of 100 μm to 1000 μm. If it is less than 100 μm, the ability to block the heat of the molten metal becomes insufficient, and the life of the mold is shortened. In addition, since the heat of the molten metal can easily escape, cooling and solidification progress, which causes poor hot water circulation. On the other hand, if the thickness exceeds 1000 μm, a large residual stress is generated in the sprayed layer, and cracking easily occurs. Therefore, the thickness of the sprayed layer 30 is desirably selected from the range of 100 μm to 1000 μm. When the sprayed layer is a multilayer, the total thickness is set within the above range.
[0019]
FIG. 4 is a principle diagram of the tempering process according to the present invention. In the tempering process, the steel workpiece 15 that has undergone the quenching process of FIG. 1 and the thermal spraying process of FIG. 2 is charged into the furnace body 41 and tempered at a temperature of 550 ° C. to 650 ° C.
[0020]
Specifically, the tempering furnace 40 includes a furnace body 41, a door 42, a roller table 43, an electric heating body 46, a motor 47, and a hot air fan 48, and the steel workpiece 15 is connected to the door of the furnace body 41. 42 is opened and charged on the roller table 43. Thereafter, the inside of the furnace is raised to a predetermined temperature by a hot air fan 48 using an electric heating body 46 and a motor 47. The hot-air fan 48 has a role of stirring the atmospheric gas to promote uniform temperature in the furnace and heat transfer to the steel workpiece 15.
[0021]
FIG. 5 is a temperature curve diagram for the tempering process of the present invention, where the horizontal axis represents time and the vertical axis represents the treatment temperature.
Primary tempering is performed at about 550 ° C. The secondary tempering is performed at a temperature several tens of degrees Celsius higher than that, and the tertiary tempering is performed at a temperature lower than the secondary tempering temperature.
[0022]
Tempering is originally intended to improve toughness, but an alloy tool steel that is usually used as a mold can be obtained with appropriate hardness by tempering a plurality of times.
That is, the steel workpiece material is, for example, JIS SKD61, and SKD61 is an alloy tool steel and generally does not perform tempering a plurality of times, but mechanical properties when applied to a mold or the like as in the present invention. It is desirable to repeat tempering three times for the purpose of improving. The temperature and the number of times of tempering may be appropriately determined according to the steel type and the shape of the workpiece.
[0023]
FIG. 6 is a cross-sectional view of a main part of a steel workpiece obtained by the present invention. When the steel workpiece 15 is tempered, the sprayed layer 30 is in a state in which the ceramic powder 31... Is dispersed in the self-fluxing alloy 33 after tempering, and the sprayed layer 30 is bonded to the steel workpiece 15 by the diffusion bonding layer 34. To do.
[0024]
The above operation will be described with reference to a flowchart.
FIG. 7 is a flowchart according to the method of the present invention, and STxx indicates a step number.
ST01: Perform a workpiece machining step.
ST02: A quenching process is performed as shown in FIG.
ST03: The thermal spraying process is performed as shown in FIGS.
ST04: A tempering step is performed as shown in FIGS.
Thereby, the cross-sectional structure of FIG. 6 is obtained.
[0025]
The above flow diagram is documented as follows.
A quenching process in which a workpiece formed by processing a steel material into a desired shape is subjected to a quenching process, and a thermal spraying process in which a mixed powder of ceramic powder and self-fluxing alloy powder is sprayed on the surface of the quenched workpiece; A method of joining a sprayed layer and a steel member, characterized by comprising a tempering step of subjecting a thermally sprayed workpiece to a tempering process a plurality of times, wherein the thermally sprayed layer is metallurgically joined to the workpiece. It is.
[0026]
Since the self-fluxing alloy is employed, a diffusion bonding layer can be formed at the boundary surface between the sprayed layer and the steel member, and this diffusion bonding layer exhibits an effect of increasing the bonding strength between the sprayed layer and the steel member.
In addition, the self-fluxing alloy plays a role of appropriately dispersing the ceramic powder by tempering after thermal spraying.
Therefore, by adopting the self-fluxing alloy, the bonding strength between the sprayed layer and the steel member can be increased, and the ceramic powder can be appropriately dispersed.
As a result, the life and durability of the steel workpiece can be dramatically improved.
[0027]
Another embodiment according to the present invention will be described next.
FIG. 8 is a cross-sectional view of a main part of a steel workpiece according to another embodiment of FIG. 6. A thermal spray layer 35 made of only self-fluxing powder is formed on the steel workpiece 15 by thermal spraying, and ceramic powder and The thermal spray layer 30 made of a mixed powder obtained by mixing the self-fluxing alloy powder is formed. This shows that a workpiece obtained by laminating the two thermal spray layers 35 and 30 on the steel workpiece 15 is obtained, and that the diffusion bonding layer 34 can be formed between the steel workpiece 15 and the thermal spray layer 35.
[0028]
According to this structure, since it has a layer which consists only of a self-fluxing alloy in the middle of a thermal spray layer and a steel member, stronger diffusion joining can be made.
[0029]
FIG. 9 is a cross-sectional view of an essential part of a workpiece according to still another embodiment of FIG. 6, in which a thermal spray layer 35 made of only self-fluxing powder is formed on a steel workpiece 15 by thermal spraying. A thermal spray layer 30A made of a mixed powder obtained by mixing a soluble alloy powder is formed, and the thermal spray layer 30B is made of a mixed powder in which the mixing ratio of the self-fluxing alloy powder is lowered by this thermal spray layer 30A and the mixing ratio of the ceramic powder is increased. Form. In addition, it is possible to obtain a workpiece obtained by laminating the sprayed layers 35, 30 </ b> A, 30 </ b> B having an inclined structure on the steel workpiece 15, and to form the diffusion bonding layer 34 between the steel workpiece 15 and the sprayed layer 35. It shows that.
[0030]
According to this structure, since it has a layer which consists only of a self-fluxing alloy in the middle of a thermal spray layer and a steel member, stronger diffusion joining can be made.
Since the sprayed layer has an inclined structure, the surface layer can enhance the wear resistance, and the vicinity of the diffusion bonding layer 34 can improve durability and adhesion.
[0031]
【Example】
Embodiments according to the present invention will now be described.
○ Thermal spraying conditions:
Steel member: casting mold alloy sprayed material: ZrO ₂ powder 50% by mass + Ni—Cr—B—Si self-fluxing powder 50% by mass
Thermal spray layer thickness: 300 μm
[0032]
○ Quenching and tempering conditions:
Heating temperature: 1025 ° C
Tempering frequency: 3 times Tempering temperature: 1st time: 550 ° C, 2nd time: 650 ° C, 3rd time: 600 ° C
[0033]
○ Casting molds obtained under conditions above evaluation are expected to increase the number of castings by 1.2 to 1.5 times compared to conventional sprayed casting molds that do not use self-fluxing alloys. It was.
[0034]
As a result of repeated experiments, the following was found.
If the ratio of the ZrO ₂ powder / Ni—Cr—B—Si self-fluxing powder constituting the thermal spray layer is in the range of 5/95 to 95/5, the effects and effects of the present invention can be expected.
If it is less than 5/95, the heat insulation and wear resistance will be insufficient. If it exceeds 95/5, all of lubricity, film strength and adhesion will be insufficient.
[0035]
The ZrO ₂ powder is suitably stabilized or partially stabilized zirconia containing 6 to 30% by mass of additive components such as MgO, Y ₂ O ₃ , and CeO _2. Among them, 8% by mass of Y ₂ O ₃ is suitable. The added partially stabilized zirconia was suitable and was most excellent in heat fatigue resistance.
[0036]
【The invention's effect】
The present invention exhibits the following effects by the above configuration.
Claim 1 is a quenching process in which a workpiece formed by processing a steel material into a desired shape is subjected to a quenching process, and a mixed powder of ceramic powder and self-fluxing alloy powder is applied to the surface of the workpiece that has been quenched. The thermal spraying process and the steel are characterized by comprising a thermal spraying process for thermal spraying and a tempering process for subjecting the thermal sprayed work to tempering a plurality of times. This is a coupling method with a member.
[0037]
Since the self-fluxing alloy is employed, a diffusion bonding layer can be formed at the boundary surface between the sprayed layer and the steel member, and this diffusion bonding layer exhibits an effect of increasing the bonding strength between the sprayed layer and the steel member.
In addition, the self-fluxing alloy plays a role of appropriately dispersing the ceramic powder by performing tempering a plurality of times after thermal spraying.
Therefore, by adopting a self-fluxing alloy, it is possible to suppress the progress of cracks between the thermal spraying layer and between the steel workpiece and the thermal spraying layer, to increase the bonding strength between the thermal spraying layer and the steel member, and to disperse the ceramic powder appropriately. it can.
As a result, the life and durability of the workpiece can be dramatically improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing the principle of a quenching process according to the present invention. FIG. 2 is a diagram showing a principle of a thermal spraying process according to the present invention. FIG. 3 is an enlarged view of a part 3 of FIG. FIG. 5 is a temperature curve diagram for the tempering process of the present invention. FIG. 6 is a cross-sectional view of the main part of a steel workpiece obtained by the present invention. FIG. 7 is a flow chart according to the method of the present invention. FIG. 9 is a cross-sectional view of a main part of a workpiece according to another embodiment of FIG. 6; FIG. 10 is a reprint of FIG. 2 of Patent Document 1;
DESCRIPTION OF SYMBOLS 15 ... Steel workpiece, 23 ... Mixed powder, 30 ... Sprayed layer, 31 ... Ceramic powder, 32 ... Self-fluxing alloy powder, 33 ... Self-fluxing alloy after tempering, 34 ... Diffusion bonding layer.

Claims (1)

A quenching process in which a workpiece formed by processing a steel material into a desired shape is subjected to a quenching process, and a thermal spraying process in which a mixed powder of ceramic powder and self-fluxing alloy powder is sprayed on the surface of the quenched workpiece; A method of joining a sprayed layer and a steel member, characterized by comprising a tempering step of subjecting a thermally sprayed workpiece to a tempering process a plurality of times, wherein the thermally sprayed layer is metallurgically joined to the workpiece. .

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