JP2811866B2 - Hardfacing method for aluminum alloy substrate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to hardfacing of metal (hard facing), and more particularly, to hardfacing of an aluminum alloy substrate.

[Conventional technology]

Overlay layer (welded metal layer) on the surface of aluminum alloy substrate
In general, it is difficult to form an aluminum-based or copper-based metal material as a cladding material.
It is difficult to build up an aluminum alloy base material other than these metal materials, and the composition ratio is changed with an aluminum-based or copper-based build-up material, and the build-up according to the application is performed. .

[Problems to be solved by the invention]

Aluminum-based or copper-based overlay materials have limitations in hardness and heat resistance, and cannot be used where high temperature and wear resistance are required.

An object of the present invention is to provide a method for forming a hardfacing layer that replaces the conventional aluminum-based or copper-based cladding layer.

[Means for solving the problem]

The above purpose is as follows: Chromium (Cr): 10 ~ 70wt% Carbon (C): 0.3 ~ 3wt% Iron and unavoidable impurities: The rest of the overlay material is placed on an aluminum alloy base material and irradiated by laser. This is achieved by a method for hardfacing an aluminum alloy substrate, which is characterized by forming a weld metal layer.

In addition, 30 wt% or less of nickel (N
i) It is possible to improve the corrosion resistance or wear resistance by adding at least one of cobalt (Co) of 20 wt% or less and carbide forming element of 10 wt% or less.

[Action]

The composition of the hardfacing layer according to the present invention is basically iron (Fe).
Although it is a base metal material, it cannot be clad on an aluminum alloy substrate with the widely used heat source of TIG or MIG arc, but only the cladding material is melted using laser energy. The present inventors have found that if they can be overlaid, they can be built up.

The reasons for defining the composition range of the hardfacing layer as described above are as follows.

If the chromium content is less than 10 wt%, it will be difficult to build up, while if it is more than 70 wt%, bead cracks are likely to occur. If the carbon content is less than 0.3 wt%, the build-up layer is diluted (alloyed) into the base aluminum alloy, and the build-up layer becomes brittle, while if it is more than 3 wt%, bead cracks occur. Nickel and co-part are elements that improve the corrosion resistance. However, if nickel is 30 wt% or more, it is difficult to build up, and if cobalt is 20 wt% or more, it is difficult to build up. And, the carbide forming element is tungsten (W),
Molybdenum (Mo) and the like improve abrasion resistance, but those added in an amount of 10 wt% or more are difficult to build up.

In the present invention, the above-mentioned overlay material is prepared as an alloy powder,
It is preferable that the surface is placed on the surface of the aluminum alloy base material, and a laser beam is scanned and irradiated on the surface under the following conditions to form a weld metal layer (facing layer).

Laser output: 3.5 to 10 kW Laser beam area: 0.1 to ⁵ mm ² Overlay forming speed: 300 to 1500 mm / min The base material (base material) aluminum alloy has a relatively low melting point (approx.
(500-600 ° C) and is easier to melt than the iron-based overlay material (Fe-Cr material, melting point about 1300-1400 ° C) of the present invention, so the heating energy is concentrated only on the overlay material It is necessary to use a laser beam capable of reducing the heating energy application area. If the irradiation area, which is the area of the laser beam, is 0.1 mm ² or less, the processing area is too small, and the build-up time is too long. On the other hand, if the thickness is 5 mm ² or more, the energy density will be low, and the iron-based overlay material will not melt. Will also dissolve. The alloy-forming layer in this case is hard, brittle and inhomogeneous, especially when the iron concentration is high, which is not preferable. If the laser output is 3.5 kW or less, it is difficult to form the cladding due to insufficient input energy.
Further, if the build-up speed (the length of the formed build-up layer divided by time) is 300 mm / min or less, the productivity is low, whereas if it is 1500 mm / min or more, bead cracks occur.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings by way of experimental examples including exemplary embodiments of the present invention.

Experiment 1 Molten alloys were prepared from a number of samples composed of chromium, carbon, and iron (Fe-Cr-C) and having chromium and carbon contents as shown in FIG. An overlay material was prepared as a powder.

An aluminum alloy casting (AC2B: JIS H5202) plate was prepared as an aluminum alloy base material, and a build-up material of an alloy powder was continuously placed on the plate, and a laser was applied thereto under the following conditions.

Laser output: 4 kW Laser beam area: 0.5 mm ² Overlay forming speed: 800 mm / min Laser oscillation width: 6 mm Oscillation number: 200 Hz Laser irradiation dissolves the overlay material and aluminum welded metal layer (facing layer) It was formed on an alloy casting plate, and its appearance, hardness and the like were examined. The results shown in FIG. 1 were obtained. In FIG. 1, A is a sample that was not overlaid, B
Indicates a sample in which the deposited metal layer has been diluted (alloyed) into the casting plate, and C indicates a sample in which bead cracking has occurred. The overlay was formed at a certain composition ratio of the round bar in the figure, and the respective hardness (Vickers hardness HV) was entered above the round bar.

FIG. 2 shows a cross section (X10) of the cladding layer (HV374) of the composition Fe-30Cr-1.5C with the cast aluminum alloy plate, and FIG. 3 shows the structure of the cladding layer (X400).

Further, the chromium content (30 wt%) and the carbon content (1.5 wt%) were kept constant, and F containing 30 wt% of nickel was added.
FIG. 4 shows the structure of the overlay layer (HV293) of e-30Cr-30Ni-1.5C, and Fe-30Cr-20Co-1 containing 20 wt% of cobalt.
Fig. 5 shows the structure of the 5C overlay layer (HV395.3), and Fig. 6 shows the structure of the Fe-30Cr-10W-1.5C overlay layer (HV465.3) added with 10wt% tungsten. And a cladding layer of Fe-30Cr-10Mo-1.5C to which 10 wt% of molybdenum is added (HV44
Fig. 7 shows the structure of 5.7). These build-up layers are formed under the above-mentioned conditions. The corrosion resistance is improved by adding nickel and cobalt, and the hardness is increased by adding tungsten and molybdenum.

Experiment 2 A cladding layer was formed on an aluminum alloy casting (AC2B) plate using a cladding material having a composition of Fe-30Cr-1.5C under the laser processing conditions shown in Table 1.

Note that the laser oscillation width was 6 mm, and the number of oscillations was 200 Hz.

By changing any of the laser output, the beam area, and the buildup speed based on the conditions surrounded by the bold line in Table 1 (for example, changing only the output, setting the beam area and the buildup speed in the bold line) Under the conditions of the values), the overlay was formed, and the results are shown in Table 2.

In the table, ○ indicates that the build-up property was good, X indicates that the build-up property was poor, and Δ indicates an intermediate between these. * Indicates that the laser output is large and alloying with the base material has occurred, and ** indicates that bead cracking has occurred.

〔The invention's effect〕

As described above, according to the present invention, an iron-based cladding layer can be formed on an aluminum alloy base material, and has much higher hardness and higher heat resistance than conventional aluminum-based or copper-based cladding layers. The hardfacing layer enables hardfacing of aluminum alloy parts (for example, a skirt portion, a ring groove, a cylinder head seat portion, etc., of a piston made of aluminum alloy) exposed to high temperatures which could not be handled conventionally.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an alloy composition and a build-up forming layer when a weld metal layer is formed on a build-up material having an Fe—Cr—C composition by laser irradiation. FIG. 3 is a micrograph of the metal structure showing a cross section of the −30Cr-1.5C overlay layer with the aluminum alloy casting plate, and FIG. 3 is a micrograph of the metal structure of the Fe-30Cr-1.5C overlay layer; FIG. 4 is a micrograph of the metal structure of the Fe-30Cr-30Ni-1.5C overlay, and FIG. 5 is a micrograph of the metal structure of the Fe-30Cr-20Co-1.5C overlay. FIG. 6 is a micrograph of the metal structure of the Fe-30Cr-10W-1.5C overlay, and FIG. 7 is a micrograph of the metal structure of the Fe-30Cr-10Mo-1.5C overlay. A: Sample that cannot be overlaid B: Sample (diluted (alloyed) of the aluminum alloy casting material to the deposited metal layer) C: Bead cracked sample

Continued on the front page (72) Inventor Hiroyuki Murase 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Minoru Kawasaki 1 Toyota Town Toyota City, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) Reference Reference JP 5-5585 (JP, B2) JP 60-5395 (JP, B2) “Welding technology”, Vol. 34, No. 8, p. 47, 48 (58) Field surveyed (Int. Cl. ⁶ , DB name) B23K 35/30 B23K 26/00

Claims (2)

(57) [Claims] 1. The following composition: Chromium: 10 to 70 wt% Carbon: 0.3 to 3 wt% Iron and unavoidable impurities: The remaining build-up material is placed on an aluminum alloy base material, and the deposited metal layer is formed by laser irradiation. A method for hardfacing on an aluminum alloy substrate characterized by the following features. 2. The following composition: Chromium: 10 to 70% by weight Carbon: 0.3 to 3% by weight Nickel up to 30% by weight, cobalt up to 20% by weight and 10% by weight
at least one of carbide forming elements of not more than wt%: iron and unavoidable impurities: an aluminum alloy base characterized by placing the remaining build-up material on an aluminum alloy base material and forming a deposited metal layer by laser irradiation. Hardfacing method for materials.