JPS6153413A - Engine valve - Google Patents

Abstract

PURPOSE:To reduce cost by forming Fe-Cr system alloy of specified composition on a face surface to ensure the face surface performance equivalent to that of prior stellite by the use of economical material. CONSTITUTION:A valve body 2 is formed on the face base surface 3 with an alloy layer 1 consisting of 10-60wt% of Cr, 1-8wt% of C and total 5-20wt% of one or at least two kinds of Mo, Ni, W, B, Si, Co and the remaining Fe to constitute a face surface 4 with this alloy layer 1. Then, when said alloy 1 is formed, the alloy powder of said composition is welded and blasted onto the face base surface 3, then irradiated by a high density energy medium like laser to alloy portionally the connection to the valve body 2 and ground to be finished to have a predetermined dimension and shape. Thus, antiwear property, heat resisting property and corrosion resistance equivalent to those of prior stellite filling can be ensured by the use of economical materials.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine valve for an internal combustion engine, and more particularly, to an engine valve whose shift ace surface is improved in performance through surface treatment (prior art).

In general, intake valves are made from martentate heat-resistant steel (
For example, 5UH3) is used for the exhaust valve, while austenitic heat-resistant steel (for example, 8UH31) is used for the exhaust valve. However, in recent years, the operating conditions for internal combustion engines have tended to become more severe.
), using the above-mentioned heat-resistant steel as a base material, we applied stellite coating to the surface of the 7th surface, which is the surface in contact with the valve seat (K), to improve wear resistance, heat resistance, etc. Much improved engine valves are used.

(Problems to be Solved by the Invention) However, in the engine valves coated with stellite, the stellite itself is an expensive alloy based on cobalt (CO), and thin-walled acid is difficult to produce. In view of the fact that the amount of water used is increasing, there has been a problem that it has to become extremely expensive.

The present invention is intended to solve the above-mentioned problems, and aims to provide an inexpensive engine valve that guarantees the same performance in terms of space as Stellite.

(Means for solving the problem) The problem mentioned above is that the face surface is made of chrome (Cr).
) 10-60 wt%, carbon (C) 1-awt%, molybdenum (Mo), nickel (Ni), tungsten (
The problem is solved by using an engine pulp made of an alloy consisting of one or more of W), carbon (33), silicon (Si), and Co in a total amount of 5 to 20 wt%, and the balance being iron (Fe).

(Function) In the engine pulp nitrogen configured as above, Cr
combines with C to form carbide, which contributes to improving hardness, that is, improving wear resistance.

M) It acts to strengthen the IJ socks and increase their heat resistance. However, if the content is less than 10 wt%, the desired wear resistance and heat resistance cannot be ensured, while if it exceeds 6 wt%, the alloying properties with the pulp base material will deteriorate, so this should be avoided. It was determined to be 10 to 60 wt%.

C combines with Cr, W, Mo, etc. to form hard carbides and improves wear resistance, but if it is less than 1 wt%, the desired effect cannot be obtained, while if it exceeds S wt%, impact resistance decreases. Therefore, this was set as 1 to awtchi.

Furthermore, Mo, Ni, W, B, Si, and Co contribute to improving wear resistance by forming carbides, and improving heat resistance and corrosion resistance by strengthening the matrix.

If the total of one or more of them is less than 5 wt%, the desired effect cannot be obtained, while if it exceeds 20 wt%, the economical efficiency deteriorates, so it is recommended to use 5 to z.

It was wt Chi.

In order to form an alloy having the above composition on the valve face, an alloy powder having the above composition is prepared in advance, and this powder is applied in seven steps.
Thermal spray on the base surface and then laser.

The joint with the pulp base material (
The base surface of the face) is partially alloyed and finally polished to the desired size and shape.

Therefore, the hardness of the face surface is HY400-80.
In addition, it has the same wear resistance, heat resistance, and corrosion resistance as conventional stellite metal alloys, and also has improved bonding strength with the base material.

Overall, it is possible to obtain inexpensive engine pulp with excellent face surface performance.

(Example) An embodiment of the present invention will be described below with reference to the accompanying drawings.

Example 1 Cr 20. Owt%, CI Owt%, Ni 10
wt%, the balance being Fe;
Thermal spraying was applied to the base surface of the valve body made of UH31 as a base material, and then the sprayed portion was irradiated with a laser.

Finally, the face was polished to the desired size and shape.

FIG. 1 shows the main structure of the engine pulp obtained as described above. In the figure, reference numeral 1 denotes an alloy layer according to the present invention formed on the base surface 3 of the valve body 2, which itself constitutes the face surface 4. Note that the thickness of the alloy layer 1 is at most 0.2 to 0.6 rran.
That's about it.

On the other hand, an alloy having the same composition as above was separately formed on the surface of a test piece under the same thermal spraying conditions, and the polished stone was subjected to a Vickers hardness test, a Dalian rapid wear test, and a microscope test.

Example 2 Cr 20.0wt%, CI Owt%, Mo
Equipped with an alloy powder consisting of 10.0 wt% and the balance Fe,
This was thermally sprayed onto the surface of a test piece formed using SUH:31 as a base material, and the polished stone was subjected to various tests similar to those in Example 1.

Comparative Example 5 Stellite was built up on the surface of a test piece formed using UH31 as a base material, and the abrasive stone was subjected to a hardness test and a Dalian rapid abrasion test.

The test results of Examples 1 and 2 and Comparative Examples will be described below.

Figure 2 shows the results of the Dalian rapid abrasion test, and it shows that Examples 1 and 2 according to the present invention are equivalent to the comparative example in which Stellite was deposited. It was confirmed that the abrasion resistance was slightly better than that. In addition, the hardness of Example 2 is higher than that of Example 1.
Example 2: )Iv600-700) The needle wear resistance was also slightly superior to that of Example 2.

FIG. 3 shows the microscopic structure of Example 1, and FIG. 4 shows the microscopic structure of Example 2. In these figures, the white part represents the Cr-generated double carbide, and the black part represents the matrix (Fe-Cr), but as a whole, a uniform structural state is obtained.

(Effects of the Invention) As explained in detail above, the engine pulp according to the present invention has a Fe-Cr alloy formed on the face surface instead of the conventional stellite, and is equivalent to stellite. While ensuring face surface performance, the material cost was low, making it possible to produce inexpensive engine pulp.

Brief explanation of the previous aspects Fig. 1 is a side view partially showing the main structure of the engine pulp according to the present invention in cross section, and Fig. 2 shows a test piece produced by the same procedure as the present engine pulp production. A graph showing the results of the abrasion test in comparison with the results of a comparative example with stellite overlay, and FIG. 3 is a micrograph of Example 1.

FIG. 4 is a microscopic photograph of Example 2.

1... Alloy layer 4... Face patent applicant
Toyota Motor Corporation Figure 1 Figure 22!゛3 Figure 4 Amendment to figure procedure (Revised) December 24, 1981 Patent Application No. 172246 of 1988 2, Name of overcharging engine valve 3, Relationship with the person making the amendment Name of patent applicant ( 320)) Yota Jidosha Co., Ltd. 4, Agent Address: 6 Shufunotomo Building 6, Kanda Surugadai, Chiyoda-ku, Tokyo, Subject of amendment

[Brief explanation of the drawing]

7. Details of amendment 4, page 7, i20 - page 8, line 1 "Figure 3...
...This is a microscopic photograph. '' to ``Figure 3 is a wJ microphotograph showing an example of the metal structure of an engine valve made of wood M[J], and Figure 4 is a microphotograph showing another example of the metal structure.'' to correct. =6C

Claims (1)

[Claims] (1) Face surface: Cr10-60wt%, C1-8
1. An engine valve characterized in that it is made of an alloy consisting of a total of 5 to 20 wt% of one or more of Mo, Ni, W, B, Si, and Co, with the balance being Fe.