JPS6338415B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention has excellent high temperature hardness, thermal shock resistance,
and Co-based alloys that have lead oxide corrosion resistance and are suitable for use in castings or overlay welding in the manufacture of engine valves and valve seats for internal combustion engines that particularly require these characteristics. It is. [Prior art] Conventionally, when manufacturing engine valves and valve seats for internal combustion engines, welding was performed using American Welding Association standard 5.13R Co Cr-A (C: 0.9 to 1.4) for overlay welding.
%, Si: 2.0% or less, Mn: 1.0% or less, W: 3.0~
6.0%, Cr: 26-32%, Ni: 3.0% or less, Fe: 3.0
% or less, Mo: 1.0% or less, Co and unavoidable impurities: remainder), 5.13R Co Cr-B (C: 1.2 to 1.7
%, Si: 2.0% or less, Mn: 1.0% or less, W: 7.0~
9.5%, Cr: 26-32%, Ni: 3.0% or less, Fe: 3.0
% or less, Mo: 1.0% or less, Co and unavoidable impurities: the remainder, weight % or less) (hereinafter referred to as conventional Co-based alloy) have been widely used. On the other hand, in recent years, as the performance of internal combustion engines has improved, the engine valves and valve seats of internal combustion engines have also been required to have even better characteristics. In general, both types have high-temperature hardness with a Bitkers hardness of 285 or higher at a temperature of 800°C in the overlay welding state, and when repeatedly water-cooled after being held at a temperature of 700°C for 15 minutes. Thermal shock resistance of 7 or more operations before cracking occurs in the welded weld, and a weight loss of 0.09 g/cm ² / after being immersed in molten lead oxide heated to 915°C for 1 hour. It has become necessary to have lead oxide corrosion resistance of hr or less. It goes without saying that engine valve castings and valve seat castings for internal combustion engines manufactured by casting are similarly required to have these characteristics. [Problems to be solved by the invention] However, although the above-mentioned conventional Co-based alloys satisfy the above requirements in terms of high-temperature hardness, they do not satisfy the above requirements in terms of thermal shock resistance and lead oxide corrosion resistance. Therefore, when the conventional Co-based alloy is used for overlay welding and for casting in the production of engine valves and valve seats for high-performance engines, it has a sufficiently satisfactory service life. The current situation is that it does not show this. [Means for Solving the Problems] Therefore, from the above-mentioned viewpoint, the present inventors have improved the high-temperature hardness and thermal shock resistance required for engine valves and valve seats for internal combustion engines, particularly high-performance engines. As a result of research to develop a material that has lead oxide corrosion resistance and can be used for overlay welding and casting, we found that C: 0.5 to 3.0%, Si: more than 3%. 7.0%, Cr: 10~35%, W: 0.1~17.0%, Mo: 0.1~10.0%, Ti: 0.01~3.0%, Al: 0.01~3.5%, and further contains Mn: 0.01 as necessary. ~2.0
%, Ni: 8-32%, Fe: 1-16%, Nb: 0.01-
1.50% and B: 0.001 to 1.50%, and the remainder is Co and inevitable impurities (preferably Co: 40% or more content). Alloy Temperature: 800
It has extremely high temperature hardness with a Bitkers hardness of 310 or higher at temperature: 700℃, and in a thermal shock test in which one cycle is heating to 700℃ for 15 minutes followed by water cooling, the number of cycles until cracking is Shows excellent thermal shock resistance of 9 times or more, and furthermore, temperature: 915
In a lead oxide corrosion test conducted by immersing it in molten lead oxide heated to ℃ for 1 hour, it showed excellent lead oxide corrosion resistance with a weight loss of less than 0.026 g/cm ² /hr, and is used for overlay welding and casting. Therefore, we have obtained the knowledge that this Co-based alloy exhibits excellent performance over an extremely long period of time when used in the manufacture of high-performance engine valves and valve seats. This invention has been made based on the above knowledge, and the reason will be explained below by limiting the component composition as described above. (a) C The C component combines with Cr, W, Mo, Ti, Nb, etc. to form carbides and has the effect of improving hardness at room temperature and high temperature.
If the content is less than 0.5%, the desired high hardness cannot be secured, while if the content exceeds 3.0%, the thermal shock resistance will deteriorate in relation to Si, so the content should be reduced to 0.5 to 3.0%. It was determined that (b) Si The Si component has the effect of improving castability, overlay weldability, and melt flow, but its content is
If the content is less than 3.0%, the desired improvement effect on the above action cannot be obtained, and on the other hand, if the content exceeds 7.0%, no further improvement effect can be expected. Therefore, the content was set at more than 3% to 7.0%. . (c) Cr A part of the Cr component dissolves in solid solution in the base material, and the remaining part forms carbide, which particularly improves high-temperature hardness and high-temperature wear resistance, as well as oxidation resistance. It has the effect of improving corrosivity, but
If the content is less than 10%, the desired effect cannot be obtained, while if the content exceeds 35%,
Since thermal shock resistance tends to decrease in relation to Si, its content was set at 10 to 35%. (d) W The W component has the effect of refining carbides, forming carbides themselves, solid-dissolving in the base material, strengthening it, and improving the high-temperature hardness and high-temperature strength of the alloy. However, its content is
If the content is less than 0.1%, the desired effect cannot be obtained, while if the content exceeds 17.0%, overlay weldability and machinability will deteriorate, so the content is set at 0.1 to 17.0%. Ta. (e) Mo Mo component, when coexisting with W, forms a solid solution in the base material, strengthens it, and forms carbides to improve the high-temperature hardness (high-temperature wear resistance) and high-temperature strength of the alloy. It has an effect, but its content is
If the content is less than 0.1%, the desired effect cannot be obtained, while if the content exceeds 10.0%, the thermal shock resistance and toughness will deteriorate, so the content was set at 0.1 to 10.0%. . (f) Ti The Ti component not only suppresses the growth of crystal grains in the base material, but also makes the crystal grains finer, and combines with MC type carbides and nitrides, as well as Ni and Al to form Ni ₃ ( Al, Ti) have the effect of forming intermetallic compounds to improve high-temperature hardness and thermal shock resistance, as well as high-temperature strength and toughness, but if the content is less than 0.01%, the desired effect is not achieved. On the other hand, if the content exceeds 3.0%, the amount of carbides increases, thermal shock resistance and toughness deteriorate in relation to Si, and lead oxide corrosion resistance also tends to deteriorate. Therefore, its content is 0.01
It was set at ~3.0%. (g) Al The Al component, along with Cr, improves lead oxide corrosion resistance, combines with Ni and Ti to form an intermetallic compound of Ni ₃ (Al, Ti), and contains nitrides. It has the effect of improving hardness at room temperature and high temperature, further increasing wear resistance, and further improving thermal shock resistance and high temperature strength.
If the content is less than 0.01%, the desired effect cannot be obtained, while if the content exceeds 3.5%, the weldability and toughness will also decrease in relation to Si, making it impractical. content
It was set at 0.01-3.5%. (h) Mn The Mn component has the effect of improving overlay weldability, so it is included as necessary when especially overlay weldability is required, but the content is 0.01
If the content is less than 2.0%, the desired improvement effect on overlay weldability cannot be obtained, and on the other hand, if the content exceeds 2.0%, no further improvement effect will be obtained. Therefore, the content was set at 0.01 to 2.0%. (i) Ni The Ni component stabilizes the austenite base and improves thermal shock resistance and toughness.
Combines with Al and Ti to form an intermetallic compound: Ni ₃ (Al,
These properties are especially required because it forms Ti), improves high-temperature hardness (high-temperature wear resistance) and high-temperature strength, and also improves lead oxide corrosion resistance when coexisting with Cr. However, if the content is less than 8%, the desired effect on the above action cannot be obtained, and on the other hand, if the content exceeds 32%, no further improvement effect can be obtained. Therefore, its content was set at 8 to 32%. (j) Fe The Fe component has the effect of further improving the thermal shock resistance of the alloy, so it is included as necessary when the above properties are required, but if the content is less than 1%, the desired The effect of improving thermal shock resistance cannot be obtained, and on the other hand, if the content exceeds 16%, the high temperature hardness decreases, so the content was set at 1 to 16%. (k) Nb and B These components have high temperature hardness (high temperature wear resistance)
and has the effect of further improving high-temperature strength, so it is included as necessary especially when the above-mentioned effect is required, but the content of each is
If Nb: less than 0.01% and B: less than 0.001%, the desired effect of improving the above action cannot be obtained, while if each content exceeds 1.50%, thermal shock resistance will deteriorate. The amount is Nb: 0.01~1.50%, B: 0.001~1.50%
It was determined that [Example] Next, the Co-based alloy of the present invention will be specifically explained using Examples and in comparison with Comparative Examples. Co-based alloys 1 to 42 of the present invention having the compositions shown in Table 1 and conventional Co-base alloys 1 and 2 having compositions corresponding to the conventional Co-base alloys described above were prepared by a normal melting method. By melting and then continuous casting under normal conditions, the diameter:
A welding rod with a diameter of 4.8 mm was formed. Next, the resulting Co-based alloy 1 of the present invention
~42, and conventional Co-based alloys 1 and 2 welding rods, using a TIG automatic welding machine, diameter: 120mmφ×
Thickness: On the surface of the base metal made of stainless steel (SUS316) with dimensions of 20 mm, outer diameter: 100 mm x width:
A circular bead of 20 mm x thickness: 5 mm was welded in two layers. Subsequently, the annular bead formed on the base metal was tested for Rockwell hardness (C scale) at room temperature and Bitker hardness at 800°C.

【table】

〔Effect of the invention〕

From the results shown in Table 1, Co-based alloys 1 to 42 of the present invention all have better high-temperature hardness, thermal shock resistance, and lead oxide corrosion resistance than conventional Co-based alloys 1 and 2. It is clear that it has. In the above example, a case was described in which the Co-based alloy of the present invention was used for overlay welding, but even when used for casting, it can exhibit the same excellent properties as for overlay welding. Of course. As mentioned above, the Co-based alloy of the present invention has excellent high-temperature hardness, thermal shock resistance, and satisfies the above-mentioned strict conditions required for engine valves and valve seats of high-performance engines. It also has lead oxide corrosion resistance, so when used for overlay welding and casting in the manufacture of these parts, the resulting parts exhibit excellent performance over a long period of time.

Claims (1)

[Claims] 1 C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0% , Al: 0.01 to 3.5%, and the remainder is Co and unavoidable impurities (weight %) for engine valves and valve seats of internal combustion engines.
Co-based alloy. 2 C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains Mn: 0.01 to 2.0%, and the remainder is Co and unavoidable impurities (weight %), for use in engine valves and valve seats of internal combustion engines. alloy. 3C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains Ni: 8 to 32%, with the remainder consisting of Co and unavoidable impurities (weight %)
A Co-based alloy for engine valves and valve seats of internal combustion engines, characterized by having the following. 4 C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains Fe: 1 to 16%, with the remainder consisting of Co and unavoidable impurities (weight %)
A Co-based alloy for engine valves and valve seats of internal combustion engines, characterized by having the following. 5 C: 0.5 to 3.0%, Si: more than 3% to 7.0%, Cr: 10 to 35%, W: 0.1 to 17.0%, Mo: 0.1 to 10.0%, Ti: 0.01 to 3.0%, Al: 0.01 to 3.5 %, and further contains Nb: 0.01-1.50% and B:
Contains one or two of 0.001 to 1.50%,
A Co-based alloy for engine valves and valve seats of internal combustion engines, characterized by having a composition (by weight %) with the remainder consisting of Co and unavoidable impurities. 6 C: 0.5 to 3.0%, Si: more than 3% to 7.0%, Cr: 10 to 35%, W: 0.1 to 17.0%, Mo: 0.1 to 10.0%, Ti: 0.01 to 3.0%, Al: 0.01 to 3.5 %, and further contains Mn: 0.01~2.0% and Ni: 8~
A Co-based alloy for engine valves and valve seats of internal combustion engines, characterized by having a composition (by weight %) containing 32% Co and the remainder consisting of Co and unavoidable impurities. 7 C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains Mn: 0.01~2.0% and Fe: 1~
A Co-based alloy for engine valves and valve seats of internal combustion engines, characterized by having a composition (by weight %) containing 16% Co and the remainder consisting of Co and unavoidable impurities. 8 C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, further contains Mn: 0.01 to 2.0%, and Nb: 0.01
-1.50% and one or two of B: 0.001-1.50%, with the remainder consisting of Co and inevitable impurities (weight%); Co-based alloy for valve seats. 9 C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains Ni: 8 to 32% and Fe: 1 to 16%.
%, with the remainder consisting of Co and unavoidable impurities (weight %), for use in engine valves and valve seats of internal combustion engines.
Co-based alloy. 10 C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains Ni: 8 to 32% and Nb: 0.01 to
1.50% and B: 0.001 to 1.50%. An engine valve for an internal combustion engine characterized by having a composition (weight %) containing one or two of B: 0.001 to 1.50%, and the remainder consisting of Co and inevitable impurities. Co-based alloy for seats. 11 C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains Fe: 1~16% and Nb: 0.01~
1.50% and B: 0.001 to 1.50%. An engine valve for an internal combustion engine characterized by having a composition (weight %) containing one or two of B: 0.001 to 1.50%, and the remainder consisting of Co and inevitable impurities. Co-based alloy for seats. 12C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains Mn: 0.01~2.0% and Ni: 8~
A Co-based alloy for engine valves and valve seats of internal combustion engines, characterized by having a composition (weight %) of Fe: 32%, Fe: 1 to 16%, and the remainder consisting of Co and unavoidable impurities. 13C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains Mn: 0.01~2.0% and Ni8~32
%, Nb: 0.01-1.50% and B: 0.001-1.50%
A Co-based alloy for engine valves and valve seats of internal combustion engines, characterized by containing one or two of the above, with the remainder consisting of Co and unavoidable impurities (weight percent). 14 C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains 8~32% Ni and 1~16% Fe.
and one or two of Nb: 0.01 to 1.50% and B: 0.001 to 1.50%, with the remainder consisting of Co and inevitable impurities (weight %). Co-based alloy for engine valves and valve seats. 15 C: 0.5 to 3.0%, Si: more than 3% to 7.0%, Cr: 10 to 35%, W: 0.1 to 17.0%, Mo: 0.1 to 10.0%, Ti: 0.01 to 3.0%, Al: 0.01 to 3.5 %, and further contains Mn: 0.01~2.0% and Fe: 1~
16%, Nb: 0.01~1.50% and B: 0.001~1.50
%, and the rest is Co.
A Co-based alloy for engine valves and valve seats of internal combustion engines, characterized by having a composition (by weight % or more) consisting of unavoidable impurities. 16C: 0.5-3.0%, Si: more than 3%-7.0%, Cr: 10-35%, W: 0.1-17.0%, Mo: 0.1-10.0%, Ti: 0.01-3.0%, Al: 0.01-3.5 %, and further contains Mn: 0.01~2.0% and Ni: 8~
32%, Fe: 1 to 16%, Nb: 0.01 to 1.50%, and B: 0.001 to 1.50%. ) for engine valves and valve seats of internal combustion engines, characterized by having
Co-based alloy.