JPS6032701B2 - Ni-based alloy for engine valves and valve seats of internal combustion engines - Google Patents

Description

Detailed Description of the Invention The present invention has excellent high-temperature hardness, thermal shock resistance, and lead oxide corrosion resistance, and is particularly suitable for overlay welding of engine valves and valve seats of internal combustion engines, and for these. This relates to a Ni-based alloy that has been passed through for use in castings.

Regarding overlay welding of engine valves and valve seats of internal combustion engines, American Welding Association Standard 5.1 Amendment C is required.
oCr-A (C: 0.9-1.4%, 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%
Below, Mo: 1.0% or less, Co and inevitable impurities:
remaining) and the same 5.1 field CoCr-B (C: 1.2 to 1.
7%, Si: 2.0% or less, Nh: 1.0% or less, W:
7.0% to 9.5%, Cr: 26 to 32%, Ni: 3.
0% or less, Fe: 3.0% or less, Mo: 1.0% or less,
Co and unavoidable impurities: remaining, more than % by weight)
O-based alloys (hereinafter referred to as conventional Co-based alloys) 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 are required to have even better characteristics. , both are in the overlay welding state, and if the Vickers hardness at a temperature of 80 qo is high temperature and is held at a temperature of 700 qo for 15 minutes and then the water cooling operation is repeated, cracks will occur in the overlay weld. Thermal shock resistance is such that the number of operations described above is 7 or more times until the occurrence of It is now required to be resistant to lead chloride corrosion.

It goes without saying that these characteristics are similarly required for engine valve castings and valve seat castings for internal combustion engines manufactured by casting. However, although the above-mentioned conventional Co-based alloys satisfy the above requirements in terms of high-temperature hardness, they do not have properties that satisfy these requirements in terms of thermal shock resistance and iron oxide corrosion resistance. Currently, when used for overlay welding of engine valves and valve seats, or for casting, it does not have a sufficiently satisfactory service life.

From the above-mentioned viewpoint, the present invention provides a Ni-based alloy having characteristics that satisfy the above-mentioned conditions required for materials for overlay welding and casting of engine valves and valve seats of internal combustion engines, particularly high-performance engines. Provided, in weight%, C: 1.0 to 3.5%, Sj: 0.1 to 2.0%, M
n: 0.1-2.0%, W: 5-20%, Cr: 20-20%
Contains 40%, and further contains Fe: 1 to 30% as necessary
and Mo: 1 to 9%, and has a composition consisting of Ni and the remainder of unavoidable impurities, and has excellent high temperature hardness, thermal shock resistance, and lead oxide corrosion resistance. However, when it contains Fe, the thermal shock resistance is further improved, and when it contains Mo, the high-temperature hardness is further improved.It is especially suitable for overlay welding of engine valves and valve seats of internal combustion engines, and for casting. It is a Ni-based alloy that exhibits excellent performance when used.

Next, the reason why the composition range of the Ni-based alloy of the present invention is limited as described above will be explained.

[a) C The C component has the effect of forming carbides with Cr, W, Mo, etc. to improve hardness at room temperature and high temperature, but if its content is less than 1.0%, the desired effect is not achieved. However, if the content exceeds 3.5%, the thermal shock resistance will decrease, so the content should be reduced to 1.0%.
It was set at ~3.5%.

[b'Si] In order to ensure the desired deoxidizing effect, castability, overlay workability, and melt flowability, a minimum content of 0.1% is required, while a content exceeding 2.0% is required. Since further improvement effects cannot be expected even if the content is reduced to 0.1 to 2
．． It was set as 0%.

[c} The MnMn component has a deoxidizing and desulfurizing effect as well as an effect of improving overlay workability, but its content is 0.1
If it is less than 2.%, the desired effect cannot be obtained.
Since further improvement effects cannot be expected even if the content exceeds 0%, the content was set at 0.1 to 2.0%.

[d} The VV W component has the effect of forming carbides and solid solution strengthening of the base material, thereby improving the high-temperature hardness and high-temperature strength of the alloy, but if its content is less than 5%, the above-mentioned However, if the content is less than 5%, the desired effect cannot be obtained, while if the content exceeds 20%, overlay weldability and machinability will deteriorate.
Its content was set at 5-20%.

(e} Cr The Cr component has the effect of solid-solution strengthening the base material and improving high-temperature hardness and oxidation resistance.

However, if the content is less than 20%, the desired effect cannot be ensured, so it is necessary to contain more than 20%, but if the content exceeds 40%, it will become like arms, so if the content exceeds 40%, Don't let it happen. 'f - The FeFe component has the effect of further improving the thermal shock resistance of the alloy, but if its content is less than 1%, the desired effect cannot be obtained; on the other hand, if it is contained in excess of 30%, Since the high-temperature hardness decreases and it becomes impossible to maintain a Vickers hardness of 285 or higher at 800 o'clock, the content is set at 1 to 30%.

'g}The MoMo component has the effect of further improving the high-temperature hardness of the alloy, but if its content is less than 2%, the desired effect cannot be obtained; on the other hand, if it is contained in an amount exceeding 9%. The content was determined to be 2 to 9% because the quality of the sea bream deteriorates.

Next, the Ni-based alloy of the present invention will be explained using examples.

First, by a normal melting and casting method, the alloy welding rods 1 to 1 of the present invention were
Comparative alloy welds 1 to 8 whose 18-component compositions were outside the scope of the present invention, and conventional alloy welds 1 to 2 whose compositions corresponded to the above-mentioned subordinate Co-based alloys were manufactured, respectively.

The compositions of these welding rods are shown in Table 1. Next, using these welding rods, welded an outer diameter of 10 m on the surface of a stainless steel (SUS16) alloy with dimensions of 12 m in diameter x 2 Q m in thickness using an automatic welding machine (Q + C 2 gas per day). Gundam×
A circular bead with a width of 2 broadsides and a thickness of 5 sails was welded in one layer.

Next, regarding the annular bead on the above alloy, the Rockwell hardness (C scale) at room temperature and temperature 800
While measuring the Vickers hardness at ℃, the alloy forming the annular bead was heated to a temperature of 700 qo, held for 18 minutes, and then water-cooled repeatedly, and cracks occurred in the annular bead. A thermal shock resistance test was conducted to measure the number of operations described above, and a test piece with dimensions of 15 skins ◇/height 12 women was cut out, and a test piece was cut out at a temperature of 915 cm.
After the test piece was immersed for 1 hour in molten lead oxide heated to 40 °C, a high-temperature corrosion test (lead oxide corrosion resistance test) was conducted to measure the weight loss.

These measurement results are also shown in Table 1. As shown in Table 1, the present invention alloys 1 to 18 are the conventional alloys 1 and 2.
It has superior high-temperature hardness, thermal shock resistance, and lead oxide corrosion resistance compared to other materials, and has characteristics that easily satisfy the conditions required for engine valves and valve seats in internal combustion engines. .

Furthermore, looking at Invention Alloys 1 to 4 and Comparative Alloys 1 and 2, Comparative Alloy 1, whose C content is lower than the range of this invention, cannot obtain the desired high-temperature hardness; Comparative alloy 2, which is out of the range, exhibits only extremely low thermal shock resistance, whereas alloys 1 to 4 of the present invention all exhibit excellent properties.

Furthermore, Invention Alloys 5 to 7, in which the Cr content was varied within the range of this invention, Comparative Alloy 3, in which the Cr content was lower than the range of this invention, and Comparative Alloy 3, in which the Cr content was also higher than the range of this invention. Looking at Comparative Alloy 4-1, Comparative Alloy 3 has significantly inferior high-temperature hardness and lead oxide corrosion resistance, while Comparative Alloy 4 has inferior thermal shock resistance. It is clear that all of the alloys 5 to 7 of the present invention satisfactorily have excellent properties.

Regarding the W component, looking at Invention Alloys 8 to 10 and Comparative Alloys 5 and 6, in which the W content was varied, Comparative Alloy 5, in which the W content was lower than the range of the present invention, was hardened at high temperatures. Comparative Alloy 6, which has a higher Cr content, has significantly deteriorated thermal shock resistance, whereas Invention Alloys 8 to 1, which have a Cr content within the range of this invention,
0 indicates excellent characteristics. Similarly, F
Alloys 11 to 14 of the present invention in which the content of e was varied within the range of the present invention, and alloys 11 to 14 in which the content of Fe was varied within the range of the present invention, and
As is clear from the results shown for Comparative Alloy 7, as the Fe content increases, the thermal shock resistance further improves in proportion to this, but when Fe content exceeds 30%, It can be seen that the high-temperature hardness and lead oxide corrosion resistance are significantly reduced.

Similarly, from the results shown for Invention Alloys 15 to 17, in which the Mo content was varied within the range of this invention, and Comparative Alloy 8, whose Mo content was higher than the range of this invention, it was found that M
As o increases, the high-temperature hardness will further improve in proportion to this, but if the amount of M exceeds 9%,
It can be seen that when o is contained, thermal shock resistance and lead oxide corrosion resistance are reduced.

Inventive alloy 18 containing Fe and Mo has also been shown to have further improved high temperature hardness and thermal shock resistance.

In addition, in the above example, a case was described in which the Ni-based alloy of the present invention was used for overlay welding, but even when used for casting, it exhibits the same excellent characteristics as for overlay welding. Of course.

As mentioned above, the Ni-based alloy of the present invention has excellent high-temperature hardness, thermal shock resistance, and lead oxide corrosion resistance, so it is suitable for internal combustion engines, especially internal combustion engines that use leaded gasoline. It is suitable for use in overlay welding and casting of valves and valve seats.

Claims (1)

[Claims] 1 C: 1.0 to 3.5%, Si: 0.1 to 2.0%,
Mn: 0.1-2.0%, W: 5-20%, Cr: 20
~40%, Ni and unavoidable impurities: remaining (more than 40% by weight)
) A Ni-based alloy for use in engine valves and valve seats of internal combustion engines, which has excellent high-temperature hardness, thermal shock resistance, and lead oxide corrosion resistance. 2C: 1.0-3.5%, Si: 0.1-2.0%,
Mn: 0.1-2.0%, W: 5-20%, Cr: 20
-40%, Fe: 1-30%, Ni and unavoidable impurities: the balance (or more by weight) Internal combustion with excellent high-temperature hardness, thermal shock resistance, and lead oxide corrosion resistance. Ni-based alloy for engine valves and valve seats. 3C: 1.0-3.5%, Si: 0.1-2.0%,
Mn: 0.1-2.0%, W: 5-20%, Cr: 20
~40%, Mo: 2-9%, Ni and inevitable impurities:
A Ni-based alloy for use in engine valves and valve seats of internal combustion engines, which has a composition consisting of the remainder (more than % by weight), and has excellent high-temperature hardness, thermal shock resistance, and lead oxide corrosion resistance. 4C: 1.0-3.5%, Si: 0.1-2.0%,
Mn: 0.1-2.0%, W: 5-20%, Cr: 20
-40%, Fe: 1-30%, Mo: 2-9%, Ni and unavoidable impurities: the remainder (more than weight %) High-temperature hardness, thermal shock resistance, and oxidation resistance Ni-based alloy for internal combustion engine engine valves and valve seats with excellent lead corrosion resistance.