JPS59153872A - Fe-cr-ni alloy with high toughness for valve and valve seat of internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the hardness of the resulting titled alloy at high temp. as well as the thermal shock resistance and the resistance to corrosion due to lead oxide by providing a specified composition consisting of C, Si, Mn, Cr, Ni, W, Mo, Ti, Al and the balance essentially Fe. CONSTITUTION:This Fe-Cr-Ni alloy with high toughness for the valves and valve seats of an internal-combustion engine has a composition consisting of, by weight, 0.65-2.5% C, 0.1-3% Si, 0.1-2% Mn, 25-37% Cr, 7-<25% Ni, 0.1- 15% W, 0.1-10% Mo, 0.01-4.5% Ti, 0.01-4.5% Al and the balance essentially Fe. 1-10% Co and/or 0.01-1.5% each of Nb and/or B may be substituted for part of Fe.

Description

[Detailed description of the invention] This invention has excellent high temperature hardness and thermal shock resistance.

and high toughness Fe - which has lead oxide corrosivity and is suitable for use in casting or overlay welding in the production of engine valves and valve seats for internal combustion engines that particularly require these characteristics. This relates to an Or-Ni alloy.

Conventionally, when manufacturing engine valves and valve seats for internal combustion engines, American Welding Society standard 5.13 RCoCr-A (C: 0.9 to 1.4) was used for overlay welding.
%, Sj,: 2.0% or less, Mn: 1.0% or less,
W: 3.0-6.0%, Or: 26-32%, N
i: 3.0% or less, Fe: 30% or less, Mo: 1.0
% or less, Co and unavoidable impurities: remainder), and 5.
13 ROoOr-B (c: 1.2-1.7%,
Si: 2.0% or less, Mn: 1.0% or less, V/
: 7.0~9.5%, Cr: 26~32%,
Ni, 30% or less, Fe: 3.0% or less, Mo: 1.
0'1 or less.

Co and inevitable impurities: remaining 1 or more type @%), etc.
O-based alloys (hereinafter referred to as CO-based alloys) have been widely used.

On the other hand, in recent years, as the performance of internal combustion engines has been improved, the engine valve and valve seats of internal combustion engines are also required to have all the excellent characteristics. In particular, when high toughness is required, the Vickers hardness at a temperature of near 00℃ is 310 or higher in the overlay welding state, and after being held at a temperature of 2600℃ for 15 minutes, When the water cooling operation is repeated, cracks occur in the overlay weld.
It is now required that the lead oxide corrosion resistance shows a weight loss of 0.09 j/i/hr or less after being immersed for one hour in a molten oxidation vessel heated to 0°C. It goes without saying that a word having these characteristics is 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 all of 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 lead oxide corrosion resistance. The current situation is that the conventional CO-based alloy does not have a sufficiently satisfactory service life when used for full overlay welding or for casting in the production of engine valves and valve seats for high-performance engines that require toughness. It is.

Therefore, from the above-mentioned viewpoint, the present inventors have developed the high-temperature hardness and heat shock resistance required for engine valves and valve seats for internal combustion engines, especially high-performance engines that require high toughness. , and lead oxide corrosion resistance, and as a result of research to develop a material that can be used for overlay welding and casting, we found that O: 0.65 to 2.5, Si: 0. .1-3%, Mn: 0.1-2%, Cr
: 25-37%, Ni: 7-25%, 1 to 3.
W: 0.1~15%, Mo: 0.1~IO section,
Ti: 0.01-45, All: 0.01-4
Co: 1 to 10%, if necessary.
.

Nb: 0.01-1.5%, and B: 0.01-1.
Contains one or more of the five elements, and the rest is Fe.
F having a composition C or higher (weight ratio) consisting of unavoidable impurities
The e -Or -Ni alloy has an extremely high high temperature hardness with a Vickers hardness of 320 or higher at a temperature of near 00°C, and is also susceptible to thermal shock, with one cycle of heating to 600°C for 15 minutes followed by water cooling. In the test, it showed excellent thermal shock resistance with a cycle count of 18 or more times until cracking occurred, and it also showed VC1 in molten lead oxide heated to a temperature of 920°C.
In the time immersion lead oxide corrosion test, the weight loss was 0.051 f.
It exhibits excellent lead oxide corrosion resistance of i'/7/hr or less, and can be used for overlay welding and casting. They found that when used in the production of barbunto, it exhibits excellent performance over an extremely long period of time.

This invention has been made based on the findings described in Section 2, and the reason why the composition of all components is limited to the above-mentioned one will be explained below.

(a) CC components include Cr, W, Mo, Ti, and N
1), etc., to form a carbide, which has the effect of improving the hardness at both room temperature and high temperature, but its content is o, 65%
If it is less than 2, the desired high hardness cannot be secured;
．． If the content exceeds 5% 'i, the thermal shock resistance will deteriorate, so the content @k0.65~25
The person in charge was appointed as the person in charge.

(b) S= In order to ensure the desired deoxidizing effect, castability, build-up weldability, and melt flowability, a minimum content of 0.1% is required;
On the other hand, since a further improvement effect cannot be expected even if the content exceeds 30 parts, the content was set at 0.1 to 3.0 parts.

In addition, since the S1 component has a deoxidizing effect as mentioned above, when it is used as a deoxidizing agent, it may be contained as an unavoidable impurity in a range of less than 0.1 part. In such cases, the total content, including the content of unavoidable impurities, may be set to 01 or higher.

(C) Mn In addition to deoxidizing and desulfurizing, the Mn component has the effect of improving overlay weldability, but if its content is less than 0.1%, the desired effect cannot be obtained, On the other hand, even if the content exceeds 2.0%, no further white-ball effect will be produced due to the above-mentioned action, so the content was set at 0.1 to 20%.

- Also, since the Mn component has a deoxidizing and desulfurizing effect as mentioned above, when it is used as a deoxidizing and desulfurizing agent, U
Like the Si component, it may be contained as an unavoidable impurity in a range of less than 0.1%, but in this case as well, the components should be adjusted so that the total content, including the unavoidable impurity content, is 01 coefficient or higher. .

(d) A part of the CrOr acid component dissolves in the base material, and the remaining part forms a carbide, which particularly improves high-temperature hardness and high-temperature wear resistance, as well as lead oxidation resistance. It has the effect of improving the overall corrosion resistance, but if the content is less than 25eI, the desired effect cannot be obtained, while if the content exceeds 37eI, the thermal shock resistance tends to decrease. Therefore, the content was determined to be between 25 and 37.

(e) Ni The N1 component has the effect of stabilizing the austenite base and improving its thermal shock resistance and toughness, as well as improving its resistance to lead oxide corrosion when coexisting with Or. If the content is less than 25%, the desired effect cannot be obtained; on the other hand, if the content is more than 25%, the toughness tends to decrease and it becomes difficult to ensure high toughness. It was set at ~25%.

(f) W The W component not only refines the carbide, but also forms carbide itself and dissolves in the matrix to strengthen fL, thereby improving the high-temperature hardness and high-temperature strength of the alloy. However, if the content exceeds 111 to 0.1, the desired effect cannot be obtained, while if the content exceeds 154, the overlay weldability and machinability will deteriorate. Therefore, its content was determined to be 0.1 to 15%.

<g> M.

In the coexistence with MO acid components H and w, it forms a solid solution in the substrate,
It has the effect of strengthening this and forming carbides to improve the high-temperature hardness, high-temperature wear resistance and high-temperature strength of the alloy, but if the content is less than 0.1%, the desired effect cannot be obtained. On the other hand, if the content exceeds 10%, the thermal shock resistance and toughness will deteriorate as in the case of the W component, so the content 'ft: '0.1 to 10
The person in charge was appointed as the person in charge.

(h) Ti The T1 component not only suppresses the growth of crystal grains in the base material, but also refines the crystal grains and forms MO-type carbides and nitrides, resulting in high-temperature hardness and thermal shock. sex,
Furthermore, it has the effect of improving high temperature strength and toughness,
If the content is less than 0.014, the desired effect cannot be obtained; on the other hand, if the content exceeds 45, the amount of carbide becomes too large, resulting in deterioration of thermal shock resistance and toughness. , Since a tendency of deterioration also appears in the lead oxide corrosivity, the content i0.01 ~
It was set at 4.5%.

(1) The M component, along with Or, has the effect of improving lead oxide corrosion resistance and improving thermal shock resistance and high-temperature strength, but if its content is less than 0.01%, the desired effect may not be achieved. On the other hand, if the content exceeds 4.5%, not only will the fluidity and castability of the molten metal decrease;
Since weldability and toughness also decrease and it becomes impractical, its content was set at 0.01 to 4.5%.

(j) C.

The co-acid component dissolves in the base material to further improve thermal shock resistance and toughness, and also has the effect of improving high-temperature hardness (high-temperature hardness and high-temperature wear resistance), so it is necessary when these properties are further required. It is contained according to the amount of 1q
If it is less than b, the desired effect cannot be obtained,
On the other hand, even if the content exceeds 1.0, no further improvement effect can be obtained, and in consideration of economic efficiency, the content should be increased from 1 to 10.
The person in charge was appointed as the person in charge.

(k) Nb and B These components have the effect of further improving high-temperature hardness, high-temperature wear resistance) and high-temperature strength, so they can be used as necessary when these properties are required. However, if the content is less than 0.01%, the desired effect of improving the above effects cannot be obtained, while if the content exceeds 1.5%, the thermal shock resistance deteriorates. In addition, the toughness and weldability also decrease, so the Nb content was reduced to 0.01 to 1.5%, respectively.
, B: 0.01 to 1.5%.

Next, the Fe-Cr-Ni alloy of the present invention will be specifically explained by comparing examples and comparative examples.

Examples Alloys 1 to 28 of the present invention having the compositions shown in Table 1 were prepared by a conventional melting method. Comparative Alloys 1 to 10 and Conventional Alloy 1.2'ff having a composition corresponding to the conventional CO-based alloy described above: By melting and subsequently continuous casting under normal conditions, diameter: 4. A welding rod of 8wnφ was molded. It should be noted that Comparative Alloys 1-10 all have compositions in which the content of one of the constituent components (those marked with * in Table 1) is outside the scope of the present invention.

Next, the resulting alloys of the present invention 1 to 28° and comparative alloys 1 to 10. And using conventional alloy 1 and 2 welding rods, welded with T-G automatic welding machine, diameter: 120mmφ x thickness:
On the surface of a stainless steel (5US316) base metal with dimensions of 20 holes, outer diameter: 100 mm x width: 20 mm x thickness: 5 mm.
The working annular bead was welded in two layers.

Subsequently, the annular bead formed on the base metal was measured for Rockwell hardness C scale at room temperature and Vickers hardness at near 00°C, and the annular bead was measured for the alloy formed entirely. ,temperature:
A thermal shock resistance test was conducted in which the operation of heating to 600° C., holding for 15 minutes, and then cooling with water was repeated for one cycle, and the number of cycles at which cracks occurred in the annular bead was measured. Furthermore, a piece of stainless steel (SUS3
16) Two-layer overlay welding with a thickness of 5 mm was performed on one end face of the steel piece, and a test piece with dimensions of diameter: 12rrrmφ x thickness: 12# was cut out from the overlay part of this steel piece. Using this test piece, a lead oxide corrosion resistance test was conducted by immersing it in 40 g of molten lead oxide heated to a temperature of 920°C for 1 hour, and the total weight loss of the built-up part after the test was measured.These measurements were performed. Results first
Shown in the table.

From the results shown in Table 1, the present invention alloys 1 to 28 all have superior high-temperature hardness, plane 1 thermal shock resistance, and lead oxide corrosion resistance compared to conventional alloy 1.2. is clear. On the other hand, Comparison N] Base alloys 1 to 10
As seen in the above, if the content of any one of the constituent components falls outside the range of the present invention, at least one of the above properties may be inferior to that of the alloy of the present invention. it is obvious.

In addition, in the above example, Fe-Cr-N of this invention
Although the case where the i-series alloy is used for full overlay welding has been described, it goes without saying that even when used for casting, it exhibits excellent properties similar to those for overlay welding.

As mentioned above, the Fe-Cr-Ni alloy of the present invention is
In particular, it has excellent high-temperature hardness, thermal shock resistance, and lead oxide corrosion resistance that satisfies the above-mentioned strict conditions required for engine valves and valve seats for high-performance engines that require particularly high toughness. Therefore, when used for overlay welding and casting in the production of these parts, the resulting parts will exhibit excellent performance over an extremely long period of time.

Applicant: Mitsubishi Metals Corporation Agent Tomi 1) Kazuo and 1 other person

Claims (4)

[Claims] (1) c: 0.65-2.5 ratio. Si: 0.1-3%, Mn: 0.1-2%, Or: 25-37%, Ni minial 25%. W: 01-15%, Mo: 0.1-10. Internal combustion characterized by having a composition (hereinafter referred to as "dual weight %") containing Ti: 0.01 to 4.5%, M: 0.01 to 4.5%, and the remainder consisting of Fe and unavoidable impurities. High toughness Fe-Cr for engine valves and valve seats
-Ni alloy. (2) C: 0.65-2.5%, Si: 0.
1 to 3%, Mn: 0.1 to 2%, Cr: 25 to 37%, N11 near to 25%, W: 0.1 to 15%. Mo: 0.1-10%. Ti: 0.01 to 45%, M: o, oi to 4.5%, CQ: 1 to 10%, and the remainder is Fe and unavoidable impurities. ) High toughness Fe-Or for engine valves and valve seats of internal combustion engines characterized by containing
-Ni alloy. (3) C: 0.65 to 2.5. Si: 0.1-3%. Mn: O, 1-2%, Cr: 25-37%, Ni minal less than 2%, W: 01-15%, Mo: 0.1-10%. Ti: 0.01 to 4. 5%. M: 0.01-45%, total content, further Nb: 0.01-1.5%, B: 0.01-15%. A high-toughness Fe'-Or for engine valves and valve seats of internal combustion engines, characterized by containing one or two of the following, and having a composition (the above weight %) consisting of Fe and unavoidable impurities. -Ni alloy. (4) C: 0.65-2.5, Si: 0.1
~3L Ivtn: 0.1~2%. Cr: 25-37%, N1 near-less than 25%, W: 01-15%. Contains M: 01 to 10 parts, Ti: 0.01 to 45 parts, and further contains CO: 1 to 10 parts, Nb: 0.01 to 1.5 parts, and B: 0.01 to 1. 5 ai), and an engine valve for an internal combustion engine characterized by containing one or two of the following, with the remainder consisting of Fe and inevitable impurities (hereinafter referred to as "double content"), and the same valve 7
- High toughness Fe -0r-N] alloy for use in metals.