JPS6151625B2 - - Google Patents
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- Publication number
- JPS6151625B2 JPS6151625B2 JP57086826A JP8682682A JPS6151625B2 JP S6151625 B2 JPS6151625 B2 JP S6151625B2 JP 57086826 A JP57086826 A JP 57086826A JP 8682682 A JP8682682 A JP 8682682A JP S6151625 B2 JPS6151625 B2 JP S6151625B2
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- JP
- Japan
- Prior art keywords
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- heat
- Prior art date
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- 229910001208 Crucible steel Inorganic materials 0.000 claims description 9
- 229910052726 zirconium Inorganic materials 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 2
- 239000000463 material Substances 0.000 description 27
- 230000000694 effects Effects 0.000 description 8
- 239000000523 sample Substances 0.000 description 8
- 230000032683 aging Effects 0.000 description 6
- 239000011651 chromium Substances 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- UFGZSIPAQKLCGR-UHFFFAOYSA-N chromium carbide Chemical compound [Cr]#C[Cr]C#[Cr] UFGZSIPAQKLCGR-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 229910003470 tongbaite Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Turbine Rotor Nozzle Sealing (AREA)
Description
本発明は耐熱鋳鋼に関する。
従来、高温用材料としてJIS SCH13（25％Cr
−12％Ni）、SCH22（25％Cr−20％Ni）などが各
種用途に多用されている。
しかしながら、上記従来材を600〜1000℃の高
温域で使用すると、その顕微鏡組織はマトリツク
スに多量の二次炭化物が析出した組織となるの
で、室温にもどすと延性が著しく劣化する。従つ
て、高温域と低温域とに繰返し加熱・冷却される
使用条件下では、熱疲労により割れが発生し易
く、割の進展も容易なため、早期に破損に到ると
いう問題がある。
本発明は、上期問題を解消したものであり、高
温時効延性や高温クリープ破断強度のほか、熱疲
労に対する耐久性にすぐれた耐熱鋳鋼を提供す
る。
本発明耐熱鋳鋼は、C0.2〜0.5％（重量％、以
下同じ）、Si1.5％以下、Mn1.5％以下、Cr22〜28
％、Ni10〜16％、Nb0.5〜2.0％、および、Ｂ、
Ti、Zrから選ばれる２種または３種の元素を、
それらの合計量が0.2％を超えない範囲内で、そ
れぞれ0.01％以上含有し、残部実質的にFeから
なる。また、必要に応じ、Ｎ含有量が0.05％以下
に規制された鋼組成を有する。以下、本発明耐熱
鋳鋼の成分限定理由を説明する。
Ｃ：0.2〜0.5％
Ｃは高温クリープ破断強度を高める。含有量が
0.2％に満たないと、その効果が十分でなく、ま
た高温使用中にσ相が析出し易く脆化を招くので
0.2％以上とする。しかし、含有量が多くなる
と、クロム炭化物の多量の析出により延性および
熱疲労に対する耐久性の低下が顕著になるので、
0.5％を上限とする。
Si：1.5％以下
Siは脱酸剤として、また鋳造性を確保するため
の元素として必要であるが、1.5％をこえると高
温使用中にσ相が現出し易く、組織が不安定とな
る。よつて1.5％以下とする。
Mn：1.5％以下
MnはSiと同様に脱酸および鋳造性確保に必要
な元素であるが、1.5％をこえると、高温強度の
低下をきたすので、1.5％を上限とする。
Cr：22〜28％
Crは高温での耐酸化性を確保するのに必要な
元素である。含有量が22％に満たないとその効果
が不足する。含有量の増加とともに効果も増す
が、多量の含有はCr炭化物の晶出および析出量
の増大とそれに伴う脆化が著しくなるので、28％
を上限とする。
Ni：10〜16％
Niは高温強度の確保に必要である。含有量が
10％に満たないと、高温強度が不足し、また高温
使用中でのσ相が現出し易く、脆化を引起す。含
有量を増すとともに効果も増大するが、16％をこ
えると、高温破断強度改善効果や延性低下防止効
果はほゞ飽和に達するので、それ以上の含有は不
経済である。よつて16％を上限とする。
Nb：0.5〜2.0％
Nbは高温使用中におけるクロム系二次炭化物
の析出を防止するのに有効な元素である。0.5％
未満ではその効果が不足する。一方、2.0％をこ
えると、σ相の現出が助長され、却つて延性劣化
をきたす。よつて0.5〜2.0％とする。
Ｂ、TiおよびZr：0.01〜0.2％
Ｂ、TiおよびZrはいづれも高温強度、特に熱
衝撃抵抗の向上にすぐれた効果を有する。これら
の元素は、それぞれ0.01％を下限値としてその２
種または３種が同時に添加される。２種以上の元
素を同時に添加した場合、同じ添加量を１種の元
素だけでまかなう場合に比し、より大きな添加効
果が奏される。特に３種の元素を複合含有すると
き、高温強度、熱衝撃抵抗は顕著に向上する。
たゞし、含有量が過度に多くなると、Ｂの場合
は、著しい延性低下と溶接性劣化をきたし、Ti
およびZrの場合は、溶湯が酸化され、鋳造時に多
量の酸化物が混入するほか、溶湯の流動性が悪化
し鋳造が困難となる。よつて、上記２種または３
種の元素の含有量の上限を0.2％とする。
本発明耐熱鋳鋼は、通常の溶解法により溶製さ
れた場合、0.08％程度までのＮを含有しているの
が一般である。その程度の含有量であれば、本発
明の趣旨が損なわれることはないが、特に0.05％
以下に抑制すると、熱疲労に対する抵抗性が顕著
に向上する。よつて、Ｎ含有量は好ましくは0.05
％以下とする。
なおＰ、Ｓその他の不純物は従来材の
SCH13、22など、この種の鋼に許容される通常
の範囲内であればよい。
次に本発明耐熱鋳鋼の材料特性を実施例により
具体的に説明する。
実施例
第１表に示す各成分組成の供試材を溶製し、そ
れぞれについて室温引張特性、高温クリープ破断
強度および熱疲労に対する耐久性を測定した。供
試材No.1〜12は本発明材、No.101〜109は比較材
（No.102：SCH13相当、No.103：SCH22相当）で
ある。
各試験法および結果は次のとおりである。
室温引張特性：
各供試材の鋳放し材と800℃×1000時間の時効
処理材とにつき、室温における引張強さ、0.2％
耐力および伸びを測定し、第２表に示す結果を得
た。表中、「ａ」欄は鋳放し材、「ｂ」欄は時効処
理材である。各供試材の伸びを比較すると、比較
材No.101、No.102（SCH13）、No.103（SCH22）
は鋳放し材(a)の伸び29.5％、23.3％および21.6％
が、時効処理後(b)ではそれぞれ17.6％、10.9％、
7.0％に激減しているのに対し、本発明No.1〜12
は時効処理後も大きな低下はなく、少くとも22％
をこえる伸びを有する。すなわち、本発明材は高
温時効延性にすぐれている。なお、本発明材の引
張強さ、0.2％耐力は従来材のSCH13（No.102）、
SCH22（No.103）と同等もしくはそれ以上であ
り、強度についても何ら問題ないことがわかる。
クリープ破断強度：
各供試材について、(i)温度871℃・荷重6.8Kg/
mm2、および(ii)温度871℃・荷重4.5Kg/mm2における
クリープ破断試験結果（クリープ破断時間）を第
３表に示す。本発明材No.1〜12は従来材である
SCH13（供試No.102）やSCH22（供試No.103）
等に比し格段にすぐれていることがわかる。特
に、Ｂ、TiおよびZrを複合含有する供試材
No.4、８および11はよりすぐれたクリープ破断
強度を有する。
耐熱疲労強度：
各供試材につき、第１図に示す形状に調製した
偏心リング状試験片（外径Ｄ：50mm、内径ｄ：25
mm、Ｒ：３mm、厚さＴ：10mm）を使用し、「温度
950℃×30分の加熱後水冷」の加熱・冷却を繰返
す熱処理に付し、その試験片に発生した割れが５
mmの長さに成長するまでの繰返し回数を測定し
た。その結果を第４表に示す（表中の値は平均値
である）。比較材No.101、No.102（SCH13）、
No.103（SCH22）の平均繰返し回数はそれぞれ
650、270、170であるのに対し、本発明材No.1〜
12の平均繰返し回数は870回以上に達し、従来材
に比し熱疲労に対する耐久性にすぐれている。ま
た、本発明材のうち、Ｂ、TiおよびZrを複合含
有する供試材No.4、No.8およびNo.11は特に耐熱
疲労強度が高い。なお、本発明材No.1〜12のう
ち、No.1〜４はＮ含有量が0.05％をこえるもの、
No.5〜12はＮ含有量が0.05％以下に規制されたも
のである。両グループの特性を比較すると、時効
後の伸び（第２表）、クリープ破断強度（第３
表）にはそれほどの差異はないが、第４表に示さ
れるように、Ｎ含有量0.05％以下の規制により、
耐熱疲労強度のレベルが向上することがわかる。
The present invention relates to heat-resistant cast steel. Conventionally, JIS SCH13 (25% Cr
-12%Ni), SCH22 (25%Cr-20%Ni), etc. are widely used for various purposes. However, when the above-mentioned conventional material is used in a high temperature range of 600 to 1000°C, its microscopic structure becomes a structure in which a large amount of secondary carbide is precipitated in the matrix, so that when the material is returned to room temperature, the ductility deteriorates significantly. Therefore, under usage conditions in which heating and cooling are repeated in high temperature and low temperature ranges, cracks are likely to occur due to thermal fatigue and cracks can easily develop, leading to early failure. The present invention solves the problems in the first half, and provides a heat-resistant cast steel that has excellent high-temperature aging ductility, high-temperature creep rupture strength, and durability against thermal fatigue. The heat-resistant cast steel of the present invention has C0.2-0.5% (weight%, same below), Si1.5% or less, Mn1.5% or less, Cr22-28
%, Ni10-16%, Nb0.5-2.0%, and B,
Two or three elements selected from Ti and Zr,
Each of them is contained in an amount of 0.01% or more within a range in which the total amount thereof does not exceed 0.2%, and the remainder substantially consists of Fe. In addition, if necessary, the steel composition has a N content regulated to 0.05% or less. The reasons for limiting the components of the heat-resistant cast steel of the present invention will be explained below. C: 0.2 to 0.5% C increases high temperature creep rupture strength. The content is
If it is less than 0.2%, the effect will not be sufficient and the σ phase will easily precipitate during high temperature use, leading to embrittlement.
Must be 0.2% or more. However, as the content increases, a large amount of chromium carbide precipitates, resulting in a noticeable decrease in ductility and durability against thermal fatigue.
The upper limit is 0.5%. Si: 1.5% or less Si is necessary as a deoxidizing agent and as an element to ensure castability, but if it exceeds 1.5%, the σ phase tends to appear during high temperature use and the structure becomes unstable. Therefore, it should be 1.5% or less. Mn: 1.5% or less Mn, like Si, is an element necessary for deoxidation and ensuring castability, but if it exceeds 1.5%, high temperature strength decreases, so 1.5% is the upper limit. Cr: 22-28% Cr is an element necessary to ensure oxidation resistance at high temperatures. If the content is less than 22%, the effect will be insufficient. The effect increases as the content increases, but if the content is large, the crystallization and precipitation of Cr carbides will increase, and the resulting embrittlement will become significant, so 28%
is the upper limit. Ni: 10-16% Ni is necessary to ensure high temperature strength. The content is
If it is less than 10%, high-temperature strength is insufficient, and the σ phase tends to appear during high-temperature use, causing embrittlement. The effect increases as the content increases, but if it exceeds 16%, the effect of improving high-temperature fracture strength and preventing a decrease in ductility reach almost saturation, so it is uneconomical to contain more than that. Therefore, the upper limit is 16%. Nb: 0.5-2.0% Nb is an element effective in preventing precipitation of chromium-based secondary carbides during high-temperature use. 0.5%
If it is less than that, the effect will be insufficient. On the other hand, if it exceeds 2.0%, the appearance of the σ phase will be promoted and the ductility will deteriorate. Therefore, it should be 0.5 to 2.0%. B, Ti and Zr: 0.01 to 0.2% B, Ti and Zr all have excellent effects on improving high temperature strength, especially thermal shock resistance. Each of these elements has a lower limit of 0.01%.
The species or three species are added at the same time. When two or more types of elements are added at the same time, a greater effect of addition is achieved than when the same amount of addition is covered by only one type of element. In particular, when three types of elements are contained in combination, high temperature strength and thermal shock resistance are significantly improved.
However, if the content of B becomes excessively high, the ductility and weldability deteriorate significantly in the case of B;
In the case of Zr, the molten metal is oxidized and a large amount of oxides are mixed in during casting, and the fluidity of the molten metal deteriorates, making casting difficult. Therefore, the above 2 or 3
The upper limit of the content of seed elements is set at 0.2%. The heat-resistant cast steel of the present invention generally contains up to about 0.08% N when it is produced by a normal melting method. If the content is at that level, the purpose of the present invention will not be impaired, but in particular, 0.05%
When suppressed to below, resistance to thermal fatigue is significantly improved. Therefore, the N content is preferably 0.05
% or less. Note that P, S and other impurities are in the conventional material.
It may be within the normal range allowed for this type of steel, such as SCH13, 22. Next, the material properties of the heat-resistant cast steel of the present invention will be specifically explained using examples. Examples Test materials having the respective component compositions shown in Table 1 were melted and their room temperature tensile properties, high temperature creep rupture strength, and durability against thermal fatigue were measured. Sample materials No. 1 to 12 are materials of the present invention, and No. 101 to 109 are comparative materials (No. 102: equivalent to SCH13, No. 103: equivalent to SCH22). The test methods and results are as follows. Room temperature tensile properties: Tensile strength at room temperature of 0.2% for each sample material, as-cast material and aged material aged at 800℃ x 1000 hours.
The yield strength and elongation were measured and the results shown in Table 2 were obtained. In the table, the "a" column is the as-cast material, and the "b" column is the aged material. Comparing the elongation of each sample material, comparison materials No. 101, No. 102 (SCH13), and No. 103 (SCH22)
are the elongations of as-cast material (a) 29.5%, 23.3% and 21.6%
However, after the aging process (b), the percentages are 17.6%, 10.9%, respectively.
In contrast, the invention Nos. 1 to 12 decreased sharply to 7.0%.
does not significantly decrease after aging, at least 22%
It has an elongation exceeding . That is, the material of the present invention has excellent high temperature aging ductility. In addition, the tensile strength and 0.2% proof stress of the present invention material are the conventional material SCH13 (No. 102),
It can be seen that it is equivalent to or better than SCH22 (No. 103), and there is no problem in terms of strength. Creep rupture strength: For each sample material: (i) Temperature: 871℃・Load: 6.8Kg/
mm 2 , and (ii) creep rupture test results (creep rupture time) at a temperature of 871° C. and a load of 4.5 Kg/mm 2 are shown in Table 3. Inventive materials No. 1 to 12 are conventional materials
SCH13 (sample No. 102) and SCH22 (sample No. 103)
It can be seen that this is significantly superior to the others. In particular, test materials containing composites of B, Ti, and Zr
Nos. 4, 8 and 11 have better creep rupture strength. Heat resistance fatigue strength: For each sample material, eccentric ring-shaped test pieces prepared in the shape shown in Figure 1 (outer diameter D: 50 mm, inner diameter d: 25
mm, R: 3 mm, thickness T: 10 mm), and
After repeated heat treatment of 950℃ x 30 minutes of heating followed by water cooling, the cracks that occurred in the test piece were
The number of repetitions until it grew to a length of mm was measured. The results are shown in Table 4 (the values in the table are average values). Comparison material No.101, No.102 (SCH13),
The average number of repetitions for No.103 (SCH22) is
650, 270, and 170, whereas the present invention material No. 1~
The average number of repetitions for 12 has reached over 870 times, and it has superior durability against thermal fatigue compared to conventional materials. Furthermore, among the materials of the present invention, test materials No. 4, No. 8, and No. 11 containing a composite of B, Ti, and Zr have particularly high thermal fatigue strength. In addition, among the present invention materials No. 1 to 12, No. 1 to 4 have N content exceeding 0.05%,
Nos. 5 to 12 have N content regulated to 0.05% or less. Comparing the properties of both groups, the elongation after aging (Table 2) and creep rupture strength (Table 3)
Table) There is not much difference, but as shown in Table 4, due to the regulation of N content of 0.05% or less,
It can be seen that the level of thermal fatigue strength is improved.
【表】【table】
【表】【table】
【表】【table】
【表】
以上のように、本発明の耐熱鋳鋼は、高温時効
後の延性や高温クリープ破断強度が高く、しかも
耐熱疲労強度にすぐれるので、常温と高温との間
において繰返し加熱・冷却をうけても容易に劣化
することがなく、そのような苛酷な使用条件下に
用いられる各種装置材料、例えば熱処理用ポツ
ト、トレイ、あるいは熱処理用ハースローラなど
に好適であり、従来材であるSCH13やSCH22等
を凌駕する耐久性が得られる。[Table] As described above, the heat-resistant cast steel of the present invention has high ductility and high-temperature creep rupture strength after high-temperature aging, and also has excellent thermal fatigue strength, so it can be repeatedly heated and cooled between room temperature and high temperature. It is suitable for various equipment materials used under such harsh usage conditions, such as heat treatment pots, trays, and heat treatment hearth rollers. Provides durability that surpasses that of
第１図は供試材試験片の形状の平面説明図、
同図は正面説明図である。
Figure 1 is an explanatory plan view of the shape of the sample material test piece;
This figure is a front explanatory view.
Claims (1)
以下、Mn1.5％以下、Cr22〜28％、Ni10〜16％、
Nb0.5〜2.0％、およびＢ、Ti、Zrから選ばれる２
種または３種の元素を各々0.01％以上、合計量
0.2％以下含有し、残部実質的にFeからなる耐熱
鋳鋼。 ２ 不可避的不純物成分であるＮ含有量が0.05％
以下であることを特徴とする上記第１項に記載の
耐熱鋳鋼。[Claims] 1 C0.2 to 0.5% (weight%, same hereinafter), Si1.5%
Below, Mn1.5% or less, Cr22~28%, Ni10~16%,
Nb0.5~2.0% and 2 selected from B, Ti, and Zr
0.01% or more of each of the species or three elements, total amount
Heat-resistant cast steel containing 0.2% or less, with the remainder essentially consisting of Fe. 2 N content, an unavoidable impurity component, is 0.05%
The heat-resistant cast steel according to item 1 above, which is as follows.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8682682A JPS58204162A (en) | 1982-05-21 | 1982-05-21 | Heat-resistant cast steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8682682A JPS58204162A (en) | 1982-05-21 | 1982-05-21 | Heat-resistant cast steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58204162A JPS58204162A (en) | 1983-11-28 |
| JPS6151625B2 true JPS6151625B2 (en) | 1986-11-10 |
Family
ID=13897611
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8682682A Granted JPS58204162A (en) | 1982-05-21 | 1982-05-21 | Heat-resistant cast steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58204162A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4923454A (en) * | 1972-06-27 | 1974-03-01 | ||
| JPS5743967A (en) * | 1980-08-30 | 1982-03-12 | Nachi Fujikoshi Corp | Heat resistant cast steel with excellent heat shock fatigue resistance |
-
1982
- 1982-05-21 JP JP8682682A patent/JPS58204162A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4923454A (en) * | 1972-06-27 | 1974-03-01 | ||
| JPS5743967A (en) * | 1980-08-30 | 1982-03-12 | Nachi Fujikoshi Corp | Heat resistant cast steel with excellent heat shock fatigue resistance |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58204162A (en) | 1983-11-28 |
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