JPS6140743B2 - - Google Patents
Info
- Publication number
- JPS6140743B2 JPS6140743B2 JP13413579A JP13413579A JPS6140743B2 JP S6140743 B2 JPS6140743 B2 JP S6140743B2 JP 13413579 A JP13413579 A JP 13413579A JP 13413579 A JP13413579 A JP 13413579A JP S6140743 B2 JPS6140743 B2 JP S6140743B2
- Authority
- JP
- Japan
- Prior art keywords
- weight
- alloy
- content
- carburization
- creep rupture
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 229910045601 alloy Inorganic materials 0.000 claims description 25
- 239000000956 alloy Substances 0.000 claims description 25
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 11
- 238000005266 casting Methods 0.000 claims description 9
- 229910052742 iron Inorganic materials 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 229910052758 niobium Inorganic materials 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 229910052721 tungsten Inorganic materials 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 229910052804 chromium Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 230000000694 effects Effects 0.000 description 13
- 238000005255 carburizing Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 229910000640 Fe alloy Inorganic materials 0.000 description 5
- 239000000654 additive Substances 0.000 description 5
- 230000000996 additive effect Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Landscapes
- Turbine Rotor Nozzle Sealing (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Description
本発明は高温における耐浸炭性およびクリープ
破断強度の優れた耐熱鋳造合金に関するものであ
り、石油化学関係等の反応装置材料として長時間
の使用に耐えられる耐熱鋳造用合金を提供するこ
とを目的としたものである。
近年石油化学工業界などにおいて生産性の増大
及び装置の大型化の傾向にあり、必然的に化学反
応速度の増大のため、より高温、高圧の苛酷な使
用条件となつた。
このことは従来、使用されてきたASTM規格
のHKやHP材では高温（1000℃以上）での強度の
不足及び浸炭性に問題があり、改良合金の必要性
が出て来た。
この種の材料としての合金は、高温における良
好な耐クリープ性と共に、特に高温酸化に対する
すぐれた耐腐食性も具備しなければならない。
前述の如き要求に基いて本発明者は種々研究の
結果、前記の如き諸特性を具備しかつ耐浸炭性を
有する耐熱鋳造用鉄基合金の開発に成功したもの
であり、本発明の要旨とするところは前記特許請
求の範囲に明記した如き各成分と組成範囲から構
成される鋳造用鉄基合金に存する。
即ち、本発明の耐熱鋳造用合金は、従来のFe
−Cr−Ni合金に少量添加成分としてTi、Ｗ、Nb
及びMoを加えることにより耐浸炭性及びクリー
プ破断強度を大幅に向上するとともに、鋳造性、
溶接性の良好な耐熱鋳造用鉄基合金を提供するも
のである。
しかし乍ら、前記添加成分中Ti及びNbの含有
量はクリープ破断強度の改善に及ぼす両添加元素
の相乗作用を効果的に発揮せしめるために、（Ti
＋Nb）含有量を0.5〜1.0重量％の範囲内とするこ
とが好ましい。
前述した如く、本発明にかかわる耐浸炭性耐熱
鋳造用合金はCr、Ni、Ｗ、Moを基本合金組成と
し、これに（Ti＋Nb）を複合添加し、これらの
両元素の相乗作用により著しく、その耐浸炭性、
クリープ破断強度、鋳造性、溶接性を改善したこ
とに特徴があるものである。
本発明の耐熱鋳造用鉄基合金の成分の組成範囲
を特許請求の範囲に記載の如く限定した理由を以
下に詳述する：
本発明にかかわるような耐熱合金のクリープ破
断強度は炭素含有量によつて大きく影響されるこ
とは、すでによく知られた処である。炭素含有量
が0.30重量％未満ではクリープ破断強度が低下し
0.60重量％をこえると急激に靭性が劣化し、実用
鋳造合金として不適当である。よつて炭素の含有
範囲を0.30重量％〜0.60重量％の範囲に決定し
た。
Siの含有量については、(a)耐浸炭性、(b)耐酸化
性、(c)脱酸作用を考慮し、0.50重量％未満ではこ
れらの効果がなく、2.0重量％をこえると上記３
項については満足されるが、溶接時の熱間亀裂感
受性の逆効果が作用するために0.50重量％〜2.00
重量％の範囲に決定した。
Niの含有量はクリープ破断強度の点より一般
に決定されている本合金においては耐浸炭性に主
体をおいて、その含有範囲を決定した。第１図に
示した実験結果よりNiが30重量％未満では耐浸
炭性の効果が出ず、40重量％をこえるとその効果
が少なくなり、価格の面においても実用的でな
い。従つて30.0重量％〜40.0重量％の範囲に決定
した。尚、第１図の実験は0.4C−26Cr−1.5W−
Fe合金の浸炭に対するNi含有量の影響を示すグ
ラフであり、浸炭温度1100℃、浸炭時間200時間
で、固体浸炭材を用いた。
Crはクリープ破断強度と共に酸化に対する抵
抗性に重要な影響を与える。第２図は大気中にお
いて1100℃に100時間加熱した場合の0.4C−35Ni
−1.5W−Fe合金の酸化に対するCr含有量の影響
を調べた実験結果であるが、23.0重量％以上では
ほゞ飽和状態になつている。又Cr含有量が28.0重
量％を超えると靭性を損うばかりでなく、σ相の
生成による脆化現象が発生する。
又、本発明合金には（Ti＋Nb）が複合添加さ
れ、Ti炭化物、Nb炭化物が生成し、Cr炭化物と
共存してクリープ破断強度を改善することも本発
明の特徴である。
Moは耐酸化性及びクリープ破断強度の向上に
重要な添加成分であるが、Ｗ含有量との合計量が
４重量％を超えると室温での靭性が低下する。第
３図は0.4C−26Cr−35Ni−Fe合金にＷを単独添
加した場合（Ａ曲線）と0.4C−26Cr−35Ni−
1.5W−Fe合金にMoを複合添加した場合（Ｂ曲
線）の室温における靭性への影響を示す実験結果
である。第３図から明らかな如くMo含有量が
2.00重量％を超えると靭性が急速に劣下する。
Ｗはクリープ破断強度及び耐浸炭性に極めて有
効な添加成分である。前述した第３図から明らか
な如く、Ｗ含有量が2.5重量％を超えると室温で
の低下が起る。又、第４図は0.4C−26Cr−35Ni
−Fe合金の浸炭に対するＷ含有量の影響を示す
曲線であり、実験条件は固体浸炭材を用いて浸炭
温度1100℃で浸炭時間は200時間である。第４図
から明らかな如く、Ｗ含有量が0.5重量％未満で
は効果が小さく、2.5重量％を超えると効果が飽
和状態となる。これらの理由によりＷ含有量は
0.50〜2.50重量％と決定した。
Nb及びTiを適正な割合で複合添加することに
より、鋳放し状態で粒界に連続して晶出するCr
炭化物をおさえて靭性の向上を図り、又高温
（1000゜〜1150℃）で長時間使用した場合、析出
する二次炭化物の析出及び凝集粗大化速度を著し
く遅らせ、クリープ破断強度の向上を目的とした
ものである。従つて本発明合金はオーステナイト
基地内に晶出及び析出するCr炭化物、Nb炭化
物、Ti炭化物の量及び形状に特徴がある。これ
ら３種の添加成分は炭素含有量と下式の如き関係
がある：
Nb重量％＝３〜5Ti重量％ ……(1)
Nb重量％＋Ti重量％／Ｃ重量％＝1.5〜2.5
……(2)
上記(1)及び(2)式の関係にある場合、クリープ破
断強度が著しく増大するものであり、これらの理
由からNb含有量を0.10〜1.50重量％、Ti含有量を
0.05〜1.00重量％の範囲と決定した。
本発明合金と他の合金（ASTM−HK及びHP）
とのクリープ破断時間を表に対比して示す：
The present invention relates to a heat-resistant casting alloy with excellent carburization resistance and creep rupture strength at high temperatures, and an object of the present invention is to provide a heat-resistant casting alloy that can withstand long-term use as a material for reactors in petrochemical and other industries. This is what I did. In recent years, there has been a trend in the petrochemical industry to increase productivity and increase the size of equipment, which inevitably increases the rate of chemical reactions, resulting in harsher operating conditions such as higher temperatures and pressures. This is because the ASTM standard HK and HP materials that have been used in the past have problems with insufficient strength and carburization at high temperatures (above 1000°C), creating the need for improved alloys. Alloys as materials of this type must have good creep resistance at high temperatures as well as good corrosion resistance, especially against high temperature oxidation. As a result of various studies based on the above-mentioned requirements, the present inventor has succeeded in developing a heat-resistant casting iron-based alloy that has the above-mentioned properties and has carburization resistance. The iron-based alloy for casting consists of the components and composition ranges specified in the claims. That is, the heat-resistant casting alloy of the present invention
-Ti, W, Nb as small amounts of added ingredients to Cr-Ni alloy
By adding and Mo, carburization resistance and creep rupture strength are greatly improved, and castability and
The present invention provides an iron-based alloy for heat-resistant casting with good weldability. However, the content of Ti and Nb in the above additive components is determined in order to effectively exhibit the synergistic effect of both additive elements on improving the creep rupture strength.
+Nb) content is preferably within the range of 0.5 to 1.0% by weight. As mentioned above, the carburization-resistant, heat-resistant casting alloy according to the present invention has a basic alloy composition of Cr, Ni, W, and Mo, to which (Ti + Nb) is added in combination, and the synergistic effect of these two elements significantly improves its performance. carburization resistance,
It is characterized by improved creep rupture strength, castability, and weldability. The reason why the composition range of the components of the heat-resistant cast iron-based alloy of the present invention is limited as described in the claims is detailed below: The creep rupture strength of the heat-resistant alloy as related to the present invention depends on the carbon content. It is already well known that this will have a major impact. Creep rupture strength decreases when the carbon content is less than 0.30% by weight.
If it exceeds 0.60% by weight, the toughness deteriorates rapidly and is unsuitable as a practical casting alloy. Therefore, the carbon content range was determined to be 0.30% to 0.60% by weight. Regarding the content of Si, consider (a) carburization resistance, (b) oxidation resistance, and (c) deoxidizing effect.If it is less than 0.50% by weight, it will not have these effects, and if it exceeds 2.0% by weight, it will not be effective.
However, due to the adverse effect of hot crack susceptibility during welding, 0.50% to 2.00% by weight
The range of weight percent was determined. The content of Ni is generally determined from the viewpoint of creep rupture strength, but in this alloy, the content range was determined mainly based on carburization resistance. The experimental results shown in FIG. 1 show that if Ni is less than 30% by weight, the carburization resistance effect is not achieved, and if it exceeds 40% by weight, the effect decreases and it is not practical in terms of price. Therefore, the range was determined to be 30.0% by weight to 40.0% by weight. The experiment shown in Figure 1 was conducted at 0.4C−26Cr−1.5W−.
This is a graph showing the influence of Ni content on carburization of Fe alloy, using a solid carburizing material at a carburizing temperature of 1100°C and a carburizing time of 200 hours. Cr has an important influence on resistance to oxidation as well as creep rupture strength. Figure 2 shows 0.4C−35Ni when heated at 1100℃ in the atmosphere for 100 hours.
The results of an experiment investigating the effect of Cr content on the oxidation of -1.5W-Fe alloy show that it is almost saturated at 23.0% by weight or more. Furthermore, if the Cr content exceeds 28.0% by weight, not only the toughness is impaired but also embrittlement occurs due to the formation of σ phase. Another feature of the present invention is that (Ti+Nb) is added in combination to the alloy of the present invention, so that Ti carbide and Nb carbide are formed, which coexist with Cr carbide to improve the creep rupture strength. Mo is an important additive component for improving oxidation resistance and creep rupture strength, but if the total amount including W content exceeds 4% by weight, the toughness at room temperature decreases. Figure 3 shows the case where W is added alone to 0.4C-26Cr-35Ni-Fe alloy (curve A) and 0.4C-26Cr-35Ni-
These are experimental results showing the effect on toughness at room temperature when Mo is added in combination to a 1.5W-Fe alloy (Curve B). As is clear from Figure 3, the Mo content is
If it exceeds 2.00% by weight, toughness will rapidly deteriorate. W is an extremely effective additive component for creep rupture strength and carburization resistance. As is clear from the above-mentioned FIG. 3, when the W content exceeds 2.5% by weight, a decrease occurs at room temperature. Also, Figure 4 shows 0.4C−26Cr−35Ni
- This is a curve showing the influence of W content on carburization of Fe alloy, and the experimental conditions were a solid carburizing material, a carburizing temperature of 1100° C., and a carburizing time of 200 hours. As is clear from FIG. 4, when the W content is less than 0.5% by weight, the effect is small, and when it exceeds 2.5% by weight, the effect is saturated. For these reasons, the W content is
It was determined to be 0.50-2.50% by weight. By adding Nb and Ti in an appropriate proportion, Cr can be continuously crystallized at the grain boundaries in the as-cast state.
The purpose is to suppress carbides to improve toughness, and to significantly slow down the precipitation and agglomeration coarsening rate of secondary carbides that precipitate when used for long periods of time at high temperatures (1000° to 1150°C), and to improve creep rupture strength. This is what I did. Therefore, the alloy of the present invention is characterized by the amount and shape of Cr carbide, Nb carbide, and Ti carbide that crystallize and precipitate within the austenite matrix. These three additive components have a relationship with the carbon content as shown in the following formula: Nb weight % = 3 to 5 Ti weight % ... (1) Nb weight % + Ti weight % / C weight % = 1.5 to 2.5 ... ( 2) When the relationships expressed by equations (1) and (2) above are met, the creep rupture strength increases significantly.For these reasons, the Nb content is set to 0.10 to 1.50% by weight, and the Ti content is set to 0.10 to 1.50% by weight.
It was determined to be in the range of 0.05 to 1.00% by weight. Invention alloy and other alloys (ASTM-HK and HP)
The table shows the creep rupture times for:
【表】
本発明合金を一実施例に基いて更に諸特性を詳
述する。
実施例
この実施例に用いた本発明合金の化学組成は下
記の通りである（重量％で示す）：
Ｃ 0.40 ％
Si 1.84 ％
Mn 0.80 ％
Ｐ 0.014％
Ｓ 0.013％
Ni 34.51 ％
Cr 26.61 ％
Mo 1.06 ％
Ｗ 1.80 ％
Nb 0.68 ％
Ti 0.15 ％
Fe 残部
上記組成の本発明合金を金型遠心鋳造したまゝ
の状態で測定した諸特性は次の通りである。[Table] The various properties of the alloy of the present invention will be further detailed based on one example. EXAMPLE The chemical composition of the inventive alloy used in this example is as follows (expressed in weight percent): C 0.40% Si 1.84% Mn 0.80% P 0.014% S 0.013% Ni 34.51% Cr 26.61% Mo 1.06 %W 1.80% Nb 0.68% Ti 0.15% Fe balance The properties of the alloy of the present invention having the above composition as it was centrifugally cast in a mold are as follows.
【表】
下記の表は耐酸化水を類似の組成を有する他
の合金と対比して表記する。試験条件は酸化性雰
囲気において1100℃に100時間曝したものであ
る。[Table] The table below shows the oxidation resistance of water compared to other alloys with similar compositions. The test conditions were exposure to 1100°C for 100 hours in an oxidizing atmosphere.
【表】
第５図は前記合金の鋳造片の顕微鏡写真（400
倍）で、粒界に前述の３種の金属炭化物が析出し
ている状態を示している。[Table] Figure 5 is a micrograph of a cast piece of the above alloy (400
(x) shows a state in which the three types of metal carbides mentioned above are precipitated at the grain boundaries.
第１図は浸炭に対するNi含有量の影響を示す
グラフ、第２図は大気中における酸化に対する
Cr含有量の影響を示すグラフ、第３図はＷ単独
添加(A)とＷとMoを複合添加(B)した場合の室温に
おける靭性への影響を示すグラフ、第４図は浸炭
に対するＷ含有量の影響を示すグラフ、第５図は
本発明合金鋳造片の顕微鏡写真である。
Figure 1 is a graph showing the effect of Ni content on carburization, Figure 2 is a graph showing the effect of Ni content on carburization, and Figure 2 is a graph showing the effect of Ni content on carburization.
A graph showing the influence of Cr content. Figure 3 is a graph showing the influence of W addition alone (A) and combined addition of W and Mo (B) on toughness at room temperature. Figure 4 is a graph showing the influence of W content on carburization. A graph showing the effect of quantity, and FIG. 5 is a micrograph of a cast piece of the alloy of the present invention.
Claims (1)
0.50〜2.00％Mn、0.04％以下のＰ、0.04％以下の
Ｓ、30.0〜40.0％Ni、23.0〜28.0％Cr、0.05〜
2.00％Mo、0.50〜2.50％Ｗ、0.10〜1.50％Nb、
0.05〜1.00％Ti、残部鉄からなる耐浸炭性を有す
る耐熱鋳造用鉄基合金。1% by weight: 0.30-0.60% C, 0.50-2.00% Si,
0.50-2.00% Mn, 0.04% or less P, 0.04% or less S, 30.0-40.0% Ni, 23.0-28.0% Cr, 0.05-
2.00%Mo, 0.50~2.50%W, 0.10~1.50%Nb,
A heat-resistant casting iron-based alloy with carburization resistance consisting of 0.05-1.00% Ti and the balance iron.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13413579A JPS5658953A (en) | 1979-10-19 | 1979-10-19 | Heat resistant iron alloy with carburizing resistance for casting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13413579A JPS5658953A (en) | 1979-10-19 | 1979-10-19 | Heat resistant iron alloy with carburizing resistance for casting |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5658953A JPS5658953A (en) | 1981-05-22 |
| JPS6140743B2 true JPS6140743B2 (en) | 1986-09-10 |
Family
ID=15121281
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13413579A Granted JPS5658953A (en) | 1979-10-19 | 1979-10-19 | Heat resistant iron alloy with carburizing resistance for casting |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5658953A (en) |
-
1979
- 1979-10-19 JP JP13413579A patent/JPS5658953A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5658953A (en) | 1981-05-22 |
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