JPH01268836A - Engine exhaust-system material - Google Patents
Engine exhaust-system materialInfo
- Publication number
- JPH01268836A JPH01268836A JP9423288A JP9423288A JPH01268836A JP H01268836 A JPH01268836 A JP H01268836A JP 9423288 A JP9423288 A JP 9423288A JP 9423288 A JP9423288 A JP 9423288A JP H01268836 A JPH01268836 A JP H01268836A
- Authority
- JP
- Japan
- Prior art keywords
- corrosion
- amount
- added
- intergranular corrosion
- content
- 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.)
- Pending
Links
- 239000000463 material Substances 0.000 title claims abstract description 23
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 13
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 11
- 229910052715 tantalum Inorganic materials 0.000 claims abstract description 11
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 6
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 5
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 229910052742 iron Inorganic materials 0.000 claims abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
- 238000000034 method Methods 0.000 abstract description 12
- 229910052799 carbon Inorganic materials 0.000 abstract description 8
- 229910052748 manganese Inorganic materials 0.000 abstract description 3
- 229910052710 silicon Inorganic materials 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 230000007797 corrosion Effects 0.000 description 35
- 238000005260 corrosion Methods 0.000 description 35
- 239000011651 chromium Substances 0.000 description 13
- 238000012360 testing method Methods 0.000 description 12
- 229910000831 Steel Inorganic materials 0.000 description 11
- 239000010959 steel Substances 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 8
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000000087 stabilizing effect Effects 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 206010070834 Sensitisation Diseases 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 229910052761 rare earth metal Inorganic materials 0.000 description 4
- 230000008313 sensitization Effects 0.000 description 4
- 150000001247 metal acetylides Chemical class 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 238000011282 treatment Methods 0.000 description 3
- 230000004913 activation Effects 0.000 description 2
- GVEHJMMRQRRJPM-UHFFFAOYSA-N chromium(2+);methanidylidynechromium Chemical compound [Cr+2].[Cr]#[C-].[Cr]#[C-] GVEHJMMRQRRJPM-UHFFFAOYSA-N 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000009991 scouring Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 229910003470 tongbaite Inorganic materials 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- -1 CrzzCa Chemical class 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は、耐久性に優れ、しかも安価なエンジン排気
系材料に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to an engine exhaust system material that has excellent durability and is inexpensive.
内燃機関の排ガス温度は、エンジンの高出力化に伴なっ
て益々上昇する傾向にある。The exhaust gas temperature of internal combustion engines tends to rise more and more as the engine output becomes higher.
排気系材料の高温部位には、優れた高温強度と耐高温腐
食性を有するオーステナイト系ステンレス鋼が専ら使用
されている。中でも、Ｓ Ｕ３３１０Ｓ （２５Ｃｒ
−２ＯＮ ｉ ）は高性能であることからその使用比率
が高まっているが、この種の材料は高価なため、排気系
の材料費負担が増加して来ている。Austenitic stainless steel, which has excellent high-temperature strength and high-temperature corrosion resistance, is exclusively used for the high-temperature parts of the exhaust system. Among them, S U3310S (25Cr
-2ON i ) is used more and more because of its high performance, but since this type of material is expensive, the cost of materials for the exhaust system is increasing.
そこで、５ＵＳ３１０Ｓと同等かもしくはそれ以上の耐
久性を発揮する低度材の開発が進められている。Therefore, efforts are being made to develop low-grade materials that exhibit durability equal to or greater than 5US310S.
既に検討された中で、一応の効果が認められるものとシ
テは、規格鋼ではＳ Ｕ ３３０２ Ｂ （１８０ｒ−
９Ｎ ｉ −２，５Ｓ ｉ） 、ＳＵＳＸＭＩ５Ｊ １
（１９Ｃｒ１３Ｎ ｉ −３，５３ｉ ）があり、いず
れも、Ｓｉの添加により耐高温酸化性を向上させている
。Among the items that have already been considered, the one that has been found to be somewhat effective is S U 3302 B (180r-
9N i -2,5S i), SUSXMI5J 1
(19Cr13N i -3,53i), and both have improved high-temperature oxidation resistance by adding Si.
さらに、希土類元素を添加することにより、スケールの
密着性を良くして繰り返し加熱冷却時の耐剥離性の改善
に効果を上げているものもある。Furthermore, some products have been effective in improving peeling resistance during repeated heating and cooling by improving scale adhesion by adding rare earth elements.
ところが、それ等は、いずれも、繰り返し高温ガス腐食
試験などの加速試験では良好な成績を示すが、エンジン
への実装による耐久試験では、今だ、５ＬＩＳ３１０Ｓ
並の耐久性が得られていない。However, although all of them show good results in accelerated tests such as repeated high-temperature gas corrosion tests, in durability tests by mounting them on engines, the 5LIS310S
It does not have the same level of durability.
そこで、本発明者は、加速試験では良好な成績を示すＳ
ｉ添加オーステナイト系ステンレス鋼が、耐久試験では
何故良い成績が得られないのかを綿密に調査し、その原
因が粒界腐食にあることを究明した。即ち、耐久試験時
には、高温腐食に加え、冷却時の結露現象で生しる塩／
８液によって粒界腐食が生じており、これが原因で耐久
性が不充分になっていることが判った。Therefore, the present inventor investigated S
We conducted a thorough investigation into why i-added austenitic stainless steel did not achieve good results in durability tests, and determined that the cause was intergranular corrosion. In other words, during durability tests, in addition to high-temperature corrosion, salt/
It was found that intergranular corrosion was caused by Liquid 8, and that this was the cause of insufficient durability.
粒界腐食は周知のように、粒界付近に偏析する炭素がク
ロムと反応してＣｒｚｚＣａなどの炭化物となり、それ
によって耐食性を支えている実効クロム量が減少する結
果、粒界に沿って腐食が進行する現象である。As is well known, intergranular corrosion is a phenomenon in which carbon segregated near grain boundaries reacts with chromium to form carbides such as CrzzCa, which reduces the effective amount of chromium that supports corrosion resistance, and as a result, corrosion occurs along grain boundaries. It is a progressive phenomenon.
クロム炭化物析出反応、いわゆる鋭敏化反応は、オース
テナイト系ステンレス鋼の場合、４００〜８５０℃で起
こる。The chromium carbide precipitation reaction, the so-called sensitization reaction, occurs at 400-850°C in the case of austenitic stainless steel.
これに対し、オーステナイト系材料が使用される高温部
位では、エンジンの運転中、上の温度域にあることが多
く、従って容易に鋭敏化反応が起こり、運転時間と共に
進行する。On the other hand, high-temperature areas where austenitic materials are used are often in the upper temperature range during engine operation, and therefore sensitization reactions easily occur and progress over time.
また、排ガス中には、燃料に含まれる不純物、燃焼によ
って生じる水蒸気や微量の亜硫酸、窒素酸化物、塩素等
が含まれており、従って、冷却によって結露水が発生し
、それがｓｏ、”−１ＮＯ！−Ｃ１−等を含む塩溶液と
なって排気系部材に付着する。In addition, the exhaust gas contains impurities contained in the fuel, water vapor generated by combustion, trace amounts of sulfite, nitrogen oxides, chlorine, etc. Therefore, condensation water is generated by cooling, which is It becomes a salt solution containing 1NO!-C1- and the like and adheres to exhaust system members.
このように、排気系の高温部位では、鋭敏化反応によっ
て腐食感受性が高まり、そこに、粒界腐食効果の大きい
Ｓ０４！″、ＮＯ３−を含む溶液が提供されることにな
るため、粒界に沿って容易に腐食が進む。しかも、この
粒界腐食は従来改善の対象としていた全面腐食に先行し
て排気系材料を侵食する。耐食性が５ＵＳ３１０Ｓに及
ばないのはここに原因があるが、粒界腐食のメカニズム
は全面腐食のそれと異なる。従って、上の原因を取り除
くには、新たな改善策を講じる必要がある。As described above, in the high-temperature parts of the exhaust system, the sensitization reaction increases corrosion susceptibility, and S04!, which has a large intergranular corrosion effect, increases the corrosion sensitivity. Since a solution containing NO3- is provided, corrosion easily progresses along the grain boundaries.Moreover, this intergranular corrosion precedes the general corrosion, which was the target of conventional improvement, and causes exhaust system materials to be damaged. This is the reason why the corrosion resistance is not as good as 5US310S, but the mechanism of intergranular corrosion is different from that of general corrosion.Therefore, it is necessary to take new improvement measures to eliminate the above causes.
そのための、従来技術としては、次の２つの方法がある
。There are the following two methods as conventional techniques for this purpose.
ｆｌ＋ 材料中の炭素量を極力低減し、クロム炭化物
の析出による実効クロム量の低下を防ぐ方法。fl+ A method of reducing the amount of carbon in the material as much as possible and preventing a decrease in the effective amount of chromium due to precipitation of chromium carbide.
（２）鋭敏化反応の発生領域において、炭素との親和力
がクロムよりも強く、クロムに優先して炭化物を形成す
るＮｂ、Ｔａ又はＴｉを添加し、これによって実効クロ
ム量の低下を防ぐ方法。(2) A method of preventing a decrease in the effective amount of chromium by adding Nb, Ta, or Ti, which has a stronger affinity with carbon than chromium and forms carbides in preference to chromium, in the region where the sensitization reaction occurs.
しかしながら、（１１の方法は、脱炭のための溶製コス
トが高くつく。一方、（２）の方法は、実効クロム量の
低下防止効果が充分に得られる量のＮｂ、Ｔａ又はＴｉ
をＳｉ含有鋼に添加すると、材料の熱間加工性が悪くな
って生産性が著しく低下し、或いは熱間加工後の手入れ
が必要になって材料の歩留まりが低下する。従って、い
ずれの方法も経済性が失われると云う問題がある。However, in method (11), the melting cost for decarburization is high.On the other hand, in method (2), Nb, Ta, or Ti is used in an amount sufficient to prevent a decrease in the effective chromium content.
When added to Si-containing steel, the hot workability of the material deteriorates, resulting in a significant drop in productivity, or the yield of the material decreases due to the need for care after hot working. Therefore, both methods have the problem of loss of economic efficiency.
この発明は、実効クロム量の低下をコストをかけずに防
止して所望の材料の耐久性と経済性を両立させることを
目的としている。The object of the present invention is to prevent the effective chromium content from decreasing without increasing costs, thereby achieving both desired durability and economic efficiency of the material.
この発明のエンジン排気系材料は、重量比でＮｉを７〜
１０％。Ｃ「を１５〜２０％、Ｓｉを１〜５％、Ｍｎを
≦２％、Ｎｂ、Ｔａ、、Ｔｉの中の１種又は２種以上を
Ｏ，ＯＳ〜０．８％、Ｃを５０．０７％含み、残部が鉄
と不可避不純物から成るものである。The engine exhaust system material of this invention has a weight ratio of Ni of 7 to 7.
10%. 15 to 20% of Si, 1 to 5% of Mn, ≦2% of Mn, O, OS~0.8% of one or more of Nb, Ta, Ti, and 50% of C. 0.7%, with the remainder consisting of iron and unavoidable impurities.
この材料は、前述のような事実観察に基いて実験を重ね
た結果、
（イ） Ｃの含有量を０．０７％以下、望ましくは０．
０５％以下に調整する。As a result of repeated experiments based on the above-mentioned factual observations, this material was found to have (a) a carbon content of 0.07% or less, preferably 0.07% or less;
Adjust to 0.5% or less.
（ｏ） Ｎｂ、Ｔａ、Ｔｉの中の１種または２種以上
を０．０５〜０．８％添加する。(o) One or more of Nb, Ta, and Ti is added in an amount of 0.05 to 0.8%.
（ハ） Ｎｉｌを１０％以下に止める。(c) Keep Nil below 10%.
以上３点の処理を併用すると、相乗効果が生じて従来の
Ｓｉ含有オーステナイト系ステンレス鋼、或いはさらに
、希土類元素が添加された当該ステンレス鋼の耐粒界腐
食性が著しく改善されることを見出して開発に成功した
ものであって、５ＵＳ３１０Ｓと同等の高温強度をもち
ながら、５ＵＳ３１ＯＳよりも耐久性に優れ、しかも安
価である。It has been discovered that when the above three treatments are used in combination, a synergistic effect occurs and the intergranular corrosion resistance of conventional Si-containing austenitic stainless steel or stainless steel to which rare earth elements are added is significantly improved. It has been successfully developed and has high-temperature strength equivalent to 5US310S, but is more durable than 5US31OS and is less expensive.
粒界腐食は、先にも述べた通り、ＣがＣｒと反応して生
じる現象であるので、前々項で述べた（１）の手法によ
って、つまり、精練過程で自然に混入するＣの含有量を
減らすことによって実効Ｃｒｌの低下を防ぐことができ
る。この場合、ＪＩＳの該光調ではＣ５０，０３％に規
定されている。しかし、Ｃ含ＩＩの低減のみで所望の効
果を得ようとすると、Ｃ含有量の低い厳選された材料を
用い、さらに、長時間の脱炭精練を経て溶製する必要が
あるため、高価になる。As mentioned earlier, intergranular corrosion is a phenomenon that occurs when C reacts with Cr, so by the method (1) mentioned in the previous section, in other words, the content of C that is naturally mixed in during the scouring process is By reducing the amount, a decrease in effective CRL can be prevented. In this case, the JIS light adjustment is defined as C50.03%. However, in order to obtain the desired effect only by reducing C-containing II, it is necessary to use carefully selected materials with low C content and to melt them through long decarburization and scouring, resulting in high costs. Become.
これに対し、Ｃの量を０，０７％以下に低減することは
比較的容易なため、経済性は損われない。On the other hand, since it is relatively easy to reduce the amount of C to 0.07% or less, economic efficiency is not impaired.
一方、前々項の（２）の手法、即ち、Ｃとの親和力がＣ
ｒよりもはるかに強い元素を添加してその炭化物を生成
することも、耐食性を支えている実効Ｃｒ量の低下を防
止するのに有効である。この場合、安定化元素の添加量
は、通常、ＴｉはＣ含有量の５倍以上、Ｎｂ、Ｔａは１
０倍以上が必要とされている。On the other hand, the method (2) in the previous section, that is, the affinity with C is
Adding an element much stronger than r to form a carbide is also effective in preventing a decrease in the effective amount of Cr, which supports corrosion resistance. In this case, the amount of stabilizing elements added is usually at least 5 times the C content for Ti, and 1 for Nb and Ta.
0 times or more is required.
しかしながら、通常のオーステナイト系ステンレス鋼に
比して熱間加工性が劣る傾向にあるＳｔ添加オーステナ
イト系ステンレス鋼、或いはさらに微量の希土類元素を
添加して酸化膜の耐ｆｆ１ｌｌ ！性を高めた耐高温酸
化性鋼に、上記した倍率の世の希土類元素を添加すると
、熱間加工性が著しく低下し、生産性や歩留の大巾低下
を招いて経済性が失なわれる。かと云って、Ｎｂ、Ｔａ
或いはＴｉの添加量を微量に減らすと添加の効果が現わ
れない。However, St-added austenitic stainless steel tends to have poorer hot workability than normal austenitic stainless steel, or even a small amount of rare earth element is added to improve the ff1ll resistance of the oxide film! If rare earth elements of the above-mentioned ratio are added to high-temperature oxidation-resistant steel with increased properties, hot workability will be significantly lowered, resulting in a significant drop in productivity and yield, resulting in a loss of economic efficiency. . However, Nb, Ta
Alternatively, if the amount of Ti added is reduced to a very small amount, the effect of the addition will not appear.
ところが、上述したように、Ｃの含有量を０．０７％以
下、望ましくは０．０５％以下にした」二でＮｂ等の添
加を行なうと、０．０５〜０．８％の熱間加工性を害し
ない範囲の量で添加効果が認められ、経済的に耐粒界腐
食性を高め得ることが判った。However, as mentioned above, when the C content is reduced to 0.07% or less, preferably 0.05% or less, and Nb etc. are added, hot processing of 0.05 to 0.8% occurs. It was found that the addition effect was observed in an amount within a range that did not impair the properties, and it was found that intergranular corrosion resistance could be economically improved.
但し、上の２つの方策を講じるだけでは、所望の性能を
得るには至らない。However, just taking the above two measures does not lead to obtaining the desired performance.
そこで、さらに実験を重ねた結果、Ｎｉ含有量が１０％
以下のときに５ＩＩＳ３１０Ｓに勝る耐粒界腐食性が得
られることを見出した。Therefore, as a result of further experiments, the Ni content was 10%.
It has been found that intergranular corrosion resistance superior to 5IIS310S can be obtained when:
オーステナイト相を安定に保って５ＵＳ３１０Ｓに匹敵
する高温強度を得るには、Ｎｉを少なくとも７％以上添
加する必要があるが、ＮｉはＣを活性化させる働きがあ
り、オーステナイト鋼は、そのＮｉの含有量の増加に伴
なって鋭敏化領域の温度下における粒界付込へのＣの偏
析傾向が強まる（これがＣｒ欠乏の程度を助長して粒界
腐食感受性が高まる）ため、含有量が１０％を越えた場
合、Ｃ量の更なる低減、或は安定化元素の更なる増加が
必要になって前述の（イ）、（ロ）の方策による効果が
充分に生かされないのである。In order to keep the austenite phase stable and obtain high-temperature strength comparable to 5US310S, it is necessary to add at least 7% Ni, but Ni acts to activate C, and austenitic steel is As the content increases, the tendency of C to segregate into grain boundaries at temperatures in the sensitized region increases (this promotes the degree of Cr deficiency and increases the susceptibility to intergranular corrosion); therefore, the content of 10% If it exceeds the above, it becomes necessary to further reduce the amount of C or further increase the stabilizing element, and the effects of the above-mentioned measures (a) and (b) cannot be fully utilized.
第１図に、この発明を完成するに至った材料の試作、試
験結果を示す。FIG. 1 shows the trial production and test results of the material that led to the completion of this invention.
この表に示す数値は、真空熔解／熱間加工／冷間加工を
経て同図のｆａｔにおいては１８％Ｃｒ−３％Ｓｉ鋼を
ヘースにＮｂ及びＣの添加量を変えた板厚０．８ｍｍの
試料を、一方同図ｆｂｌにおいては１８％Ｃｒ−’１％
Ｓｉ＠をベースにＮｉとＣの量を変えた（ａｌと同一板
厚の試料を各々作成し、それを、［大気中７００℃で３
０分間加熱の後、Ｓ０４′＼ＮＯ３−を含む水溶液中に
浸漬」を１サイクルとする高温酸化−粒界腐食試験に供
して上のサイクルを１００回繰返えし、その後、粒界腐
食層を含む全酸化層を測定したものである。The values shown in this table are based on 18%Cr-3%Si steel with a thickness of 0.8mm after vacuum melting/hot working/cold working with varying amounts of Nb and C. On the other hand, in the same figure fbl, 18%Cr-'1%
Using Si@ as a base, the amounts of Ni and C were changed (we prepared samples with the same thickness as Al, and
After heating for 0 minutes, one cycle of immersion in an aqueous solution containing S04'\NO3- was applied to a high-temperature oxidation-intergranular corrosion test, and the above cycle was repeated 100 times. This is a measurement of the entire oxide layer including.
以下に、材料中の各成分の量を限定した理由をまとめて
記す。The reasons for limiting the amounts of each component in the materials are summarized below.
Ｎｉニア％未満ではオーステナイトの安定性に欠け、ま
た、充分な高温強度が得られない。一方、１０％を越す
と、本発明におけるＣの量及び安定化元素の量ではＣの
活性化に起因した粒界腐食感受性の高まりを充分に抑え
ることができない。If the Ni content is less than %, the austenite will lack stability and sufficient high-temperature strength will not be obtained. On the other hand, if it exceeds 10%, the amount of C and the amount of stabilizing element in the present invention cannot sufficiently suppress the increase in intergranular corrosion susceptibility caused by activation of C.
Ｃｒ：高温での耐酸化性、耐ガス腐食性及び耐粒界腐食
性を維持するための基本的な元素で、上の３つの性能を
不足なく確保するために最低１５％は必要である。一方
、２０％を越える添加は、Ｓｉ含有鋼の場合、オーステ
ナイト組織の安定性維持のために特に、多量のＮｉが必
要になるので好ましくない。Cr: A basic element for maintaining oxidation resistance, gas corrosion resistance, and intergranular corrosion resistance at high temperatures, and a minimum content of 15% is required to ensure the above three performances. On the other hand, addition of more than 20% is not preferable in the case of Si-containing steel, since a large amount of Ni is required to maintain the stability of the austenitic structure.
Ｍｎ：Ｎｉと同様にオーステナイト相の安定化に有効な
ものであるが、耐食性を悪化させる元素でもあるので、
上限を２％とした。Mn: Like Ni, it is effective in stabilizing the austenite phase, but it is also an element that worsens corrosion resistance.
The upper limit was set at 2%.
Ｓｉ：耐高温酸化性を改善する効果があり、少なくとも
１％は必要、５％を越える添加は、オーステナイト相の
安定性を欠き、δフェライトが多量に発生し、熱間加工
性が低下する。Si: Effective in improving high-temperature oxidation resistance, at least 1% is required; addition of more than 5% results in lack of austenite phase stability, generation of large amounts of δ ferrite, and deterioration of hot workability.
Ｃ：粒界腐食の元凶元素であって、その添加量が０．０
７％を越すと安定化元素の必要添加■が本発明の範囲を
越え、経済性が失われる。C: An element that causes intergranular corrosion, and the amount added is 0.0
If it exceeds 7%, the required addition of the stabilizing element (2) exceeds the scope of the present invention, and economic efficiency is lost.
Ｎｂ、Ｔａ、Ｔｌ ： Ｃｒに優先して炭化物を形成し
、耐粒界腐食性を改善する。その足はＣ含有量に対し、
通常前述したようにＴｉは５倍以上、Ｎｂ、Ｔａは１０
倍以上を必要とする。Nb, Ta, Tl: Forms carbides in preference to Cr and improves intergranular corrosion resistance. The foot is relative to the C content.
Usually, as mentioned above, Ti is 5 times or more, and Nb and Ta are 10 times more.
Requires more than double.
しかしながら、本発明によるＣｆ１ｔ調整及びＮＨ２ｔ
調整を併用した腹合処理では、０．０５％からその効果
が現れる０反面、これ等の元素のＳｉ含有鋼への添加は
、熱間加工性を阻止する傾向が強く、従って、その上限
は熱間加工性を維持できる０、８％に抑えた。However, Cf1t adjustment and NH2t according to the present invention
In the adjustment process combined with adjustment, the effect appears from 0.05%, but on the other hand, the addition of these elements to Si-containing steel has a strong tendency to inhibit hot workability, so the upper limit is It was kept to 0.8% to maintain hot workability.
真空溶解炉を用いて第１表に示す化学組成の鋳比較鋼Ａ
、Ｂ、Ｃは、上から順に従来の５ＵＳ３０２ Ｂ、ＳＵ
ＳＸＭ１５Ｊ １．５ＵＳ３１０Ｓの規格鋼である。Comparison steel A with the chemical composition shown in Table 1 was prepared using a vacuum melting furnace.
, B, C are conventional 5US302 B, SU from top to bottom.
SXM15J 1.5US310S standard steel.
次に、これ等の鋳塊をいずれも熱間加工して厚さ３關の
板状となし、更に冷間加工して厚さ０．８顛の試料に仕
上げた。Next, each of these ingots was hot worked into a plate shape with a thickness of 3 mm, and further cold worked into a sample with a thickness of 0.8 mm.
そして、この試料を１０８０℃で１分間溶体化処理した
後、２０００時間の台上耐久試験に供した。This sample was subjected to solution treatment at 1080°C for 1 minute, and then subjected to a 2000 hour bench durability test.
試験終了後の試料を取り出し、断面の顕微鏡観察により
、試料の粒界腐食層を含む全腐食層の厚みを測定した結
果を第２図に示す。After the test was completed, the sample was taken out, and the thickness of the entire corrosion layer, including the intergranular corrosion layer, of the sample was measured by microscopic observation of the cross section. The results are shown in FIG.
なお、腐食による剥離層は、試料の残厚と試験前の試料
の厚みの差とみなし、全腐食層に加えた。The peeled layer due to corrosion was considered to be the difference between the remaining thickness of the sample and the thickness of the sample before the test, and was added to the total corrosion layer.
この第２図から、発明鋼１及び２の耐久性は、５ＵＳ３
１０Ｓのそれを上回ることが判る。From this figure 2, the durability of invention steels 1 and 2 is 5US3
It can be seen that it exceeds that of 10S.
以上述べたように、この発明のエンジン排気系材料は、
Ｓｉ含有オーステナイト系ステンレス鋼のＣ含有量を溶
製コストに負担のない０．０７％以下に制限し、また、
熱間加工性を害しない範囲でＮｂ、Ｔａ、Ｔｉの少なく
とも１種を添加し、さらに、それらの処理によって実効
Ｃｒ１ｌｌの低下防止効果が充分に引出されるようにＮ
ｉｌを１０％以下としてＣのＮｉによる活性化を抑える
と云う経済負担のかからない方法で５ＵＳ３１Ｏ３を上
回る耐久性を確保したものであるから、エンジンの高出
力化に伴う排気系の材料費負担の増加に歯止めをかける
ことができ、かつ、排気系のメンテナンスフリー化にも
寄与できると云う効果がある。As mentioned above, the engine exhaust system material of the present invention is
Limiting the C content of Si-containing austenitic stainless steel to 0.07% or less, which does not burden the melting cost, and
At least one of Nb, Ta, and Ti is added within a range that does not impair hot workability, and N is added so that the effective Cr1ll reduction prevention effect can be sufficiently brought out by these treatments.
Durability exceeding that of 5US31O3 is achieved by suppressing the activation of C by Ni by reducing il to 10% or less, which is a method that does not impose an economic burden. Therefore, the material costs for the exhaust system will increase as the engine output increases. This has the effect of being able to put a brake on the problem and also contribute to making the exhaust system maintenance-free.
第１図のｔａ＋、ｆｂｌは、本発明を完成するのに至っ
た各種の試作材料の高温酸化−粒界腐食試験結果を示す
折線グラフ、第２図は、本発明鋼と比較鋼の耐久試験結
果を示す棒グラフである。
特許出願人 日産自動車株式会社
同 住友電気工業株式会社
同 代理人 鎌 １） 文 −第２図ta+ and fbl in Fig. 1 are line graphs showing the high temperature oxidation-intergranular corrosion test results of various prototype materials that led to the completion of the present invention, and Fig. 2 is a durability test of the inventive steel and comparative steel. It is a bar graph showing the results. Patent applicant: Nissan Motor Co., Ltd. Sumitomo Electric Industries, Ltd. Agent: Kama 1) Text - Figure 2
Claims (1)
、Ｓｉを１〜５％、Ｍｎを≦２％、Ｎｂ、Ｔａ、Ｔｉの
中の１種又は２種以上を０．０５〜０．８％、Ｃを≦０
．０７％含み、残部が鉄と不可避不純物から成るエンジ
ン排気系材料。(1) 7-10% Ni and 15-20% Cr by weight
, 1 to 5% of Si, ≦2% of Mn, 0.05 to 0.8% of one or more of Nb, Ta, and Ti, and ≦0 of C.
．． Engine exhaust system material containing 0.7% and the remainder consisting of iron and unavoidable impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9423288A JPH01268836A (en) | 1988-04-15 | 1988-04-15 | Engine exhaust-system material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9423288A JPH01268836A (en) | 1988-04-15 | 1988-04-15 | Engine exhaust-system material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01268836A true JPH01268836A (en) | 1989-10-26 |
Family
ID=14104562
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9423288A Pending JPH01268836A (en) | 1988-04-15 | 1988-04-15 | Engine exhaust-system material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01268836A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013114777A1 (en) * | 2012-02-02 | 2013-08-08 | 住友電気工業株式会社 | Method for evaluation testing of material for internal combustion engine |
| WO2014061830A1 (en) * | 2012-12-25 | 2014-04-24 | 住友電気工業株式会社 | Evaluation test method for internal combustion engine material |
| US10472527B2 (en) | 2015-03-25 | 2019-11-12 | Ngk Insulators, Ltd. | Circumference coating material, bonding material, honeycomb structure, and method of producing honeycomb structure |
-
1988
- 1988-04-15 JP JP9423288A patent/JPH01268836A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013114777A1 (en) * | 2012-02-02 | 2013-08-08 | 住友電気工業株式会社 | Method for evaluation testing of material for internal combustion engine |
| JP2013178220A (en) * | 2012-02-02 | 2013-09-09 | Sumitomo Electric Ind Ltd | Evaluation test method for material for internal combustion engines |
| CN104081182A (en) * | 2012-02-02 | 2014-10-01 | 住友电气工业株式会社 | Method for evaluation testing of material for internal combustion engine |
| WO2014061830A1 (en) * | 2012-12-25 | 2014-04-24 | 住友電気工業株式会社 | Evaluation test method for internal combustion engine material |
| JP2014126401A (en) * | 2012-12-25 | 2014-07-07 | Sumitomo Electric Ind Ltd | Evaluation test method of material for internal combustion engine |
| CN104884951A (en) * | 2012-12-25 | 2015-09-02 | 住友电气工业株式会社 | Evaluation test method for internal combustion engine material |
| US9702838B2 (en) | 2012-12-25 | 2017-07-11 | Sumitomo Electric Industries, Ltd. | Method for evaluation testing of material for internal combustion engine |
| US10472527B2 (en) | 2015-03-25 | 2019-11-12 | Ngk Insulators, Ltd. | Circumference coating material, bonding material, honeycomb structure, and method of producing honeycomb structure |
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