JP2712666B2 - High yield ratio martensitic stainless steel - Google Patents
High yield ratio martensitic stainless steelInfo
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- JP2712666B2 JP2712666B2 JP1314669A JP31466989A JP2712666B2 JP 2712666 B2 JP2712666 B2 JP 2712666B2 JP 1314669 A JP1314669 A JP 1314669A JP 31466989 A JP31466989 A JP 31466989A JP 2712666 B2 JP2712666 B2 JP 2712666B2
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- martensitic stainless
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、高降伏比を実現したマルテンサイト系ステ
ンレス鋼に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a martensitic stainless steel having a high yield ratio.
マルテンサイト系ステンレス鋼は、Cr量を11〜18％と
し、Ｃ含有量を高くして高温の焼入温度におけるオース
テナイト組織から冷却することによって焼入マルテンサ
イト組織が得られるステンレス鋼で、通常13Crステンレ
ス鋼と呼ばれるものである。この13Crステンレス鋼は、
高い強度と硬さが得られ、優れた耐摩耗性を有し、また
比較的腐食性の弱い環境中においては不働態を形成して
良好な耐食性を示すため、構造用材および刃物等などに
多く用いられる。Martensitic stainless steel is a stainless steel having a chromium content of 11 to 18%, a high C content, and cooling from an austenitic structure at a high quenching temperature to obtain a quenched martensitic structure. This is called stainless steel. This 13Cr stainless steel
High strength and hardness are obtained, excellent abrasion resistance, and in a relatively weak corrosive environment, it forms a passive state and shows good corrosion resistance, so it is often used for structural materials and cutting tools etc. Used.
さらに詳しくは、前記マルテンサイト系ステンレス鋼
は、熱間加工後950℃〜1000℃で焼入れた後、さらにAc1
点以下の温度で焼戻しが行われ、その機械的性質が調整
されて所定の降伏応力強度が付与される。一般にマルテ
ンサイト系ステンレス鋼の場合には、降伏比（降伏強度
／引張強度）は0.75程度とされている。More particularly, the martensitic stainless steel, after quenching at 950 ° C. to 1000 ° C. After hot working, further Ac 1
Tempering is performed at a temperature equal to or lower than the point, and its mechanical properties are adjusted to give a predetermined yield stress strength. Generally, in the case of martensitic stainless steel, the yield ratio (yield strength / tensile strength) is about 0.75.
たとえば、SUS420鋼種で代表される前記マルテンサイ
ト系ステンレス鋼は、CO2を含む腐食環境下で優れた耐
食性を示すことから、油井管等の材料として好適とさ
れ、その利用に供されているが、近年、深井戸化および
油井掘削環境の悪化につれ、前記油井管の高強度化なら
びに高靭性化が要求されるとともに、耐応力腐食割れ性
の向上が望まれるようになった。For example, the martensitic stainless steel represented by SUS420 steel type, since it exhibits excellent corrosion resistance in a corrosive environment containing CO 2, is a suitable as a material such as oil well pipes have been subjected to its use In recent years, along with the deepening of wells and the deterioration of the oil well drilling environment, it has been required to increase the strength and toughness of the oil country tubular goods and to improve stress corrosion cracking resistance.
しかしながら、前記問題を解決するために、たとえば
鋼の降伏強度を上げた場合には、同時に引張強度もそれ
に比例して高くなり高硬度化するため、靭性および硫化
水素腐食環境下での割れ感受性が悪化してしまうという
問題点があった。However, in order to solve the above-mentioned problem, for example, when the yield strength of steel is increased, the tensile strength is also increased in proportion thereto and the hardness is increased, so that the toughness and the susceptibility to cracking in a hydrogen sulfide corrosion environment are reduced. There was a problem that it would get worse.
そこで本発明の目的は、引張強度を上げることなし
に、すなわち高硬度化させることなしに降伏強度のみを
向上させるとともに、靭性および耐応力腐食割れ性を向
上させたマルテンサイト系ステンレス鋼を提供すること
にある。Accordingly, an object of the present invention is to provide a martensitic stainless steel that has improved yield strength only without increasing tensile strength, that is, without increasing hardness, and has improved toughness and stress corrosion cracking resistance. It is in.
上記課題を解決するために本発明は、Ｃ＝0.16〜0.25
％、Si＝0.10〜0.80％、Mn＝0.10〜1.00％、Ｐ≦0.025
％、Ｓ≦0.005％、Cr＝11.00〜14.0％、Al≦0.005％、
Ｎ＝0.01〜0.05％を含有するマルテンサイト系ステンレ
ス鋼において、 Ｖを、0.20％以下とし、かつ、 ここに、［Ｖ］:V含有％量、［Ｎ］:N含有％量 を満たすように添加した後、焼入れおよび焼戻しを行う
ことを特徴とするものである。In order to solve the above-mentioned problems, the present invention provides C = 0.16 to 0.25.
%, Si = 0.10-0.80%, Mn = 0.10-1.00%, P ≦ 0.025
%, S ≦ 0.005%, Cr = 11.00-14.0%, Al ≦ 0.005%,
In a martensitic stainless steel containing N = 0.01 to 0.05%, V is set to 0.20% or less, and Here, quenching and tempering are performed after adding so as to satisfy [V]: V content% and [N]: N content%.
一般に、マルテンサイト系ステンレス鋼の靭性および
硬度の向上を図るためには、Ｖ添加が最も有効な方法で
あることは知られている。しかし、前記したように、降
伏強度を上げた場合には、同時に引張強度も上がり、高
硬度化するため逆に靭性等を低下させてしまうおそれが
あった。It is generally known that V addition is the most effective method for improving the toughness and hardness of martensitic stainless steel. However, as described above, when the yield strength is increased, the tensile strength is also increased at the same time, and the hardness is increased, so that the toughness may be reduced.
そこで本発明者は種々の実験を行い、Ｖの添加量をＮ
との相関関係から管理し、ある相関関係の場合には降伏
強度の増加よりも降伏強度の増加が上回り、結果的に高
降伏比のマルテンサイト系ステンレス鋼が得られること
を知見した。具体的には以下に示す式においてVact量が
0.02以上の場合には、その効果を奏しうることが各種試
験の結果明らかとなった。Therefore, the present inventors conducted various experiments and found that the amount of added V was N
It was found that in the case of a certain correlation, the increase in the yield strength exceeded the increase in the yield strength, and as a result, a martensitic stainless steel with a high yield ratio was obtained. Specifically, in the formula shown below, the amount of Vact
In the case of 0.02 or more, it was clarified from various tests that the effect can be obtained.
上式中、Vact;Nと結合しない有効なＶ含有％量 ［Ｖ］;V含有％量 ［Ｎ］;N含有％量 51;Vの原子量 0.003 ;他の元素と結合するため、Ｖと結合で
きないＮの％量 また、上式を満たすことによって、降伏比が上昇する
ため、その分焼戻し温度を高温とすることができるよう
になり、結果的に同一降伏レベルであっても低硬材が得
られ、優れた靭性と耐応力腐食割れ性を向上させること
ができる。 In the above formula, Vact; effective V content% that does not bond with N [V]; V content% [N]; N content 51%; atomic weight of V 0.003; bonds with V to bond with other elements % Of N that cannot be satisfied Further, by satisfying the above expression, the yield ratio is increased, so that the tempering temperature can be increased by that much, and as a result, even if the yield level is the same, the low-hardened material can be reduced. As a result, excellent toughness and stress corrosion cracking resistance can be improved.
本発明に係るマルテンサイト系ステンレス鋼の成分限
定について述べる。The component limitation of the martensitic stainless steel according to the present invention will be described.
（１）炭素［Ｃ］;0.16〜0.25％ Ｃは、焼入れ性を高め、マルテンサイト系ステンレス
鋼の強度を高めるために添加されるが、0.25％を超える
と低温靭性が悪化するとともに、クロム炭化物が増大す
るため耐食性に有効なCr量が減少し、耐食性を損なう恐
れがあるため、0.25％以下とした。また、0.16％未満で
は、焼入性、強度とも劣るため、0.16〜0.25％とした。(1) Carbon [C]; 0.16 to 0.25% C is added in order to enhance hardenability and increase the strength of martensitic stainless steel, but if it exceeds 0.25%, low-temperature toughness deteriorates and chromium carbide is added. Is increased, the amount of Cr effective for corrosion resistance is reduced, and the corrosion resistance may be impaired. If the content is less than 0.16%, the hardenability and the strength are inferior, so the content is set to 0.16 to 0.25%.
（２）ケイ素［Si］;0.10〜0.80％ Siは、脱酸のため添加されるが、0.10％未満では脱酸
不足となり、熱間加工性を悪化させる。また、0.80％を
超えると高温加熱時にδフェライトが生成し熱間加工性
が低下する。したがって、0.10〜0.80％とした。ただ
し、好ましくは、0.20〜0.60％とされる。(2) Silicon [Si]; 0.10 to 0.80% Si is added for deoxidation. However, if it is less than 0.10%, deoxidation becomes insufficient and hot workability is deteriorated. On the other hand, when the content exceeds 0.80%, δ ferrite is generated at the time of high temperature heating, and the hot workability decreases. Therefore, it was set to 0.10 to 0.80%. However, preferably, it is 0.20 to 0.60%.
（３）マンガン［Mn］;0.10〜1.00％ Mnは、靭性および熱間加工性の向上のため添加される
が、0.10％未満ではその効果が小さく、また1.00％を超
えると耐応力腐食割れ性が悪化するため、0.10〜1.00％
とした。(3) Manganese [Mn]; 0.10 to 1.00% Mn is added to improve toughness and hot workability. However, if it is less than 0.10%, its effect is small, and if it exceeds 1.00%, stress corrosion cracking resistance is increased. 0.10-1.00%
And
（４）リン［Ｐ］;0.025％以下 Ｐは靭性上の点からは少ない方が望ましいが、極端に
低くすると、脱リンコストが高くなり経済上好ましくな
いため、上限を0.025％とした。(4) Phosphorus [P]; 0.025% or less P is desirably small from the viewpoint of toughness. However, if P is extremely low, the dephosphorization cost increases, which is not economically preferable. Therefore, the upper limit is set to 0.025%.
（５）硫黄［Ｓ］;0.005％以下 Ｓは、靭性上およびMnSを形成し熱間加工性および耐
食性を劣化させるため、低い方が好ましいが、極度に低
下させると脱硫黄コストが高くなり経済上好ましくない
ため、上限を0.005％とした。(5) Sulfur [S]: 0.005% or less S is preferable in terms of toughness and forming MnS to deteriorate hot workability and corrosion resistance. Since this is not preferable, the upper limit is set to 0.005%.
（６）クロム［Cr］;11.00〜14.00％ Crは、耐食性を確保するために必須の成分であるが、
11.00％未満では耐食性が極端に低下し、また14.00％を
超えると熱間加工性および経済性上好ましくないため、
11.00〜14.00％とした。ただし、好ましくは12.00〜14.
00％とされる。(6) Chromium [Cr]; 11.00-14.00% Cr is an essential component for ensuring corrosion resistance.
If it is less than 11.00%, the corrosion resistance is extremely reduced, and if it exceeds 14.00%, it is not preferable in terms of hot workability and economy,
11.00 to 14.00%. However, preferably 12.00 to 14.
00%.
（７）窒素［Ｎ］;0.01〜0.05％ Ｎは、耐食性向上のため添加されるが、0.01％未満で
はその効果も小さく、また0.05％を超えた場合には熱間
加工性が低下させるため好ましくないため、0.01〜0.05
％とした。(7) Nitrogen [N]: 0.01 to 0.05% N is added for improving corrosion resistance. However, if its content is less than 0.01%, its effect is small, and if it exceeds 0.05%, hot workability is reduced. Unfavorable, 0.01-0.05
%.
（８）バナジウム［Ｖ］;0.20％以下で、かつ下式によ
る ここに、Vact;Nに結合されない有効なＶ含有％量 ［Ｖ］;V含有％量 ［Ｎ］;N含有％量 Vact≧0.02 Ｖは、発明の効果を奏し得るための元素であり、Vact
量≧0.02は実施例に示される試験結果により見出される
範囲である。Vactが0.02未満では、降伏比が0.76〜0.75
となり本発明の要旨となる効果を奏しえなく、Vactが0.
02以上になると初めて降伏比が0.8レベルまで上昇す
る。ただし、Ｖ添加はコストアップとなり、また過剰Ｖ
は、Ｖの炭窒化物が析出し靭性上好ましくないため、0.
20％以下とした。(8) Vanadium [V]: 0.20% or less and according to the following formula Here, effective V content% not bound to Vact; N [V]; V content% [N]; N content% Vact ≧ 0.02 V is an element for achieving the effects of the invention, and
Amount ≧ 0.02 is the range found by the test results shown in the examples. When Vact is less than 0.02, the yield ratio is 0.76-0.75
Vact is 0.
For the first time above 02, the yield ratio rises to the 0.8 level. However, the addition of V increases the cost, and the excess V
Is not preferable from the viewpoint of toughness due to precipitation of carbonitrides of V.
20% or less.
（９）アルミニウム［Al］;0.005％以下 Alは脱酸剤として添加し、0.005％を超える場合にはA
l2O3系介在物が増加し鋼の清浄度を損なうため、0.005
％以下に制限される。(9) Aluminum [Al]: 0.005% or less Al is added as a deoxidizing agent.
l 2 O 3 inclusions increase and impair the cleanliness of the steel.
%.
以下実施例により本発明の効果を明らかにする。 Hereinafter, the effects of the present invention will be clarified by examples.
（実施例−１） 表−１に示される８種類のマルテンサイト系ステンレ
ス鋼に対して引張試験を行い、得られた結果を第１図に
示す。Example 1 Ten kinds of martensitic stainless steels shown in Table 1 were subjected to a tensile test, and the obtained results are shown in FIG.
前記８種類のマルテンサイト系ステンレス鋼は、表−
１の右方に示されるような組合せで夫々ＮとＶ量を変化
させ溶製し、製造した185mmφ丸ビレットをピアサー・
プラグミル・サイザーの装置によって順次、圧延・加工
され得られた73mmφ×5.51mmt、114.3mmφ×6.88mmtお
よび127mmφ×9.19mmtの鋼管を940℃〜1050℃で焼入れ
し、さらに675℃〜750℃で焼戻しを行ったものである。The eight martensitic stainless steels are listed in Table-
The 185mmφ round billet produced and melted by changing the amounts of N and V respectively in the combination shown on the right side of No. 1
The 73mmφ × 5.51mmt, 114.3mmφ × 6.88mmt and 127mmφ × 9.19mmt steel pipes obtained by rolling and processing sequentially by the plug mill and sizer equipment are quenched at 940 ° C to 1050 ° C and further tempered at 675 ° C to 750 ° C. It was done.
第１図は縦軸に降伏比（Y.R）を示し、横軸にVact量
を示している。第１図よりVact量が0.02以上になると降
伏比が急激に上がっていることが判明している。FIG. 1 shows the yield ratio (YR) on the vertical axis and the Vact amount on the horizontal axis. FIG. 1 shows that when the Vact amount becomes 0.02 or more, the yield ratio sharply increases.
（実施例−２） 第２実施例も第１実施例と同様の試験を行い、さらに
前記効果を確認した。(Example-2) In the second example, the same test as in the first example was performed, and the above-mentioned effect was further confirmed.
本実施例においては、Ｃ＝0.18〜0.20％、Si＝0.33〜
0.40％、Mn＝0.60〜0.75％、Cr＝12.50〜13.00％、Al≦
0.005％以下、Ｐ≦0.025％以下、Ｓ≦0.005％以下の範
囲の元素を含有するマルテンサイト系ステンレス鋼に対
して、ＮとＶ量を変えて添加させ、溶製し製造した185m
mφ丸ビレットからマンネスマン・マンドレル法によっ
て、73mmφ×5.51mmtおよび114.3mmφ×6.88mmtに圧延
後、1000℃で加熱し焼入れを行い、降伏応力56kg/mm2の
規格となるように焼戻しを行い、そして得られたマルテ
ンサイト系ステンレス鋼の供試体に対して引張試験を行
い、得られた結果を第２図に示す。縦軸は降伏比（Y.
R）を示し、横軸はＮ量とＹ量から得られるVact量であ
る。本実施例の場合も第１実施例同様、第２図から降伏
比（Y.R）は、Vact量が0.02以上になると急激に上昇す
ることが判明している。In this embodiment, C = 0.18 to 0.20%, Si = 0.33 to
0.40%, Mn = 0.60-0.75%, Cr = 12.50-13.00%, Al ≦
185m produced by melting and adding to martensitic stainless steel containing elements in the range of 0.005% or less, P ≦ 0.025% or less and S ≦ 0.005% or less while changing the amounts of N and V
by Mannesmann mandrel method from mφ round billet, after rolling into 73mmφ × 5.51mmt and 114.3mmφ × 6.88mmt, perform quenching heated at 1000 ° C., subjected to tempering so that the yield stress 56kg / mm 2 standard, and A tensile test was performed on the obtained martensitic stainless steel specimen, and the obtained results are shown in FIG. The vertical axis shows the yield ratio (Y.
R), and the horizontal axis is the Vact amount obtained from the N amount and the Y amount. In the case of this embodiment, as in the first embodiment, it is clear from FIG. 2 that the yield ratio (YR) sharply increases when the Vact amount becomes 0.02 or more.
（実施例−３） 第３実施例の場合は、ＮおよびＶをおれぞれ変えたマ
ルテンサイト系ステンレス鋼に対して、引張試験の他に
硬さ試験、シャルピー試験および定荷重応力腐食試験を
行った。 (Example-3) In the case of the third example, a hardness test, a Charpy test, and a constant load stress corrosion test were performed on a martensitic stainless steel in which N and V were changed, in addition to a tensile test. went.
本実施例においては、Ｃ＝0.20％、Si＝0.35％、Mn＝
0.70％、Ｐ＝0.015％、Ｓ＝0.001％、Al＝0.002％、Cr
＝12.75％をそれぞれ含有するマルテンサイト系ステン
レス鋼に対して、表−２に示すような組合せでＮとＶ量
を変化させ溶製し、製造した185mmφ丸ビレットからマ
ンネスマン・マンドレル法によつて114.3mmφ×6.68mmt
に圧延後、950℃〜1000℃で加熱し焼入れした後、700℃
〜730℃で焼戻しを行い、降伏応力56.2kg/mm2以上の規
格に製造された８種類のマルテンサイト系ステンレス鋼
に対して、引張試験および硬さ試験並びにシャルピー試
験を行い、その結果を表−２に示す。In this embodiment, C = 0.20%, Si = 0.35%, Mn =
0.70%, P = 0.015%, S = 0.001%, Al = 0.002%, Cr
Of martensitic stainless steel containing 12.75% each was melted by changing the amounts of N and V in combinations shown in Table 2, and the resulting 185 mmφ round billet was manufactured by the Mannesmann-Mandrel method to obtain 114.3%. mmφ × 6.68mmt
After rolling to 950 ° C to 1000 ° C and quenching, 700 ° C
Perform tempering at ～730 ° C., with respect to eight martensitic stainless steel produced in yield stress 56.2kg / mm 2 or more standards, subjected to tensile test and hardness test and Charpy test, the table and the results -2.
表中、Y.S;降伏強度 T.S;引張強度 Y.R;降伏強度と引張強度の比 VEO:1/2サブサイズ試験片によるシャルピー
吸収エネルギー σth ;NACE・TM−01−07で規定されている液中
で定荷重応力腐食試験における破断限界応力 SMYS ;規定された最小降伏応力 実施例−３の場合には、Vact量≧0.02の場合には表−
２から判明するように、Y.Rが全て0.8以上となってお
り、比較鋼に比べると、同一降伏レベルであるにもかか
わらず、降伏比が高くなっている。また、低硬度剤とな
り、靭性および耐応力腐食割れ特性の優れたマルテンサ
イト系ステンレス鋼となっていることが判明する。In the table, YS: Yield strength TS; Tensile strength YR: Ratio of yield strength to tensile strength VE O : Charpy absorbed energy by 1/2 sub-size test piece σth: In liquid specified by NACETM-01-07 Breaking stress SMYS in constant load stress corrosion test with specified minimum yield stress In the case of Example-3, when Vact amount ≧ 0.02, the table
As is clear from FIG. 2, the YRs are all 0.8 or more, and the yield ratio is higher than that of the comparative steel despite the same yield level. In addition, it turns out to be a low-hardening agent and a martensitic stainless steel excellent in toughness and stress corrosion cracking resistance.
〔発明の効果〕 以上詳説したように本発明によれば、マルテンサイト
系ステンレス鋼において、Ｎとの関係式で算出されるＶ
量を一定の値以上添加することにより、高降伏比が得ら
れるとともに、靭性および耐応力腐食割れ性に優れたマ
ルテンサイト系ステンレス鋼を得ることができる。[Effects of the Invention] As described above in detail, according to the present invention, in martensitic stainless steel, V calculated by a relational expression with N is used.
By adding the amount more than a certain value, a high yield ratio can be obtained and a martensitic stainless steel excellent in toughness and stress corrosion cracking resistance can be obtained.
第１図は第１実施例における試験結果を示す図、第２図
は第２実施例における試験結果を示す図である。FIG. 1 is a diagram showing test results in the first embodiment, and FIG. 2 is a diagram showing test results in the second embodiment.
Claims (1)
＝0.10〜1.00％、Ｐ≦0.025％、Ｓ≦0.005％、Cr＝11.0
0〜14.00％、Al≦0.005％、Ｎ＝0.01〜0.05％を含有す
るマルテンサイト系ステンレス鋼において、 Ｖを、0.20％以下とし、かつ、 ここに、［Ｖ］:V含有％量、［Ｎ］:N含有％量 を満たすように添加した後、焼入れおよび焼戻しを行う
ことを特徴とする高降伏比のマルテンサイト系ステンレ
ス鋼。(1) C = 0.16 to 0.25%, Si = 0.10 to 0.80%, Mn
= 0.10-1.00%, P ≦ 0.025%, S ≦ 0.005%, Cr = 11.0
In a martensitic stainless steel containing 0 to 14.00%, Al ≦ 0.005%, and N = 0.01 to 0.05%, V is set to 0.20% or less, and A martensitic stainless steel with a high yield ratio characterized by adding [V]: V content% and [N]: N content%, followed by quenching and tempering.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1314669A JP2712666B2 (en) | 1989-12-04 | 1989-12-04 | High yield ratio martensitic stainless steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1314669A JP2712666B2 (en) | 1989-12-04 | 1989-12-04 | High yield ratio martensitic stainless steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03177541A JPH03177541A (en) | 1991-08-01 |
| JP2712666B2 true JP2712666B2 (en) | 1998-02-16 |
Family
ID=18056122
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1314669A Expired - Lifetime JP2712666B2 (en) | 1989-12-04 | 1989-12-04 | High yield ratio martensitic stainless steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2712666B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019196530A (en) * | 2018-05-11 | 2019-11-14 | 株式会社デンソー | Martensitic stainless steel |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6169947A (en) * | 1984-09-13 | 1986-04-10 | Kobe Steel Ltd | Martensitic stainless steel superior in sulfide stress cracking resistance |
| EP0210122B1 (en) * | 1985-07-09 | 1990-01-03 | Mitsubishi Jukogyo Kabushiki Kaisha | Steam turbine rotor for high temperature and method for manufacturing same |
-
1989
- 1989-12-04 JP JP1314669A patent/JP2712666B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03177541A (en) | 1991-08-01 |
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