JPH0452218A - Manufacture of high toughness cast steel - Google Patents
Manufacture of high toughness cast steelInfo
- Publication number
- JPH0452218A JPH0452218A JP2163387A JP16338790A JPH0452218A JP H0452218 A JPH0452218 A JP H0452218A JP 2163387 A JP2163387 A JP 2163387A JP 16338790 A JP16338790 A JP 16338790A JP H0452218 A JPH0452218 A JP H0452218A
- Authority
- JP
- Japan
- Prior art keywords
- cast steel
- toughness
- molten metal
- amount
- austenite
- 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.)
- Granted
Links
- 229910001208 Crucible steel Inorganic materials 0.000 title claims abstract description 18
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 8
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 44
- 239000002184 metal Substances 0.000 claims abstract description 36
- 229910052751 metal Inorganic materials 0.000 claims abstract description 36
- 238000001816 cooling Methods 0.000 claims abstract description 27
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 16
- 238000005266 casting Methods 0.000 claims abstract description 11
- 230000000717 retained effect Effects 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 238000005279 austempering Methods 0.000 abstract description 19
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 16
- 229910002804 graphite Inorganic materials 0.000 abstract description 14
- 239000010439 graphite Substances 0.000 abstract description 14
- 229910001567 cementite Inorganic materials 0.000 abstract description 12
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 abstract description 12
- 229910052799 carbon Inorganic materials 0.000 abstract description 6
- 230000015572 biosynthetic process Effects 0.000 abstract description 5
- 229910052802 copper Inorganic materials 0.000 abstract description 2
- 238000010438 heat treatment Methods 0.000 abstract 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 abstract 1
- 239000010949 copper Substances 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 14
- 239000000463 material Substances 0.000 description 11
- 229910052748 manganese Inorganic materials 0.000 description 8
- 229910052717 sulfur Inorganic materials 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 238000001000 micrograph Methods 0.000 description 6
- 229910052750 molybdenum Inorganic materials 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 5
- 229910052698 phosphorus Inorganic materials 0.000 description 5
- 239000004576 sand Substances 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 238000005275 alloying Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000007712 rapid solidification Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- -1 s~1.2% Inorganic materials 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
Description
【発明の詳細な説明】 ［産業上の利用分野］ 本発明は高靭性鋳鋼の製造方法に関する。[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing high toughness cast steel.
［従来の技術］
鋳゛鋼には、フェライト系、パーライト系、ベイナイト
系、マルテンサイト系がある。しかしながら、−船釣に
鋳鋼では高靭性を得ることが困難である。そこで、鋳鋼
を鋳造した後に、オーステンパー処理して、基地組織を
ベイナイト組織として高靭性を得ている。[Prior Art] Cast steels include ferritic, pearlite, bainite, and martensitic steels. However, it is difficult to obtain high toughness with cast steel for boat fishing. Therefore, after casting the cast steel, it is subjected to austempering treatment to change the base structure to a bainite structure to obtain high toughness.
例えば、カナダ特許第１１３０６１７号では、重量比で
Ｃ；Ｏ、ｓ〜１．２％、Ｓ ｉ；２．０〜２．６％、Ｍ
ｎ；０．３〜１．０％、ＣｒおよびＮｉ；１％以下、そ
の他にＮｂ、ＡＩ、Ｍｏ等を少量含有する鋼をオーステ
ンパー処理することにより、ベイナイト−オーステナイ
ト組織とし、高強度で高靭性の鋼を得ている。この発明
においては、高Ｓｉ含有量とすることにより、オーステ
ンパー処理におけるセメンタイトの析出を防止し、生成
するベイナイトのＣ含有量を低めるとともに、結果とし
て残留オーステナイトのＣ含有量を増加し、残留オース
テナイトが安定化して、高強度および高靭性が得られて
いる。For example, in Canadian Patent No. 1130617, C; O, s~1.2%, Si; 2.0~2.6%, M
By austempering steel containing n: 0.3 to 1.0%, Cr and Ni: 1% or less, and small amounts of Nb, AI, Mo, etc., it becomes a bainite-austenite structure with high strength and high strength. You are getting toughness steel. In this invention, by setting a high Si content, precipitation of cementite during austempering treatment is prevented, the C content of the generated bainite is lowered, and as a result, the C content of retained austenite is increased, and the retained austenite is is stabilized, resulting in high strength and toughness.
また、特開昭６２−１１２７３５号公報においては、重
量比でＣ；０．３〜１．０％、Ｓ ｉ；２．０〜４．５
％、Ｍｎ；０．８％以下、Ｍｏ；０．０５〜１．０％、
Ｎ ｉ；２．０％以下を含有する鋳鋼を、オーステンパ
ー処理し、基地組織中のベイナイト量を４０％以上とし
、鋳放し状態ではパーライト基地組織中にフェライトお
よび黒鉛を多量に析出させて優れた被剛性を確保し、機
械加工後の所定のオーステンパー処理により、基地組織
を均一なベイナイト組織とすることによって、優れた強
度特性と高い縦弾性係数を得ている。Furthermore, in JP-A-62-112735, the weight ratio of C: 0.3 to 1.0%, Si: 2.0 to 4.5
%, Mn; 0.8% or less, Mo; 0.05 to 1.0%,
Cast steel containing Ni: 2.0% or less is austempered to make the amount of bainite in the matrix structure 40% or more, and in the as-cast state, a large amount of ferrite and graphite are precipitated in the pearlite matrix structure, making it excellent. Excellent strength characteristics and a high modulus of longitudinal elasticity are obtained by ensuring high rigidity and by making the base structure a uniform bainite structure through a predetermined austempering treatment after machining.
［発明が解決しようとする課題］
しかしながら、前記発明のおいては、ＣおよびＳｉ含有
量が高いため、鋳造時またはオーステンパー処理時に含
有されているＣが黒鉛化し易く、靭性の低下をきたす。[Problems to be Solved by the Invention] However, in the above invention, since the C and Si contents are high, the C contained during casting or austempering tends to graphitize, resulting in a decrease in toughness.
さらに、−船釣な鋳造法では、均一微細な組織かえられ
に＜＜、かつＭＯ等を含有させると、遊離セメンタイト
が晶出し、さらに靭性を低下する。Furthermore, in the conventional casting method, if the uniform fine structure is changed and MO is added, free cementite will crystallize, further reducing the toughness.
ｔた、鋳鋼は一般に砂型に鋳造されるが、砂型で鋳造す
る場合は、溶湯の凝固速度が遅いため、Ｍｏ、Ｍｎ等が
偏析し、未変態オーステナイトが多量に残留する。この
未変態オーステナイトは非常に不安定であるため、マル
テンサイト変態しやすく、靭性が大きく低下する。この
ことは、未変態オーステナイト量と衝撃値の関係を示す
第２図から、未変態オーステナイトの増加により、衝撃
値が急激に低下することから明らかである。In addition, cast steel is generally cast in a sand mold, but when cast in a sand mold, the solidification rate of the molten metal is slow, so Mo, Mn, etc. segregate, and a large amount of untransformed austenite remains. Since this untransformed austenite is very unstable, it is easily transformed to martensitic material, resulting in a significant decrease in toughness. This is clear from FIG. 2, which shows the relationship between the amount of untransformed austenite and the impact value, because the impact value rapidly decreases as the amount of untransformed austenite increases.
また、遊離セメンタイトが多量に残留するので、脆化す
るとともに、黒鉛が析出し易くなり、伸びが低下し脆く
なる。その上、凝固組織が粗大化しているため、オース
テンパー処理により得られるベイナイト組織は不均一て
、粗いものとなり靭性が低下する等の問題点がある。Furthermore, since a large amount of free cementite remains, it becomes brittle and graphite tends to precipitate, resulting in decreased elongation and brittleness. Moreover, since the solidified structure is coarsened, the bainite structure obtained by the austempering process is uneven and coarse, resulting in problems such as reduced toughness.
本発明は鋳造後オーステンパー処理してベイナイト組織
を得て鋳鋼を強靭化する高靭性鋳鋼の製造方法における
前記のごとき問題点に鑑みてなされたものであって、未
変態オーステナイトが少なく、均一微細なベイナイト組
織が得られる高靭性鋳鋼の製造方法を提供することを目
的とする。The present invention has been made in view of the above-mentioned problems in the manufacturing method of high-toughness cast steel, in which austempering treatment is performed after casting to obtain a bainite structure to strengthen the cast steel. The purpose of the present invention is to provide a method for manufacturing high-toughness cast steel that provides a bainite structure.
［課題を解決するための手段］
本発明の高靭性鋳鋼の製造方法は、重量比で、Ｃ；０．
３〜０．７％、Ｓｉ；１．８〜３．０％を含有し、残部
がＦｅおよび不純物元素からなる溶湯を、４℃／ｓｅｃ
以上の冷却速度で鋳造した後、オーステンパー処理し均
一微細なベイナイトと安定な残留オーステナイトの混合
組織とすることを要旨とする。[Means for Solving the Problems] The method for producing high toughness cast steel of the present invention has a weight ratio of C: 0.
A molten metal containing 3 to 0.7% Si, 1.8 to 3.0% Si, and the balance consisting of Fe and impurity elements was heated at 4°C/sec.
After casting at the above cooling rate, the material is austempered to form a mixed structure of uniformly fine bainite and stable retained austenite.
発明者は、第２図の未変態オーステナイト量と衝撃値の
関係に示すように、未変態オーステナイト量が５％を越
えると急激に衝撃値が低下することから、少なくとも未
変態オーステナイト量を５％以下にすべきであることを
認識した。そこで、溶湯の冷却速度と未変態オーステナ
イト量との関係を研究したところ、第１図に示すような
結果を得た。そして、発明者は第１図の結果より、未変
態オーステナイト量を５％未満に抑えるには、溶湯の冷
却速度を４℃／ｓｅｅ以上にすると良いということを新
たに知見した。As shown in the relationship between the amount of untransformed austenite and the impact value in Figure 2, the impact value decreases rapidly when the amount of untransformed austenite exceeds 5%, so the inventor determined that the amount of untransformed austenite should be at least 5%. I realized that I should do the following. Therefore, when we studied the relationship between the cooling rate of the molten metal and the amount of untransformed austenite, we obtained the results shown in Figure 1. From the results shown in FIG. 1, the inventors have newly found that in order to suppress the amount of untransformed austenite to less than 5%, it is better to set the cooling rate of the molten metal to 4° C./see or higher.
また、オーステンパー処理によって、黒鉛が析出せず、
遊離セメンタイトの生成の少ない均一微細なベイナイト
組織を得るために、合金成分について鋭意検討を重ねた
。その結果、低Ｃ化により黒鉛の析出を抑制し、遊離セ
メンタイトの生成を防止する範囲にＳｉ量を規制して、
本発明を完成した。In addition, due to austempering treatment, graphite does not precipitate,
In order to obtain a uniform, fine bainite structure with little free cementite formation, we conducted extensive research on alloy components. As a result, the amount of Si was regulated within a range that suppressed graphite precipitation by lowering C and prevented the formation of free cementite.
The invention has been completed.
なお、Ｍｎは脱酸脱硫のために加えられ、オーステナイ
トを安定化して鋼に靭性をｆ１与するが、本発明におい
ては０８％を越えて含有されると、偏析により靭性が劣
化するので、Ｍｎ含有量は０゜８％以下とすることが望
ましい、また、ＰおよびＳは有害元素であり、出来るだ
け少ない方が望ましいが、本発明においては脆化を防止
するためには、Ｐは０．１％以下の含有量に、Ｓは０．
０７％以下の含有量にすることが望ましい。Note that Mn is added for deoxidation and desulfurization, stabilizes austenite, and imparts toughness f1 to steel. It is desirable that the content be 0.8% or less, and P and S are harmful elements, so it is desirable that they be as low as possible; however, in the present invention, in order to prevent embrittlement, P should be 0.8% or less. When the content is 1% or less, S is 0.
It is desirable that the content be 0.7% or less.
さらに、本発明においては、オーステナイトを安定化し
結晶粒度を微細化するため、ＭＯ５Ｃｕ、Ｖ、Ｎｉ、Ａ
Ｉ等の合金元素のうちの１種または２種以上を少量含有
せしめることは差し支えない。Furthermore, in the present invention, in order to stabilize austenite and refine grain size, MO5Cu, V, Ni, A
There is no problem in containing a small amount of one or more of alloying elements such as I.
しかし、ＭＯは０．７％を越えて含有されると、遊離セ
メンタイトが晶出し脆化するので、上限を０７％とする
ことが望ましい、また、その他の合金元素も多量に含有
されると脆化するので、Ｃｕ、■、Ｎｉにあっては１％
を、Ａ１にあっては０．１％を上限とすることが望まし
い。However, if MO is contained in an amount exceeding 0.7%, free cementite will crystallize and become brittle, so it is desirable to set the upper limit to 0.7%.Additionally, if large amounts of other alloying elements are also contained, it will become brittle. 1% for Cu, ■, and Ni.
For A1, it is desirable to set the upper limit to 0.1%.
［作用］
本発明方法においては、溶湯の冷却速度を４℃／ｓｅｃ
以上として鋳造するので、未変態オーステナイト量を５
％未満にすることができ、衝撃値が著しく改善される。[Function] In the method of the present invention, the cooling rate of the molten metal is set at 4°C/sec.
Since casting is performed as above, the amount of untransformed austenite is 5
%, the impact value is significantly improved.
また、オーステンパー処理をしても、低Ｃにより黒鉛の
析出しないベイナイト組織が得られるため、黒鉛による
局部応力集中、脆化が低減し、強度、靭性が向上する。Furthermore, even when austempering is performed, a bainite structure in which graphite does not precipitate is obtained due to the low C, so local stress concentration and embrittlement due to graphite are reduced, and strength and toughness are improved.
さらに、低Ｃと急速凝固を組み合わせることにより、黒
鉛、未変態の塊状オーステナイト、遊離セメンタイト等
の少ない、均一微細なベイニティックフェライトと残留
オーステナイトの混合組織が得られる。また、低Ｃのた
め延性に富んだ組織となる。これにより、優れた強度と
靭性が得られる。Furthermore, by combining low C and rapid solidification, a uniform and fine mixed structure of bainitic ferrite and retained austenite with little graphite, untransformed massive austenite, free cementite, etc. can be obtained. In addition, due to the low carbon content, the structure is highly ductile. This provides excellent strength and toughness.
次に、本発明において合金元素の組成範囲を限定した理
由について説明する。Next, the reason why the composition range of alloying elements is limited in the present invention will be explained.
Ｃ；０．３〜０７％
Ｃは鋳鋼の強度を確保し安定なオーステナイトを残留さ
せるために必要な元素である。０．３％未満であると、
安定なオーステナイトが残留せず、靭性が低下するので
、下限を０．３％とした。しかし、０ 、７ ％を越え
て含有されると、黒鉛が生成し靭性が低下するので、上
限を０ 、７ ％とした。C: 0.3-07% C is an element necessary to ensure the strength of cast steel and to maintain stable austenite. If it is less than 0.3%,
Since no stable austenite remains and the toughness decreases, the lower limit was set at 0.3%. However, if the content exceeds 0.7%, graphite will be generated and the toughness will decrease, so the upper limit was set at 0.7%.
Ｓｉ；１．８〜３．０％
Ｓｉは炭化物特に遊離セメンタイトの生成を抑制する元
素である。１．８％未満の含有量であると、炭化物の形
成が起こり易くなり、安定なオーステナイトが多量に残
留しなくなるので、１．８％以上含有させる必要がある
。しかし、３ 、０ ％を越えて含有させると、フェラ
イトを脆くして靭性を劣化するので、上限を３．０％と
した。Si: 1.8 to 3.0% Si is an element that suppresses the formation of carbides, especially free cementite. If the content is less than 1.8%, carbide formation tends to occur and a large amount of stable austenite will not remain, so the content should be 1.8% or more. However, if the content exceeds 3.0%, the ferrite becomes brittle and its toughness deteriorates, so the upper limit was set at 3.0%.
また、本発明において、溶湯の冷却速度を４℃／ｓｅｃ
以上としたのは、４℃／ｓｅｅ未満であると、未変態オ
ーステナイト量が５％以上となり、衝撃値が急激に劣化
するからである。In addition, in the present invention, the cooling rate of the molten metal is set at 4°C/sec.
The reason for this is that if the temperature is less than 4° C./see, the amount of untransformed austenite will be 5% or more, and the impact value will deteriorate rapidly.
［実施例］
本発明の実施例について比較例とともに説明し、本発明
の効果を明らかにする。[Example] Examples of the present invention will be explained together with comparative examples to clarify the effects of the present invention.
（実施例１）
０．５％Ｃ２２，５％Ｓｉ、０．３％Ｍｎ、０．０１５
％Ｐ、ｏ、ｏｏｓ％Ｓ、０．３％Ｍｏ、０．３％Ｎｉ、
０．０５％ＡＩを含有し、残部が実質的にＦｅである溶
湯を、調水冷型を有する金型を用いて鋳造を行った９な
お、溶湯の冷却速度は１５℃／ｓｅｃであった。未変態
オーステナイト量を測定した後、オーステンパー処理（
オーステナイト化：９００℃Ｘ１ｈｒ、ベイナイト化：
４００℃Ｘ ｌ ｈｒ）を施した。(Example 1) 0.5%C22, 5%Si, 0.3%Mn, 0.015
%P, o, oos%S, 0.3%Mo, 0.3%Ni,
A molten metal containing 0.05% AI and the balance being substantially Fe was cast using a mold having a water-controlled cooling mold.9 The cooling rate of the molten metal was 15° C./sec. After measuring the amount of untransformed austenite, austempering treatment (
Austenitization: 900°C x 1 hr, Bainitization:
400°C x 1 hr).
次いで、所定の試験片を調製して、引張強さおよび衝撃
値を測定した。Then, predetermined test pieces were prepared and the tensile strength and impact value were measured.
（実施例２）
実施例１で用いたと同じ成分組成の溶湯を、調水冷型を
有する金型を用いて鋳造を行った。なお、溶湯の冷却速
度は１５℃／ ！ＩＩ ｅ ｅであった。未変態オース
テナイト量を測定した後、オーステンパー処理（オース
テナイト化：９００℃×１ｈ「、ベイナイト化：３７０
℃Ｘ１ｈｒ）を施した０次いで、所定の試験片を調製し
て、引張強さおよび衝撃値を測定した。(Example 2) A molten metal having the same composition as that used in Example 1 was cast using a mold having a controlled water cooling mold. The cooling rate of the molten metal is 15℃/! It was II ee. After measuring the amount of untransformed austenite, austemper treatment (Austenitization: 900°C x 1h, Bainitization: 370℃
Then, prescribed test pieces were prepared and the tensile strength and impact value were measured.
（実施例３）
実施例１と同じ成分組成の溶湯を、調水冷型を有する金
型を用いて鋳造を行った。なお、溶湯の冷却速度は１５
℃／ｓｅｅであった。未変態オーステナイト量を測定し
ｆＳ後、オーステンパー処理（オーステナイト化：９０
０℃Ｘ１ｈｒ、ベイナイト化＝３３０℃Ｘ２ｈｒ）を施
した。次いで、所定の試験片を調製して、引張強さおよ
び衝撃値を測定した。(Example 3) A molten metal having the same composition as in Example 1 was cast using a mold having a controlled water cooling mold. The cooling rate of the molten metal is 15
℃/see. After measuring the amount of untransformed austenite and performing fS, austempering treatment (austenitization: 90
0° C. for 1 hr, bainitization = 330° C. for 2 hr). Then, predetermined test pieces were prepared and the tensile strength and impact value were measured.
（実施例４）
実施例１と同じ成分組成の溶湯を、調水冷型を有する金
型を用いて鋳造を行った。なお、溶湯の冷却速度は１５
℃／ｓｅｅであった。未変態オーステナイト量を測定し
た後、オーステンパー処理（オーステナイト化：９００
℃Ｘ１ｈｒ、ベイナイト化：２８５℃Ｘ２ｈｒ）を施し
た。次いで、所定の試験片を調製して、引張強さおよび
衝撃値を測定した。(Example 4) A molten metal having the same composition as in Example 1 was cast using a mold having a controlled water cooling mold. The cooling rate of the molten metal is 15
℃/see. After measuring the amount of untransformed austenite, austemper treatment (austenitization: 900
℃×1hr, bainitization: 285℃×2hr). Then, predetermined test pieces were prepared and the tensile strength and impact value were measured.
（実施例５）
０．３％Ｃ，３％Ｓｉ、０．５％Ｍｎ、０．０１５％Ｐ
、０．０１％Ｓ、０．５％Ｃｕ、０．５％Ｖ、Ｏ。(Example 5) 0.3%C, 3%Si, 0.5%Mn, 0.015%P
, 0.01% S, 0.5% Cu, 0.5% V, O.
０８％Ａ１を含有し、残部が実質的にＦｅである溶湯を
、調水冷型を有する金型を用いて鋳造を行った。なお、
溶湯の冷却速度は１５℃／ｓｅｅであった。未変態オー
ステナイト量を測定した後、オ−ステンパー処理（オー
ステナイト化＝９００℃×１ｈｒ、ベイナイト化：３７
０℃Ｘ １ ｈｒ）を施した。次いで、所定の試験片を
調製して、引張強さおよび衝撃値を測定しな。A molten metal containing 0.08% A1 and the remainder being substantially Fe was cast using a mold having a water-controlled cooling mold. In addition,
The cooling rate of the molten metal was 15°C/see. After measuring the amount of untransformed austenite, austempering treatment (austenitization = 900°C x 1 hr, bainitization: 37
0° C. x 1 hr). Then, prepare a given test specimen and measure the tensile strength and impact value.
（実施例６）
０．７％Ｃ２２，２％Ｓｉ、０．２％Ｍｎ、０．０２％
Ｐ、０．００４％Ｓ、０．２％Ｍｏを含有し、残部が実
質的にＦｅである溶湯を、調水冷型を有する金型を用い
て鋳造を行った。なお、溶湯の冷却速度は１５℃／ｓｅ
ｅであった。未変態オーステナイト量を測定した後、オ
ーステンパー処理（オーステナイト化＝９３０℃Ｘ１ｈ
ｒ、ベイナイト化：３５０℃Ｘ２ｈｒ）を施した０次い
で、所定の試験片を調製して、引張強さおよび衝撃値を
測定した。(Example 6) 0.7%C22, 2%Si, 0.2%Mn, 0.02%
A molten metal containing P, 0.004% S, and 0.2% Mo, with the remainder being substantially Fe, was cast using a mold having a controlled water cooling mold. Note that the cooling rate of the molten metal is 15°C/sec.
It was e. After measuring the amount of untransformed austenite, austempering treatment (austenitization = 930°C x 1 hour)
bainitization: 350° C. for 2 hours) Then, prescribed test pieces were prepared, and the tensile strength and impact value were measured.
（比較例１）
１．０％Ｃ２２，４％Ｓｉ、０．５％Ｍｎ、０．３％Ｎ
ｉ、０．１％Ｍｏ、０，０５％ＡＩを含有し、残部が実
質的にＦｅである溶湯を、生砂型へ重力鋳造法にて鋳造
した。なお、溶湯の冷却速度は２．５”Ｃ／ｓｅｅであ
った。未変態オーステナイト量を測定した後、オーステ
ンパー処理（オーステナイト化＝９００℃×１ｈ「、ベ
イナイト化＝３７０℃×１ｈｒ）を施した。次いで、所
定の試験片を調製して、引張強さおよび衝撃値を測定し
た。(Comparative Example 1) 1.0%C22, 4%Si, 0.5%Mn, 0.3%N
A molten metal containing I, 0.1% Mo, and 0.05% AI, with the remainder being substantially Fe, was cast into a green sand mold by gravity casting. The cooling rate of the molten metal was 2.5"C/see. After measuring the amount of untransformed austenite, it was subjected to austempering treatment (austenitization = 900°C x 1h, bainitization = 370°C x 1hr). Then, prescribed test pieces were prepared and the tensile strength and impact value were measured.
（比較例２）
０．５％Ｃ５２，５％Ｓｉ、０．３％Ｍｎ、０．０１５
％Ｐ、ｏ 、ｏ ｏ ｓ％Ｓ、０．３％Ｍｏ、０．３％
Ｎｉ、０．０５％Ａ１を含有し、残部が実質的にＦｅで
ある溶湯を、生砂型へ重力鋳造法にて鋳造した。(Comparative Example 2) 0.5%C52, 5%Si, 0.3%Mn, 0.015
%P,o,o s%S, 0.3%Mo, 0.3%
A molten metal containing Ni and 0.05% A1, with the remainder being substantially Fe, was cast into a green sand mold by gravity casting.
なお、溶湯の冷却速度は２，５℃／ｓｅｃであった。Note that the cooling rate of the molten metal was 2.5° C./sec.
未変態オーステナイト量を測定した後、オーステンパー
処理（オーステナイト化：９００℃Ｘ１ｈｒ、ベイナイ
ト化二３７０℃Ｘ １ ｈｒ）を施した。次いで、所定
の試験片を調製して、引張強さおよび衝撃値を測定した
。After measuring the amount of untransformed austenite, austemper treatment (austenitization: 900°C x 1 hr, bainitization: 370°C x 1 hr) was performed. Then, predetermined test pieces were prepared and the tensile strength and impact value were measured.
（比較例３）
０．５％Ｃ１０，５％Ｓｉ、０．３％Ｍｎ、０．０１５
％Ｐ、０．００９％Ｓを含有し、残部が実質的にＦｅで
ある溶湯を、生砂型へ重力鋳造法にて鋳造した。なお、
溶湯の冷却速度は２．５℃／ｓｅｅであった。焼ならし
を施した後、所定の試験片を調製して、引張強さおよび
衝撃値を測定した。(Comparative Example 3) 0.5%C10, 5%Si, 0.3%Mn, 0.015
A molten metal containing % P and 0.009% S, with the remainder being substantially Fe, was cast into a green sand mold by gravity casting. In addition,
The cooling rate of the molten metal was 2.5°C/see. After normalizing, specified test pieces were prepared and their tensile strength and impact value were measured.
得られた結果を第１表に示す。また、第３図に実施例２
で得られた本発明材２の金属組織を表す顕微鏡写真を、
第４図に比較例１で得られ比較材１の金属組織を表す顕
微鏡写真を、第５図に比較例２で得られた比較材２につ
いての金属組織を表す顕微鏡写真をそれぞれ示す。The results obtained are shown in Table 1. In addition, Fig. 3 shows Example 2.
The micrograph showing the metal structure of the present invention material 2 obtained in
FIG. 4 shows a micrograph showing the metal structure of Comparative Material 1 obtained in Comparative Example 1, and FIG. 5 shows a microphotograph showing the metal structure of Comparative Material 2 obtained in Comparative Example 2.
（以下余白）
第１表に示したように、比較例１〜３は溶湯の冷却速度
が２．５℃／’Ｓｅｃと遅いため、未変態オーステナイ
ト量が１２〜１７％と多い。これに対して、本発明例で
ある実施例１〜６は溶湯の冷却速度が１５℃／ｓｅｃと
速いため、未変態のオーステナイト量が０．２〜０．６
％と極めて少ない。(The following is a blank space) As shown in Table 1, in Comparative Examples 1 to 3, the cooling rate of the molten metal was as slow as 2.5° C./'Sec, so the amount of untransformed austenite was as large as 12 to 17%. On the other hand, in Examples 1 to 6, which are examples of the present invention, the cooling rate of the molten metal is as fast as 15°C/sec, so the amount of untransformed austenite is 0.2 to 0.6
%, which is extremely small.
また、オーステンパー処理後の引張強さについては、比
較材１〜３が６８〜８９ｋｇｆ／′ｌｌｌｍ２であるの
に対し、本発明例の実施例１〜６は８７〜１３４ｋＨｆ
／ｍｍ’であって、優れた強度を有することが確認され
た。In addition, regarding the tensile strength after austempering treatment, comparative materials 1 to 3 have a tensile strength of 68 to 89 kgf/'llm2, whereas Examples 1 to 6 of the present invention have a tensile strength of 87 to 134 kHz.
/mm', and was confirmed to have excellent strength.
オーステンパー処理後の室温における衝撃値については
、比較材１〜３が３．２〜３．８ ｋｇｆ／ ａｍ２で
あるのに対し、実施例１〜６の本発明材１〜６は、５．
２〜９ 、８ ｋｇｆ ／ ａｍ２であって、靭性にお
いても優れた特性を有することが判明した。Regarding the impact value at room temperature after austempering treatment, Comparative Materials 1 to 3 are 3.2 to 3.8 kgf/am2, while Inventive Materials 1 to 6 of Examples 1 to 6 have an impact value of 5.5 kgf/am2.
2 to 9,8 kgf/am2, and was found to have excellent properties in terms of toughness as well.
さらに、第３図〜第５図の金属組織を表す顕微鏡写真か
ら明らかなように、第４図の比較材１および第５図の比
較材２の金属組織は、黒鉛または遊離セメンタイトが認
められ、粗くて不均一なベイナイト組織となっている。Furthermore, as is clear from the micrographs showing the metallographic structures in FIGS. 3 to 5, graphite or free cementite is observed in the metallographic structures of Comparative Material 1 in FIG. 4 and Comparative Material 2 in FIG. It has a coarse and uneven bainite structure.
これに対して第３図の本発明材の金属組織は、黒鉛およ
び遊離セメンタイトが全く認められず、均一微細なベイ
ナイト組織になっていることが確認された。On the other hand, the metal structure of the material of the present invention shown in FIG. 3 was confirmed to have a uniform and fine bainite structure without any graphite or free cementite.
［発明の効果］
本発明の高靭性鋳鋼の製造方法は以上説明したように、
溶湯の冷却速度を４℃／ Ｓ ｅ ｅ以上として鋳造す
るので、未変態オーステナイト量を５％未満にすること
ができ、衝撃値が著しく改善される。[Effects of the Invention] As explained above, the method for producing high toughness cast steel of the present invention includes the following steps:
Since the molten metal is cast at a cooling rate of 4° C./Se or more, the amount of untransformed austenite can be reduced to less than 5%, and the impact value is significantly improved.
また、低Ｃ化とＳｉ含有量の規制により、オーステンパ
ー処理しても、黒鉛の析出しないベイナイト組織が得ら
れるため、黒鉛による局部応力集中、脆化が低減し、強
度、靭性が向上する。さらに、低Ｃと急速凝固を組み合
わせることにより、黒鉛、未変態の塊状オーステナイト
、遊離セメンタイト等の少ない、均一微細なベイニティ
ックフェライトと残留オーステナイトの混合組織が得ら
れるので、強度と靭性ともに優れた鋳鋼が得られる。In addition, by lowering the carbon content and regulating the Si content, a bainite structure in which graphite does not precipitate can be obtained even during austempering treatment, thereby reducing local stress concentration and embrittlement due to graphite, and improving strength and toughness. Furthermore, by combining low C and rapid solidification, a uniformly fine mixed structure of bainitic ferrite and retained austenite with little graphite, untransformed massive austenite, or free cementite can be obtained, resulting in excellent strength and toughness. Cast steel is obtained.
第１図は溶湯の冷却速度と未変態オーステナイト量の関
係を示すＩａ１２Ｉ、第２図は未変態オーステナイト量
と衝撃値との関係を示す線図、第３図は本発明例の金属
組織を表す顕微鏡写真、第４図および第５図は比較例の
金属組織を表す顕微鏡写真である。
第１図
冷却速度と未変態オーステナイト量の関係特許出願人
トヨタ自動車株式会社
代 理 人 弁理士 大 川 宏
第２図
未変態オーステナイト量と衝撃値の関係未変態オーステ
ナイト量（％）Figure 1 is Ia12I showing the relationship between the cooling rate of the molten metal and the amount of untransformed austenite, Figure 2 is a diagram showing the relationship between the amount of untransformed austenite and impact value, and Figure 3 is the metal structure of the example of the present invention. The micrographs, FIGS. 4 and 5, are micrographs showing the metal structure of the comparative example. Figure 1 Relationship between cooling rate and amount of untransformed austenite Patent applicant
Toyota Motor Corporation Representative Patent Attorney Hiroshi Okawa Figure 2 Relationship between amount of untransformed austenite and impact value Amount of untransformed austenite (%)
Claims (1)
〜３．０％を含有し、残部がＦｅおよび不純物元素から
なる溶湯を、４℃／ｓｅｃ以上の冷却速度で鋳造した後
、オーステンパー処理し均一微細なベイナイトと安定な
残留オーステナイトの混合組織とすることを特徴とする
高靭性鋳鋼の製造方法。(1) Weight ratio: C: 0.3-0.7%, Si: 1.8
After casting the molten metal containing ~3.0% and the balance consisting of Fe and impurity elements at a cooling rate of 4°C/sec or more, it is austempered to form a mixed structure of uniformly fine bainite and stable retained austenite. A method for producing high-toughness cast steel.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16338790A JP2803331B2 (en) | 1990-06-21 | 1990-06-21 | Manufacturing method of high toughness cast steel |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16338790A JP2803331B2 (en) | 1990-06-21 | 1990-06-21 | Manufacturing method of high toughness cast steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0452218A true JPH0452218A (en) | 1992-02-20 |
| JP2803331B2 JP2803331B2 (en) | 1998-09-24 |
Family
ID=15772925
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16338790A Expired - Fee Related JP2803331B2 (en) | 1990-06-21 | 1990-06-21 | Manufacturing method of high toughness cast steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2803331B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003306741A (en) * | 2002-04-16 | 2003-10-31 | Japan Science & Technology Corp | High-tensile cast steel and production method thereof |
| WO2009086461A3 (en) * | 2007-12-26 | 2009-09-24 | Wayne State University | Development of a high strength high toughness bainitic steel |
| CN102747199A (en) * | 2012-07-16 | 2012-10-24 | 鑫光热处理工业(昆山)有限公司 | Continuous isothermal quenching method for C50E4 steel workpieces |
| JP2016130352A (en) * | 2015-01-15 | 2016-07-21 | トヨタ自動車株式会社 | Method for heat-treating steel material |
| JP2020509195A (en) * | 2016-12-21 | 2020-03-26 | ポスコＰｏｓｃｏ | Hot rolled steel sheet excellent in formability and fatigue properties and method for producing the same |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01108342A (en) * | 1987-10-21 | 1989-04-25 | Mazda Motor Corp | Ferrous casting having high strength, high hardness, and high toughness and its manufacture |
-
1990
- 1990-06-21 JP JP16338790A patent/JP2803331B2/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01108342A (en) * | 1987-10-21 | 1989-04-25 | Mazda Motor Corp | Ferrous casting having high strength, high hardness, and high toughness and its manufacture |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003306741A (en) * | 2002-04-16 | 2003-10-31 | Japan Science & Technology Corp | High-tensile cast steel and production method thereof |
| WO2009086461A3 (en) * | 2007-12-26 | 2009-09-24 | Wayne State University | Development of a high strength high toughness bainitic steel |
| US20110114233A1 (en) * | 2007-12-26 | 2011-05-19 | Wayne State University | Development of a high strength high toughness bainitic steel |
| US8657972B2 (en) | 2007-12-26 | 2014-02-25 | Wayne State University | Development of a high strength high toughness steel |
| CN102747199A (en) * | 2012-07-16 | 2012-10-24 | 鑫光热处理工业(昆山)有限公司 | Continuous isothermal quenching method for C50E4 steel workpieces |
| JP2016130352A (en) * | 2015-01-15 | 2016-07-21 | トヨタ自動車株式会社 | Method for heat-treating steel material |
| CN105803161A (en) * | 2015-01-15 | 2016-07-27 | 丰田自动车株式会社 | Heat treatment method for steel material |
| US10301694B2 (en) | 2015-01-15 | 2019-05-28 | Toyota Jidosha Kabushiki Kaisha | Heat treatment method for steel material |
| JP2020509195A (en) * | 2016-12-21 | 2020-03-26 | ポスコＰｏｓｃｏ | Hot rolled steel sheet excellent in formability and fatigue properties and method for producing the same |
| US11591664B2 (en) | 2016-12-21 | 2023-02-28 | Posco Co., Ltd | Hot rolled steel sheet having excellent formability and fatigue properties and manufacturing method therefor |
| US11970749B2 (en) | 2016-12-21 | 2024-04-30 | Posco Co., Ltd | Hot rolled steel sheet having excellent formability and fatigue properties and manufacturing method therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2803331B2 (en) | 1998-09-24 |
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