EP0572246B1 - Pièce forgée et procédé pour sa fabrication - Google Patents

Pièce forgée et procédé pour sa fabrication Download PDF

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Publication number
EP0572246B1
EP0572246B1 EP93304100A EP93304100A EP0572246B1 EP 0572246 B1 EP0572246 B1 EP 0572246B1 EP 93304100 A EP93304100 A EP 93304100A EP 93304100 A EP93304100 A EP 93304100A EP 0572246 B1 EP0572246 B1 EP 0572246B1
Authority
EP
European Patent Office
Prior art keywords
weight
percent
forging
fatigue strength
billet
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 - Lifetime
Application number
EP93304100A
Other languages
German (de)
English (en)
Other versions
EP0572246A1 (fr
Inventor
Vesa Ollilainen
Ilkka Lahti
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ovako Bar Oy
Original Assignee
Imatra Steel Oy AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Imatra Steel Oy AB filed Critical Imatra Steel Oy AB
Publication of EP0572246A1 publication Critical patent/EP0572246A1/fr
Application granted granted Critical
Publication of EP0572246B1 publication Critical patent/EP0572246B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium

Definitions

  • This invention relates to a method for producing a forging with good fatigue strength and to a forging having good fatigue strength.
  • the fatigue strength Sv is most often a critical feature which determines the dimensions of the element.
  • the problem is that the static strength of the element in question, for example its tensile strength Rm, has an affect on the machinability of the material. With regard to the total production cost of an element the optimum static tensile strength is about 1000 MPa. If the element has a static tensile strength essentially exceeding this value, the machinability of the material is poor in many cases causing, in particular, high speed steel tools to wear rapidly when machining the material resulting in unreasonably high tool costs. If the fatigue strength of an element can be increased without increasing its static strength, the element can be made more slender and high cutting costs can be avoided. Then the element will be lighter and the production costs will be lower, resulting in a rise in the value of the element and/or lower total production costs.
  • the cold cropping of bars to produce forging billets which precedes the forging of modern microalloyed steels, often causes a problem, in particular when the tensile strength in the rolling phase exceeds 900 MPa. In particular the cropping usually creates cracks on the shear surface of the cropped billet. If the fatigue strength of the final forging can be raised without raising the tensile strength of the bar blank, the alloying of the steel can be reduced, inter alia with regard to manganese. Then the tensile strength is reduced and at the same time the cold cropping properties are improved without any reduction of the fatigue strength of the final forged product. In this way the cold cutting difficulties can be eliminated and the alloying costs can be reduced.
  • the combination of the steel composition according to the invention and the treatment according to the invention essentially reduces the necessity of surface treatment for the type of products referred to, thereby reducing their production costs.
  • the object of the invention is to produce a forging with a high fatigue strength without the above-described technical drawbacks. At the same time the advantages mentioned above are achieved.
  • the object of the invention is obtained by the method of claim 1 and the forging of claims 6 and 7.
  • Alloyed steels resembling the alloyed steel of the forging according to the invention have been used before, inter alia as raw material for steel springs and different fastening elements, as described in the Finnish laid open publication FI 48204.
  • the main difference between the forging according to the invention and the known springs and fastening elements is that, according to the invention, the microstructure will be mostly (typically to more than 90 percent) ferritic-perlitic, which is obtained by air cooling, while the microstructure of the elements described in FI 48204 is martensite or bainite for the greatest part, which is obtained by quenching and tempering or austempering.
  • the billets are hot forged at a temperature of more than 800°C and after that they are allowed to cool in air.
  • This treatment is known per se as a treatment method for microalloyed steels for the purpose of eliminating a separate quench and temper treatment in order to reduce the production costs.
  • the treatment result is different.
  • the high silicon content provides an improved fatigue strength. It is assumed that this is caused by the fact that small amounts of residual austenite are formed which, under fatigue stress, turn into martensite. Thereby a so-called cyclic work hardening takes place, which increases the fatigue strength.
  • Novel in the invention is the combination of a steel according to the invention, containing a high degree of silicon, and a working method generally used in the production of other microalloyed steel forgings. This results, for the reasons explained above, in a product with a fatigue strength that is essentially better than in previously known microalloyed steel products.
  • a silicon content higher than normal in air-cooled microalloyed steels is known from DE-A-3009443.
  • the invention differs from this, firstly in that the silicon content is higher, and secondly, in that the object is to improve the fatigue strength, whereas the object of the known technique is to improve the notch toughness, not the fatigue strength.
  • an element according to the invention that its production process includes, before hot forging, heating to such a high temperature that the vanadium carbonitrides of the element dissolve. This improves the strength of the element so that it is usually near the optimum value mentioned on the first page of this specification, which also is of advantage with respect to the fatigue strength.
  • the advantage is achieved that large nitride particles harmful for the fatigue strength, will not be formed. This is ensured, in particular, if the continuous casting method is used in the manufacturing process of the material.
  • the cooling of the forging can be effected by using flowing air as coolant, preferably air moistened, for instance by water spray. It is of advantage to use this kind of forced cooling when the temperature of the element is above 600°C.
  • the forced cooling causes the forging to obtain a sufficient strength without any negative influence on its toughness. This is because forced cooling results in a finer micro structure of the element. The grain size becomes smaller and the interlamellar spacing of the perlite remains small, whereby the strength is improved but the toughness remains unaltered.
  • the fatigue strength Sv was determined in a rotating bending test, load alternations 10 million revolutions.
  • the ultimate tensile strength Rm influences the fatigue strength, which means that the ratio of fatigue strength and tensile strength must be observed.
  • the improvement in the fatigue strength to tensile strength ratio for steels produced according to the invention is from about 10 to 30%.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Forging (AREA)
  • Prostheses (AREA)
  • Paper (AREA)
  • Heat Treatment Of Steel (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
  • Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)

Claims (7)

  1. Procédé de production d'une pièce forgée avec une bonne résistance à la fatigue, caractérisé par la combinaison du fait que la billette pour la pièce forgée souhaitée est faite d'une matière qui, en plus du fer, contient les éléments suivants : C de 0,2 à 0,6 pour cent en poids Si de 1,25 à 2,0 pour cent en poids Mn de 0,5 à 1,5 pour cent en poids V de 0,04 à 0,2 pour cent en poids S de 0 à 0,2 pour cent en poids Cr de 0 à 0,5 pour cent en poids Al de 0 à 0,1 pour cent en poids N de 0 à 0,04 pour cent en poids Nb de 0 à 0,1 pour cent en poids Ti de 0 à 0,05 pour cent en poids
    et du fait que la billette est forgée à une température supérieure à 800°C et du fait que la pièce forgée est ensuite refroidie dans l'air ou dans un gaz agissant d'une manière sensiblement uniforme sur la pièce forgée.
  2. Procédé selon la revendication 1, caractérisé en ce que la billette avant le formage à chaud est chauffée à une température, à laquelle ses carbonitrures de vanadium se dissolvent.
  3. Procédé selon la revendication 1 ou 2, caractérisé en ce que la teneur en azote de la matière ne dépasse pas 0,012 pour cent en poids.
  4. Procédé selon la revendication 1, 2 ou 3, caractérisé en ce que la teneur en titane de la matière ne dépasse pas 0,01 pour cent en poids.
  5. Procédé selon l'une quelconque de revendications précédentes, caractérisé en ce que pour le refroidissement de la pièce forgée, au moins lorsque sa température est supérieure à 600°C, il est utilisé un flux d'air ou de gaz sec ou humide comme gaz de refroidissement.
  6. Pièce forgée produite par le procédé de l'une quelconque des revendications 1 à 5.
  7. Pièce forgée avec une bonne résistance à la fatigue, caractérisée en ce qu'elle est faite d'une matière qui en plus du fer, contient les éléments suivants: C de 0,2 à 0,6 pour cent en poids Si de 1,25 à 2,0 pour cent en poids Mn de 0,5 à 1,5 pour cent en poids V de 0,04 à 0,2 pour cent en poids S de 0 à 0,2 pour cent en poids Cr de 0 à 0,5 pour cent en poids Al de 0 à 0,1 pour cent en poids N de 0 à 0,04 pour cent en poids Nb de 0 à 0,1 pour cent en poids Ti de 0 à 0,05 pour cent en poids
    et en ce que la microstructure de la pièce forgée est principalement ferritique - perlitique.
EP93304100A 1992-05-29 1993-05-26 Pièce forgée et procédé pour sa fabrication Expired - Lifetime EP0572246B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI922461 1992-05-29
FI922461A FI922461A (fi) 1992-05-29 1992-05-29 Smidesstycke och dess framstaellningsfoerfarande

Publications (2)

Publication Number Publication Date
EP0572246A1 EP0572246A1 (fr) 1993-12-01
EP0572246B1 true EP0572246B1 (fr) 1997-01-15

Family

ID=8535372

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93304100A Expired - Lifetime EP0572246B1 (fr) 1992-05-29 1993-05-26 Pièce forgée et procédé pour sa fabrication

Country Status (5)

Country Link
EP (1) EP0572246B1 (fr)
AT (1) ATE147799T1 (fr)
DE (1) DE69307393T2 (fr)
FI (1) FI922461A (fr)
NO (1) NO931961D0 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1700925A1 (fr) 2005-03-09 2006-09-13 Imatra Steel Oy Ab Acier à haute résistance mechanique refroidi par air, la procèdè de fabrication et son produit à chaud.

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2746683B1 (fr) * 1996-03-29 1998-04-30 Ascoforge Safe Procede de fabrication d'une ebauche de bielle forgee
ES2128240B1 (es) * 1996-07-26 2000-01-01 Gsb Grupo Siderurgico Vasco S Procedimiento de fabricacion de aceros microaleados.
DE19751640A1 (de) * 1997-11-21 1999-05-27 Bayerische Motoren Werke Ag Geschmiedetes Pleuel für Hubkolbenmaschinen aus Kohlenstoffstahl mit bruchgetrenntem Lagerdeckel
IT1398688B1 (it) * 2009-06-12 2013-03-08 F A C E M S P A Procedimento per la produzione di un pezzo in acciaio da cementazione, basato su stampaggio a caldo seguito da raffreddamento condizionato e ricottura subcritica, e relativo impianto
JP6299321B2 (ja) * 2014-03-25 2018-03-28 愛知製鋼株式会社 被削性と疲労強度に優れ、硬さばらつきの小さい省ｖ型熱間鍛造非調質部品及びその製造方法
JP6693206B2 (ja) * 2016-03-23 2020-05-13 愛知製鋼株式会社 クランクシャフト及びその製造方法並びにクランクシャフト用鋼
MX2020004500A (es) * 2017-10-31 2020-08-13 Nippon Steel Corp Material de acero forjado en caliente.
DE102019123334A1 (de) 2019-08-30 2021-03-04 Mannesmann Precision Tubes Gmbh Stahlwerkstoff für eine Antriebswelle, Verfahren zur Herstellung einer Antriebswelle aus diesem Stahlwerkstoff und Antriebswelle hieraus
CN114769481B (zh) * 2022-05-05 2023-12-26 无锡派克新材料科技股份有限公司 一种提高不锈钢冲击的锻造工艺

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3173782A (en) * 1962-06-13 1965-03-16 Bethlehem Steel Corp Vanadium nitrogen steel
SU301371A1 (ru) * 1969-06-04 1971-04-21 В. В. Рунов, К. Шепел козский , В. М. Семенов Научно исследовательский институт автотракторных материалов Пружинная сталь
BE821354A (nl) * 1974-03-04 1975-04-23 Een hoge sterkte bezittend staal
SU522264A1 (ru) * 1975-03-20 1976-07-25 Ордена Трудового Красного Знамени Центральный Научно-Исследовательский Институт Черной Металлургии Им.И.П.Бардина Конструкционна сталь
DE3009443C2 (de) * 1980-03-12 1981-11-19 Thyssen Edelstahlwerke AG, 4000 Düsseldorf Verwendung eines Stahls hoher Festigkeit und Zähigkeit
JPS5925024B2 (ja) * 1980-06-26 1984-06-13 株式会社神戸製鋼所 懸架ばね用鋼

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1700925A1 (fr) 2005-03-09 2006-09-13 Imatra Steel Oy Ab Acier à haute résistance mechanique refroidi par air, la procèdè de fabrication et son produit à chaud.

Also Published As

Publication number Publication date
FI922461A0 (fi) 1992-05-29
NO931961D0 (no) 1993-05-28
DE69307393T2 (de) 1997-05-15
DE69307393D1 (de) 1997-02-27
FI922461A (fi) 1993-11-30
ATE147799T1 (de) 1997-02-15
EP0572246A1 (fr) 1993-12-01

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