EP2546374A1 - Stahl für extrusionswerkzeuge - Google Patents

Stahl für extrusionswerkzeuge Download PDF

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Publication number
EP2546374A1
EP2546374A1 EP11752761A EP11752761A EP2546374A1 EP 2546374 A1 EP2546374 A1 EP 2546374A1 EP 11752761 A EP11752761 A EP 11752761A EP 11752761 A EP11752761 A EP 11752761A EP 2546374 A1 EP2546374 A1 EP 2546374A1
Authority
EP
European Patent Office
Prior art keywords
steel
extrusion
content
tools
mass
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.)
Withdrawn
Application number
EP11752761A
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English (en)
French (fr)
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EP2546374A4 (de
Inventor
Celso Antonio Barbosa
Rafael Agnelli Mesquita
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.)
Villares Metals SA
Original Assignee
Villares Metals SA
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Filing date
Publication date
Application filed by Villares Metals SA filed Critical Villares Metals SA
Publication of EP2546374A1 publication Critical patent/EP2546374A1/de
Publication of EP2546374A4 publication Critical patent/EP2546374A4/de
Withdrawn legal-status Critical Current

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    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
    • 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
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy

Definitions

  • the present invention relates to a steel intended for use in various hot form tools and dies, particularly for extrusion of aluminum alloys or other non-ferrous metals.
  • the material can also be employed in other hot forming processes, in which the metal to be formed withstands temperatures above 600 °C, although the said steel can be employed in processes at lower temperatures or even at ambient temperature.
  • the composition of the steel in question allows it to be classified as hot work tool steel, whose primary characteristic the lower content of high-cost alloying elements, such as molybdenum and vanadium, but with tempering resistance (or resistance to loss of hardness) greater than that of conventional steels of prior art concept.
  • An additional alternative to the steel of the present invention is provided to increase hardness after nitriding, and may result in performance levels even greater than those of conventional steels, at the same time that the cost is kept low due to a simpler chemical composition.
  • Such an effect is possible by carefully designing the alloy, and setting the optimum ranges of the elements: carbon, chromium, molybdenum and aluminum.
  • hot work tools is applied to a large number of hot-forming operations, employed in industries and focused on the production of parts for mechanical applications, especially automotive parts.
  • the most popular hot-forming processes are forging of steel, and the extrusion or casting of non-ferrous alloys.
  • Other applications performed at high temperature, typically above 500/600°C, can also be classified as hot work.
  • molds, dies, punches, inserts and other forming devices are classified by the generic term: hot work tools. These tools are usually made of steels, which require special properties to withstand high temperatures and the mechanical efforts of the processes in which those tools are employed.
  • tempering resistance resistance after high temperature tempering
  • tempering resistance resistance to the loss of hardness
  • toughness the hardenability
  • physical properties such as thermal conductivity and specific heat.
  • the extrusion dies used for non-ferrous alloys, especially aluminum alloys are main hot work target for applying the steel of the present invention.
  • These typical dies comprise an important segment of the tool steel market both in Brazil and abroad.
  • the steels are very standardized, based on steels such as ABNT H13 (see Table 1), with quality requirements not as strict as those of other applications, e.g., pressure die casting, but with emphasis on lower production costs.
  • Low-alloy steels have been employed, such as DIN 1.2714 (chemical composition given in Table 1). However, their low wear resistance due to reduced hot strength and lower postnitriding hardness prevents them from being applied.
  • a third problem of invention US 2009/0191086 relates to the hardness of the die core, which may be lower due to decreased hardenability as a result of reduced Cr and Mo contents.
  • the alloys of invention US 2009/0191086 have higher Mn content, which lead to higher hardenability, potential segregation problems (banding) and excessive austenite retention. Both effects may impair the final hardness and toughness and, thus, the tool life.
  • a final aspect can also be mentioned, with regard to the high Mn content: Scrap from this steel can hardly be incorporated into the production of conventional, low-Mn-content hot work steels.
  • invention US 2009/0191086 is considered by the authors as a cost-reducing solution, but with inferior properties.
  • the authors quantify the expected efficiency loss, of about 20 to 30% lower than that of steel H13.
  • this efficiency loss can be considered quite significant, thus requiring a reduction of the cost of the material by more than 30% to compensate the substitution.
  • a 30% lower life can only be viable if the cost of the new material is half the cost of the conventional material. From 2005 to 2008, when the cost of raw materials peaked, this could be true (though still difficult to occur, because the cost difference required is too high).
  • cost reduction can hardly be achieved for steel H13, considering only the reduction of the Mo and Cr contents.
  • reduction in cost associated with efficiency loss of the alloy of patent US 2009/0191086 can be currently considered impractical for such application.
  • the steel of the present invention has a composition of alloying elements, which, in percentage by mass consists of:
  • Mo Given its chemical similarity to W, Mo can be replaced with W, 2W:1 Mo ratio by mass.
  • Al can be added simultaneously to the alloys of the present invention to provide gains in terms of hardness after nitriding, but also negative effects in terms of toughness and complexity of the steel-making process.
  • the Al content must be dosed as follows, in percentage by mass:
  • compositions should be characterized by balance by Fe (iron) and metallic or non-metallic deleterious substances inevitable to the steelmaking process, in which said non-metallic deleterious substances include but are not limited to the following elements, in percentage by mass:
  • Carbon is primarily responsible for martensite hardening under low temperature conditions. However, together with the alloying elements, carbon also plays a role in the secondary hardening, important for the hardening at high temperature. In these cases, the C content is more important for hardness at temperatures below 600 °C, when hardness still depends on the martensite hardness or formation of cementite or Cr carbides. Furthermore, carbon is an important hardenability-promoting element, and causes no increase in cost. It is also considered important to increase hardness to 45 HRC and up, carbon contents of at least 0.40% are recommended, preferably above 0.45%.
  • the C content should be limited to a maximum value of 0.60%, preferably below 0.55%. This limitation also plays a role in the reduction of the amount of retained austenite, preventing problems associated with dimensional instability and embrittlement.
  • the chromium content should be higher than 2.5%, preferably greater than 3.0%, because this element favors hardenability, which is important for application in large tools.
  • the Cr content should be limited.
  • the present invention has incorporated the concept of reducing the Cr content to improve tempering resistance.
  • the mechanisms of this effect are not fully understood but they may be related to the formation of secondary Cr carbides, M 7 C 3 -type, which dissolve Mo and V are the first carbides to be formed. Therefore, the lower the Cr content, the lower the amount of M 7 C 3 carbides and, thus, the greater the amount of Mo and V available for the formation of fine carbides M 2 C and MC, which are also important for secondary hardening.
  • the end result is a significantly higher tempering resistance in steels with lower Cr content, thus enabling the reduction of the Mo content when compared to steels of prior art concept.
  • Mo and W low concentrations of Mo have been employed in the present invention not only for the purpose of cost reduction, but also to promote the highest secondary hardness and tempering resistance equivalent or even greater than that of steel H13 in association with Cr and C contents.
  • the alloy of the present invention must contain at least 0.30%, preferably above 0.50%.
  • an extremely high Mo content might harm toughness due to deposition of proeutectic carbides during the quenching phase and can increase significantly the alloy cost, in an opposite direction to the cost-reduction goal of the present invention.
  • the Mo content should be limited to 0.90%, preferably below 0.70%.
  • Tungsten and molybdenum produce similar effects in the tool steel of the present invention, forming M 2 C or M 6 C secondary carbides. Thus, they can be jointly specified through the tungsten equivalent relationship (W eq ) given by the sum W + 2Mo, which normalizes the differences in atomic weight between the two elements.
  • V Vanadium is primarily important for the formation of MC secondary carbides. Because they are very thin, these carbides block the movement of dislocation lines, increasing mechanical strength. V also improves grain growth, allowing high austenitizing temperatures (above 1000°C). For such effects, V must be above 0.1%, preferably above 0.3%. However, excessively high V grades may generate primary, difficult-to-solubilize carbides, thus reducing toughness, and also promote significant increase of costs. Hence, the V content should be lower than 1.0%, preferably below 0.6%.
  • Si silicon produces a strong effect on secondary hardening and toughness.
  • toughness improves due to a better distribution of secondary carbides. Therefore, the Si content of the material of the present invention must be lower than 1.0%, typically below 0.5%.
  • Mn high Mn contents may be considered undesirable for promoting intense micro-segregation generating banding at different degrees of hardness, and for increasing the retained austenite content; therefore Mn is considered a deleterious element in the present invention.
  • the Mn content should be limited to 1.0%, preferably below 0.8%, typically below 0.50%.
  • the alloys' Al content can be high.
  • the Al content, under these conditions, should be limited to 1.0% because they lead to decreased toughness.
  • Al contents between 0.40% and 0.60% may be of interest for this purpose.
  • the Al content of the alloy of the present invention can be ⁇ 0.1 %, typically below 0.05%.
  • Residual Elements Other elements such as Ni and Co should be considered as deleterious substances associated with the steelmaking deoxidation processes or inherent to the manufacturing processes. Hence, the Ni and Co content should be limited to 1.5%, preferably below 1.0%. In terms of formation of inclusions, the sulfur content should be controlled, because such inclusions may lead to cracking during operation; therefore the S content should remain below 0.050%, preferably below 0.020%. Also, for high toughness purposes, embrittling elements such as P should be avoided, being desirable P ⁇ 0.030%, preferably P ⁇ 0.015%, typically P ⁇ 0.010%. Indeed, a low Cr content also helps to reduce the P content in electric arc furnace steelmaking processes, thus leading to conclusions that are not contradictory to the cost reduction philosophy desired.
  • the alloy as described above, can be produced as rolled or forged products through conventional or special processes such as powder metallurgy, spray forming or continuous casting, such as wire rods, bars, wires, sheets and strips.
  • Hardness after tempering at 600°C is shown in Figure 1 , highlighting the effects of reduced Mo and Cr contents, and also the effect of higher C content.
  • Mo content a lower Mo concentration results in lower hardness after tempering.
  • Cr content drops, post-tempering hardness rises.
  • a possibility is that a lower Cr content reduces the amount of M 7 C 3 which, in turn, dissolves Mo.
  • a higher content of free Mo should be present in alloys of lower Cr content, which explains a more intense response to tempering.
  • alloy PI 2 becomes interesting for having toughness > 200J and extremely high hardness of the nitrified layer (almost 1400 HV). Alloy PI 3 does not show gains in terms of the nitrified layer, but toughness is far lower.
  • alloy PIl seems more appropriate, also showing hardness after nitriding similar to that of steel H13, reaching more than 1000 HV on surface, which is the typical specification for extrusion tools. Furthermore, as previously shown in Figure 5 , alloy PI 1 also presents improved hot strength properties.
  • alloys of the present invention show results equivalent to or better than those of steel H13. Such results are quite relevant for non-ferrous alloy extrusion dies, e.g., Al alloys, or hot forging dies.
  • Alloy PI 1 has improved tempering resistance, but hardness after nitriding and toughness equivalent to steel H13, while alloy PI 2 has lower toughness, but tempering resistance and hardness after nitriding significantly higher than steel H13.
  • the alloy should be selected on the basis of the most critical properties required for the application. However, in all cases, significant cost reductions can be obtained due to the low Mo and V content of the alloys of the present invention.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Powder Metallurgy (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
EP11752761.4A 2010-03-08 2011-03-04 Stahl für extrusionswerkzeuge Withdrawn EP2546374A4 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BRPI1003185-5A BRPI1003185A2 (pt) 2010-03-08 2010-03-08 aço para ferramentas de extrusão
PCT/BR2011/000059 WO2011109881A1 (pt) 2010-03-08 2011-03-04 Aço para ferramentas de extrusão

Publications (2)

Publication Number Publication Date
EP2546374A1 true EP2546374A1 (de) 2013-01-16
EP2546374A4 EP2546374A4 (de) 2015-02-18

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EP11752761.4A Withdrawn EP2546374A4 (de) 2010-03-08 2011-03-04 Stahl für extrusionswerkzeuge

Country Status (11)

Country Link
US (1) US20130243639A1 (de)
EP (1) EP2546374A4 (de)
JP (1) JP2013521411A (de)
KR (1) KR20130004591A (de)
CN (1) CN103097562A (de)
BR (1) BRPI1003185A2 (de)
CA (1) CA2792615A1 (de)
MX (1) MX2012010394A (de)
RU (1) RU2012142660A (de)
WO (1) WO2011109881A1 (de)
ZA (1) ZA201207378B (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10407763B2 (en) 2015-04-14 2019-09-10 Hyundai Motor Company Carbon steel composition for reduced thermal strain steering rack bar and method for manufacturing same

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103334054A (zh) * 2013-06-18 2013-10-02 上海大学 经济型含铝热挤压模具钢及其制备、热处理和表面处理方法
JP6410612B2 (ja) * 2015-01-08 2018-10-24 日産自動車株式会社 窒化部材及びそれを用いた摩擦伝動変速機
CN104805362A (zh) * 2015-03-31 2015-07-29 吉林大学 含铝中合金铸造冷作模具钢
CN104805366B (zh) * 2015-05-20 2017-05-24 中南大学 一种粉末冶金低合金钢及其制备方法
JP2020132891A (ja) * 2019-02-12 2020-08-31 山陽特殊製鋼株式会社 熱伝導率に優れる金型用鋼
CN115418467B (zh) * 2022-09-27 2023-06-06 江苏隆达超合金股份有限公司 一种铜镍合金管挤压用h13穿孔针热处理工艺
CN116810360A (zh) * 2023-06-30 2023-09-29 安徽铜都流体科技股份有限公司 一种可更换式刀箱制作方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2051984C1 (ru) * 1993-04-28 1996-01-10 Нижнетагильский металлургический комбинат Сталь
US20090191086A1 (en) * 2006-04-06 2009-07-30 Uddeholm Tooling Aktiebolag Hot-working steel

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Publication number Priority date Publication date Assignee Title
US6478898B1 (en) * 1999-09-22 2002-11-12 Sumitomo Metal Industries, Ltd. Method of producing tool steels
JP3612459B2 (ja) * 1999-11-09 2005-01-19 山陽特殊製鋼株式会社 小ロット生産用金型鋼
CN1138017C (zh) * 2000-06-08 2004-02-11 顺德市世创金属科技有限公司 一种中合金铬系热作模具钢
JP2003268500A (ja) * 2002-03-15 2003-09-25 Daido Steel Co Ltd 被削性に優れた熱間工具鋼及びその製造方法
CA2488790C (en) * 2002-06-13 2012-06-19 Uddeholm Tooling Aktiebolag Steel and mould tool for plastic materials made of the steel
SE533988C2 (sv) * 2008-10-16 2011-03-22 Uddeholms Ab Stålmaterial och förfarande för framställning därav

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2051984C1 (ru) * 1993-04-28 1996-01-10 Нижнетагильский металлургический комбинат Сталь
US20090191086A1 (en) * 2006-04-06 2009-07-30 Uddeholm Tooling Aktiebolag Hot-working steel

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO2011109881A1 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10407763B2 (en) 2015-04-14 2019-09-10 Hyundai Motor Company Carbon steel composition for reduced thermal strain steering rack bar and method for manufacturing same

Also Published As

Publication number Publication date
US20130243639A1 (en) 2013-09-19
CN103097562A (zh) 2013-05-08
CA2792615A1 (en) 2011-09-15
ZA201207378B (en) 2013-06-26
JP2013521411A (ja) 2013-06-10
MX2012010394A (es) 2012-10-05
WO2011109881A1 (pt) 2011-09-15
RU2012142660A (ru) 2014-04-20
KR20130004591A (ko) 2013-01-11
EP2546374A4 (de) 2015-02-18
BRPI1003185A2 (pt) 2012-02-07

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