TWI907440B

TWI907440B - Hot work tool steel

Info

Publication number: TWI907440B
Application number: TW110121439A
Authority: TW
Inventors: 瑟班天彥傑馬克; 安德斯卡法內德; 理查歐維爾
Original assignee: 瑞典商伍德赫爾恩股份有限公司
Priority date: 2020-06-12
Filing date: 2021-06-11
Publication date: 2025-12-11

Abstract

The present invention relates to a hot work tool steel for hot forging, press hardening, die casting or hot extrusion consisting of in weight % (wt.%): C 0.5-0.9 Si 0.03-0.8 Mn 0.1-1.8 Cr 4.0-6.6 Mo 1.8-3.5 V 1.3-2.3 Al ≤0.1 N ≤0.12 Ni ≤1 W ≤1 Co ≤5 Cu ≤1 Nb ≤0.1 Ti ≤0.05 Zr ≤0.05 Ta ≤0.05 B ≤0.01 Ca ≤0.01 Mg ≤0.01 REM ≤0.2 balance Fe and impurities.

Description

Hot working tool steel

本發明關於一種基質型熱加工工具鋼。This invention relates to a base-type hot-working tool steel.

釩合金基質工具鋼在市場上已有幾十年之歷史，因其兼具高耐磨損性、出色的尺寸穩定性及良好的韌性而引起了人們極大的興趣。基質工具鋼為一種不含任何一級碳化物或僅含有極低含量之少一級碳化物且具有由回火麻田散鐵組成之基質之鋼。Vanadyl alloy base tool steel has been on the market for decades, attracting great interest due to its high wear resistance, excellent dimensional stability, and good toughness. Base tool steel is a type of steel that contains no primary carbides or only very low amounts of primary carbides and has a matrix composed of tempered martensite.

US 3117863可能為第一個針對基質鋼之專利。US 3117863之基本構想為製造一種具有已知高速鋼（high speed steel；HSS）基質之組成之鋼。開發此類鋼之結構以藉由細化微結構來改良鋼之韌性及疲勞強度。US 3117863 may be the first patent specifically for a base steel. The basic concept of US 3117863 is to manufacture a steel with a composition similar to that of known high-speed steel (HSS). The structure of this type of steel is developed to improve its toughness and fatigue strength by refining the microstructure.

本申請人之WO 03/106727 A1揭示一種熱加工基質鋼，其具有優異的韌性及延展性以及良好的熱強度及耐磨損性。該材料在市場上以名稱UNIMAX ^®為人所知。 This applicant's WO 03/106727 A1 discloses a hot-workable base steel with excellent toughness and ductility, as well as good hot strength and wear resistance. This material is known in the market under the name ^UNIMAX® .

EP1 300 482 A1揭示另一種基質鋼，其具有高硬度及耐磨損性以及非常高的韌性，因此特別適用於在高溫下受壓之工具，諸如用於熱成型及溫成型之工具。此種鋼在市場上以名稱W360 ISOBLOC ^®為人所知，標稱成分為0.50% C、0.20% Si、0.25% Mn、4.5% Cr、3.00% Mo及0.60% V。 EP1 300 482 A1 discloses another base steel with high hardness, wear resistance, and very high toughness, making it particularly suitable for tools subjected to pressure at high temperatures, such as those used in hot forming and warm forming. This steel is commercially known as W360 ^ISOBLOC® , with a nominal composition of 0.50% C, 0.20% Si, 0.25% Mn, 4.5% Cr, 3.00% Mo, and 0.60% V.

基質鋼通常藉由真空電弧重熔（vacuum arc re-melting；VAR）或電渣重熔（electro slag re-melting；ESR）所製造，以改善化學均勻性及微觀清潔度。Base steel is typically manufactured by vacuum arc remelting (VAR) or electroslag remelting (ESR) to improve chemical homogeneity and microscopic cleanliness.

JP2003226939A、EP3050986A1、US2004/0187972A1及US2005/0161125A1提供了熱加工工具基質鋼之其他實例。JP2003226939A, EP3050986A1, US2004/0187972A1 and US2005/0161125A1 provide other examples of base steels for hot-working tools.

最新的基質鋼是在用於計算作為溫度函數之相圖及平衡相平衡之軟體之幫助下所開發。Themo-Calc ^®（TC）是用於此目的之用戶友善且經常使用之軟體，用於找出在浸泡溫度下致使大奧氏體單相區域之組成，其是因為在鑄造期間藉由偏析所形成之可能存在的MC碳化物之溶解是最重要的。 The latest base steels were developed with the help of software used to calculate phase diagrams as a function of temperature and equilibrium phase balances. Themo- ^Calc® (TC) is a user-friendly and frequently used software for this purpose, used to find the composition of the large austenitic single-phase region at immersion temperatures, because the dissolution of MC carbides that may be present during casting via segregation is of paramount importance.

熱加工基質鋼具有廣泛的應用，諸如壓鑄及鍛造。此等鋼通常藉由習知冶金及電渣重熔（ESR）所製造。然而，已知鋼之缺點在於耐磨損性有限。特別地，耐磨料磨損性可能會限制已知鋼在諸如熱鍛、擠壓及加壓硬化等要求苛刻的熱加工操作中之壽命。此等工具價格昂貴，而且經常需要焊接維修。因此，可焊接性是很重要的。然而，通常認為含碳量高之工具鋼之可焊接性較差，需要採取諸如高預熱溫度等的特殊措施。因此，若鋼可用標準焊接耗材焊接，最好不用預熱，那將是有用的。Hot-workable base steels have a wide range of applications, such as die casting and forging. These steels are typically manufactured using conventional metallurgy and electroslag remelting (ESR). However, a drawback of known steels is their limited wear resistance. In particular, abrasive resistance can limit the lifespan of known steels in demanding hot-working operations such as hot forging, extrusion, and pressure hardening. These tools are expensive and frequently require welding repairs. Therefore, weldability is important. However, tool steels with high carbon content are generally considered to have poor weldability, requiring special measures such as high preheating temperatures. Therefore, if the steel can be welded using standard welding consumables, it is beneficial to avoid preheating.

本發明之目的為提供一種基質型熱加工工具鋼，在苛刻的應用中具有改善的耐磨料磨損性。特別地，該鋼應適用於熱鍛、壓鑄或熱擠壓應用。其亦應適用於加壓硬化，特別是先進高強度鋼（Advanced High Strength Steel；AHSS）之加壓硬化。對於此等應用，耐熱耐磨損性需求是很高的。The purpose of this invention is to provide a base-type hot-workable tool steel with improved resistance to abrasive wear in demanding applications. Specifically, the steel should be suitable for hot forging, die casting, or hot extrusion applications. It should also be suitable for pressure hardening, particularly for advanced high-strength steel (AHSS). For these applications, high heat and wear resistance are required.

耐回火性是一個重要的性質，因為鋼在使用過程中可能會受到長時間之高溫。因此，鋼較佳不僅在硬化後具有高硬度而且硬度很少降低。其他重要的性質包括高延展性及韌性，此意指鋼應具有高微渣清潔度、完全不含晶界碳化物以及厚度達300 mm之均勻硬度。Temper resistance is an important property because steel may be subjected to high temperatures for extended periods during use. Therefore, steel should ideally possess high hardness after hardening and exhibit minimal decrease in hardness. Other important properties include high ductility and toughness, meaning the steel should have high slag cleanliness, be completely free of grain boundary carbides, and have uniform hardness up to 300 mm thick.

應可能在大間隔內調整硬度，以便針對所欲用途最佳化鋼。亦應有可能獲得高拉伸強度及屈服強度以及足夠的延展性。The hardness should be adjustable within a wide range to optimize the steel for the desired application. It should also be possible to obtain high tensile strength and yield strength, as well as sufficient ductility.

藉由提供具有如請求項中所述之組成之熱加工工具鋼，將前述目的以及額外的優點實現至顯著的程度。By providing hot-working tool steel having the composition described in the request, the aforementioned objectives and additional advantages are realized to a significant degree.

本發明是在請求項中所定義。This invention is defined in the request.

以下簡要說明各個元素及其相互作用的重要性以及所請合金之化學成分之限制。在整個說明書中，鋼之化學組成之所有百分比是以重量%（wt.%）提供。硬相之量是以體積%（vol.%）提供。個別元素的上限及下限可在請求項所述之限制內自由組合。數值之算術精度可提高一或二位。因此，給出之值例如0.1%亦可表示為0.10%或0.100%。The following is a brief explanation of the importance of each element and their interactions, as well as the limitations on the chemical composition of the requested alloy. Throughout this specification, all percentages of the steel's chemical composition are provided in weight % (wt.%). The amount of the hard phase is provided in volume % (vol.%). Upper and lower limits for individual elements can be freely combined within the limits stated in the request. The arithmetic precision of the values can be increased to one or two decimal places. Therefore, a given value, such as 0.1%, can also be expressed as 0.10% or 0.100%.

碳（0.5%-0.9%）是以0.5%，較佳至少0.55%、0.60%、0.66%、0.67%或0.68%之最小含量存在。碳之上限為0.9%，且可設定為0.85%、0.80%、0.75%、0.74%、0.73%或0.72%。較佳範圍為0.6%-0.8%及0.65%-0.75%。在任何情況下，應控制碳之量，使得鋼中M ₂₃C ₆、M ₇C ₃及M ₆C型之一級碳化物之量受到限制，較佳地，鋼不含此種一次碳化物。 Carbon (0.5%-0.9%) is present at a minimum content of 0.5%, preferably at least 0.55%, 0.60%, 0.66%, 0.67%, or 0.68%. The upper limit for carbon is 0.9%, and it can be set to 0.85%, 0.80%, 0.75%, 0.74%, 0.73%, or 0.72%. The preferred ranges are 0.6%-0.8% and 0.65% _-0.75 %. In any case, the amount of carbon should be controlled so that the amount of primary carbides of type _M23C6 , _M7C3 , and _M6C in the steel is limited, _and preferably, the steel does not contain such primary carbides.

矽（0.03%-0.8%）矽是用於脫氧。Si以溶解的形式存在於鋼中。Si為強鐵氧體形成體（ferrite former），且增加碳活性，因此增加了形成非所欲的碳化物之風險，此對衝擊強度產生負面影響。矽亦易於界面分離，此可能致使韌性及耐熱疲勞性降低。因此，Si被限制為0.8%。上限可為0.7%、0.6%、0.5%、0.40%、0.35%、0.30%、0.28%、0.27%、0.26%、0.25%、0.24%、0.23%及0.22%。下限可為0.05%、0.10%、0.11%、0.12%、0.13%、0.14%或0.15%。 Silicon (0.03%-0.8%) is used for deoxidation. Si exists in steel in dissolved form. Si is a strong ferrite former and increases carbon reactivity, thus increasing the risk of forming undesirable carbides, which negatively impacts impact strength. Silicon is also prone to interfacial separation, which may lead to reduced toughness and heat fatigue resistance. Therefore, Si is limited to 0.8%. Upper limits are 0.7%, 0.6%, 0.5%, 0.40%, 0.35%, 0.30%, 0.28%, 0.27%, 0.26%, 0.25%, 0.24%, 0.23%, and 0.22%. Lower limits are 0.05%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, or 0.15%.

錳（0.1%-1.8%）錳有助於改善鋼之硬化性，並且與硫錳一起有助於藉由形成硫化錳來改善機械加工性。因此，錳應以0.1%之最小含量存在，較佳至少0.2%、0.3%、0.35%或0.4%。在較高的硫含量下，錳防止鋼中的紅脆性。Mn亦可能引起非所欲的微偏析，致使呈帶狀結構。鋼應含有最大1.8%，較佳最大0.8%、0.75%、0.7%、0.6%、0.55%或0.5%。 Manganese (0.1%-1.8%): Manganese helps improve the hardening properties of steel and, together with manganese sulfate, helps improve machinability by forming manganese sulfide. Therefore, manganese should be present in a minimum content of 0.1%, preferably at least 0.2%, 0.3%, 0.35%, or 0.4%. At higher sulfur contents, manganese prevents red brittleness in steel. Mn can also cause undesirable microsegregation, resulting in a banded structure. Steel should contain a maximum of 1.8%, preferably a maximum of 0.8%, 0.75%, 0.7%, 0.6%, 0.55%, or 0.5%.

鉻（4.0%-6.6%）鉻是以至少4%之含量存在，以在熱處理期間在較大橫截面中提供良好的硬化性。若鉻含量過高，則可能致使形成高溫鐵氧體，此降低了熱加工性。下限可為4.5%、4.6%、4.7%、4.8%或4.9%。上限可為6.0%、5.9%、5.8%、5.7%、5.6%、5.5%、5.4%、5.3%、5.2%或5.1%。 Chromium (4.0%-6.6%) is present at a content of at least 4% to provide good hardening properties in a larger cross-section during heat treatment. Excessive chromium content may lead to the formation of high-temperature ferrite, which reduces hot workability. Lower limits are 4.5%, 4.6%, 4.7%, 4.8%, or 4.9%. Upper limits are 6.0%, 5.9%, 5.8%, 5.7%, 5.6%, 5.5%, 5.4%, 5.3%, 5.2%, or 5.1%.

鉬（1.8%-3.5%）已知Mo對硬化性具有非常有利的影響。鉬對於獲得良好的二次硬化反應是必要的。最低含量為1.8%，且可設定為1.9%、2.0%、2.1%、2.15%或2.2%。鉬為一種強碳化物形成元素，且亦為一種強鐵氧體形成體。因此，鉬之最大含量為3.5%。Mo被限制為2.9%、2.7%、2.6%、2.5%、2.4%或2.3%。 Molybdenum (1.8%-3.5%): Mo is known to have a very favorable effect on hardening properties. Molybdenum is necessary to obtain a good secondary hardening reaction. The minimum content is 1.8%, and it can be set to 1.9%, 2.0%, 2.1%, 2.15%, or 2.2%. Molybdenum is a strong carbide-forming element and also a strong ferrite-forming element. Therefore, the maximum content of molybdenum is 3.5%. Mo is limited to 2.9%, 2.7%, 2.6%, 2.5%, 2.4%, or 2.3%.

鎢（W≤0.5%）鎢不為本發明之必要元素。上限為0.5%，且可設定為0.4%、0.3%、0.2%或0.1%。 Tungsten (W≤0.5%) Tungsten is not a necessary element of this invention. The upper limit is 0.5%, and it can be set to 0.4%, 0.3%, 0.2% or 0.1%.

鎳（≤1%）鎳不為本發明之必要元素。上限可設定為0.5%、0.4%、0.3%或0.25%。 Nickel (≤1%) is not an essential element of this invention. The upper limit can be set to 0.5%, 0.4%, 0.3% or 0.25%.

釩（1.3%-2.3%）釩在鋼基質中形成均勻分佈的VC及V（C,N）型一級沉澱碳化物及碳氮化物。此等碳化物及碳氮化物亦可表示為MX，其中M主要為V但可存在Cr及Mo，以及X為C、N及B中之一或多者。然而，在下文中將僅使用VC，其含義與MX相同。釩是用於形成受控量之相對較大的VC，因此釩應以1.3%-2.3%之量存在。下限可設定為1.35%、1.4%、1.45%、1.5%或1.55%。上限可設定為2.2%、2.1%、2.0%、1.9%、1.8%、1.7%或1.65%。 Vanadium (1.3%-2.3%) forms uniformly distributed VC and V(C,N) type primary precipitates of carbides and carbonitrides in a steel matrix. These carbides and carbonitrides can also be represented as MX, where M is primarily V but may contain Cr and Mo, and X is one or more of C, N, and B. However, VC will be used hereinafter, and its meaning is the same as MX. Vanadium is used to form a relatively large controlled amount of VC, therefore vanadium should be present in an amount of 1.3%-2.3%. The lower limit can be set at 1.35%, 1.4%, 1.45%, 1.5%, or 1.55%. The upper limit can be set at 2.2%, 2.1%, 2.0%, 1.9%, 1.8%, 1.7%, or 1.65%.

鋁（≤0.1%）鋁可與Si及Mn組合用於脫氧。下限設定為0.001%、0.003%、0.005%或0.007%，以確保良好的脫氧。上限限制為0.1%，以避免沉澱非所欲的相（諸如AIN）。上限可為0.05%、0.04%或0.3%。 Aluminum (≤0.1%): Aluminum can be combined with Si and Mn for deoxidation. Lower limits are set at 0.001%, 0.003%, 0.005%, or 0.007% to ensure good deoxidation. Upper limits are limited to 0.1% to avoid precipitation of undesirable phases (such as AlN). Upper limits can be 0.05%, 0.04%, or 0.3%.

氮（≤0.12%）氮為視情況選用之元素。N被限制為0.12%，以避免硬相（特別是V（C,N））量過高。然而，氮含量可與釩含量平衡以形成主要沉澱之富釩碳氮化物。這些在奧氏體化步驟期間會部分地溶解，然後在回火步驟期間作為奈米尺寸的粒子沉澱。釩碳氮化物之熱穩定性被視為優於釩碳化物之熱穩定性，因此可改善工具鋼之耐回火性以及在高奧氏體化溫度下提高耐晶粒生長性。若出於上述原因有意控制氮含量，則下限可設定為0.006%、0.007%、0.08%、0.09%、0.01%、0.012%、0.013%、0.014%或0.015%。上限可為0.11%、0.10%、0.09%、0.08%、0.07%、0.06%、0.05%、0.04%或0.03%。 Nitrogen (≤0.12%) Nitrogen is an element selected on a case-by-case basis. N is limited to 0.12% to avoid excessive amounts of hard phases (especially V(C,N)). However, the nitrogen content can be balanced with the vanadium content to form vanadium-rich carbonitrides as the main precipitate. These partially dissolve during the austenitizing step and then precipitate as nanoscale particles during the tempering step. The thermal stability of vanadium carbonitrides is considered superior to that of vanadium carbides, thus improving the tempering resistance of tool steels and enhancing resistance to grain growth at high austenitizing temperatures. If nitrogen content is intentionally controlled for the reasons mentioned above, the lower limit can be set to 0.006%, 0.007%, 0.08%, 0.09%, 0.01%, 0.012%, 0.013%, 0.014%, or 0.015%. The upper limit can be 0.11%, 0.10%, 0.09%, 0.08%, 0.07%, 0.06%, 0.05%, 0.04%, or 0.03%.

銅（≤1%） Cu為視情況選用之元素，其可有助於增加鋼的硬度及耐腐蝕性。然而，一旦添加了銅，就不可能自鋼中提取銅。這嚴重地使得廢料處理更加困難。出於此原因，通常不會故意添加銅。上限可限制為0.5%、0.4%、0.3%、0.2%或0.15%。 Copper (≤1%) is an element selected on a case-by-case basis, which can help increase the hardness and corrosion resistance of steel. However, once copper is added, it is impossible to extract copper from steel. This significantly makes waste disposal more difficult. For this reason, copper is usually not intentionally added. The upper limit can be limited to 0.5%, 0.4%, 0.3%, 0.2%, or 0.15%.

鈷（≤5%） Co為視情況選用之元素。Co致使固相線溫度升高，因此提供了提高硬化溫度的機會。因此在奧氏體化期間可溶解更大部分的碳化物，從而提高硬化性。然而，Co價格昂貴且大量之Co亦會致使韌性及耐磨損性降低。因此，最大量為5%。然而，通常不會故意添加Co。最大含量可設定為2%、1%、0.5%或0.2%。 Cobalt (≤5%) is an element selected on a case-by-case basis. Co raises the solidus temperature, thus providing an opportunity to increase the hardening temperature. Therefore, it can dissolve a larger portion of the carbides during austenitization, thereby improving hardenability. However, Co is expensive, and large amounts of Co can also reduce toughness and wear resistance. Therefore, the maximum content is 5%. However, Co is usually not intentionally added. Maximum content can be set at 2%, 1%, 0.5%, or 0.2%.

鈮（≤0.1%）鈮與釩之相似之處在於其形成M（N,C）型碳氮化物。然而，Nb致使M（N,C）之形狀更有棱角，並且在高含量下可能降低硬化性。因此，最大量為0.1%，較佳為0.05%。Nb沉澱物比V沉澱物更穩定，因此可用於晶粒細化，因為NbC的細分散發揮了釘扎晶粒邊界的作用，致使晶粒細化以及高溫下改善的韌性及改善的耐軟化性。出於此原因，Nb為一種視情況選用之元素，並且可以≤0.1%之量存在。上限可設定為0.06%、0.05%、0.04%、0.03%、0.01%或0.005%。下限可設定為0.005%、0.006%、0.007%、0.008%、0.009%或0.01%。 Niobium (≤0.1%) Niobium is similar to vanadium in that it forms M(N,C) type carbonitrides. However, Nb causes the M(N,C) shape to be more angular, and at high contents, it may reduce hardenability. Therefore, the maximum amount is 0.1%, preferably 0.05%. Nb precipitates are more stable than V precipitates and can therefore be used for grain refinement, as the fine dispersion of NbC acts to anchor grain boundaries, resulting in grain refinement and improved toughness and softening resistance at high temperatures. For this reason, Nb is an element to be selected on a case-by-case basis and can be present in amounts ≤0.1%. The upper limits can be set to 0.06%, 0.05%, 0.04%, 0.03%, 0.01%, or 0.005%. The lower limit can be set to 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, or 0.01%.

鈦、鋯及鉭此等元素為碳化物形成體，並且可以所請範圍存在於合金中以改變硬相之組成。然而，通常不會添加此等元素。各元素之量較佳為≤0.5%、0.1%或≤0.05%，更佳為0.01%或0.005%。 Titanium, zirconium, and tantalum are carbide forgings and can be present in the alloy within the claimed range to modify the composition of the hard phase. However, these elements are usually not added. The amounts of each element are preferably ≤0.5%, 0.1%, or ≤0.05%, more preferably 0.01% or 0.005%.

硼（≤0.01%）可使用B以進一步增加鋼之硬度。該量限制為0.01%，較佳≤0.006%，更佳0.005%。 Boron (≤0.01%) can be used to further increase the hardness of steel. This amount is limited to 0.01%, preferably ≤0.006%, and even more preferably 0.005%.

Ca 、 Mg 及 REM（rare earth metal；稀土金屬）此等元素可以所請量添加至鋼中以改質非金屬夾雜物及/或以進一步改善機械加工性、熱加工性及/或可焊接性。Ca及Mg之量較佳為≤0.01%，更佳為≤0.005%。REM之量較佳為≤0.2%，更佳為≤0.1%，或甚至為0.05%。 Ca , Mg , and REM (rare earth metals) can be added to steel in appropriate amounts to modify non-metallic inclusions and/or further improve machinability, hot workability, and/or weldability. The amounts of Ca and Mg are preferably ≤0.01%, more preferably ≤0.005%. The amounts of REM are preferably ≤0.2%, more preferably ≤0.1%, or even 0.05%.

雜質元素雜質元素在製造鋼期間是無法避免的。因此，雜質元素被包括在餘量中，並且該等元素之程度對於本發明之定義不為必要的。 P、S及O為主要的雜質，其通常對鋼的機械性質產生負面影響。此等元素是無法避免的，可能會以常見之雜質含量出現在鋼中。然而，由於此等元素可能對鋼之性質產生負面影響，因此雜質含量可能會受到進一步限制。較佳限制如下所述。P可被限制為0.1%、0.05%或0.03%。S可被限制為0.5%、0.1%、0.05%、0.0015%、0.0010%、0.0008%、0.0005%或甚至0.0001%。O可被限制為0.01%、0.003%、0.0015%、0.0012%、0.0010%、0.0008%、0.0006%或0.0005%。 Impurities are unavoidable during steelmaking. Therefore, impurities are included in the balance, and the extent of these elements is not essential to the definition of this invention. P, S, and O are the main impurities, which generally have a negative effect on the mechanical properties of steel. These elements are unavoidable and may appear in steel at common impurity levels. However, because these elements may have a negative effect on the properties of steel, the impurity content may be further limited. Preferred limits are as follows: P may be limited to 0.1%, 0.05%, or 0.03%. S may be limited to 0.5%, 0.1%, 0.05%, 0.0015%, 0.0010%, 0.0008%, 0.0005%, or even 0.0001%. O can be limited to 0.01%, 0.003%, 0.0015%, 0.0012%, 0.0010%, 0.0008%, 0.0006%, or 0.0005%.

鋼之製造Steel manufacturing

具有所請化學組成之工具鋼可藉由習知冶金所製造，包括在電弧爐（electric arc furnace；EAF）中熔化並且在澆桶（ladle）中進一步精煉，視情況在鑄造之前進行真空處理。錠亦可經受電渣重熔（ESR）以進一步改善錠之清潔度及微觀結構均勻性。此外，鋼亦可經受真空感應熔煉（vacuum induction melting；VIM）及/或真空電弧重熔（vacuum arc remelting；VAR）。所請之鋼之另一種加工路線為將其氣體霧化，然後將其經受熱等靜壓（hot isostatic pressing；HIP）以形成HIPed錠，該錠亦可在as-HIPed條件下使用。錠可經受進一步熱加工至最終尺寸以及軟退火至≤360 HBW，較佳≤300 HBW之布氏硬度（Brinell hardness）。布氏硬度為用直徑為10 mm之碳化鎢球及3000 kgf（29400N）之負載所測量，亦可表示為HBW _10/3000。鋼在使用前可經受硬化及回火。 Tool steel with the requested chemical composition can be manufactured using conventional metallurgy, including melting in an electric arc furnace (EAF) and further refining in a ladle, with vacuum treatment as needed before casting. The ingot can also undergo electroslag remelting (ESR) to further improve its cleanliness and microstructure uniformity. Additionally, the steel can be subjected to vacuum induction melting (VIM) and/or vacuum arc remelting (VAR). Another processing route for the requested steel involves atomizing it into a gas and then subjecting it to hot isostatic pressing (HIP) to form a HIPed ingot, which can also be used under as-HIPed conditions. The ingots can be further heat-worked to final dimensions and soft-annealed to a Brinell hardness of ≤360 HBW, preferably ≤300 HBW. Brinell hardness is measured using a 10 mm diameter tungsten carbide ball under a load of 3000 kgf (29400 N) and can also be expressed as HBW _10/3000 . The steel can be hardened and tempered before use.

鋼通常在軟退火狀態下交付給客戶，該鋼具有鐵氧體基質，碳化物均勻分佈於其中。軟退火鋼對於大尺寸亦具有均勻性質，並且根據較佳具體實例，硬度之均勻性應具有≤360 HBW之平均硬度，並且對於至少100 mm之厚度，根據ASTM E10-01測量在厚度方向上之平均布氏硬度值之最大偏差小於10%，較佳小於5%，其中壓痕中心與試樣邊緣或另一個壓痕邊緣之最小距離應至少為壓痕直徑之2又1/2倍，最大距離應不超過壓痕直徑之4倍。The steel is typically delivered to customers in a soft-annealed state. This steel has a ferrite matrix with uniformly distributed carbides. Soft-annealed steel exhibits uniformity even for large dimensions, and, according to preferred specific examples, should have an average hardness of ≤360 HBW. For thicknesses of at least 100 mm, the maximum deviation of the average Brinell hardness value in the thickness direction, measured according to ASTM E10-01, should be less than 10%, preferably less than 5%. The minimum distance between the indentation center and the edge of the specimen or another indentation edge should be at least 2 1/2 times the indentation diameter, and the maximum distance should not exceed 4 times the indentation diameter.

霧化粉末亦可用於積層製造。Atomized powders can also be used in the fabrication of layers.

在下文中將更詳細地描述本發明。The invention will be described in more detail below.

根據本發明之熱加工鋼按重量百分比（wt.%）由以下組成： C 0.5-0.9 Si 0.03-0.8 Mn 0.1-1.8 Cr 4.0-6.6 Mo 1.8-3.5 V 1.3-2.3 Al ≤0.1 N ≤0.12 Ni ≤1 W ≤1 Co ≤5 Cu ≤1 Nb ≤0.1 Ti ≤0.05 Zr ≤0.05 Ta ≤0.05 B ≤0.01 Ca ≤0.01 Mg ≤0.01 REM ≤0.2 餘量為鐵及雜質。 The hot-workable steel according to the present invention comprises the following components by weight percentage (wt.%): C 0.5-0.9 Si 0.03-0.8 Mn 0.1-1.8 Cr 4.0-6.6 Mo 1.8-3.5 V 1.3-2.3 Al ≤0.1 N ≤0.12 Ni ≤1 W ≤1 Co ≤5 Cu ≤1 Nb ≤0.1 Ti ≤0.05 Zr ≤0.05 Ta ≤0.05 B ≤0.01 Ca ≤0.01 Mg ≤0.01 REM ≤0.2 The remainder consists of iron and impurities.

較佳地，熱加工工具鋼滿足以下條件中之至少一者： C 0.6-0.8 Si 0.05-0.6 Mn 0.2-0.8 Cr 4.4-5.6 Mo 2.0-2.5 V 1.5-1.9 Al ≤0.05 N ≤0.08 Ni ≤0.5 W ≤0.5 Co ≤2 Cu ≤0.5 Nb ≤0.05 Ti ≤0.01 Zr ≤0.01 Ta ≤0.01 B ≤0.006 Ca ≤0.005 Mg ≤0.005 REM ≤0.1。 Preferably, the hot-working tool steel satisfies at least one of the following conditions: C 0.6-0.8 Si 0.05-0.6 Mn 0.2-0.8 Cr 4.4-5.6 Mo 2.0-2.5 V 1.5-1.9 Al ≤0.05 N ≤0.08 Ni ≤0.5 W ≤0.5 Co ≤2 Cu ≤0.5 Nb ≤0.05 Ti ≤0.01 Zr ≤0.01 Ta ≤0.01 B ≤0.006 Ca ≤0.005 Mg ≤0.005 REM ≤0.1.

更佳地，鋼之組成滿足以下條件中之一或多者： C 0.65-0.75 Si 0.15-0.5 Mn 0.4-0.5 Cr 4.9-5.1 Mo 2.2-2.3 V 1.5-1.7 Al ≤0.03 N ≤0.05 Ni 0.25 W ≤0.2 Co ≤1 Cu ≤0.2 Nb ≤0.005 Ti ≤0.005 Zr ≤0.005 Ta ≤0.005 REM ≤0.05。 More preferably, the composition of the steel satisfies one or more of the following conditions: C 0.65-0.75 Si 0.15-0.5 Mn 0.4-0.5 Cr 4.9-5.1 Mo 2.2-2.3 V 1.5-1.7 Al ≤0.03 N ≤0.05 Ni 0.25 W ≤0.2 Co ≤1 Cu ≤0.2 Nb ≤0.005 Ti ≤0.005 Zr ≤0.005 Ta ≤0.005 REM ≤0.05.

較佳地，鋼滿足以下條件中之至少一者： C 0.66-0.75 Si 0.15-0.25 V 1.52-1.68 Al 0.001-0.03 N ≤0.05 W ≤0.1 Cu ≤0.15。 Preferably, the steel satisfies at least one of the following conditions: C 0.66-0.75 Si 0.15-0.25 V 1.52-1.68 Al 0.001-0.03 N ≤0.05 W ≤0.1 Cu ≤0.15.

在一個特別較佳具體實例中，所有此等條件皆被滿足。In a particularly good concrete example, all such conditions are satisfied.

為了提高耐磨料磨損性，可調整組成，使得在硬化及回火條件下之鋼含有少量且可控量之尺寸大於或等於1 μm之碳化釩。尺寸以等效圓直徑（equivalent circular diameter；ECD）形式提供，其為根據圖像分析中獲得之圖像面積（A）計算得出。ECD具有與粒子相同的投影面積，等於2√（A/π）。To improve the wear resistance of the abrasive, the composition can be adjusted so that the steel under hardening and tempering conditions contains a small, controllable amount of vanadium carbide with a size greater than or equal to 1 μm. The size is provided in the form of an equivalent circular diameter (ECD), which is calculated based on the image area (A) obtained from image analysis. The ECD has the same projected area as the particle, equal to 2√(A/π).

鋼應較佳含有0.2-4體積%，較佳0.5-3體積%，更佳1.5-2.3體積%之VC。The steel should preferably contain 0.2-4% by volume, preferably 0.5-3% by volume, and even more preferably 1.5-2.3% by volume of vitamin C.

M ₆C及M ₇C ₃之量應分別限制為2體積%，較佳0.5體積%，更佳0.1體積%。 The amounts _of _M6C and _M7C3 should be limited to 2 volumes, preferably 0.5 volumes, and even more preferably 0.1 volumes, respectively.

可藉由選擇適當的奧氏體化時間及溫度，表示為800℃至500℃溫度區間內之冷卻時間（t _5/8）之冷卻速度以及回火溫度之組合來調節鋼之硬度。通常，鋼經過二個小時回火二次（2x2h），以減少殘餘奧氏體之量至小於2體積%。 The hardness of steel can be adjusted by selecting appropriate austenitizing time and temperature, expressed as a combination of cooling rate (t _5/8 ) within a temperature range of 800℃ to 500℃ and tempering temperature. Typically, the steel is tempered twice (2x2h) over two hours to reduce the amount of retained austenite to less than 2 volumes.

鋼在硬化及回火至硬度為55-57 HRC後之機械性質應較佳滿足以下條件之至少一者：屈服強度（Rp0.2）：≥1700 MPa，較佳≥1725 MPa，更佳≥1750 MPa。拉伸強度（Rm）：≥1950 MPa，較佳≥2050 MPa，更佳≥2050 MPa，最佳≥2100 MPa。伸長率（A5）：≥3%，較佳≥4，更佳≥5%，最佳≥6%。減少面積（Z）：≥5%，較佳≥10，更佳≥15%，最佳≥20%。實施例1 The mechanical properties of steel after hardening and tempering to a hardness of 55-57 HRC should preferably satisfy at least one of the following conditions: Yield strength (Rp0.2): ≥1700 MPa, preferably ≥1725 MPa, more preferably ≥1750 MPa. Tensile strength (Rm): ≥1950 MPa, preferably ≥2050 MPa, more preferably ≥2050 MPa, best ≥2100 MPa. Elongation (A5): ≥3%, preferably ≥4%, more preferably ≥5%, best ≥6%. Reduction area (Z): ≥5%, preferably ≥10%, more preferably ≥15%, best ≥20%. Example 1

表1揭示洛氏硬度C（hardness in Rockwell C；HRC）與硬化參數奧氏體化時間及溫度之函數。可看出，可在49至61 HRC範圍內容易地調整硬度。ESR錠之組成如下：C 0.71%、Si 0.22%、Mn 0.46%、Cr 5.01%、Mo 2.24%、V 1.62%、Al 0.007%。Table 1 shows the function of Rockwell hardness C (HRC) and the hardening parameters austenitizing time and temperature. It can be seen that the hardness can be easily adjusted within the range of 49 to 61 HRC. The composition of the ESR ingot is as follows: C 0.71%, Si 0.22%, Mn 0.46%, Cr 5.01%, Mo 2.24%, V 1.62%, Al 0.007%.

奧氏體化溫度（°C）時間（min） 540 °C 560 °C 580 °C 600 °C 610 °C 1050 30 57.3 56.2 54.9 52.4 48.9 1100 30 59.1 58.1 57.5 54.5 52.0 1130 10 60.4 59.1 58.4 55.9 53.7 1150 10 61.2 61.0 59.6 56.7 54.8 表1. 硬化及回火條件下之硬度（HRC）。對於所有在真空中冷卻之樣品，t _8/5= 300 s，回火2x2h。 Austenitizing temperature (°C) Time(min) 540 °C 560 °C 580 °C 600 °C 610 °C 1050 30 57.3 56.2 54.9 52.4 48.9 1100 30 59.1 58.1 57.5 54.5 52.0 1130 10 60.4 59.1 58.4 55.9 53.7 1150 10 61.2 61.0 59.6 56.7 54.8 Table 1. Hardness (HRC) under hardening and tempering conditions. For all samples cooled in vacuum, t _8/5 = 300 s, tempering 2 x 2 h.

分別檢測在1130°C下奧氏體化及在580°C及600°C下回火之鋼之耐回火性。將鋼樣品在600°C下加熱10小時。在第一種情況下，硬度從58.4 HRC降低至53.6 HRC，而對於第二個樣品，硬度從55.9 HRC降低至52.8 HRC。因此，硬度損失分別為4.8 HRC及3.1 HRC。The tempering resistance of steels austenitized at 1130°C and tempered at 580°C and 600°C was tested, respectively. The steel samples were heated at 600°C for 10 hours. In the first case, the hardness decreased from 58.4 HRC to 53.6 HRC, while for the second sample, the hardness decreased from 55.9 HRC to 52.8 HRC. Therefore, the hardness losses were 4.8 HRC and 3.1 HRC, respectively.

此等值可與開頭提到之鋼UNIMAX ^®之相應值進行比較。製備具有標稱成分C 0.5%、Si 0.2%、Mn 0.5%、Cr 5.0%、Mo 2.3%及V 0.5%之鋼樣品。藉由以t _8/5= 300 s在1050°C下奧氏體化30分鐘並且在540°C下回火2x2h，將鋼硬化至57.8 HRC。初始硬度為57.8 HRC，並且在600°C下10小時後之硬度為49.4 HRC。因此，已知鋼之硬度損失為8.4 HRC。因此可得到結論，與已知鋼相比，本發明之鋼具有優異的耐回火性。 These values can be compared with the corresponding values of the ^UNIMAX® steel mentioned at the beginning. A steel sample with the nominal composition of 0.5% C, 0.2% Si, 0.5% Mn, 5.0% Cr, 2.3% Mo, and 0.5% V was prepared. The steel was hardened to 57.8 HRC by austenitizing at 1050°C for 30 minutes at t _8/5 = 300 s and tempering at 540°C for 2 x 2 hours. The initial hardness was 57.8 HRC, and the hardness after 10 hours at 600°C was 49.4 HRC. Therefore, the hardness loss of the known steel is 8.4 HRC. Thus, it can be concluded that the steel of this invention has superior tempering resistance compared to known steels.

根據ASTM E45-97，方法A，板I-r，針對微渣檢測本發明之鋼之清潔度並且在表2中提供結果。According to ASTM E45-97, Method A, Plate I-r, the cleanliness of the steel of the present invention was tested for micro-slag and the results are provided in Table 2.

A A B B C C D D T H T H T H T H 0.5 0 0.5 1.0 0 0 0.5 1.0 表2. 根據ASTM E45-97，方法A，板I-r之清潔度。實施例2 A A B B C C D D T H T H T H T H 0.5 0 0.5 1.0 0 0 0.5 1.0 Table 2. Cleanliness of Plate Ir according to ASTM E45-97, Method A. Example 2

實施例1之ESR錠被熱軋至196 mm之直徑，沿LC2方向從該錠中取出三個樣品並且進行機械性質檢測。藉由在1050°C下奧氏體化30分鐘，以t _8/5= 300秒在真空中冷卻，然後在560°C下回火2小時二次，將該鋼樣品硬化至硬度為56 HRC。下面給出了以下檢測之平均值：屈服強度（Rp0.2）：1761 MPa 抗拉強度（Rm）：2117 MPa 伸長率（A5）：7% 減少面積（Z）：26% 實施例3 In Example 1, the ESR ingot was hot-rolled to a diameter of 196 mm. Three samples were taken from the ingot along the LC2 direction and their mechanical properties were tested. The steel sample was hardened to a hardness of 56 HRC by austenitizing at 1050°C for 30 minutes, cooling in vacuum for t _8/5 = 300 seconds, and then tempering twice at 560°C for 2 hours. The average values of the following tests are given below: Yield strength (Rp0.2): 1761 MPa; Tensile strength (Rm): 2117 MPa; Elongation (A5): 7%; Reduction area (Z): 26%. Example 3

在此實施例中，將本發明之鋼與使用之標準基質鋼或鍛造工具進行比較。In this embodiment, the steel of the present invention is compared with the standard base steel or forging tools used.

該等合金具有以下組成（以wt.%計）本發明之鋼對比鋼 C 0.7 0.5 Si 0.2 0.2 Mn 0.5 0.5 Cr 5.0 4.2 Mo 2.3 2.0 V 1.6 1.2 W 0.01 1.6 餘量為Fe及雜質。 These alloys have the following composition (in wt.%): Steel of the Invention Comparative Steel C 0.7 0.5 Si 0.2 0.2 Mn 0.5 0.5 Cr 5.0 4.2 Mo 2.3 2.0 V 1.6 1.2 W 0.01 1.6 The balance is Fe and impurities.

合金經受標準熱處理、鍛造及軟退火至硬度為約300 HBW。兩種鋼均藉由加熱至1100°C 30分鐘進行硬化及回火，在二小時內在540°C下進行兩次淬火及回火（2x2h）。本發明之鋼之硬度為57HRC，對比鋼之硬度為56HRC。使用同批次之800目氧化鋁紙藉由Pin on Disk方法檢測鋼之耐磨損性。發現本發明之鋼之磨損損失為178 mg/min，對比鋼之磨損損失為219 mg/min。The alloy underwent standard heat treatment, forging, and soft annealing to a hardness of approximately 300 HBW. Both steels were hardened and tempered by heating to 1100°C for 30 minutes, followed by two quenching and tempering cycles at 540°C within two hours (2 x 2 h). The steel of this invention has a hardness of 57 HRC, while the comparative steel has a hardness of 56 HRC. The wear resistance of the steels was tested using the same batch of 800-mesh alumina paper via the pin-on-disk method. The wear loss of the steel of this invention was found to be 178 mg/min, while that of the comparative steel was 219 mg/min.

製備本發明之鋼之另一樣品以獲得與對比鋼相同的硬度。此是藉由加熱至1100°C 30分鐘並且在540°C下回火2x2h來實現。硬度為56 HRC。正如預期，與硬度為57 HRC之鋼相比，該樣品之磨損損失略高（189 mg/min），但明顯低於具有相同硬度之對比鋼。實施例4 Another sample of the steel of the present invention was prepared to obtain the same hardness as the comparative steel. This was achieved by heating to 1100°C for 30 minutes and tempering at 540°C for 2 x 2 hours. The hardness was 56 HRC. As expected, the wear loss of this sample was slightly higher (189 mg/min) compared to the steel with a hardness of 57 HRC, but significantly lower than that of the comparative steel with the same hardness. Example 4

製備與實施例1中相同組成之鋼樣品用於焊接測試。鋼之實心塊被銑削成具有銳利的90°內角，樣品進行了二種不同的硬化處理。第一次熱處理包括在1050°C下奧氏體化30分鐘，以t _8/5= 300秒在真空中冷卻，然後在560°C下回火2小時二次。第二次熱處理與此不同之處在於，在1130℃下進行奧氏體化10分鐘。 Steel samples with the same composition as in Example 1 were prepared for welding tests. Solid steel blocks were milled to have sharp 90° internal angles, and the samples underwent two different hardening treatments. The first heat treatment consisted of austenitizing at 1050°C for 30 minutes, cooling in vacuum for t⁸ _/⁵ = 300 seconds, and then tempering twice at 560°C for 2 hours. The second heat treatment differed in that it involved austenitizing at 1130°C for 10 minutes.

然後在室溫（room temperature；RT）、80°C、225°C及325°C下使用直徑為1.6 mm之焊條及三種不同的標準焊接耗材對樣品進行TIG焊接。申請人擁有來自UTP Schweissmaterial GmbH之Caldie TIG及QRO 90 TIG以及UTP A 696 TIG。The samples were then TIG welded at room temperature (RT), 80°C, 225°C, and 325°C using 1.6 mm diameter electrodes and three different standard welding consumables. The applicant owns Caldie TIG and QRO 90 TIG, as well as UTP A 696 TIG, from UTP Schweissmaterial GmbH.

使用耗材Caldie TIG在所有溫度下都會出現裂紋。然而，令人驚訝的是，發現另外二種耗材亦可用於在RT下進行無裂紋焊接而不會產生裂紋。因此，本發明之鋼具有令人驚訝良好的可焊接性。產業利用性 Using Caldie TIG consumables resulted in cracking at all temperatures. Surprisingly, however, two other consumables were found to be suitable for crack-free welding at RT without inducing cracks. Therefore, the steel of this invention exhibits surprisingly good weldability. Industrial Applicability

本發明之鋼可用於工具經受磨料磨損之熱加工應用。特別地，該鋼適合作為用於熱鍛、加壓硬化、壓鑄、高壓壓鑄或熱擠壓之工具。The steel of this invention can be used in hot working applications where tools are subjected to abrasive wear. In particular, the steel is suitable for use in tools for hot forging, pressure hardening, die casting, high-pressure die casting, or hot extrusion.

無without

Claims

A hot-working tool steel for hot forging, pressure hardening, die casting, or hot extrusion, comprising the following components by weight percentage (wt.%): C 0.5-0.9, Si 0.03-0.35, Mn 0.1-1.8, Cr 4.0-6.6, Mo 2.0-2.5, V 1.5-2.3, Al 0.001-0.1, N ≤0.12, Ni ≤1, W ≤0.3, Co ≤5, Cu ≤1, Nb ≤0.1, Ti ≤0.05, Zr ≤0.05, Ta ≤0.05, B ≤0.01, Ca ≤0.01, Mg ≤0.01, REM ≤0.2, The balance is iron and impurities.

For example, the hot-worked tool steel of claim 1, wherein the steel satisfies at least one of the following conditions: C 0.6-0.8, Si 0.05-0.35, Mn 0.2-0.8, Cr 4.4-5.6, Mo 2.0-2.5, V 1.5-1.9, Al 0.001-0.05, N ≤0.08, Ni ≤0.5, W ≤0.3, Co ≤2, Cu ≤0.5, Nb ≤0.05, Ti ≤0.01, Zr ≤0.01, Ta ≤0.01, B ≤0.006, Ca ≤0.005, Mg ≤0.005, REM ≤0.1.

For hot-worked tool steels as requested in item 1 or 2, the steel shall satisfy at least one of the following conditions: C 0.65-0.75, Si 0.15-0.35, Mn 0.4-0.5, Cr 4.9-5.1, Mo 2.2-2.3, V 1.5-1.7, Al 0.001-0.03, N ≤0.05, Ni 0.25, W ≤0.2, Co ≤1, Cu ≤0.2, Nb ≤0.005, Ti ≤0.005, Zr ≤0.005, Ta ≤0.005, REM ≤0.05.

For example, the hot-worked tool steel of claim 1 or 2, wherein the steel contains carbides with a size ≥1 μm and satisfies at least one of the following conditions regarding the amount of carbides in volume %: VC 0.2-4, _M6C _{≤2, M7C3} _≤2 .

For example, the hot-worked tool steel of claim 4, wherein the steel contains carbides with a size ≥1 μm and satisfies at least one of the following conditions regarding the amount of carbides in volume %: VC 0.5-3, _M6C ≤0.5, _M7C3 _≤0.5 .

For example, the hot-worked tool steel of claim 5, wherein the steel contains carbides with a size ≥1 μm and satisfies at least one of the following conditions regarding the amount of carbides in volume %: VC 1.5-3, _M6C ≤0.1, _M7C3 _≤0.1 .

For example, the hot-worked tool steel of claim 1 or 2, wherein the steel has a hardness of 55-57 HRC after hardening and tempering, and wherein the steel satisfies at least one of the following conditions: Yield strength (Rp0.2) ≥1750 MPa, Tensile strength (Rm) ≥2100 MPa, Elongation (A5) ≥6%, Reduction area (Z) ≥20%.

For example, the hot-worked tool steel of claim 1 or 2, wherein the steel satisfies at least one of the following conditions: C 0.66-0.75, Si 0.15-0.25, Mo 2.2-2.3, V 1.52-1.68, Al 0.001-0.03, N ≤0.05, W ≤0.1, Co ≤1, Cu ≤0.15, Nb ≤0.005, Ti ≤0.005, Zr ≤0.005.

For hot-worked tool steels as claimed in Item 1 or 2, the steel is subjected to soft annealing and has an average hardness of ≤360 HBW, and the steel has a thickness of at least 100 mm, and the maximum deviation of the average Brinell hardness value in the thickness direction as measured according to ASTM E10-01 is less than 10%, and the minimum distance between the center of the indentation and the edge of the specimen or another indentation edge shall be at least 2 1/2 times the indentation diameter, and the maximum distance shall not exceed 4 times the indentation diameter.

The use of a hot-worked tool steel as described in any of claims 1 to 9, for use as a tool for hot forging, pressure hardening, die casting, high-pressure die casting or hot extrusion.