200925295 九、發明說明： 【發明所屬之技術領域】 本發明係關於鐵基粉末。本發明尤其係關於適用於耐磨 損產品（閥座嵌環（VSI))之製造之粉末以及自該粉末製得之 組件。 【先前技術】 具有尚对磨性之產品係廣泛使用的，且不斷需要具有相 同於或優於現存產品之效能之價格較低廉產品。每年僅閥 座嵌環的產量就大於1 000 000 000組件。 具有高耐磨性之產品之製造可基於（例如）粉末，諸如鐵 或鐵基粉末，包括碳化物形式之碳。 碳化物極堅硬且具有高熔點，在許多應用中提供其高耐 磨性之特徵。此耐磨性通常使得碳化物理想地作為需要高 耐磨性之鋼（例如，高速鋼（HSS))中的組份，諸如用於鑽 頭、車床、閥座嵌環及其類似物之鋼。 内燃機中之VSI為在操作期間插入閥與汽缸頭接觸處之 環。VSI係用於限制汽缸頭上的由閥引起之磨損。此係藉 由在VSI中使用比汽缸頭材料更能抵抗磨損之材料達成（而 不造成閥上的磨損）。用於VSI之材料為鑄造材料或更通常 為壓製及燒結PM材料。 藉由粉末冶金製造閥座嵌環提供VSI組成之較大靈活性 和極具成本效益之產品。製造PM閥座嵌環之方法以製備 包括最終組件中需要之所有成份之混合物開始。粉末混合 物通常包括：在最終組件中充當基質之鐵或低合金粉末， 134678.doc 200925295 應較低或較高程度地擴散入基質材料中且增強強度及硬度 之諸如碳、銅、鎳、鈷等之基本合金元素。可添加含有碳 化物及類似相之其他硬相材料以增加合金之耐磨性。亦通 常添加機械加工性增強劑以減少在機械加工成品時的工具 磨損，以及固體潤滑劑以在引擎工作期間幫助潤滑。此 外，將蒸發潤滑劑添加至所有預備壓製之混合物以幫助緻 岔組件之壓實及頂出。由Powder Metallurgy製造之已知 ❹ VSI材料係基於呈含有碳化物之基質材料形式之高速鋼粉 末。所有所使用之粉末通常具有小於18〇 μιη之粒度。混合 物之平均粒度通常在50 μηι至100 μηι之間以允許混合物流 動且促進製造。在多種狀況下，合金及潤滑劑添加劑之粒 度與基質粉末相比係更精細的，以改良粉末混合物及成品 組件中之合金元素分布。 接著將粉末混合物饋入具有VSI環形狀之工具模腔中。 施加400-900 MPa之間的軸向壓力，得到密度在6 4·7 3 φ g/cm3之間的近淨形金屬VSI組件》在一些情況下，使用 一重壓實以減少昂貴合金元件之使用。二重壓實中使用兩 種不同的粉末混合物。具有優良耐磨性之較昂貴之粉末混 - 合物建立VSI之面向閥之磨損面且較廉價之粉末混合物提 供組件所要之高度。壓實之後個體顆粒僅經由冷焊鬆散地 結合，且隨後需要燒結操作以允許個別顆粒一起擴散及分 布合金元素。在通常以氮及氫為基礎之還原氣氛中於 1120C與1150C之間的溫度下執行燒結，但可使用高達 1300°C之溫度。在燒結期間或燒結之後，可將銅滲入組件 134678.doc 200925295 孔隙中以增加硬度及強度且改良導熱率及耐磨性。在多種 情況下’執行隨後之熱處理以達到最終性質。為達成VSI 之所要幾何精度，將其機械加工為所要求尺寸。在多種狀 況下，最終機械加工係在VSI被安裝於汽缸頭中後進行。 進行最終機械加工以提供VSI及逆止閥輪廓且具有小尺寸 偏差。 具有高耐磨性之習知鐵基粉末之實例揭示於（例如）美國 ❹ 專利案6 679 932(關於包括具有精細分散碳化物之工具鋼 粉末之粉末混合物），及美國專利案5 856 625(關於不鏽鋼 粉末）中。 鎢、飢、錮、敛及銳係強碳化物形成元素，其使得此等 兀素尤其適用於耐磨性產品之製造。鉻為另一碳化物形成 元素。然而，大部分此等習知碳化物形成金屬係昂貴的且 導致不便利的高價產品。因此，粉末冶金工業中存在對價 格較低廉之鐵基粉末或高速鋼（其可充分耐磨以用於諸如 ❹ 閥座或其類似物之應用中）之需要。 由於鉻與用於具有高耐磨性之習知粉末及硬相中之其他 此類金屬相比為低廉得多且較易獲得之碳化物形成金屬， 此夠使用鉻作為主要碳化物形成金屬將為理想的。藉此可 . 更廉價地製造粉末及（因此）壓實產品。 普通高速鋼之碳化物通常極小，但根據本發明，已出乎 意料地顯示可使用鉻作為主要碳化物形成金屬而獲得具有 同等有利耐磨性（例如，對於閥座應用）之粉末，其限制條 件為存在足夠量由少量更精細及更堅硬之碳化物支援之大 134678.doc 200925295 碳化物。 【發明内容】 因此本發明之一目的係提供用於具有高耐磨性之粉末冶 金產品之製造之廉價鐵基粉末。 此目的，以及以下論述中表明之其他目的係根據本發明 經由一種退火預合金水霧化鐵基粉末達成，該粉末包含10 重量％至低於18重量％的鉻、各0.5重量％-5重量％的銷、 鎢' 釩及鈮中至少一者、〇·5重量％-2重量％(較佳為〇 7重 ® 量％-2重量％且最佳為1重量°/。-2重量％)的碳，其中鐵基粉 末具有包含小於1〇重量％的鉻之基質。此外，鐵基粉末包 含大碳化鉻以及更精細及更堅硬之碳化鉻。 由於粉末中的高鉻含量促進大型碳化物（例如，M23C6 型）之形成’則18重量°/〇及更高之鉻含量將使精細及硬碳化 鉻之含量過低。 根據本發明，達成上述目的之新型粉末可經由製造鐵基 〇 粉末之方法獲得，其包含：使鐵基熔體（其包括1〇重量％_ 低於18重量％的鉻、各〇.5重量％_5重量％的鉬、鎢、釩及 銳中至少一者及〇.5重量％_2重量°/。（較佳為〇 7重量％_2重量 - %且最佳為1重量％·2重量％)的碳）經受水霧化以獲得鐵基 粉末粒子，及在一溫度下將該等粉末粒子退火足以獲得粒 子内所要之碳化物的一段時間。 在較佳實施例中，已發現90(rC_110(rc範圍内之溫度及 5 72 J、時範圍内之退火時間係足以獲得粒子内所要之碳 化物的。 134678.doc 200925295 【實施方式】 本發明之預合金粉末含有鉻（I 〇重量％低於1 8重量％)， 鉬、鎢、釩及鈮中至少一者（每一者為〇..5重量％_5重量％) 及碳（〇.5重量％-2重量％，較佳為07重量％2重量％且最佳 • 為1重量％·2重量。/°)，其餘為鐵、可選之其他合金元素及 不可避免之雜質。 預合金粉末可視需要地包括其他合金元素，諸如矽（直 φ 至2重罝％)。亦可視需要地包括其他合金元素或添加劑。 應特定地注意本發明之粉末中不需要極昂貴之碳化物形 成金屬鈮及鈦。 預合金粉末較佳具有40 μπι-100 μηι範圍内之平均粒度， 較佳為約80 μπι。 在較佳實施例中’預合金粉末包含1 2重量％-17重量。/〇的 絡’諸如15重量％-17重量％的絡（例如16%重量％的鉻卜 在較佳實施例中，預合金粉末包含12重量％-低於18重量 ❹ ％的鉻，1重量❶-3重量❶/。的鉬、1重量％_3.5重量％的鎢、 〇,5重量％-1，5重量％的釩、〇 2重量％-1重量％的矽、1重量 %-2重量％的碳且其餘為鐵。 ’ 在最佳實施例中’預合金粉末包含14重量％_低於18重量 - /❾的絡，1重量％_2重量°/❶的鉬、1重量％-2重量％的鎢、〇 5 重量❶5重量％的釩、0.2重量❶/。-1重量❹/。的矽、i重量％_2 重量。/〇的碳且其餘為鐵。 在另一最佳實施例中，預合金粉末包含12重量％-低於15 重置❶Λ的鉻，1重量❶/。-2重量的鉬、2重量％_3重量％的 134678.doc 200925295 鶴0.5重量％_1.5重量％的釩、〇 2重量。丨重量％的矽、1 重置％-2重量％的碳且其餘為鐵。 在較佳實施例中’大碳化鉻為M23C6型（M=鉻、鐵、 鉬、鎢），亦即，除作為主要碳化物形成元素之鉻外可 存在鐵、鉬及鎢中之一或多者。 • 在較佳實施例中，更精細且更堅硬之碳化鉻為M7c3型 (M=鉻 '鐵、釩）’亦即’除作為主要碳化物形成元素之鉻 φ 外可存在鐵及釩中之一或多者。兩種類型碳化物可亦含 有夕量除上述和疋外之其他碳化物形成元素。粉末可進一 步包含除上述外之其他碳化物類型。 本發明粉末之大碳化物較佳具有8 μιη_45 μιη範圍内之平 均尺寸，更佳為在8 μιη-30 μιη範圍内，約ιι〇0_13〇〇微維 氏硬度且較佳占總粉末體積之10%-30%。 本發明粉末之Μ?。3型較小碳化物小於且硬於M23c6型大 碳化物。本發明粉末之較小碳化物較佳具有小於8 pm之平 Φ 均尺寸，約1400-1600微維氏硬度且較佳占總粉末體積之 3%-1〇% 〇 由於碳化物具有不規則形狀，"尺寸"界定顯微鏡中量測 •得之最長延伸。 為獲得此等大碳化物，使預合金粉末經受長時間退火 (較佳在真空下）。較佳在9〇(rc_u〇(rc範圍中執行退火， 最佳在約lOOOt下執行退火，此溫度下預合金粉末之鉻與 兔反應以形成碳化絡。 在退火期間，藉由鉻與碳之間的反應，新型碳化物形成 134678.doc 200925295 並生長且存在之碳化物繼續生長。退火較佳持續1 5-72小 時，更佳為大於48小時，以獲得所要尺寸之碳化物。退火 持續時間越長，碳化物顆粒生長得越大。然而，若退火持 續長時㈤，則其消耗大量能量|可能成為製造流程瓶頸。 因此，儘管大碳化鉻之約20 μιη-3() μιη之平均碳化鉻粒度 可能為最佳的，但取決於優先權，自經濟觀點來看，當大 碳化絡之平均碳化路粒度為約1 〇 p m時，較早終止退火係 更便利的。 Φ 自退火溫度極緩慢地冷卻（較佳超過12小時^由於較大 數量之碳化物在較低溫度下熱動穩定，緩慢冷卻將允許碳 化物進步生長。緩慢冷卻將亦確保基質變為鐵素體，此 對於粉末之壓縮性係重要的。 除碳化物之生長外，將粉末退火亦具有其他優點。 在退火期間，基質顆粒亦生長且粉末粒子（作為水霧化 之結果獲得）之固有應力緩解。此等因素使得粉末硬度較 φ 低且易於壓實（例如，提供粉末較高壓縮性）。 在退火期間，可調整粉末之碳及氧含量。通常需要保持 氧含量較低。在退火期間，碳與氧反應以形成氣態碳氧化 •I其降低粉末之氧含量。對於形成碳化物及減少氧含量 兩者而言，若預合金粉末本身無充足的碳’則可提供石墨 粉末形式之額外碳以用於退火。 在退火期間隨著預合金粉末之大量鉻自遷移到碳化 物，所得退火粉末之基質具有含量小於基f之⑺重^之 -解鉻，較佳為小於9重量％且最佳為小於8重量％，此為 134678.doc 200925295 粉末並非不鏽之原因。 粉末之基質組合物係經設計使得在燒結期間鐵素體變換 為沃斯田體。藉此，燒結後之冷卻後，沃斯田體可轉變成 麻田散體。麻田散體基質中與較小及較硬之碳化物結合之 大碳化物將提供經壓製及燒結組件之優良耐磨性。 在壓實及燒結前，可將本發明之退火粉末與其他粉末組 ， 份混合（諸如其他鐵基粉末、石墨、蒸發潤滑劑、固體潤 ❹ 滑劑、機械加工性增強劑等）以製造具有高耐磨性之產 品。可將本發明之粉末與純鐵粉末及石墨粉末混合，或與 不鏽鋼粉末混合。可添加潤滑劑（諸如蠟、硬脂酸鹽、金 屬皂等，其促進壓實且接著在燒結期間蒸發）以及固體潤 滑劑（諸如MnS、CaFa、MoS2，其在燒結製品使用期間減 少摩擦且同時可增強燒結製品之機械加工性）。亦可添加 其他機械加工性增強劑’以及粉末冶金領域之其他習知添 加劑。 ❹ 由於其優良壓縮性’所獲得之混合物十分適用於壓製成 具有倒角逆止閥輪廓之近淨形VSI組件。 實例1 水霧化由“川重量％鉻、1.5重量％鉬、1.5重量％鎢、；!重 ▲ 量％釩、0.5重量％矽、1.5重量％碳及其餘為鐵組成之熔體 以形成預合金粉末。隨後將所獲得之粉末在1000〇c下真空 退火約48小時（總退火時間為約小時），此後粉末粒子在 鐵素體基質中含有約20體積％之平均粒度為約10 μιη< MuC6型碳化物及約5體積％之平均粒度為約3 μιη之]vi7C3型 134678.doc •13· 200925295 碳化物。 將所獲得之粉末（下文稱作OB 1)與0.5重量％石墨及0.75 重量％蒸發潤滑劑混合。在700 MPa壓力下將混合物壓製 成測試棒。將所獲得之樣品在1120°C之溫度下90N2/10H2 氣氛中燒結。燒結之後，使樣品在液氮中經受低溫冷卻， 接著在550°C下回火。 製備基於已知HSS粉末M3/2之類似混合物且使用與上述 方法相同之方法製造測試棒。 根據維氏方法使測試棒經受硬度測試。在三種不同溫度 下（300°C/400°C/500°C)測試熱硬度。結果總結於下表中。 混合物 孔隙率 HV0.025 HV5 熱硬度(HV5) 中粉末 (%) 300°C 400°C 500°C OB1 21 925 382 317 299 249 M3/2 17 836 415 363 326 267 OB 1測試材料之微觀結構（參見圖1)由麻田散體基質中大 及小碳化物之所要的混合物組成。參考材料具有類似微觀 結構（參見圖2)但具有小於OB1材料之碳化物。 OB 1材料具有稍微高於M3/2材料之孔隙率，此說明儘管 OB1顯微硬度高於M3/2顯微硬度，但OB1硬度值（HV5)低 於M3/2硬度值之原因。在PM VSI組件之製造中，通常藉 由燒結期間之銅滲入來消除孔隙率且因此可忽略此等效 應。鑒於此，OB1材料之硬度值與參考M3/2材料之硬度值 相當，此給出材料應具有相當财磨性之良好指示。特別 地，在高溫下維持硬度對於VSI應用中的耐磨性係重要 134678.doc •14- 200925295 的。熱硬度測試結果顯示OB 1材料滿足此等要東。 實例2 水霧化由14.5重量。/。鉻、1.5重量％鉬、2 5重量％鎢、1重 量％飢、〇.5重量％梦、1.5重量％碳及其餘為鐵組成之炼體 . 以形成預合金粉末。隨後將所獲得之粉末在1〇〇(rc下真空 ^ 退火約48小時（總退火時間為約6〇小時），此後粉末粒子在 • 鐵素體基質中含有約20體積°〆。之平均粒度為約1〇叫爪之200925295 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to iron-based powders. In particular, the invention relates to powders suitable for the manufacture of wear resistant products (V seat) and to components made from the powder. [Prior Art] Products having a grindability are widely used, and there is a continuing need for a less expensive product having the same or better performance than the existing product. The production of only the seat ring is greater than 1 000 000 000 components per year. The manufacture of products having high abrasion resistance can be based, for example, on powders, such as iron or iron-based powders, including carbon in the form of carbides. Carbide is extremely hard and has a high melting point, providing its high wear resistance characteristics in many applications. This wear resistance generally makes the carbide ideally a component in steels requiring high wear resistance (e.g., high speed steel (HSS)), such as steel for drill bits, lathes, valve seat rings, and the like. The VSI in an internal combustion engine is the ring at which the valve is inserted into contact with the cylinder head during operation. VSI is used to limit valve-induced wear on the cylinder head. This is achieved by using a material that is more resistant to wear in the VSI than the cylinder head material (without causing wear on the valve). The material used for the VSI is a cast material or, more typically, a pressed and sintered PM material. The valve seat inserts are made by powder metallurgy to provide greater flexibility and cost-effective VSI composition. The method of making a PM seat insert begins with the preparation of a mixture comprising all of the components required in the final assembly. The powder mixture typically comprises: iron or a low alloy powder that acts as a matrix in the final assembly, 134678.doc 200925295 should diffuse into the matrix material at a lower or higher degree and enhance strength and hardness such as carbon, copper, nickel, cobalt, etc. The basic alloying element. Other hard phase materials containing carbides and similar phases may be added to increase the wear resistance of the alloy. Machinability enhancers are also often added to reduce tool wear when machining finished products, as well as solid lubricants to aid lubrication during engine operation. In addition, an evaporating lubricant is added to all of the pre-compacted mixture to aid in compaction and ejection of the component. Known ❹ VSI materials manufactured by Powder Metallurgy are based on high speed steel powder in the form of a matrix material containing carbides. All of the powders used typically have a particle size of less than 18 Å μηη. The average particle size of the mixture is typically between 50 μηι and 100 μηι to allow the mixture to flow and facilitate manufacturing. In many cases, the alloy and lubricant additives are finer than the matrix powder to improve the distribution of alloying elements in the powder mixture and finished components. The powder mixture is then fed into a tool cavity having a VSI ring shape. Applying an axial pressure between 400-900 MPa to obtain a near net shape metal VSI assembly with a density between 6 4·7 3 φ g/cm 3 . In some cases, a heavy compaction is used to reduce the use of expensive alloy components. . Two different powder mixtures are used in the double compaction. The more expensive powder mix with excellent wear resistance establishes the VSI's valve-facing wear surface and the less expensive powder mixture provides the desired height of the assembly. The individual particles are loosely bonded only via cold welding after compaction, and then a sintering operation is required to allow the individual particles to diffuse and distribute the alloying elements together. Sintering is carried out at a temperature between 1120 C and 1150 C in a reducing atmosphere usually based on nitrogen and hydrogen, but a temperature of up to 1300 ° C can be used. During or after sintering, copper can be infiltrated into the pores of assembly 134678.doc 200925295 to increase hardness and strength and to improve thermal conductivity and wear resistance. Subsequent heat treatment is performed in a variety of cases to achieve the final properties. To achieve the desired geometric accuracy of the VSI, it is machined to the required dimensions. In many cases, the final machining is performed after the VSI is installed in the cylinder head. Final machining is performed to provide VSI and check valve profiles with small dimensional deviations. Examples of conventional iron-based powders having high wear resistance are disclosed, for example, in U.S. Patent No. 6,679,932 (for powder mixtures comprising tool steel powders having finely dispersed carbides), and U.S. Patent No. 5,856,625 ( About stainless steel powder). Tungsten, hunger, sputum, stagnation and sharp-type strong carbide forming elements make these bismuths especially suitable for the manufacture of wear resistant products. Chromium is another carbide forming element. However, most of these conventional carbide forming metals are expensive and result in inconvenient high cost products. Therefore, there is a need in the powder metallurgy industry for less expensive iron-based powders or high speed steels which are sufficiently resistant to use in applications such as sill seats or the like. Since chromium is a much cheaper and more readily available carbide-forming metal than conventional powders for high wear resistance and other such metals in the hard phase, it is sufficient to use chromium as the primary carbide forming metal. Ideal. This makes it possible to manufacture powders and (and therefore) compacted products more cheaply. The carbides of conventional high speed steel are generally extremely small, but according to the present invention, it has unexpectedly been shown that chromium can be used as the primary carbide forming metal to obtain a powder having equivalent advantageous wear resistance (for example, for valve seat applications), the limitation thereof The condition is that there is a sufficient amount of 134678.doc 200925295 carbide supported by a small amount of finer and harder carbides. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an inexpensive iron-based powder for the manufacture of a powder metallurgical product having high wear resistance. This object, as well as other objects indicated in the following discussion, is achieved according to the invention via an annealed pre-alloyed water atomized iron-based powder comprising from 10% by weight to less than 18% by weight of chromium, each 0.5% by weight to 5 parts by weight. At least one of % pin, tungsten 'vanadium and niobium, 〇·5 wt% to 2 wt% (preferably 〇7 wt%-2 wt% and most preferably 1 wt%/-2 wt%) Carbon, wherein the iron-based powder has a matrix comprising less than 1% by weight of chromium. In addition, iron-based powders contain large chromium carbide and finer and harder chromium carbide. Since the high chromium content of the powder promotes the formation of large carbides (e.g., M23C6 type), the chromium content of 18 weight/min and higher will result in a too low content of fine and hard carbonized chromium. According to the present invention, a novel powder for achieving the above object can be obtained by a method for producing an iron-based cerium powder comprising: an iron-based melt comprising 1% by weight _ less than 18% by weight of chromium, each 〇.5 by weight %_5 wt% of at least one of molybdenum, tungsten, vanadium and sharp and 55 wt% _2 wt% (preferably 〇7 wt% _2 wt-% and most preferably 1 wt%·2 wt%) The carbon) is subjected to water atomization to obtain iron-based powder particles, and annealing the powder particles at a temperature for a period of time sufficient to obtain a desired carbide in the particles. In a preferred embodiment, it has been found that 90 (rC_110 (the temperature in the range of rc and the annealing time in the range of 5 72 J, the time is sufficient to obtain the desired carbides in the particles. 134678.doc 200925295 [Embodiment] The present invention The prealloyed powder contains chromium (I 〇 wt% less than 18 wt%), at least one of molybdenum, tungsten, vanadium and niobium (each of which is 〇.. 5 wt% _ 5 wt%) and carbon (〇. 5 wt% to 2 wt%, preferably 07 wt% 2 wt% and most preferably 1 wt%·2 wt./°), the balance being iron, optionally other alloying elements and unavoidable impurities. The alloy powder may optionally include other alloying elements such as yttrium (straight φ to 2% 罝%). Other alloying elements or additives may optionally be included. It should be specifically noted that the powder of the present invention does not require extremely expensive carbide formation. Metal ruthenium and titanium. The prealloyed powder preferably has an average particle size in the range of 40 μπι to 100 μηι, preferably about 80 μπι. In the preferred embodiment, the 'prealloyed powder contains 12% by weight to 17% by weight. The network 'such as 15% by weight -17% by weight of the network ( For example, 16% by weight of chromium b. In a preferred embodiment, the prealloyed powder comprises from 12% by weight to less than 18% by weight of chromium, from 1% by weight to 3% by weight of molybdenum, and from 1% by weight to 3.5% by weight. % by weight of tungsten, rhodium, 5% by weight to 1%, 5% by weight of vanadium, 2% by weight to 1% by weight of cerium, 1% by weight to 2% by weight of carbon and the balance being iron. The medium pre-alloyed powder comprises 14% by weight to less than 18% by weight of lanthanum, 1% by weight to 2% by weight of lanthanum, 1% by weight to 2% by weight of tungsten, 〇5 by weight of 5% by weight of vanadium, 0.2 weight ❶ /. -1 weight ❹ / i, i weight % _2 weight / 〇 carbon and the rest is iron. In another preferred embodiment, the prealloyed powder contains 12% by weight - less than 15 weight Chromium, 1 wt%/-2 wt% molybdenum, 2 wt%_3 wt% 134678.doc 200925295 Crane 0.5 wt%_1.5 wt% vanadium, niobium 2 weight. 丨% by weight 矽, 1 Resetting %-2% by weight of carbon and the balance being iron. In the preferred embodiment, 'large chromium carbide is M23C6 type (M=chromium, iron, molybdenum, tungsten), that is, as the main carbide forming element. Outside the chrome One or more of iron, molybdenum and tungsten may be present. • In a preferred embodiment, the finer and harder chromium carbide is of the M7c3 type (M = chrome 'iron, vanadium) 'that is, 'except as the main carbonization One or more of iron and vanadium may be present in the chromium φ of the element forming element. The two types of carbides may also contain other carbide forming elements other than the above and the cerium. The powder may further comprise other than the above. Carbide type. The large carbide of the powder of the present invention preferably has an average size in the range of 8 μm to 45 μm, more preferably in the range of 8 μm to 30 μm, about ι 〇 0_13 〇〇 micro Vickers hardness and preferably total. 10%-30% of the volume of the powder. The powder of the present invention. Type 3 smaller carbides are smaller and harder than M23c6 type large carbides. The smaller carbide of the powder of the present invention preferably has a flat Φ average size of less than 8 pm, a hardness of from about 1400 to 1600 micro Vickers and preferably from 3% to 1% by weight of the total powder volume 〇 due to the irregular shape of the carbide , "Size" defines the measurement in the microscope • the longest extension. To obtain such large carbides, the prealloyed powder is subjected to a long time anneal (preferably under vacuum). Preferably, annealing is performed at 9 〇 (rc_u 〇 (irs in the rc range, preferably at about 1000 Torr, at which temperature the chromium of the prealloyed powder reacts with the rabbit to form a carbonized network. During annealing, by chromium and carbon The intervening reaction, new carbide formation 134678.doc 200925295 and growth and the presence of carbides continue to grow. Annealing preferably lasts from 1 to 5 hours, more preferably greater than 48 hours, to obtain the desired size of carbide. Annealing duration The longer the carbide particles grow, the more the carbide particles grow. However, if the annealing lasts for a long time (five), it consumes a lot of energy | may become a bottleneck in the manufacturing process. Therefore, despite the average carbonization of about 20 μιη-3 () μιη of the large chromium carbide The chromium particle size may be optimal, but depending on the priority, from the economic point of view, when the average carbonization path size of the large carbonization network is about 1 〇pm, it is more convenient to terminate the annealing system earlier. Φ Self-annealing temperature Slowly cool (preferably over 12 hours). Since a larger amount of carbide is thermally stable at lower temperatures, slow cooling will allow the carbide to progress. Slow cooling will also ensure that the matrix becomes iron. Body, which is important for the compressibility of the powder. In addition to the growth of carbides, annealing the powder has other advantages. During annealing, the matrix particles also grow and the inherent stress of the powder particles (obtained as a result of water atomization) Relief. These factors make the powder hardness lower than φ and easy to compact (for example, provide higher compressibility of the powder). During annealing, the carbon and oxygen content of the powder can be adjusted. It is usually necessary to keep the oxygen content low. During annealing Carbon reacts with oxygen to form gaseous carbon oxides. It reduces the oxygen content of the powder. For both the formation of carbides and the reduction of oxygen content, if the prealloyed powder itself does not have sufficient carbon, it can provide an additional form of graphite powder. The carbon is used for annealing. During the annealing, as the large amount of chromium of the prealloyed powder self-migrates to the carbide, the matrix of the obtained annealed powder has a content of less than (7) by weight of the base f, preferably less than 9% by weight. Preferably, it is less than 8% by weight, which is 134678.doc 200925295 The powder is not a cause of stainless. The matrix composition of the powder is designed such that iron during sintering The volume is transformed into a Worth field. By this, after cooling after sintering, the Worth field can be transformed into a Matian bulk. The large carbides in the matrix of the Matian bulk combined with the smaller and harder carbides will be pressed and Excellent wear resistance of the sintered component. The annealed powder of the present invention can be mixed with other powder groups before compaction and sintering (such as other iron-based powders, graphite, evaporative lubricants, solid lubricants, mechanical processing). A reinforcing agent, etc.) to produce a product having high abrasion resistance. The powder of the present invention may be mixed with pure iron powder and graphite powder, or mixed with stainless steel powder. Lubricants (such as wax, stearate, metal) may be added. Soap or the like, which promotes compaction and then evaporates during sintering) as well as solid lubricants (such as MnS, CaFa, MoS2, which reduce friction during use of the sintered article and at the same time enhance the machinability of the sintered article). Other machinability enhancers' and other conventional additives in the field of powder metallurgy may also be added.混合物 The mixture obtained due to its excellent compressibility is very suitable for pressing into a near net shape VSI assembly with a chamfered check valve profile. Example 1 Water atomization was carried out by a melt consisting of "Chrome wt% chromium, 1.5 wt% molybdenum, 1.5 wt% tungsten, ** wt% vanadium, 0.5 wt% rhodium, 1.5 wt% carbon and the balance iron" to form a pre-form Alloy powder. The obtained powder is then vacuum annealed at 1000 ° C for about 48 hours (total annealing time is about hour), after which the powder particles contain about 20% by volume in the ferrite matrix with an average particle size of about 10 μηη. MuC6 type carbide and about 5% by volume of the average particle size of about 3 μm] vi7C3 type 134678.doc •13· 200925295 Carbide. The obtained powder (hereinafter referred to as OB 1) and 0.5% by weight of graphite and 0.75 weight % evaporation lubricant mixing. The mixture was pressed into a test rod under a pressure of 700 MPa. The obtained sample was sintered at a temperature of 1120 ° C in a 90 N 2 / 10 H 2 atmosphere. After sintering, the sample was subjected to cryogenic cooling in liquid nitrogen. This was followed by tempering at 550° C. A test mixture was prepared based on a similar mixture of known HSS powders M3/2 and using the same method as described above. The test bars were subjected to a hardness test according to the Vickers method. (300 ° C / 400 ° C / 500 ° C) test hot hardness. The results are summarized in the following table. Mixture porosity HV0.025 HV5 heat hardness (HV5) medium powder (%) 300 ° C 400 ° C 500 ° C OB1 21 925 382 317 299 249 M3/2 17 836 415 363 326 267 The microstructure of the OB 1 test material (see Figure 1) consists of the desired mixture of large and small carbides in the matrix of the Matian bulk. The reference material has a similar microstructure. (See Figure 2) but with carbides smaller than the OB1 material. The OB 1 material has a slightly higher porosity than the M3/2 material, which shows that although the OB1 microhardness is higher than the M3/2 microhardness, the OB1 hardness value ( HV5) is lower than the M3/2 hardness value. In the manufacture of PM VSI components, the porosity is usually eliminated by copper infiltration during sintering and therefore these effects can be ignored. In view of this, the hardness value and reference of OB1 material The hardness values of the M3/2 materials are comparable, which gives the material a good indication of considerable grindability. In particular, maintaining hardness at elevated temperatures is important for wear resistance in VSI applications 134,678.doc •14-200925295. The hot hardness test results show that the OB 1 material meets these requirements. Example 2 Water atomization consists of 14.5 wt% chromium, 1.5 wt% molybdenum, 25 wt% tungsten, 1 wt% hunger, 〇5 wt% dream, 1.5 wt% carbon and the remainder consisting of iron. To form a prealloyed powder. The obtained powder is then annealed at 1 Torr (vacency for about 48 hours at rc (total annealing time is about 6 hrs), after which the powder particles contain about 20 volumes in the • ferrite matrix. °〆. The average particle size is about 1 call
〇 M23C6型碳化物及約5體積％之平均粒度為約3 pm2M7C3S 碳化物。 處理此粉末，與0_5重量％石墨及0.75重量％蒸發潤滑劑 混合，以按照與實m中相同之方式製造測試棒，得 類似於圖1中者之微觀結構。 【圖式簡單說明】 圖1顯示基於OB 1測試材料之微觀結構。 圖2顯示基於M3/2測試材料之微觀結構。 ❹ 134678.doc〇 M23C6 type carbide and an average particle size of about 5% by volume is about 3 pm2M7C3S carbide. This powder was treated, mixed with 0-5 wt% of graphite and 0.75 wt% of evaporating lubricant to produce a test rod in the same manner as in the real m, which was similar to the microstructure of Fig. 1. [Simple Description of the Drawing] Figure 1 shows the microstructure of the material based on OB 1 test. Figure 2 shows the microstructure of the material based on the M3/2 test. ❹ 134678.doc