1290073 九、發明說明： 【發明所屬之技術領域】 本發明係關於粉末冶金技術，更明確關於具有改良疲勞 性能之預合金化鉻粉末金屬零件。 【先前技術】 通常，由粉末冶金技術製造的燒結產物比通過鍛造和滾 軋步驟獲得的錠鋼在花費上有利，且廣泛在（例如）機動車 輛中用作零件。但，經燒結的產物具有在製造過程期間不 可避免形成的孔隙。與完全緻密材料比較，經燒結粉末冶 金材料的此等保留孔隙損害材料之機械性能。此係孔隙作 為應力集中之結果，亦因為孔隙在應力下降低有效體積。 因此，以鐵為主粉末冶金材料的強度、延展性、疲勞強 度、宏觀硬度等隨孔隙度增加而降低。 儘管其疲勞強度較低，但，以鐵為主的粉末冶金材料仍 在一疋範圍用於需要高疲勞強度之零件。Distal〇y® Hp(可 自瑞典，H5ganas ΑΒβ獲得）為一種可用於高性能用途之鋼 粉末。在此Distaloy®*末中，基礎粉末用昂貴合金元素鎳 合金化。該高作用材料相對昂貴，因此，需要至少具有優 良疲勞強度之廉價材料。 改良粉末冶金鋼疲勞性能的一個途徑為第二操作。全部 硬化、表面硬化或珠擊法處理（或組合）為得到零件最高可 此抗疲勞性的可能方法。為利用在表面中壓縮殘餘應力的 有u 般進行珠擊法處理。開到表面的孔隙為粉末 冶金材料中的弱點。此等孔隙至少部分由引入表面壓縮殘 102671 -960206.doc !29〇〇73 9修(¾正替換F| 餘應力而抑制。 j緊壓零件的珠擊法處理揭示於（例如）美國專利第6 J 7 J S46號。根據此專利’在珠擊法後進行最終燒結步驟。以 主的含（例如）鎳之粉末用作原料。如上所示，由於鎳 17貝對不含鎳的粉末需要正在增加。利用含錄粉末的其 他缺點為起塵問題’ S塵可在處理粉末期間發生，並可導 致產生少量過敏反應。因此，應避免使用I美國專利申 睛案第2_/〇177719號亦關於一種包括珠擊法處理之方 更月確而5，§亥申請案揭示一種方法，其中使經緊壓 :牛的-P刀表面在燒結後經過珠擊法處理。根據此申請 為改良最終緊壓零件之性能，需要—種包括粉末鍛造 或上漿之緻密方法。 ^月個目的為提供製備具有高疲勞強度之粉末冶金 7件而無需任何達到芯緻密之步驟之成本有效方法。另一 目的為提供包括不含鎳U末 【發明内容】 二Γ外地發現，藉*珠擊法處理自具有低含量鎳和鉬的 Γ 粉末製備之經燒結零件，可獲得具有高疲勞強1290073 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to powder metallurgy techniques, and more specifically to pre-alloyed chromium powder metal parts having improved fatigue properties. [Prior Art] Generally, a sintered product produced by powder metallurgy technology is cost-effective than an ingot obtained by a forging and rolling step, and is widely used as a part in, for example, a motor vehicle. However, the sintered product has pores that are inevitably formed during the manufacturing process. These retained pores of the sintered powder metallurgical material impair the mechanical properties of the material as compared to a fully dense material. This is the result of stress concentration as well as the reduction of the effective volume of the pores under stress. Therefore, the strength, ductility, fatigue strength, macroscopic hardness, etc. of iron-based powder metallurgy materials decrease with increasing porosity. Despite its low fatigue strength, iron-based powder metallurgy materials are still used in a range of parts requiring high fatigue strength. Distal〇y® Hp (available from Sweden, H5ganas ΑΒβ) is a steel powder that can be used for high performance applications. At the end of this Distaloy®*, the base powder is alloyed with the expensive alloying element nickel. This highly active material is relatively expensive and, therefore, requires inexpensive materials having at least excellent fatigue strength. One way to improve the fatigue properties of powder metallurgy steel is the second operation. All hardening, case hardening or beading treatments (or combinations) are possible ways to obtain the highest fatigue resistance of the part. In order to utilize the compressive residual stress in the surface, a beading treatment is performed. The pores that open to the surface are weak points in the powder metallurgical material. These pores are at least partially inhibited by the introduction of surface compression residues 102671 - 960206.doc !29〇〇73 9 (3⁄4 positive replacement F| residual stress. The beading treatment of j-pressed parts is disclosed in, for example, US Patent No. 6 J 7 J S46. According to this patent 'the final sintering step is carried out after the bead blasting process. The main powder containing, for example, nickel is used as a raw material. As shown above, since nickel 17 shells are required for the nickel-free powder Increasing. Other disadvantages of using recorded powders are dusting problems. 'S dust can occur during powder processing and can cause a small amount of allergic reactions. Therefore, I US Patent Application No. 2_/〇177719 should also be avoided. Regarding a method including the bead blasting method, the § hai application discloses a method in which the squeezing: the surface of the bovine-P knives is subjected to a bead blasting process after sintering. The performance of the pressed parts requires a compact method including powder forging or sizing. The purpose of each month is to provide a cost-effective method for preparing powder metallurgy with high fatigue strength without any step of achieving core densification. A purpose is to provide a nickel-free U-containing product. [Summary of the Invention] It has been found in the field that a sintered part prepared from a bismuth powder having a low content of nickel and molybdenum can be obtained by a bead blasting method to obtain a high fatigue strength.
度之零件。 W 本發明所用的粉太氣4 J θ 士 i ^ 為匕括低$鉻和鉬之預合金化以鐵為 1 °較佳量為U·3·5重量％之鉻和0.15-〇.7重量％之 ^暫粉末柯包含少量請纽3重”之猛及*可避免的 ㈣…"粉末經美國專利第6 348 _號及W0 03/106079而為已知。 102671 -960206.doc 1290073 ^ Μ ‘日綠幾)正替換頁… 使基礎粉末進一步與石墨混合，以獲得所需材料強度。 與以鐵為主粉末混合的石墨之量為g1m.g%，較佳〇15至 0.85% ^將粉末混合物在模中緊壓，以產生生體。 力為至少600百萬帕斯卡，較佳至少7〇〇百萬帕斯卡 緊壓壓 ，更佳 _百萬帕斯卡。緊壓可藉由冷緊壓或熱緊壓進行。緊壓 後，將所得生件在高於110(rc之燒結溫度燒結較佳高於 1220°C。燒結氛圍較佳為氮氣和氫氣之混合物。在燒结製 程中的正常冷卻速率為〇.rc/秒，在〇5口秒和間 之範圍較佳。燒結密度較佳高於7.15克/釐米3，更佳高於 7.3克/釐米3。利用較低鉻和鉬含量，經燒結材料中的所得 微結構主要為細珠光體（peaditic)，對於略高絡和翻含量^ 則為麻田散鐵型（mamnsitie)或較低貝氏型出c)。 已意外地發現，㈣疲勞極限顯著增加可藉由珠擊法處 理經燒結的低㈣末材料而獲得。特別顯著增加對切口零 件獲得，在此，可自以下實例看到，可獲得大於5〇%且甚 至大於70%增加。由阿爾曼(α1_)α強度界定的珠擊法處 理度較佳在0 · 2 0和〇 · 3 7毫米之間。 為使性能更加改良，可在珠擊法處理之前進行第二操 作，例如，全部硬化及表面硬化。因此，在全部硬化及隨 後回火後’材料為主要為麻田散鐵型，且疲勞極限由珠擊 法處理而增加。在表面硬化期間形成的表面中的麻田散鐵 型咸信形成對疲勞極限有利的壓縮應力。 燒結硬化為在燒結製程中應用的選擇性方法。燒姓硬化 在零件燒結製程結束利用強制冷卻，這產生硬化二。 102671 -960206.doc 1290073 r—————————^ 0讲E丨修魏)正替換頁丨 疲勞試驗對應力集中因數未切口 樣品進行。試驗顯示，對切口樣品珠擊法處理時比對未切 口樣品進行珠擊法處理時顯示更大彎曲疲勞極限增加。在 本文中，”切口”指具有高於丨·3之應力集中因數之樣品或零 件。 【實施方式】 本發明由以下非限制實例說明。 實例1 在研究中包括兩種預合金化基礎粉末Astai〇y® crL和Parts of the degree. W The powder used in the present invention is 4 J θ 士 i ^ for the pre-alloying of low chromium and molybdenum with iron as 1 °, preferably in an amount of U·3·5 wt% of chromium and 0.15-〇.7 The % by weight of the powder is contained in a small amount, and the amount of the powder is a small amount. * The powder is known by the US Patent No. 6 348 _ and WO 03/106079. 102671 -960206.doc 1290073 ^ Μ '日绿几) is replacing the page... The base powder is further mixed with graphite to obtain the required material strength. The amount of graphite mixed with iron-based powder is g1m.g%, preferably 〇15 to 0.85% ^ Pressing the powder mixture in a mold to produce a body. The force is at least 600 megapascals, preferably at least 7 megapascals, more preferably _ megapascals. The compaction can be by cold Pressing or hot pressing. After pressing, the obtained green part is sintered at a temperature higher than 110 (the sintering temperature of rc is preferably higher than 1220 ° C. The sintering atmosphere is preferably a mixture of nitrogen and hydrogen. In the sintering process The normal cooling rate is 〇.rc/sec, preferably in the range of 〇5 sec and between. The sintered density is preferably higher than 7.15 g/cm 3 , more preferably higher than 7.3. g/cm 3. With the lower chromium and molybdenum content, the resulting microstructure in the sintered material is mainly peaditic, and for slightly higher and higher content, it is mamnsitie or lower. Bayesian type c) It has been unexpectedly found that (iv) a significant increase in the fatigue limit can be obtained by the bead blasting process of the sintered low (tetra) end material. A particularly significant increase is obtained for the incision parts, which can be seen from the following examples. Up to more than 5% and even more than 70% increase is obtained. The bead stroke degree defined by the intensity of the Alman (α1_) α is preferably between 0 · 2 0 and 〇 · 3 7 mm. Improved, the second operation can be performed before the bead blasting process, for example, all hardening and surface hardening. Therefore, after all hardening and subsequent tempering, the material is mainly the granulated iron type, and the fatigue limit is treated by the bead blasting method. The increase in the surface formed during the surface hardening of the granulated iron type forms a compressive stress which is favorable for the fatigue limit. Sintering hardening is an optional method applied in the sintering process. Burning the hardening at the end of the part sintering process With forced cooling, this produces hardening. 102671 -960206.doc 1290073 r—————————^ 0 丨 E丨修魏) is replacing the page 丨 fatigue test on the stress concentration factor uncut sample. Test shows In the case of the bead blasting treatment of the incision sample, the greater bending fatigue limit is increased than when the non-incision sample is subjected to the bead blasting treatment. In this context, the "cutting" refers to a sample or a part having a stress concentration factor higher than 丨·3. [Embodiment] The present invention is illustrated by the following non-limiting examples. Example 1 Two prealloyed base powders Astai〇y® crL and
Astaloy® CrM及一種擴散合金化基礎粉末Distai〇y® HP。Astaloy® CrM and a diffusion alloyed base powder, Distai〇y® HP.
Distaloy® HP用Ni和Cu擴散合金化，且用Mo預合金化。在 此研究中包括的三種材料顯示於表1中。 表1 材料 Ni [%] Cu [%] Mo [%] Cr [%] 一 Astaloy CrL 0.2 1.5 Astaloy CrM 0.5 3.0 Distaloy HP 4.0 2.0 1.5 以下給出關於製程參數、密度和碳含量的詳細資料。在 表2中對利用約〇.8 °C/秒冷卻速率在90/10 N2/H2中燒結30分 鐘的不同合金顯示未切口樣品的平面彎曲疲勞性能。對未 切口樣品的疲勞試驗利用具有削邊的5毫米is〇3928樣品進 行。試驗在以負荷比R=-1彎曲的四點平面進行。在階梯中 以13-18個樣品使用階梯方法，且2百萬個週期作為突破極 限。階梯評估（staircase evaluation)(50%概率疲勞極限及標 準偏差）根據MPIF 56標準進行。試驗頻率為27_3〇赫茲。 102671-960206.doc 1290073 • Vt；| 4> ；:； 表 2 ι —一- .…:-…— 粉末 密度 [克/爱米3] 經燒結碳 [%] σ A, 50% [百萬帕斯 卡] 標準偏差 [百萬帕斯 卡] ^ A, 90% [百萬帕斯 卡] Astaloy CrL 7.17 0.60 244 7 234 7.16 0.80 267 5 260 Astaloy CrM 7.06 0.35 284 7.0 274 7.04 0.56 316 8.4 300 Distaloy HP 7.13 0.65 295 22.5 261 7.13 0.85 330 <5 >322 具有低於0.6%燒結碳和冷卻速率約0.8°c/秒之Astaloy CrL之微結構為較高貝氏型。高於0.74°/。的增加碳使微結構 改變成細珠光體。 1120°C燒結的Astaloy CrM材料和冷卻速率0.8°C/秒及利 用0.32%和0.49%間燒結碳含量之微結構分析顯示稠密較高 貝氏型微結構。稠密較高貝氏型具有與常規較高貝氏型相 同的特徵，即鐵素體（ferrite)和滲碳體（cementite)之不規則 混合物。差異為碳化物間的較小距離及碳化物之大小。增 加的燒結碳使微結構轉移到麻田散鐵型和較低貝氏型之混 合物。 表3顯示冷壓Astaloy CrL的緊壓壓力和碳含量之影響。 所有材料均在90/10 N2/H2中於1120°C燒結30分鐘。在表3 中，Astaloy CrL在兩個緊壓壓力和兩個量添加石墨的平面 彎曲疲勞性能（標準偏差<5)之概要顯示，散射小，且不能 應用MPIF 56評估標準偏差。表3中的樣品未切口。 102671-960206.doc -9- T290073 —«m» 妒· __⑽·_ — .... w修(緣)正替換頁 表3 材料 石墨 C-UF4 [%] 緊壓壓力 [百萬帕 斯卡] 燒結密度 [克/ 釐米3] 燒結碳 [%] σ A, 50% [百萬帕 斯卡] 標準偏差 [百萬帕 斯卡] σ A, 90% [百萬帕 斯卡] Astaloy CrL 1120°C 30分鐘 90/10 N2/H2 0.8〇C/秒 0.6 600 6.94 0.56 224 11.6 205 0.8 600 6.93 0.75 233 9.5 218 0.6 800 7.13 0.55 236 8.5 222 0.8 800 7.09 0.74 252 <5 >244 表4中顯示燒結溫度對利用未切口樣品之疲勞性能之影 響。表4中的材料之微結構表現為主要較高貝氏型（1120°C 0.58% C)和細珠光體（1120°C，〇·77% C 和 1250°C，0.74% C)之特徵。 表4 粉末 燒結溫度 燒結密度 [克/釐米3] 燒結碳 [%] σ A, 50% [百萬帕 斯卡] 標準偏差 [百萬帕斯 卡] σ A, 90% [百萬帕斯卡] Astaloy CrL 1120°C 7.10 0.58 220 11 203 1120°C 7.08 0.77 236 9.7 222 1250〇C 7.02 0.74 290 18 264 實例2 對Astaloy CrL 3毫米邊緣切口樣品研究珠擊法處理和加 熱處理與珠擊法處理之組合之影響。切口包括在壓具中， 且不進行機械加工。彎曲中的應力集中因數由FEM獲得， 達kt=l .38。試驗頻率為27-30赫茲。 材料在1280°CKH2中燒結30分鐘。冷卻速率為0.8°C/秒。 進行珠擊法處理，以獲得0·32毫米之阿爾曼A強度。 燒結和燒結+珠擊法處理的樣品之評估平面彎曲疲勞性 能顯示於表5中。 102671-960206.doc -10· •Ί 1290073 表5 粉末 燒結碳 [%] 燒結密度 [克/爱米3] 第二操作 彎曲疲勞極限 [百萬帕斯卡] 珠擊法處理 後 增加 珠擊法處 理 切口的 Astaloy CrL 0.70 7.30 否 235 是 420 +79% 未切口的 Astaloy CrL 0.85 7.30 否 340 是 450 +32% 表6中顯示全部硬化回火和珠擊法處理之樣品之評估平 面彎曲疲勞性能。完全硬化用在880 °C的奥氏體反應 (arstenitization)溫度進行。奥氏體反應後以8°C/秒進行冷 卻。最後，樣品在250°C回火1小時。 表6 粉末 燒結碳 [%] 燒結密度 [克/爱米3] 第二操作 彎曲疲 勞極限 [百萬 帕斯 卡] 珠擊法 處理後 增加 全部 硬化 250〇C 回 火1小時 珠擊法 處理 切口的 Astaloy CrL 0.50 7.30 是 是 否 285 0.50 7.30 是 是 是 490 +73% 未切口的 Astaloy CrL 0.50 7.30 是 是 否 370 0.50 7.30 是 是 是 520 +41% 可自表5和6發現，彎曲疲勞極限增加由珠擊法處理含鉻 和麵之材料達到。 102671-960206.doc -11 -Distaloy® HP is alloyed with Ni and Cu diffusion and pre-alloyed with Mo. The three materials included in this study are shown in Table 1. Table 1 Materials Ni [%] Cu [%] Mo [%] Cr [%] One Astaloy CrL 0.2 1.5 Astaloy CrM 0.5 3.0 Distaloy HP 4.0 2.0 1.5 Details on process parameters, density and carbon content are given below. The plane bending fatigue properties of the uncut samples were shown in Table 2 for different alloys sintered in 90/10 N2/H2 at a cooling rate of about 〇8 ° C / sec for 30 minutes. Fatigue testing of uncut samples was performed using a 5 mm is〇3928 sample with chamfered edges. The test was carried out in a four-point plane bent at a load ratio of R = -1. In the ladder, the ladder method was used with 13-18 samples, and 2 million cycles were used as the breakthrough limit. Staircase evaluation (50% probability fatigue limit and standard deviation) was performed according to the MPIF 56 standard. The test frequency is 27_3 Hz. 102671-960206.doc 1290073 • Vt;| 4>;:; Table 2 ι —1 — ....:-...— Powder Density [g/Amy 3] Sintered Carbon [%] σ A, 50% [Million Pascals] Standard deviation [million pascals] ^ A, 90% [million pascals] Astaloy CrL 7.17 0.60 244 7 234 7.16 0.80 267 5 260 Astaloy CrM 7.06 0.35 284 7.0 274 7.04 0.56 316 8.4 300 Distaloy HP 7.13 0.65 295 22.5 261 7.13 0.85 330 <5 > 322 The microstructure of Astaloy CrL having less than 0.6% sintered carbon and a cooling rate of about 0.8 °c/sec is a higher Babbitt type. Above 0.74°/. The addition of carbon changes the microstructure to fine pearlite. The Astaloy CrM material sintered at 1120 ° C and a cooling rate of 0.8 ° C / sec and a microstructure analysis using a sintered carbon content between 0.32% and 0.49% showed a dense higher Bayesian microstructure. The densely higher Bayesian type has the same characteristics as the conventional higher Bayesian type, i.e., an irregular mixture of ferrite and cementite. The difference is the smaller distance between the carbides and the size of the carbide. The increased sintered carbon transfers the microstructure to a mixture of the granulated iron type and the lower Bayesian type. Table 3 shows the effects of the compression pressure and carbon content of cold pressed Astaloy CrL. All materials were sintered at 1120 ° C for 30 minutes in 90/10 N2/H2. In Table 3, a summary of the plane bending fatigue properties (standard deviation < 5) of Astaloy CrL at two compacting pressures and two additions of graphite shows that the scattering is small and the MPIF 56 cannot be used to assess the standard deviation. The samples in Table 3 were not cut. 102671-960206.doc -9- T290073 —«m» 妒· __(10)·_ — .... w repair (edge) replacement page Table 3 Material Graphite C-UF4 [%] Pressing pressure [Million Pascals] Sintering Density [g / cm3] Sintered carbon [%] σ A, 50% [million pascals] Standard deviation [million pascals] σ A, 90% [million pascals] Astaloy CrL 1120°C 30 minutes 90/10 N2 /H2 0.8〇C/sec 0.6 600 6.94 0.56 224 11.6 205 0.8 600 6.93 0.75 233 9.5 218 0.6 800 7.13 0.55 236 8.5 222 0.8 800 7.09 0.74 252 <5 >244 Table 4 shows the sintering temperature versus the use of uncut samples The effect of fatigue performance. The microstructure of the materials in Table 4 is characterized by predominantly higher Babbitt type (1120 ° C 0.58% C) and fine pearlite (1120 ° C, 〇 · 77% C and 1250 ° C, 0.74% C). Table 4 Powder sintering temperature Sintering density [g/cm3] Sintered carbon [%] σ A, 50% [million pascals] Standard deviation [million pascals] σ A, 90% [million pascals] Astaloy CrL 1120°C 7.10 0.58 220 11 203 1120°C 7.08 0.77 236 9.7 222 1250〇C 7.02 0.74 290 18 264 Example 2 The effect of the combination of bead blasting and heat treatment with bead blasting was investigated for Astaloy CrL 3 mm edge incision samples. The slit is included in the press and is not machined. The stress concentration factor in bending is obtained by FEM up to kt = 1.38. The test frequency is 27-30 Hz. The material was sintered in 1280 ° CKH2 for 30 minutes. The cooling rate was 0.8 ° C / sec. A bead blasting treatment was performed to obtain an Alman A intensity of 0.32 mm. The evaluation plane bending fatigue properties of the sintered and sintered + bead blasted samples are shown in Table 5. 102671-960206.doc -10· •Ί 1290073 Table 5 Powder Sintered Carbon [%] Sintering Density [g/Amy 3] Second Operation Bending Fatigue Limit [Million Pascals] Bead Strike Treatment Increases Bead Strike Treatment Astaloy CrL 0.70 7.30 No 235 is 420 +79% Uncut Astaloy CrL 0.85 7.30 No 340 is 450 +32% Table 6 shows the evaluation of plane bending fatigue properties of all hardened temper and bead blasted samples. Complete hardening was carried out at an arstenitization temperature of 880 °C. After the austenite reaction, cooling was carried out at 8 ° C / sec. Finally, the sample was tempered at 250 ° C for 1 hour. Table 6 Powder Sintered Carbon [%] Sintering Density [g/Amy 3] Second Operation Bending Fatigue Limit [Million Pascals] After Ball Beading Treatment Increases All Hardening 250〇C Retempering 1 hour Bead Strike Treatment of Insaloy CrL 0.50 7.30 is 285 0.50 7.30 Yes Yes 490 +73% Uncut Notched Astaloy CrL 0.50 7.30 Yes 370 0.50 7.30 Yes Yes 520 +41% Can be found from Tables 5 and 6, the bending fatigue limit is increased by the bead method Handling of materials containing chromium and noodles. 102671-960206.doc -11 -