潘永寧臺灣大學：機械工程學研究所林明山Lin, Ming-shanMing-shanLin2007-11-282018-06-282007-11-282018-06-282005http://ntur.lib.ntu.edu.tw//handle/246246/61222中 文 摘 要 Invar合金中因C、Si含量低(C<0.2%，Si<0.4%)，因此有較低的熱膨脹係數，約為(1~2)x10-6/oC(或(0.56~1.1)x10-6/oF)，但鑄造性及切削性較差。傳統高Ni低熱膨脹鑄鐵的C、Si含量(重量百分比2%<C<4%，2%<Si<4%)較高，因此熱膨脹係數較高，約為(5~6)x10-6/oC(或(2.8~3.3) x10-6/oF)，但鑄造性及切削性較好。本研究的目標主要有四：(1)開發熱膨脹係數在2x10-6/oC以下之低熱膨脹鑄鐵，(2)建立低熱膨脹鑄鐵之冶金特性資料，如凝固溫度範圍及凝固和固態收縮特性，(3)建立低熱膨脹鑄鐵之冒口設計原則，(4)了解低熱膨脹鑄鐵之切削加工性，如切削力、刀具磨耗、工件表面粗糙度及切屑型態等。 本研究內容主要分為三部份：(1)探討不同的C、Si含量(1.0~2.0%)、Ni-Co組合(36%Ni、33%Ni-3%Co、30%Ni-6%Co)及石墨形態(片墨及球墨)等冶金參數對於熱膨脹係數的影響。(2)針對不同成份之低熱膨脹鑄鐵，探討其凝固溫度範圍(初、共晶溫度)及凝固收縮特性，並進一步建立低熱膨脹鑄鐵之冒口設計原則。(3)探討不同合金組成及石墨形態(片墨及球墨)對於低熱膨脹鑄鐵之切削性的影響，包括切削力、刀具磨耗、工件表面粗糙度及切屑型態等。 片墨鑄鐵之生鐵原料中因含有較高的P量(0.15%)，因此在片墨鑄鐵爐次中會析出史帝田鐵。又，在片墨鑄鐵與球墨鑄鐵中均會析出碳化物，碳化物的析出主要與碳當量和鑄件斷面厚度有關。又，由於Ni的逆偏析現象，對於Ni含量較低(約30%)的爐次，當靠近共晶細胞間的Ni當量較低時，會促使少量麻田散鐵的析出。而球墨鑄鐵之麻田散鐵比例高於相同Ni當量的片墨鑄鐵，此係由於球墨鑄鐵的Ni偏析程度較片墨鑄鐵高所致。此外，對於球墨鑄鐵之石墨形態而言，當以含稀土元素之球化劑處理時，對於1-in之Y-block試樣，當SN(＝%C＋0.2%Si＋0.06%Ni)值大於3.7時會析出塊狀石墨，且SN值愈高，塊狀石墨之析出傾向愈高。若以不含稀土元素之球化劑處理時，對於1-in之Y-block試樣，當 SN值大於4.56時才會析出塊狀石墨。而對於0.5-in之Y-block試樣，則當SN值大於5.04時才會析出塊狀石墨。 研究結果顯示，低熱膨脹鑄鐵的α值隨C、Si含量(或CE值)的降低而降低。對於1.0%C-1.0%Si-36%Ni鑄鐵而言，在50~150oC之溫度範圍間，片墨之α值為(2.3~3.3)x10-6/oC，而球墨之α值為 (3.5~3.8)x10-6/oC。在固定之NiE值(36%)條件下，以部分Co取代Ni可使α值降低，例如，合金1.0%C-1.0%Si-30%Ni-6%Co之α值為(1.2~2.5)x10-6/oC。另外，實施均質化熱處理可降低α值，在A1(1.0%C-1.0%Si-36%Ni)片墨鑄鐵，將試片加熱至950oC後保持20小時，隨即淬火於常溫的水中，α90oC值可降至約0.83x10-6/oC。對於球墨鑄鐵而言，本研究所採用之均質化熱處理溫度(900oC~950oC)偏低，對於消除Ni之偏析問題及降低α值之效果並不顯著。 對於低熱膨脹鑄鐵之凝固溫度範圍，研究結果顯示液相溫度(FG：TL, oC=-7.93(CE)2-43(CE)+1535；SG：TL, oC=-21.42(CE)2-6(CE) +1535)隨CE (CE=%C+0.33%Si+0.047%Ni-0.0055%Nix%Si)值的增加而降低。而對於共晶溫度而言，在Fe-C-Si和合金中，共晶溫度主要受到含Si量的影響，但含高Ni之低熱膨脹鑄鐵其共晶溫度與Si含量或SiE 值(SiE=%Si+0.141%Ni-0.0165 %Nix%Si) 的相關性不高。 對於1.0%C-1.0%Si- 35%Ni的片墨鑄鐵而言，凝固收縮量約為5.2%，而相同成分的球墨鑄鐵，其凝固收縮率較片墨鑄鐵高約1.5%。而，對於2.0%C-2.0%Si-35%Ni的片墨鑄鐵而言，凝固收縮率約為1.63%~2.36%，而相同成份的球墨鑄鐵，其凝固收縮率較片墨鑄鐵高約1.2%。針對C及Si含量的不同而採用二種不同的冒口設計方法補充收縮，以獲得完美鑄件。1.0%C-1.0%Si合金採用幾何設計法，而2.0%C-2.0%Si合金則採用直接應用式冒口設計，並視冒口補充情形調整冒口尺寸，以尋求完美鑄件之最佳冒口。實驗結果顯示，對低熱膨脹片墨鑄鐵而言，欲得到完美鑄件所需之冒口模數(MR)與鑄件模數(MC)比約為1.27。對低熱膨脹球墨鑄鐵而言，欲得到完美鑄件所需之冒口模數(MR)與鑄件模數(MC)比約為1.43。另外，針對冒口保溫套及發熱劑而言，合金1.0%C-1.0%Si之低熱膨脹鑄鐵，若僅使用冒口保溫套可使冒口體積縮小約78%，若同時使用保溫套及發熱劑，則可使冒口體積縮小約82%。對於2.0%C-2.0%Si之低熱膨脹鑄鐵而言，若僅使用冒口保溫套可使冒口體積縮小約65%，若同時使用保溫套及發熱劑，則可使冒口體積縮小約80%。 針對切削性而言，研究結果顯示低熱膨脹鑄鐵之切削力隨著切削速度之增加而降低，而隨著進給率及切削深度之增加而增加。剪應力則隨著進給率及切削深度之增加而降低。C、Si含量愈高，切削力及剪應力則愈小。不同Ni、Co組成對切削力之影響不大。且，球墨鑄鐵的切削力及剪應力均較片墨鑄鐵大。切削1.0%C-1.0%Si之低熱膨脹鑄鐵時，刀具會產生明顯凹坑磨耗，而切削2.0%C-2.0%Si之低熱膨脹鑄鐵時，則刀具之凹坑磨耗不明顯。B2合金因含有較多硬質之麻田散鐵相，因此，刀具易發生刀尖破裂。球墨鑄鐵切削後之表面較片墨鑄鐵光滑，且整體表面之粗糙度(Ra)變化不大。C、Si含量愈低者，加工後表面愈佳。而，切屑特性主要受C含量及石墨形態、數量和分佈的影響。切屑之裂紋主要係沿著石墨相成長而至斷裂，因此含C量愈高者，切屑愈短，而片墨之切屑長度則較球墨之切屑短。Abstract The thermal expansion coefficients of Invar are quite low, normally at (1~2)x10-6/oC(or(0.56~1.1)x10-6/oF). However, due to the low C and Si contents in the alloys (C<0.2%，Si<0.4%), and the austenitic phase in the microstructure, Invar experiences relatively poor machinability and castability. The high-Ni (34~37%) austenitic cast irons, due to their relatively high C and Si contents in the alloys (2%<C<4%，2%<Si< 4%), have thermal expansion coefficients of (5~6) x 10-6/oC ( or (2.8~3.3) x 10-6/oF), while exhibit much better machinability and castability than Invar. The objective of this research was fourfold：(1) to develop low thermal expansion cast irons with the coefficients less than 2x10-6/oC, (2) to obtain the data of the solidification temperature ranges and the solidification shrinkage and solid contraction of the alloys, (3) to derive the riser design rules for the low thermal expansion cast irons, and (4) to understand the machinability of low thermal expansion cast irons, including cutting force, tool wear, surface roughness and chip characteristic. The contents of this research include: (1) Investigate the effects of C and Si contents (both in the range of 1.0~2.0%), Ni and Co contents (36%Ni, 33%Ni-3%Co and 30%Ni-6%Co), homogenizing heat treatment and graphite morphology (both flaky and spheroidal) on the thermal expansion coefficient. (2) Measure the solidification temperatures (liquidus and eutectic) and the percentages of solidification shrinkage and solid contraction, together with the design of risers. (3) Study the effects of alloy composition and graphite morphology (both flaky and spheroidal) on the machinability, including cutting force, tool wear, surface roughness and chip characteristic, of low thermal expansion cast irons. Microstructure observations indicate that very small amounts of steadite were observed in the microstructures of FG irons. The presence of steadite is due to a somewhat higher P content in the charge materials. Carbides are also observed in heats whose CE values are relatively low. For Heats that contain somewhat lower Ni content (about 30%), sporadic martensite can be found adjacent to the eutectic cell boundaries. The formation of martensite in the otherwise austenitic matrix may be due to the negative segregation of Ni, resulting in a depletion of Ni near the cell boundaries. Furthermore, the amount of martensite in the microstructure is slightly higher in SG irons than in FG irons, implying that the degree of Ni segregation is more severe in the former than in the latter. For SG irons, chunky graphite forms in 1-in thick specimens when SN (%C+ 0.2%Si+0.06%Ni) value exceeds 3.7 and 4.56 for alloys treated with a nodularizer that contains rare earths and without rare earths, respectively. On the other hand, chunky graphite appears in 0.5-in thick specimens when SN value exceeds 5.04 for alloys treated with a nodularizer without rare earths. The results of thermal expansion coefficient measurements indicate that α value decreases with decreasing C and/or Si contents (or CE). For cast irons with nominal compositions of 1.0%C-1.0%Si-36%Ni, the α values in the temperature range of 50 to 150oC are (2.3 ~ 3.3) x 10-6/oC and (3.5 ~ 3.8) x 10-6/oC for FG and SG irons, respectively. The coefficient value can be further lowered by replacing a fraction of Ni with Co at a constant NiE of 36%. As an example, α values of (1.2 ~ 2.5) x 10-6/oC were achieved for alloys containing nominal 1.0%C-1.0%Si- 30%Ni-6%Co. In addition, the results show that the α value was reduced further when the alloy was homogenized. For cast irons containing 1.0%C-1.0%Si-36%Ni, the α value of 0.83 x 10-6/oC (at 90oC) when the alloy was homogenized at 950oC for 20 hours and then quenched in water. Thermal analysis results conclude that the alloy liquidus temperatures can be expressed in terms of CE value for both flake and spheroidal graphite cast irons (FG：TL, oC=－7.93(CE)2－43(CE)+1535；SG：TL, oC=－21.42(CE)2－6(CE)+1535). The CE here is defined as follows : CE = %C + 0.33%Si + 0.047%Ni－0.0055%Ni x %Si. It has been well recognized that in the Fe-C-Si system the eutectic temperatures of both stable and metastable reactions are influenced mainly by the Si content or SiE(SiE=%Si+0.141%Ni-0.0165%Ni x %Si). Whereas, the coefficients of determination are not high enough to assume satisfactory correlation. The measurement results of alloy solidification shrinkage and solid contraction indicate that the percent solidification shrinkage for FG irons that contain 1.0%C-1.0%Si-35%Ni is about 5.2%, while an additional 1.5% should be added for SG irons of similar compositions. For FG irons that contain 2.0%C-2.0%Si-35%Ni, the percent solidification shrinkage is about 1.63% ~ 2.36%, while an additional 1.2% should be added for SG irons of similar compositions. Due to the contents of C and Si, the riser design concept used in this study is different --- “geometric method” is for 1.0%C-1.0%Si alloys, and “directly applied riser design method” is for 2.0%C-2.0%Si alloys. The experimental results indicate that the suitable ratio of the riser modulus(MR) to casting modulus(MC) is about 1.27 for FG irons, whereas, 1.43 for SG irons. In addition, when riser sleeve was used, the riser volume can be reduced by some 78% for LTE cast irons that contain 1.0%C-1.0%Si-35%Ni. Furthermore, when both riser sleeve and exothermal compounds were used, the riser volume can be reduced by 82%. When riser sleeve was used, the riser volume can be reduced by some 65% for LTE cast irons that contain 2.0%C- 2.0%Si-35%Ni. Furthermore, when both riser sleeve and exothermal compounds were used, the riser volume can be reduced by 80%. Regarding the machinability of low thermal expansion cast irons, the results indicate that as the C and Si contents decrease, both the cutting force and the shear stress increase; the length of the chips increases; the extent of crater wear on the tool rake face increases, and the surface finish of the workpieces improves. Replacing 6% Ni with an equivalent amount of Co only slightly affects machinability. With respect to graphite morphology, the results reveal that cast iron with flake graphite has shorter chips than that with spheroidal graphite, because of a better chip breaking effect of the flake graphite. Moreover, the long, flaky shape and interconnectedness of flake graphite in a eutectic cell accounts for the observed cracking and tearing on the machined surface of LTE FG cast irons. Therefore, LTE FG cast irons exhibit a poorer surface finish than LTE SG cast irons. Finally, the machinability of LTE cast irons with lacy or chunky graphite are between that of LTE FG and SG cast irons.目 錄 中文摘要……………………………………………………………... I 英文摘要………………………………………………………….. IV 目錄..……………………………………………………………… VIII 表目錄……………………………………………………………… XII 圖目錄……………………………………………………………… XIV 第一章 緒論………………………………………………………….. 1 第二章 文獻探討…………………………………………………….. 4 2.1低熱膨脹鑄鐵之開發過程及特性探究…………………….......... 4 2.1.1開發過程……………………………………………………. 4 2.1.2低熱膨脹特性之探究………………………………………. 5 2.2影響熱膨脹係數之冶金及製程參素……………………….......... 6 2.2.1 合金元素的影響………………………………………….... 6 2.2.1.1 C的影響……………………………………………….. 6 2.2.1.2 Si的影響……………………………………………….. 7 2.2.1.3 Ni的影響……………………………………………..... 7 2.2.1.4 Co的影響…………………………………………….... 8 2.3.1.5 Nb的影響…………………………………………….... 8 2.2.2 熱處理的影響………………….........................…………... 8 2.3 鑄造性…………………………………………………………... 9 2.3.1凝固收縮特性……………………………………………… 9 2.3.1.1鑄鋼的凝固收縮……………………………………...... 9 2.3.1.2鑄鐵的凝固收縮特性………………………………..... 9 2.3.2冒口設計…………………………………………………... 10 2.3.2.1冒口設計基本概念………………………………….... 10 2.3.2.2鑄鋼之冒口設計…………………………………….... 10 2.3.2.3石墨鑄鐵之冒口設計.................................................... 12 2.4 切削性…………………………………………………………... 16 第三章冶金及製程參數對於鑄鐵熱膨脹係數之影響……... 31 3.1 研究目的………………………………………………………... 31 3.2 研究架構與實驗設計…………………………………………... 31 3.2.1研究架構…………………………………………………... 31 3.2.2合金設計…………………………………………………... 32 3.2.3熔鑄作業............................………………………………... 32 3.2.4模型設計.....................…………………………………….. 32 3.2.5熱膨脹係數量測....………………………………………... 33 3.2.6熱處理......…………………………………………………. 33 3.2.7金相組織………………..................………………………. 34 3.2.8 Ni偏析現象觀察…………………………………..……… 34 3.3實驗結果................…………………………………………….... 35 3.3.1熱膨脹係數………………………………………………... 35 3.3.1.1 Ni-Co成份組合的影響…………...…………………... 35 3.3.1.2 C與Si的影響……………………………………....... 35 3.3.1.3石墨形態的影響……………………………………… 36 3.4討論.............................................……………………………….. 36 3.4.1金相組織之觀察………...................……………………… 36 3.4.1.1基地組織....................................................................... 37 3.4.1.2石墨形態觀察................................................................ 38 3.4.2均質化熱處理對Ni偏析的影響…………………………. 39 3.4.3均質化熱處理對α值的影響............................................. 40 3.4.4 C與CE含量對α值的影響.............................................. 42 3.5 結論.......................................................................................... 43 第四章 低熱膨脹鑄鐵之鑄造性探討………………………… 76 4.1研究目的…………………………………………………........... 76 4.2實驗設計……....................……………………………………… 76 4.2.1 合金設計………………………………………………….. 76 4.2.2 模型設計............................................................................... 77 4.2.2.1 凝固溫度量測................................................................ 77 4.2.2.2 凝固收縮量測............................................................... 77 4.2.3.3 冒口設計....................................................................... 78 4.3實驗結果…………………………………….............…………... 78 4.3.1 凝固溫度分析...................................................................... 78 4.3.2 凝固收縮與固態收縮.......................................................... 80 4.3.3 冒口設計.............................................................................. 81 4.3.3.1 1.0%C-1.0%Si合金之冒口設計................................... 81 4.3.3.2 2.0%C-2.0%Si合金之冒口設計................................... 83 4.3.3.3 冒口保溫套及發熱劑對冒口設計的影響................... 84 4.3.4 電腦模擬結果分析............................................................. .85 4.3.4.1 C1(片墨鑄鐵)合金........................................................ 85 4.3.4.2 D1(球墨鑄鐵)合金........................................................ 86 4.4 討論...................................……………………………………... 86 4.4.1 Ni、Co對冒口設計之影響................................................. 86 4.4.2 C、Si對冒口設計之影響.................................................... 87 4.4.3 保溫套與發熱劑對冒口設計之影響.................................. 88 4.4.4 鑄件模數與冒口模數之關係.............................................. 88 4.5結論................................................................................................ 89 第五章 低熱膨脹鑄鐵之切削加工性............................................ 135 5.1 研究目的.................................................................................... 135 5.2實驗設計...................................................................................... 135 5.2.1 合金設計............................................................................. 135 5.2.2 模型設計............................................................................ 135 5.2.2.1 切削試棒..................................................................... 135 5.2.3 切削力分析........................................................................ 136 5.2.4 刀具磨耗分析.................................................................... 136 5.2.5 工件表面特性及粗糙度分析............................................ 136 5.3 實驗結果..................................................................................... 136 5.3.1 顯微組織觀察.................................................................... 136 5.3.2 切削性................................................................................ 137 5.3.2.1 切削力......................................................................... 137 5.3.2.2 剪應力......................................................................... 137 5.3.2.3 刀具磨耗..................................................................... 138 5.4 討論............................................................................................. 138 5.4.1 石墨形態與C含量對切削力的影響............................... 138 5.4.2 石墨形態與C含量對剪應力的影響............................... 139 5.4.3 石墨形態與C含量對切屑特性的影響........................... 140 5.4.4 石墨形態與C含量對工件表面粗糙度的影響............... 141 5.4.5 較佳之切削加工條件........................................................ 142 5.5 結論............................................................................................. 143 第六章 綜合結論.............................................................................. 166 未來研究建議.................................................................................... 170 參考文獻………………………………………………………….... 172 表 目 錄 Table 2.1 Chemical compositions of various Invar-type alloys.…….. 21 Table 3.1 Alloy design for thermal expansion characteristics (series A & B).……………............................................................. 45 Table 3.2 Chemical analyses and CE, SN and NiE values for each heat........................................................................................ 46 Table 3.3 Experimental data of α value from 50oC to 400oC............... 47 Table 3.4 Chemical analyses of nodulizers used in this study............. 48 Table 3.5 The matrix structure and graphite shape of experimental heats..................................................................................... .49 Table 3.6 The graphite shape of experimental heats........................... 49 Table 4.1 Alloy design......................................................................... 91 Table 4.2 Chemical analyses of all heats............................................. 91 Table 4.3 Riser dimensions of alloy 1.0%C+1.0%Si........................... 92 Table 4.4 Riser dimensions of alloy 2.0%C+2.0%Si........................... 93 Table 4.5 Measurement results of liquidus and eutectic temperatures 94 Table 4.6 Results of solidification shrinkage and solid contraction tests...................................................................................... 95 Table 4.7 Estimations of solid contraction.......................................... 95 Table 4.8 Estimations of external contraction, pipe, and porosity of C1 (flake graphite) for various riser dimensions................. 96 Table 4.9 Estimations of external contraction, pipe, and porosity of C2 (flake graphite) for various riser dimensions................. 96 Table 4.10 Estimations of external contraction, pipe, and porosity of D1 (spheroidal graphite) for various riser dimensions....... 97 Table 4.11 Estimations of external contraction, pipe, and porosity of D2 (spheroidal graphite) for various riser dimensions...... 97 Table 4.12 Dimension of riser with sleeve for C1, C3, D1 and D3..... 98 Table 4.13 The minimum riser volume to attain sound castings for risers with and without sleeves for C1, C3, D1 and D3..... 98 Table 4.14 Dimensions of risers with sleeve and risers with both sleeve & exothermic compound for C1, C3, D1 and D3... 98 Table 4.15 The minimum riser required for attaining of sound castings among risers without sleeve, risers with sleeve and risers with both sleeve & exothermic compound for C1, C3, D1 and D3.......................................................................... 99 Table 4.16 The relationship of casting modulus and riser modulus.... 99 Table 5.1 Summary of alloy design................................................... 144 Table 5.2 Chemical analyses of all heats.......................................... 144 Table 5.3 Cutting conditions used in this study................................ 145 Table 5.4 The matrix and graphite structures of all heats for machining test................................................................... 145 Table 5.5 The cutting forces of all cutting conditions for various alloys................................................................................ 146 Table 5.6 The shear stress of all cutting conditions for various alloys................................................................................. 147 Table 5.7 The Brinell hardness number at the surface and in the center of specimens after machining............................................ 148 圖 目 錄 Fig. 2.1 Coefficient of linear expansion at 20 oC vs. nickel content for Fe-Ni alloys containing 0.4%Mn and 0.1%C.….................... 22 Fig. 2.2 Phase diagram of Fe-Ni alloy.…............................................. 22 Fig. 2.3 Change in length of a typical Invar over different ranges of temperature.……………........................................................ 23 Fig. 2.4 Illustration to the low thermal expansion characteristics of Invar alloys.…………………………………........................ 23 Fig. 2.5 Correlation between nickel content and α value at various temperatures in Fe-Ni alloys.…………………................ 24 Fig. 2.6 Volume change pattern for solidifying ductile iron................. 24 Fig. 2.7 A sectional view of a side riser for the geometric method...... 25 Fig. 2.8 Flow chart of the applied riser design system ..…………..... 26 Fig. 2.9 Standardized riser shapes.…………………………………... 27 Fig. 2.10 Schematic illustrations of pressure control risering principle 27 Fig. 2.11 Relationship of significant modulus(Ms) to transfer modulus(Mt).…...................................................................... 28 Fig. 2.12 Representative lathe-tool showing American Standards Association nomenclature...................................................... 28 Fig. 2.13 Effective rake angle for oblique cutting............................... 29 Fig. 2.14 Approximation of turning by the orthogonal cutting............ 29 Fig. 2.15 Relation between cutting depth and chip thickness.............. 30 Fig. 3.1 Configurations and dimensions of Y-block pattern refer to the ASTM A439 specification.……………………………….... 50 Fig. 3.2 The sectioning procedures for producing specimens for thermal expansion coefficient measurements.…………....... 50 Fig. 3.3 Schematic diagrams of various heat treatment cycles............ 51 Fig. 3.4 Results of α values with respect to Ni-Co contents in series A heats (FG)........................................................................... 52 Fig. 3.5 Results of α values with respect to Ni-Co contents in series B heats (SG).............................................................................. 53 Fig. 3.6 Results of α values with respect to carbon and silicon contents in series A heats (FG)............................................................. 54 Fig. 3.7 Change in α values with respect to CE value at various temperatures in series A heats (FG)....................................... 55 Fig. 3.8 Results of α values with respect to carbon and silicon contents in series B heats (SG)............................................................. 56 Fig. 3.9 A comparison of α value between Heat A1 (FG) and Heat B1 (SG) that have similar chemical compositions...................... 57 Fig. 3.10 Very few carbides were observed in series A heats.............. 58 Fig. 3.11 Very few Steadites were observed in series A heats............. 58 Fig. 3.12 Martensite was observed along boundaries of eutectic cells 59 Fig. 3.13 The phase diagram of Ni-Cr stainless materials................... 59 Fig. 3.14 Ni distribution curve in the matrix of Heat A1 (FG, 1.03%C+1.18%Si+35.8%Ni)............................................... 60 Fig. 3.15 Ni distribution curve in the matrix of Heat B1 (SG, 1.06%C+1.20%Si+36.1%Ni)............................................... 60 Fig. 3.16 Lacy graphite observed in Heats A2 and A3 which contain 1.0%C+1.0%Si..................................................................... 61 Fig. 3.17 Flaky graphite observed in Heats A7 which contain 2.0%C+2.0%Si..................................................................... 61 Fig. 3.18 The graphite structure of Heats B2 which contain 1.0%C+1.0%Si........................................................................ 62 Fig. 3.19 Chunky graphite was observed in Heats B5 which contain 1.5%C and 1.5%Si................................................................ 62 Fig. 3.20 The microstructures of the specimen of Heat B13 (2.4%C+2.4%Si+36 %)........................................................ 63 Fig. 3.21 SEM photomicrography of chunky graphite in the specimen of Heat B4.............................................................................. 63 Fig. 3.22 Chunky graphite forms in 1-in thick specimens when SN value exceeds 3.7 for alloys treated with a nodularizer that contains rare earths .............................................................................. 64 Fig. 3.23 The varied amounts of chunky graphite observed in Heats B4 and B6.................................................................................... 64 Fig. 3.24 Chunky graphite forms in 1-in thick specimens when SN value exceeds 4.56 for alloys treated with a nodularizer containing no rare earths ...................................................... 65 Fig. 3.25 Chunky graphite forms in 0.5-in thick specimens when SN value exceeds 5.04 for alloys treated with a nodularizer containing no rare earths........................................................ 65 Fig. 3.26 Ni distribution curves in the matrix of Heat A1(FG ,1.03%C+1.18%Si+35.8% Ni) with various heat treatment conditions (EPMA line scanning)......................... 66 Fig. 3.27 Ni distribution curves in the matrix of Heat A1(FG ,1.03%C+1.18%Si+35.8 %Ni) with various heat treatment conditions (EPMA line scanning).......................... 67 Fig. 3.28 Ni distribution curves in the matrix of Heat B1(SG,1.06%C+1.20%Si+36.1% Ni) with various heat treatment conditions (EPMA line scanning).......................... 68 Fig. 3.29 Ni distribution curves in the matrix of Heat B1(SG,1.06%C+1.20%Si+36.1% Ni) with various heat treatment conditions (EPMA line scanning).......................... 69 Fig. 3.30 Change in α values with temperature of Heats A1~A3 (FG, 1.0%C+1.0%Si) due to different heat treatment conditions... 70 Fig. 3.31 Change in α values with temperature of Heats A1 due to different heat treatment conditions......................................... 71 Fig. 3.32 Change in α values with temperature of Heats A1 due to different heat treatment conditions......................................... 72 Fig. 3.33 Change in α values with temperature of Heats B1~B3 (SG, 1.0%C+1.0%Si) due to different heat treatment conditions.. 73 Fig. 3.34 Change in α values with temperature of Heats B1 due to different heat treatment conditions........................................ 74 Fig. 3.35 The relationship of (a) C content and α value, (b) CE value and α value........................................................................... 75 Fig. 4.1 An example of the solidification cooling curve..................... 100 Fig. 4.2 Pattern for solidification and solid shrinkage test.................. .100 Fig. 4.3 Mold design for solidification and solid shrinkage feeding test......................................................................................... 101 Fig. 4.4 Schematic illustration of various shrinkages......................... 101 Fig. 4.5 Riser mold design for solidification and solid shrinkage feeding test........................................................................... 102 Fig. 4.6 The liquidus temperature with respect to CE value for (a) A & C (FG), and (b) B & D (SG).................................. 103 Fig. 4.7 The euetectic temperature with respect to Si value for (a) A &C (FG), (b) B & D (SG).................................................... .104 Fig. 4.8 The euetectic temperature with respect to SiE value for (a) A & C (FG), (b) B & D (SG)................................................... 105 Fig. 4.9 The solidification cooling curves of Heats B7~B9 which contain chunky graphite....................................................... 106 Fig. 4.10 A sectional view of a typical solidification shrinkage test Casting................................................................................ 107 Fig. 4.11 A comparisons of the volume shrinkage in irons of 1.0%C+ 1.0% Si with different combinations of Ni and Co (a) Flake graphite irons, and (b) Spheroidal graphite irons............ 108 Fig. 4.12 A comparison of the solidification shrinkage in irons of 1.0%C+1.0% Si with different combinations of Ni and Co (a) Flake graphite irons, and (b) Spheroidal graphite irons..... 109 Fig. 4.13 A comparison of the volume shrinkage in irons of 2.0%C+ 2.0% Si with different combinations of Ni and Co (a) Flake graphite irons, and (b) Spheroidal graphite irons............... 110 Fig. 4.14 A comparison of the solidification shrinkage in irons of 2.0%C+2.0% Si with different combinations of Ni and Co (a) Flake graphite irons, and (b) Spheroidal graphite irons..... 111 Fig. 4.15 Sectional views of risers and castings for C1 (1.0%C+1.0%Si+35%Ni, FG)............................................ 112 Fig. 4.16 Sectional views of risers and castings for C2 (1.0%C+1.0%Si+29%Ni+6.0%Co, FG)............................. 113 Fig. 4.17 Sectional views of risers and castings for D1 (1.0%C+1.0%Si+35%Ni, SG)........................................... 114 Fig. 4.18 Sectional views of risers and castings for D2 (1.0%C+1.0%Si+29%Ni+6.0% Co, SG)........................... 115 Fig. 4.19 Sectional views of risers and castings for C3 (2.0%C+2.0%Si+35%Ni, FG)............................................ 116 Fig. 4.20 Sectional views of risers and castings for C4 (2.0%C+2.0%Si+29%Ni+6.0%Co, FG).............................. 117 Fig. 4.21 Sectional views of risers and castings for D3 (2.0%C+2.0%Si+35%Ni, SG).............................................. 118 Fig. 4.22 Sectional views of risers and castings for D4 (2.0%C+2.0%Si+29%Ni+6.0%Co, SG)............................. 119 Fig. 4.23 Sectional views of risers and castings for C1 (FG) with exothermic sleeve riser......................................................... 120 Fig. 4.24 Sectional views of risers and castings for D1 (SG) with exothermic sleeve riser........................................................ 121 Fig. 4.25 Sectional views of risers and castings for (a) C1 (FG), (b) C3 (FG), and (c) D1 (SG), and (d) D3 (SG) with risers having exothermic sleeve and exothermic compound......... 122 Fig. 4.26 The comparisons of the minimum riser size for attaining sound castings among the original riser, riser with exothermic sleeve and riser with exothermic sleeve and exothermic compound of C1, C3, D1 and D3.................................... 123 Fig. 4.27 (a) Physical properties, (b) the solidification and shrinkage curves of C1......................................................................... 124 Fig. 4.28 (a) The simulation result according to alloy density, (b) Sectional views of the riser and casting, (c) The simulation result indicating the hot spot of casting C1.......................... 125 Fig. 4.29 (a) Physical properties, (b) the solidification and shrinkage curves of D1........................................................................ 126 Fig. 4.30 (a) The simulation result according to alloy density, (b) Sectional views of the riser and casting, (c) The simulation result indicating the hot spot of casting D1.......................... 127 Fig. 4.31 A comparison of the (a)pipe, and (b) porosity with different combinations of Ni and Co for flake graphite irons containing 1.0%C+1.0%Si..................................................................... 128 Fig. 4.32 A comparison of the (a)pipe, and (b) porosity with different combinations of Ni and Co for spheroidal graphite irons containing 1.0%C+1.0% Si.................................................. 129 Fig. 4.33 A comparison of the (a)pipe, and (b) porosity with different combinations of Ni and Co for flake graphite irons containing 2.0%C+2.0% Si................................................................... 130 Fig. 4.34 A comparison of the (a)pipe, and (b) porosity with different combinations of Ni and Co for spheroidal graphite irons containing 2.0%C+2.0% Si.................................................. 131 Fig. 4.35 A comparison of the (a)pipe, and (b) porosity with different combinations of C and Si for flake graphite irons............... 132 Fig. 4.36 A comparison of the (a)pipe, and (b) porosity with different combinations of C and Si for spheroidal graphite irons....... 133 Fig. 4.37 The surface characteristic of a riser with exothermic sleeve 134 Fig. 4.38 The surface of a riser with exothermic sleeve which sinks after solidification................................................................ 134 Fig. 5.1 The configuration and dimensions of the Y-block casting, in which the shaded areas are the locations taken for machining specimens............................................................................. 149 Fig. 5.2 The relations between cutting force and cutting depth for different feeds at a constant cutting speed of 82.5m/min.... 150 Fig. 5.3 The relations between shear stress and cutting depth for different feeds at a constant cutting speed of 82.5m/min.... 151 Fig. 5.4 Observations of tool wear at the flank surface of specimens after machining for 25 minutes. (a) C1, (b) C2, (c) C3, and (d) C4 152 Fig. 5.5 Observations of tool wear at the flank surface of specimens after machining for 25 minutes. (a)D1, (b)D2, (c)D3, and (d)D4. 153 Fig. 5.6 Comparisons of cutting force for various alloys under the machining condition of : Cutting speed : 82.5m/min, Feed rate : 0.2mm/rev, Depth of cut : 0.3mm........................................... 154 Fig. 5.7 Comparisons of cutting force for various alloys under the machining condition of : Cutting speed : 82.5m/min; Feed rate : 0.1mm/rev, 0.2mm/rev, 0.3mm/rev; Depth of cut : 0.2mm, 0.3mm, 0.4mm....................................................................... 154 Fig. 5.8 Comparisons of shear stress for various alloys under the machining condition of : Cutting speed : 82.5m/min, Feed rate : 0.2mm/rev, Depth of cut : 0.3mm........................................... 155 Fig. 5.9 Comparisons of shear stress among various alloys for three different cutting speeds.......................................................... 155 Fig. 5.10 Comparisons of shear stress for various alloys under the machining condition of : Cutting speed : 82.5m/min; Feed rate : 0.1mm/rev, 0.2mm/rev, 0.3mm/rev; Depth of cut : 0.2mm, 0.3mm, 0.4mm....................................................................... 156 Fig. 5.11 The shape of chips for various alloys C1, C2, C3, C4, D1, D2, D3, and D4...................................................................... 157 Fig. 5.12 The microstructures of chips of alloy C1............................ 158 Fig. 5.13 The microstructures of chips of alloy C2............................ 158 Fig. 5.14 The microstructures of chips of alloy C3............................ 158 Fig. 5.15 The microstructures of chips of alloy C4............................ 159 Fig. 5.16 The microstructures of chips of alloy D1............................ 159 Fig. 5.17 The microstructures of chips of alloy D2........................... 159 Fig. 5.18 The microstructures of chips of alloy D3........................... 160 Fig. 5.19 The microstructures of chips of alloy D4........................... 160 Fig. 5.20 The shape of chips for stainless steel (304)........................ 160 Fig. 5.21 Microstructures at the cutting surface of various alloys C1, C2, C3, and C4..................................................................... 161 Fig. 5.22 The surface roughness (Ra) of various alloys.................... 162 Fig. 5.23 Microstructures at the cutting surface of various alloys D1, D2, D3, and D4..................................................................... 163 Fig. 5.24 Analysis of surface roughness for various alloys C1(Ra=1.58), C2(Ra=1.96), C3(Ra=4.3), and C4(Ra=2.46)..................... 164 Fig. 5.25 Analysis of surface roughness for various alloys D1(Ra=1.58), D2(Ra=1.48),D3(Ra=2.34), and D4(Ra=2.44)................... 1654599947 bytesapplication/pdfen-US切削性冒口設計熱分析均質化熱處理膨脹係數鑄鐵Riser designMachinabilityCast ironExpansion coefficientThermal analysisHomogenizing heat treatmentthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/61222/1/ntu-94-D89522010-1.pdf