潘永寧教授臺灣大學:機械工程學研究所鄭進華Cheng, Chin-HuaChin-HuaCheng2010-06-302018-06-282010-06-302018-06-282009U0001-2807200911083700http://ntur.lib.ntu.edu.tw//handle/246246/187090本研究的主要目的為建立薄壁縮墨鑄鐵之鑄造技術，鑄件之厚度標的為2~3mm，研究上探討一些相關製程及冶金參數對於顯微組織（包含縮化率、石墨數目、肥粒鐵、波來鐵、碳化物）以及熱疲勞性質之影響，以期獲致優良薄壁縮墨鑄鐵之最佳製程參數條件。驗結果顯示，欲得到有效的縮化處理，需將含縮化劑之鐵罐壓扁，並固定於澆斗底部，以避免澆鑄時上浮，如此可避免縮化不完全及不良石墨型態出現。在固定C（2.88%）及Si（5.0%）成分下，縮化劑處理量在0.3％應可得到縮狀石墨鑄鐵。相同C、Si含量下，2mm鑄件之石墨數目均高於3mm鑄件，對於縮化率而言，其3mm鑄件之縮化率均高於2mm鑄件。改變造模材料（化學模、濕砂模），對於石墨數目與縮化率之影響不大。在固定C（3.0％）及處理條件下（縮化劑0.3%、接種劑0.15%），對任一厚度、造模材料而言，石墨數目及肥粒鐵量均隨Si含量之增加而逐漸增加，在約4.6％Si達到最高值。在相同Si含量下，影響肥粒鐵量的參數以鑄件厚度最大，造模材料次之。固定Si（3.0％）時，縮化劑種類對於石墨數目、肥粒鐵之影響而言，以含Ti縮化劑處理時，會明顯降低鑄件斷面敏感度，且以含Ti縮化劑處理之鑄件其石墨數目及肥粒鐵均高於以鎂-稀土縮化劑處理之鑄件。疲勞試驗之結果顯示，在固定C、Si成分及縮化率條件下，若肥粒鐵及石墨數目差異不大，熱疲勞次數隨肥粒鐵及石墨數目之增加而增加，但石墨數目與肥粒鐵差異大時，則兩者對於熱疲勞性質呈現交互影響。又，將石墨數目及肥粒鐵固定後，其熱疲勞次數隨縮化率之增加而增加，超過一定值以後則顯著降低。固定C（3.0%）及處理條件（縮化劑0.3％、接種劑0.15％）之條件下（No.11.12.13），熱疲勞次數隨Si含量之增加而增加，且其變化趨勢與石墨數目及肥粒鐵對Si量之變化趨勢一致，但對於縮化率而言並無明確的相關。此外，添加約0.5％ Mo，對於任一鑄件厚度、造模材料而言，皆明顯提昇熱疲勞性質。熱疲勞裂紋之SEM觀察，可以發現二次石墨氧化燒失而形成之空孔，使晶界強度減弱，應力容易集中。另，裂紋形成後，在裂紋界面容易氧化，高溫下氧化層與基材間之結合力減弱，造成氧化層與金屬基地分離，產生氧化起皮現象。The primary purpose of this research is to establish the optimal conditions for the production of thin-section (2?3 mm) compacted graphite cast irons for high temperature applications (up to 800℃). Experimentally, the microstructures (include vermicularity, graphite count, and matrix structure) and thermal fatigue property will be evaluated and correlated with alloy design and casting parameters, such as section size and molding material. The results show that, for a fixed C content of some 2.88% and Si content of some 5.0%, an addition of about 0.3% compactizing alloys can attain compacted graphite structure. Regarding the effects of casting parameters on microstructure, the results show that for fixed C and Si contents higher graphite counts can be obtained in castings with a thinner section, while, higher vermicularity can be obtained in castings with a thicker section. However, the effect of molding material on graphite count and vermicularity are not significant. For a fixed C content (3.0%) and treatment conditions (compactizer 0.3%、inoculant 0.15%), both the %ferrite and graphite count increase with increasing Si content, reach maxima at around 4.6% Si.he result about thermal fatigue show that, for fixed C and Si content and vermicularity, thermal fatigue cycles to failure increases with increasing %ferrite and graphite count. Further, under the conditions of fixed graphite count and ferrite content, thermal fatigue cycle increases first with increasing vermicularity, reaches maximum, and then decreases with further increases in vermicularity. ixed C content of 3.0% and constant treatment conditions (compactizer 0.3%, inoculant 0.15%), the thermal fatigue cycle increases with increasing Si content. Similar trends have also been obtained for graphite count and %ferrite. Furthermore, adding some 0.5% Mo can significantly increase thermal fatigue cycles to failure.inally, the fracture mechanism during the thermal fatigue test had also been assessed in this study.目 錄試委員會審定書............................................................................................................i...................................................................................................................................ii文摘要..........................................................................................................................iii文摘要...........................................................................................................................v一章 緒論.............................................................................................................1 1.1 前言..................................................................................................................1二章 文獻回顧.....................................................................................................4.1 Fe-C二元系統相圖..........................................................................................4.1.1鋼的凝固機制-准穩定平衡相圖...............................................................4.1.2鑄鐵的凝固機制-穩定平衡相圖...............................................................5.1.3共晶碳化物的形成.....................................................................................5.2 縮墨鑄鐵的石墨型態......................................................................................6.2.1縮墨鑄鐵的縮化率評定.............................................................................7.3 縮狀石墨鑄鐵之性能......................................................................................7.3.1抗拉性質.....................................................................................................7.3.2熱傳導性質.................................................................................................8.3.3熱疲勞性質.................................................................................................8.4 化學成分對薄件縮墨鑄鐵顯微組織之影響..................................................8.4.1碳當量與矽元素含量.................................................................................8.5 縮化劑..............................................................................................................9.5.1稀土元素之影響.........................................................................................9.5.2鈦元素之影響...........................................................................................10.6 製程參數對薄件縮墨鑄鐵顯微組織之影響................................................10.6.1縮化處理...................................................................................................10.6.2接種處理...................................................................................................12.7 耐熱鑄鐵在高溫應用時之性質要求............................................................12.7.1 高矽耐熱鑄鐵.........................................................................................13三章 實驗目的與方法.......................................................................................25.1 實驗目的........................................................................................................25.2 實驗設計........................................................................................................25.2.1 鑄造流程.................................................................................................25.2.2 模型設計.................................................................................................26.2.3 造模材料種類.........................................................................................26.2.4 熔液處理及澆鑄.....................................................................................27.2.5 金相顯微組織之觀察與影像分析.........................................................27.2.6 縮化率的評定方式.................................................................................27.3 耐熱疲勞性質測試........................................................................................27四章 結果與討論...............................................................................................35.1 縮化及接種處理對顯微組織的影響............................................................35.1.1 在固定接種劑(0.3%)之條件下，不同縮化劑添加量（縮化劑A）之影響.............................................................................................................35.2 在固定處理條件(縮化劑0.3%、接種劑0.15%)下，不同Si含量之影響......37.3 在固定製程條件下，不同縮化劑（縮化劑B，含鈦）之影響.........................39.4 參數對於熱疲勞性質之影響........................................................................40.4.1縮化率對於熱疲勞性質之影響...............................................................40.4.2 Si含量對於熱疲勞性質之影響..............................................................42.4.3添加Mo之影響........................................................................................43.5 SEM觀察........................................................................................................44.5.1熱循環裂紋生長觀察...............................................................................44五章 結論...........................................................................................................77 表...............................................................................................................................79 考 文 獻...................................................................................................................81 目 錄able 3-1 Alloy desine and treatment..............................................................................29able 3-2 Chemical analyses of all heats (mass %)........................................................29able 3-3 Chemical compositions of charge materials (mass %)..................................30able 3-4 Chemical compositions of treating alloys (mass %)......................................30 目 錄ig. 1-1. 不同石墨型態之二D顯微組織。......................................................................3ig. 1-2. 縮狀石墨在SEM觀察下之3D顯微組織。......................................................3ig. 2-1. Fe-C diagram....................................................................................................14ig. 2-2. Eutectic region for the stable and metastable reactions....................................14ig. 2-3. Solidification Cooling Curve Representing Conditions for White Iron...........15ig. 2-4. Typical Solidification Cooling Curve for Hypoeutectic Gray Iron……...…...15ig. 2-5. Solidification Cooling Curve Representing Conditions for Mottle in a Poorly Nucleated and/or Rapidly Cooled Iron............................................................16ig. 2-6. Solidification Cooling Curve Representing Conditions for the Formation of Intercellular Carbides......................................................................................16ig. 2-7. The morphology of compacted graphite……...………………………….....17ig. 2-8. The seven types of graphite as established by ASTM Specification A-247.....18ig. 2-9. According to Iron and Steel Examination Chart 1560-57……………....….18ig. 2-10. According to CNS 14438-G3266………………………...……………….…19ig. 2-11. The influence of carbon equivalent on the tensile strength of gray、ductile and compacted graphite irons.................................................................................20ig. 2-12. The thermal conductivity of different cast iron from 100℃ to 500℃..........20ig. 2-13. The number of thermal (293K~923K) cycles to produce thermal fatigue cracking in various cast irons..........................................................................21ig. 2-14. The required C.E. values for different section thicknesses to prevent carbide formation.....................................................................................................22ig. 2-15. Small variations of Mg content (0.012 ± 0.005%) lead to significant changes of microstructure..........................................................................................22ig. 2-16. Correlation between residual Mg content of cast iron and microstructure. (b) Using combination of Mg, Ce, and Ti.........................................................23ig. 2-17. Cored Wire apparatus.....................................................................................23ig. 2-18. The Sintercast Process is integrated into the foundry production route.........24ig. 2-19. The sensitivity of compacted graphite iron to both magnesium and inoculant..........................................................................................................24ig. 3-1. The flow chart of compacted graphite cast iron production..........................31ig. 3-2. Pattern drsign,(a) 2mm-plate pattern：2×60×250 mm，(b) 3mm-plate pattern：3×60×300 mm...................................................................................................32ig. 3-3. The flow chart of the treatment process............................................................32ig. 3-4. The positions of specimens for microstructure analysis and thermal fatigue test.....................................................................................................................33ig. 3-5. An example of the specimen code....................................................................33ig. 3-6. Dimensoins of thermal fatigue test specimens..................................................34ig. 3-7. (a) Schemetic drawing for thermal fatigue test apparatus, (b) Photo of the thermal fatigue test apparatus..........................................................................34ig. 4-1. 爐次3縮化劑（0.4％）上浮（縮化劑過量）之鑄件顯微組織（化學模）。...............................................................................................................46ig. 4-2. 爐次3縮化劑（0.4％）上浮之鑄件顯微組織（濕砂模）。......................... 47 ig. 4-3. 縮化劑上浮至熔液表面。................................................................................48ig. 4-4. 縮化處理不足之金相照片（爐次5）。.............................................................48ig. 4-5. 在固定0.3％接種劑之條件下，縮化劑處理量對於化學模2mm鑄件之石墨數目及肥粒鐵量之影響（括弧內之數字表示縮化劑添加量）。...............49ig. 4-6. 在固定0.3％ 接種劑之條件下，縮化劑處理量對於化學模3mm之石墨數 目及肥粒鐵量之影響（括弧內之數字表示縮化劑添加量）。.......................49ig. 4-7. 不同縮化劑處理量及鑄件厚度之化學模鑄件顯微組織。............................50ig. 4-8. 在固定0.3％接種劑之條件下，縮化劑處理量對於濕砂模2mm之石墨數目及肥粒鐵量之影響（括弧內之數字表示縮化劑添加量）。.......................51ig. 4-9. 在固定0.3％接種劑之條件下，縮化劑處理量對於濕砂模3mm之石墨數目及肥粒鐵量之影響（括弧內之數字表示縮化劑添加量）。.....................51ig. 4-10. 不同縮化劑處理量及鑄件厚度之濕砂模顯微組織。..................................52ig. 4-11. 2mm鑄件之石墨數目較3mm鑄件高約12?17％。....................................53ig. 4-12. 在固定製程條件（縮化劑0.3％、接種劑0.15％）下，Si含量對於化學模2mm之石墨數目及肥粒鐵量之影響。（括弧中之數字代表Si含量）....54ig. 4-13. 在固定製程條件（縮化劑0.3％、接種劑0.15％）下，Si含量對於化學模3mm之石墨數目及肥粒鐵量之影響。（括弧中之數字代表Si含量）。.............................................................................................................54ig. 4-14. 在固定製程條件下(縮化劑0.3％、接種劑0.15％)，不同Si含量化學模鑄件之金相照片。.............................................................................................55ig. 4-15. 在相同造模材料下（化學模）不同鑄件厚度（2mm & 3mm）之縮化率比較。.................................................................................................................56ig. 4-16. 在固定製程條件(縮化劑0.3％、接種劑0.15％)下，Si含量對於濕砂模2mm之石墨數目及肥粒鐵量之影響。.........................................................56ig. 4-17. 在固定製程條件(縮化劑0.3％、接種劑0.15％)下，Si含量對於濕砂模3mm之石墨數目及肥粒鐵量之影響。.........................................................57ig. 4-18. 在相同造模材料下（濕砂模）不同鑄件厚度（2mm & 3mm）之縮化率比較。.................................................................................................................57ig. 4-19. 在固定製程條件(縮化劑0.3％、接種劑0.15％)下，不同Si含量濕砂模鑄件之金相照片。.............................................................................................58ig. 4-20. 以含鈦縮化劑處理之金相照片(爐次10)。..................................................59ig. 4-21. 不同縮化劑種類對於2mm及3mm化學模鑄件之石墨數目的影響。.......59ig. 4-22. 不同縮化劑種類對於2mm及3mm濕砂模鑄件之石墨數目的影響。.......60ig. 4-23. 不同縮化劑種類對於2mm及3mm化學模鑄件之肥粒鐵量的影響。.......60ig. 4-24. 不同縮化劑種類對於濕砂模2mm、3mm鑄件肥粒鐵量之影響。..............61ig. 4-25. 在固定縮化率(15%)及化學成分（C、Si）含量下，3mm之化學模，基地組織（石墨數目、肥粒鐵量）與熱疲勞性質之關係。...................................61ig. 4-26. 在固定縮化率(18.5%)及化學成分（C、Si）含量下，3mm之濕砂模，基地組織（石墨數目、肥粒鐵量）與熱疲勞之關係。.......................................62ig. 4-27. 在固定縮化率及化學成分（C、Si）含量下，2mm之濕砂模，基地組織（石墨數目、肥粒鐵量）與熱疲勞之關係。.................................................62ig. 4-28. 在固定縮化率(14.2%)及化學成分（C、Si）含量下，3mm之濕砂模，基地組織（石墨數目、肥粒鐵量）與熱疲勞之關係。.......................................63ig. 4-29. 在固定石墨數目（1400 #/mm2）、肥粒鐵量（94％）下，其熱疲勞次數與縮化率之關係。.........................................................................................63ig. 4-30. 在固定石墨數目（1160 #/mm2）及肥粒鐵量（97.1％）下，其熱疲勞次數與縮化率之關係。.....................................................................................64ig. 4-31. 在固定石墨數目（1280 #/mm2）及肥粒鐵量（96.5％）下，其熱疲勞次數與縮化率之關係。.....................................................................................64ig. 4-32. 在固定石墨數目（790 #/mm2）、肥粒鐵量（94％）下，其熱疲勞次數與縮化率之關係。.........................................................................................65ig. 4-33. 在固定C(3.0%)條件下，2mm之濕砂模，不同Si含量對熱疲勞壽命之影響。.................................................................................................................65ig. 4-34. 在固定C(3.0%)條件下，3mm之濕砂模，不同Si含量對熱疲勞壽命之影響...............................................................................................66ig. 4-35. 在固定C(3.0%)條件下，2mm之化學模，不同Si含量對熱疲勞壽命之影響...................................................................................................................66ig. 4-36. 在固定C(3.0%)條件下，3mm之化學模，不同Si含量對熱疲勞壽命之影響。 ...............................................................................................................67ig. 4-37. 爐次15（添加0.5％Mo）與1~14各爐次試片比較。.....................................67ig. 4-38. 一般鑄件其熱應力與溫度隨時間的變化，其殘留拉應力增加幅度較大。.................................................................................................................68ig. 4-39. 鑄件（加Mo）其殘留拉應力增加幅度小。................................................68ig. 4-40. 片狀石墨之生長模式。 ................................................................................69ig. 4-41. 球狀石墨之生長模式。 ................................................................................69ig. 4-42. 縮狀石墨之生長模式。..................................................................................69ig. 4-43. (a)爐次6化學模2mm鑄件, (b) a之放大圖..................................................70ig. 4-44. 爐次14化學模3mm鑄件(14C3)..................................................................71ig. 4-45. 石墨沿A軸方向生長。..................................................................................72ig. 4-46. 熱斷後6C2之試片二次石墨，在高溫下氧化逸失造成空孔。....................73ig. 4-47. 裂紋表面產生之氧化起皮現象。..................................................................74ig. 4-48. 裂紋之周圍氧化形成一氧化層。..................................................................75ig. 4-49. EDAX 分析...................................................................................................767557992 bytesapplication/pdfen-US薄壁縮墨鑄鐵石墨數目縮化率肥粒鐵熱疲勞性質thin-section compacted graphite cast iron, graphite count, vermicularity, thermal fatigue property, secondary graphite.thesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/187090/1/ntu-98-R96522726-1.pdf