1、Basic Metallurgy Grey Iron.灰鐵的冶金學基本理論灰鐵的冶金學基本理論7/4/2022Developing people - creating value2Grey iron is the oldest (i.e. has existed longest) of the cast irons and thus cast iron is often synonymus with grey cast iron. Unfortunately most people know grey iron to be brittle and thus believe all cast i

2、rons to be brittle. 灰鐵是最古老的鑄鐵之一，灰鐵通常也稱之為灰口鑄鐵。不幸的事，大多數(shù)都知道灰鐵是易脆的，因此人們認為所有的鑄鐵都是易脆的。Grey iron is called grey because of the colour of its fracture surface. The carbon is present as more or less continuous flakes of graphite within a matrix of normally mostly pearlite but it can also contain some ferrite

3、. Grey iron has a good fluidity and in combination with the expansion of the graphite during solidification makes it ideal for casting of shrinkage free complex parts like engine blocks. 灰鐵之所以被稱之為灰鐵，是因為其斷口成灰色。大多數(shù)碳在灰鐵是以連續(xù)狀的片狀石墨存在于絕大多數(shù)為珠光體基體中，同時基體中也會存在少量的鐵素體?；诣F具有很好的流動性結(jié)合在凝固過程中的石墨化膨脹使得灰鐵是鑄造無縮松的發(fā)動機缸體的理想

4、材料。The flakes in grey iron are important for the mechanical properties. The graphite flakes induces stress in the iron matrix and possible cracks will rapidly propagate along the flakes. This is the cause of the very small plastic elongation before rupture. The graphite flakes makes the iron easy to

5、 machine, acting as lubricant. 灰鐵中的片狀石墨對其機械性能有著十分重要的影響。片狀石墨可以引導基體中的應力和裂紋沿著片狀石墨快速傳播。這導致了灰鐵在失效時只具有很小的塑性。片狀石墨在機加工時起到了潤滑作用，使得灰鐵很容易被加工。Introduction to Grey Cast Iron灰口鑄鐵的介紹Some examples of castings in Grey Iron一些灰鐵的應用案例7/4/2022Developing people - creating value3Why Grey Iron? 為什么選擇灰鐵 low raw material cos

6、ts 原材料成本低 low production costs 生產(chǎn)成本低 high casting yield 成品率較高 good casting qualities 好的鑄造質(zhì)量 low gas pick-up 吸氣較少 good as-cast properties 較好的毛胚件質(zhì)量 easy machinable 易加工 good damping quality 較好的減震性能 good corrosion resistance 較好的防腐蝕性能 easily alloyed 易合金化 temperature stability 耐熱性能7/4/2022Developing peopl

7、e - creating value4Grey Iron - Flake Graphite 灰鐵 片狀石墨7/4/2022Developing people - creating value5Normal Composition Range:通常的成分范圍：通常的成分范圍：2.5 - 4.0 % Carbon 碳碳1.0 - 3.0 % Silicon 硅硅0.4 - 1.0 % Manganese 錳錳0.05 - 1.0 % Phosphorous 磷磷max 0.2 % Sulphur 硫硫The composition has to be selected to satisfy: 成分

8、選擇需要滿足以下要求： required graphite shape and distribution 必要的石墨形態(tài)和分布 carbide-free structure 金相結(jié)構(gòu)中無碳化物 required matrix 必要基體組織ElkemMechanical Properties 機械性能Tensile Strength:100 - 450 MPaElongation: 1%The mechanical properties and the microstructure of grey iron depends on: 機械性能和金相結(jié)構(gòu)取決于以下：機械性能和金相結(jié)構(gòu)取決于以下：Se

9、ction size 壁厚壁厚Chemical Composition化學成分化學成分Cooling Rate 冷去速率冷去速率Nucleation Potential 形核潛力形核潛力ElkemMicrostructure金相結(jié)構(gòu)金相結(jié)構(gòu)Properties性能性能Section Size壁厚壁厚Increasing Section SizeDecreasing Cooling Rate graphite coarsening 石墨粗化石墨粗化 increasing grain size 晶粒尺寸增大晶粒尺寸增大 pearlite coarsening 珠光體變粗糙珠光體變粗糙ElkemSe

10、ction Size As the section size increases the strength of grey cast irons falls.隨著壁厚的增加灰鑄鐵的強度是在降低的。* Typical Microstructures of Cast Metals - IBFElkem* ASM Specialty HandbookFe - C Phase diagram 鐵碳相圖7/4/2022Developing people - creating value10Consists of a stable and a metastable system由穩(wěn)定和亞穩(wěn)定系統(tǒng)組成Sta

11、ble穩(wěn)定物穩(wěn)定物Metastable亞穩(wěn)定物亞穩(wěn)定物Carbon as graphite 碳以石墨形式存在Eutectic point: 4.3 wt% CTeutectic = 1153CTeutectoid =738CCarbon as Fe3C碳以滲碳體形式存在Eutectic point: 4.26 wt% CTeutectic = 1147CTeutectoid =723CEffect of Carbon in Grey Iron碳在灰鐵中的作用7/4/2022Developing people - creating value11 reduces melting temperat

12、ure 降低熔點 improves castability 改善鑄造性能 improves machinability 改善機加工性能 improves damping capacity 提高減震性 reduces need for feeding 降低縮水 increases thermal conductivity 提高熱傳導性能 decreases chilling tendency 減少白口傾向 reduces mechanical strength 降低機械強度 coarser graphite structure 粗化石墨結(jié)構(gòu)Elkem improves graphitisatio

13、n 促進石墨化 reduces chill formation 減少白口的形成 promotes ferrite 促進鐵素體 promotes stable solidification 促進穩(wěn)定凝固 increasing content leads to coarser pearlite 提高粗糙珠光體的含量 ElkemPhosphorous 磷 found in all grey irons 所有灰鐵中都含有 increases fluidity 提高流動性 forms low-melting phosphide in grey iron; steadite, Fe3P 在灰鐵中形成低熔點

14、的磷化物 ；穩(wěn)定的化合物Fe3P promotes shrinkage porosity at high levels 含量較高時促進疏松的產(chǎn)生 promotes melt penetration into mould at very low levels 較低的含量下可以促進鐵水向鑄型滲透 wear resistance increases with increasing P-content 提高磷的含量可以提高耐磨性能Carbon Equivalent 碳當量7/4/2022Developing people - creating value14Carbon equivalent form

15、ula: 碳當量的公式碳當量的公式Effect of Carbon Equivalent in Grey Iron碳當量在灰鐵中的作用7/4/2022Developing people - creating value15Strength of grey iron will, ingeneral, decrease with increasingcarbon equivalent. While amountof graphite in the structureincreases.通?；诣F的強度將會隨著碳當量的提高而降低；同時金相結(jié)構(gòu)中的石墨也會增多。Elkem ties up S and O

16、 束縛硫和氧 reduces chill formation 減少白口的形成 promotes austenite 促進奧氏體 strong pearlite promoter 強烈的珠光體促進劑 weak carbide promoter 弱的碳化物促進劑Manganese 錳7/4/2022Developing people - creating value17ElkemSulphur 硫 found in all grey irons 所有灰鐵中都有 pearlite promoter forms low-melting sulphide in grey iron, FeS balanc

17、ed out by Mn to MnS, which acts as nucleation points promotes smaller eutectic cells hardness increase with increasing S-level UTS vs Sulphur Content抗拉強度與硫含量的關(guān)系7/4/2022Developing people - creating value19Elkemwt% SHigh chilling tendencyLarge GrainsD-graphite過冷度大，晶粒較大，D型石墨High chilling tendencyFine G

18、rainsD-graphite過冷度大，晶粒細小，D型石墨Low chilling tendencyMedium Size GrainsA-graphite過冷度較小，晶粒尺寸適中，A型石墨Effect of Manganese and Sulphur錳和硫的作用7/4/2022Developing people - creating value21Equilibrium reaction MnS: Mn + S MnS反應平衡式Equilibrium reaction FeS: Fe + S FeS反應平衡式Stoichiometric balance: %Mn = 1.7%S To ens

19、ure only MnS: %Mn = 1.7%S + 0.30%To achieve maximum strength precipitation of MnS has tosuppressed to as low temperature as possible prior toonset of solidification.為了獲得最大的強度， 要確保MnS的在凝固后期較低的溫度下析出Too early MnS precipitation = 40 80MPa lower strengthMnS過早析出= 抗拉強度有40 80MPa的降低 Manganese & Sulphur a

20、s function of CE錳和硫與碳當量的關(guān)系7/4/2022Developing people - creating value22Elkem石墨片層的種類EInterdendritic SegregationPreferred orientatedDInterdendritic SegregationRandom orientatedBRosette GroupingRandom orientatedAInoculated IronsUniform distributedRandom orientatedCSuperimposed Flake SizeRandom orientate

21、dUndercooling , TC.EC.E = 4.26Flake Graphite Structures片層石墨結(jié)構(gòu)7/4/2022Developing people - creating value24Grey Iron Solidification灰鐵的凝固曲線7/4/2022Developing people - creating value25Flake Graphite Size石墨片大小7/4/2022Developing people - creating value26Effect of different elements on tensile strength一些合金

22、元素的灰鐵抗拉強度的影響7/4/2022Developing people - creating value27Chill Depth in Grey Iron灰鐵中白口深度7/4/2022Developing people - creating value28The figure shows therelative chilling power ofdifferent elements圖形展示的是不同元素的促進白口能力Effect of Vanadium釩的作用7/4/2022Developing people - creating value29Promotes formation of

23、eutectic iron carbide which can be removed by heat treatment 可以促進合金碳化物的形成，這類碳化物可以通過熱處理消除。Inoculation can help reduce formation of eutectic carbides 孕育作用有助于減少共晶碳化物的形成Low chilling tendency in high carbon irons and in combination with Cu 高碳鑄鐵和合金銅的加入可以降低白口傾向Increases nucleation in grey iron giving finer

24、 and more uniform graphite structures 提高灰鐵的形核率，從而可以細化石墨結(jié)構(gòu)提高石墨結(jié)構(gòu)的一致性Segregates with P giving hard particles with good sliding wear resistance 與磷一起偏析形成硬點，從而形成耐磨層Increases strength especially in high carbon grey iron 提高灰鐵的強度，尤其是高碳灰鐵More effective than Cr and Mo 比鉻和鉬的效率更高Factors affecting machinability影

25、響機加工的因素7/4/2022Developing people - creating value30Carbon content 碳含量 Eutectic cell count 共晶團數(shù)量 Volume of MnS particles MnS顆粒的數(shù)量 Mn level 錳的含量Sn level 錫的含量Control of Properties in Grey Iron灰鐵性能的控制7/4/2022Developing people - creating value31Fracture and cracks are initiated by the flake graphite. 斷裂和

26、裂紋是開始于石墨片。斷裂和裂紋是開始于石墨片。Size and Distribution of the graphite in Grey Iron are thus the most important tool to control the mechanical properties.灰鐵金相中的石墨的大小和分布是控制其鑄件機械性能最重要的因素。灰鐵金相中的石墨的大小和分布是控制其鑄件機械性能最重要的因素。Calculated UTS developed by Bates et.al.抗拉強度的計算有貝茨等人發(fā)明7/4/2022Developing people - creating val

27、ue32UTS = Factor A * Factor B Factor A: 101.1193*(%TC + %Si/4 + %P/2)+ 4.3887/castbar radiusFactor B: 1.00 + 0.1371Si 0.0021(Mn-1.7S) 0.3131S +0.3562Cr + 0.0282Ni + 0.1107Cu + 0.6297Mo 5.2985Ti 0.2350SnThe coefficients are developed from regression analysis.系數(shù)是由回歸分析法來計算獲得的References 參考文獻7/4/2022Deve

28、loping people - creating value33Nucleation of graphite in cast iron melts depending on manganese, sulphur and oxygen. A.Sommerfeld,B.Tonn International journal of Cats Metals Research 2008 vol 21 no 1-4 Tin-alloyed Grey Iron Cylinder Blocks A.J.Tache, R.M. Cage American Society of Automotive Engineers 14.January 1964 Eutectic cell and nodule count in cast irons E.Fras, M.Gorny, W.Kapturkiewicz, H.Lopez International journalof Cast Metals Resear