grey iron presentation灰铁的冶金

1、Basic Metallurgy Grey Iron.灰铁的冶金学基本理论灰铁的冶金学基本理论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. 灰铁是最古老的铸铁之一，灰铁通常也称之为灰口铸铁。不幸的事，大多数都知道灰铁是易脆的，因此人们认为所有的铸铁都是易脆的。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. 灰铁之所以被称之为灰铁，是因为其断口成灰色。大多数碳在灰铁是以连续状的片状石墨存在于绝大多数为珠光体基体中，同时基体中也会存在少量的铁素体。灰铁具有很好的流动性结合在凝固过程中的石墨化膨胀使得灰铁是铸造无缩松的发动机缸体的理想

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. 灰铁中的片状石墨对其机械性能有着十分重要的影响。片状石墨可以引导基体中的应力和裂纹沿着片状石墨快速传播。这导致了灰铁在失效时只具有很小的塑性。片状石墨在机加工时起到了润滑作用，使得灰铁很容易被加工。Introduction to Grey Cast Iron灰口铸铁的介绍Some examples of castings in Grey Iron一些灰铁的应用案例7/4/2022Developing people - creating value3Why Grey Iron? 为什么选择灰铁 low raw material cos

6、ts 原材料成本低 low production costs 生产成本低 high casting yield 成品率较高 good casting qualities 好的铸造质量 low gas pick-up 吸气较少 good as-cast properties 较好的毛胚件质量 easy machinable 易加工 good damping quality 较好的减震性能 good corrosion resistance 较好的防腐蚀性能 easily alloyed 易合金化 temperature stability 耐热性能7/4/2022Developing peopl

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

8、选择需要满足以下要求： required graphite shape and distribution 必要的石墨形态和分布 carbide-free structure 金相结构中无碳化物 required matrix 必要基体组织ElkemMechanical Properties 机械性能Tensile Strength:100 - 450 MPaElongation: 1%The mechanical properties and the microstructure of grey iron depends on: 机械性能和金相结构取决于以下：机械性能和金相结构取决于以下：Se

9、ction size 壁厚壁厚Chemical Composition化学成分化学成分Cooling Rate 冷去速率冷去速率Nucleation Potential 形核潜力形核潜力ElkemMicrostructure金相结构金相结构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 珠光体变粗糙珠光体变粗糙ElkemSe

10、ction Size As the section size increases the strength of grey cast irons falls.随着壁厚的增加灰铸铁的强度是在降低的。* Typical Microstructures of Cast Metals - IBFElkem* ASM Specialty HandbookFe - C Phase diagram 铁碳相图7/4/2022Developing people - creating value10Consists of a stable and a metastable system由稳定和亚稳定系统组成Sta

11、ble稳定物稳定物Metastable亚稳定物亚稳定物Carbon as graphite 碳以石墨形式存在Eutectic point: 4.3 wt% CTeutectic = 1153CTeutectoid =738CCarbon as Fe3C碳以渗碳体形式存在Eutectic point: 4.26 wt% CTeutectic = 1147CTeutectoid =723CEffect of Carbon in Grey Iron碳在灰铁中的作用7/4/2022Developing people - creating value11 reduces melting temperat

12、ure 降低熔点 improves castability 改善铸造性能 improves machinability 改善机加工性能 improves damping capacity 提高减震性 reduces need for feeding 降低缩水 increases thermal conductivity 提高热传导性能 decreases chilling tendency 减少白口倾向 reduces mechanical strength 降低机械强度 coarser graphite structure 粗化石墨结构Elkem improves graphitisatio

13、n 促进石墨化 reduces chill formation 减少白口的形成 promotes ferrite 促进铁素体 promotes stable solidification 促进稳定凝固 increasing content leads to coarser pearlite 提高粗糙珠光体的含量 ElkemPhosphorous 磷 found in all grey irons 所有灰铁中都含有 increases fluidity 提高流动性 forms low-melting phosphide in grey iron; steadite, Fe3P 在灰铁中形成低熔点

14、的磷化物 ；稳定的化合物Fe3P promotes shrinkage porosity at high levels 含量较高时促进疏松的产生 promotes melt penetration into mould at very low levels 较低的含量下可以促进铁水向铸型渗透 wear resistance increases with increasing P-content 提高磷的含量可以提高耐磨性能Carbon Equivalent 碳当量7/4/2022Developing people - creating value14Carbon equivalent form

15、ula: 碳当量的公式碳当量的公式Effect of Carbon Equivalent in Grey Iron碳当量在灰铁中的作用7/4/2022Developing people - creating value15Strength of grey iron will, ingeneral, decrease with increasingcarbon equivalent. While amountof graphite in the structureincreases.通常灰铁的强度将会随着碳当量的提高而降低；同时金相结构中的石墨也会增多。Elkem ties up S and O

16、 束缚硫和氧 reduces chill formation 减少白口的形成 promotes austenite 促进奥氏体 strong pearlite promoter 强烈的珠光体促进剂 weak carbide promoter 弱的碳化物促进剂Manganese 锰7/4/2022Developing people - creating value17ElkemSulphur 硫 found in all grey irons 所有灰铁中都有 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抗拉强度与硫含量的关系7/4/2022Developing people - creating value19Elkemwt% SHigh chilling tendencyLarge GrainsD-graphite过冷度大，晶粒较大，D型石墨High chilling tendencyFine G

18、rainsD-graphite过冷度大，晶粒细小，D型石墨Low chilling tendencyMedium Size GrainsA-graphite过冷度较小，晶粒尺寸适中，A型石墨Effect of Manganese and Sulphur锰和硫的作用7/4/2022Developing people - creating value21Equilibrium reaction MnS: Mn + S MnS反应平衡式Equilibrium reaction FeS: Fe + S FeS反应平衡式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.为了获得最大的强度， 要确保MnS的在凝固后期较低的温度下析出Too early MnS precipitation = 40 80MPa lower strengthMnS过早析出= 抗拉强度有40 80MPa的降低 Manganese & Sulphur a

20、s function of CE锰和硫与碳当量的关系7/4/2022Developing people - creating value22Elkem石墨片层的种类EInterdendritic SegregationPreferred orientatedDInterdendritic SegregationRandom orientatedBRosette GroupingRandom orientatedAInoculated IronsUniform distributedRandom orientatedCSuperimposed Flake SizeRandom orientate

21、dUndercooling , TC.EC.E = 4.26Flake Graphite Structures片层石墨结构7/4/2022Developing people - creating value24Grey Iron Solidification灰铁的凝固曲线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、元素的灰铁抗拉强度的影响7/4/2022Developing people - creating value27Chill Depth in Grey Iron灰铁中白口深度7/4/2022Developing people - creating value28The figure shows therelative chilling power ofdifferent elements图形展示的是不同元素的促进白口能力Effect of Vanadium钒的作用7/4/2022Developing people - creating value29Promotes formation of

23、eutectic iron carbide which can be removed by heat treatment 可以促进合金碳化物的形成，这类碳化物可以通过热处理消除。Inoculation can help reduce formation of eutectic carbides 孕育作用有助于减少共晶碳化物的形成Low chilling tendency in high carbon irons and in combination with Cu 高碳铸铁和合金铜的加入可以降低白口倾向Increases nucleation in grey iron giving finer

24、 and more uniform graphite structures 提高灰铁的形核率，从而可以细化石墨结构提高石墨结构的一致性Segregates with P giving hard particles with good sliding wear resistance 与磷一起偏析形成硬点，从而形成耐磨层Increases strength especially in high carbon grey iron 提高灰铁的强度，尤其是高碳灰铁More effective than Cr and Mo 比铬和钼的效率更高Factors affecting machinability影

25、响机加工的因素7/4/2022Developing people - creating value30Carbon content 碳含量 Eutectic cell count 共晶团数量 Volume of MnS particles MnS颗粒的数量 Mn level 锰的含量Sn level 锡的含量Control of Properties in Grey Iron灰铁性能的控制7/4/2022Developing people - creating value31Fracture and cracks are initiated by the flake graphite. 断裂和

26、裂纹是开始于石墨片。断裂和裂纹是开始于石墨片。Size and Distribution of the graphite in Grey Iron are thus the most important tool to control the mechanical properties.灰铁金相中的石墨的大小和分布是控制其铸件机械性能最重要的因素。灰铁金相中的石墨的大小和分布是控制其铸件机械性能最重要的因素。Calculated UTS developed by Bates et.al.抗拉强度的计算有贝茨等人发明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.系数是由回归分析法来计算获得的References 参考文献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