งานนำเสนอเรื่อง: "Chapter 4 Equilibrium Phase Diagrams and The Iron-Carbon system"— ใบสำเนางานนำเสนอ:
1Chapter 4 Equilibrium Phase Diagrams and The Iron-Carbon system Kanchala Sudtachat
2PhasesA phases is simply a form of material possessing a characteristic structure and properties.A phases has a definable structure, a uniform and identifiable chemistry.And distinct boundaries or interfaces that separate it from other different phases.
3Equilibrium Phase Diagrams is a graphic mapping of the natural tendencies of a material or a material system.There are three primary variable to be considered: temperature, pressure and composition
4Pressure-Temperature (P-T) diagram Diagram maps the stable form of water for various conditions.The region boundaries denote the melting and boiling point.It has important to make freeze drying.
5Temperature-Composition (T-C) diagram At atmospheric pressure and variations more likely to occur in temperature and composition.
6Cooling CurvesThe equilibrium phase diagram is collective presentation of cooling-curve data for an entire range of alloy compositions
7Solubility StudiesCan ice retain some salt in a single phase solid solution?Can solid salt hold some water and remain a single-phase?How much, and does the amount vary with temperature?We called solubility limit.
9Complete solubility in both liquid and solid states Liquidus line – เหนือเส้นนี้เป็นสารละลายในเฟสเหลวSolidus line – ด้านล่างของเส้นนี้เป็นสารละลายในเฟสของแข็งFreezing range: Between the liquidus and Solidus
10Partial solid solubility At the point of max solubility, 183oCLead can hold up to 19.2 wt%If T is decreased, the amount of solute that can be held in solution decreased.
16Iron-Carbon Equilibrium Diagram EutectoidEutecticPeritecticSteel, compose primarily of iron and carbon
17Iron-Carbon Equilibrium Diagram a body-cubic solid that is stable down to 1394oC, know as delta-ferrite.From 1394oC to 912oC (FCC), know as austenite.Alpha-ferrite (BCC) below 912oC
18Iron-Carbon Equilibrium Diagram At 1495oC, a peritectic reaction.At 1148oC, a eutectic with composition of 4.3% carbon2.11% carbon are classified by the general term cast ironAt 727oC, a eutectoid with composition of 0.77% carbon. Alloy with less than 2.11% carbon, know as steels
19Steels and the simplified iron-carbon diagram The key transition will be the conversion of austenite to the two-phase ferrite plus carbide mixture.
20Steels and the simplified iron-carbon diagram Pearlite (ferrite + cementite) Eutectoid composition (0.77%C)Austenite0.77%C; FCC Ferrite0.02%C; BCC + Cementite6.67%C
21Steels and the simplified iron-carbon diagram Hypoeutectoid steels (ferrite + pearlite) less than eutectoid compositionHypereutectoid steels (cementile + pearlite) greater than eutectoid composition
22Cast Irons อาจทำให้เกิด Graphite หรือ Cementite Iron-carbon alloys with more than 2.11%Wide variety properties.Contains iron, carbon, silicon, manganese, sulfur, phosphorousอาจทำให้เกิด Graphite หรือ CementiteGraphite form by slow coolingCementite form by fast cooling