Chapter 3 Metal Alloys and Heat Treatment金属合金及热处理

Contents3.1 Metal alloys 金属合金3.1.1 The Iron-Carbon System

铁-碳

3.1.2 The Iron-Iron Carbide Phase Diagram and the Development of Microstructures in Steels3.1.3 Effects of Alloying Elements in Iron

3.1.4 Cast Irons

3.2 Heat Treatment of Ferrous Alloys 铁合金热处理3.2.1 Time-temperature-transformation diagram

3.2.2 Hardenability of Ferrous Alloys3.2.3 Heat Treatment of Nonferrous Alloys and Stainless Steels 3.2.4 Annealing

3.1 Metal alloys3.1.1 The Iron-Carbon System 铁-碳

3.1.2 The Iron-Iron Carbide Phase Diagram and the Development of Microstructures in Steels 3.1.3 Effects of Alloying Elements in Iron 3.1.4 Cast Irons

3.1.1 The Iron-Carbon Systemcommercially pure iron to 0.008% C

contains up

steelscast iron

up to 2.11% Cup to 6.67% C

iron carbon equilibrium diagram

5 single-phase δ 7 two-phase

A3

graphiteAcm A1 共析 共晶Fe3C

α+γα

Cementite Fe3C

723 γ s C α p Fe3C

Ferrite

铁素体

α -FerriteBCC

from room temperature to 768 ℃

solubility of carbonMaximum solid solubility of 0.0218% C at temperature of 727 ℃

δ -FerriteBCC

above 1400℃ soft and ductile magnetic

Austenite 奥氏体 Cementite 渗碳体at 727 ℃ at temperatures between 910℃ and 1400℃ Maximum solid solubility of 2.11% C at temperature of 1148 ℃ Intermetallic compound Carbon content 6.67%

Ferrite α -iron Austenite γ -iron

BCC

solubility of carbon soft and ductile

FCC

Cementite Fe3C

very hard and brittle

3.1.2 The Iron-Iron Carbide Phase Diagram and the Development of Microstructures in Steels Proeutectoid ferrite 先共析铁素体 Proeutectoid cementite 先共析渗碳体Eutectoid 共析共析727 γs C α p Fe3C

Pearlite 珠光体

3.1.2 The Iron-Iron Carbide Phase Diagram and the Development of Microstructures in Steels

3.1.3 Effects of Alloying Elements in Iron

Shift the eutectoid temperature Shift the eutectoid composition Austenite former 奥氏体形成元素 Ni Ferrite stabilizer 铁素体 元素 Cr Mo

3.1.4 Cast Irons 铸 铁

Carbon Si

from 2.11% to 4.5% up to 3.5%

Gray cast iron, or gray iron 灰口铸铁 Ductile cast iron, nodular cast iron or spheroidal graphite cast iron 蠕墨铸铁 White cast iron 白口铸铁 Malleabable iron 可煅铸铁 Compacted graphite iron 球墨铸铁

3.1.4 Cast Irons

4.8 CAST IRON iron-carbon-silicon

alloys typically containing 2-4% C and 0.5-3% Si

Figure 4-18 Schematic drawings of the five types of cast iron: (a) gray iron, (b) white iron, (c) malleable iron, (d) ductile iron, and (e) compacted graphite iron

GRAY CAST IRON

contains small, interconnected graphite flakes low strength and ductility high-compressive strength good machiability good resistance to sliding wear good resistant to thermal fatigue good thermal

conductivity good vibration damping C+ α-ferrite C+ pearlite C+ martensite

灰口铸铁

ferritic gray iron pearlitic gray iron Martensitic gray iron

DUCTILE OR NODULAR CAST IRON球墨铸铁

contains spheroidal graphite particles.produced by treating liquid iron with a carbon

equivalent of near 4.3% with magnesium, whichcauses spheroidal graphite (called nodules).

excellent strength and ductility.stronger but not as tough as malleable irons.