工程材料_engineering materials

工程材料engineering materials

金属材料结构

晶体crystal

体心立方晶格body-centered cubic lattice (B.C. C.)

Alpha-Fe

面心立方晶格face-centred cubic lattice (F.C.C.)

gamma-Fe

密排六方晶格close-packed hexagonal lattice (C.P.H.)

Mg

晶体缺陷crystal defect

点缺陷point defect

增强内能，提高稳定性improve internal energy、stability

空位vacancy

置换displace

间隙gap

线缺陷line defect

强度高、硬度大、导电性下降higher dislocation ，higher strength、stiffness，lower conductivity

螺旋位错helical dislocation

仞型位错edge dislocation

面缺陷plane defect

more crystal boundary=smaller the grain is=塑性好 good plastic

晶界crystal boundary

亚晶界sub-boundary

金属塑性变形与再结晶plastic deformation and recrystallization

冷变形 cold deformation加工硬化work hardening

随着变形发生、金属强度、硬度提高，塑形、韧性降低with the distortion，the strength and stiffness improved，plasticity and toughness reduce

再结晶recrystallization

回复recovery

加热至0.3T熔，内应力消除，加工硬化未消除heat until 0.3 melting temperature，innerstress has been eliminated，but work hardening not

加热至0.4T熔，恢复至原来样子heated until 0.4 melting temperature，structure has been recovery

热变形 warm deformationhigher than recrystallization‘s temperature

使金属性能具有明显方向性let performance have obvious directivity

热轧、锻造hot rolling、forging

铁碳合金iron-carbon alloy

匀晶相图uniform grain phase diagram

共晶相图eutectic phase diagram

共析相图eutectoid phase diagram

铁碳相图iron-carbon phase diagram

碳素钢carbon steel

碳素结构钢carbon structural steel

0.06～0.38%

content of P、S is highers（hot shortness）p（black shortness）

优质碳素结构钢improved carbon structural steel

0.08～0.65%

碳素工具钢carbon tool steel

0.65～1.35%

硬度高、淬透性低high hardness 、low quenching degree

铸造碳钢carbon cast steel

铸铁casting iron

灰铸铁

灰铸铁，抗拉强度低，塑性低、减震性好low tensile strength 、low plastic ability、good damping ability

珠光体基体灰铸铁 强度高Pearlite-based gray cast iron

珠光体-铁素体基体灰铸铁pearlite-ferrite grey iron

铁素体基体灰铸铁ferrite grey iron

球墨铸铁spheroidal graphite cast iron

做阀体valve body

有一定塑性，疲劳强度高have plasticity，high fatigue strength

铁水中加入球化剂 Mgadd nodulizer in steel water

钢的热处理heat treatment of steel

热处理都要加热至Ac3、Acm线以上thermal treatment should heat the iron higher than Ac3、Acm全变为奥氏体all turn into austenite 过热度越大，晶粒越小 higher the superheat， the smaller grain is

冷却cooling

等温转变isothermal transformation curve

550度孕育期最短Transition time

P、S、TT 晶体小，力学性能好P晶体大，硬

马氏体：0.25为低碳马氏体，板条状马氏体 lath martensite 高强度、高硬度、塑性好 1.0为高碳马氏体，针状马氏体， acicular martensite 塑性不好

亚共析：M线上移

连续转变continuous cooling transformation(CCT) curve

又下偏移

通常用等温转变代替

钢的热处理工艺Heat treatment process

退火annealing

完全退火full annealing

亚共析钢hypoeutectoid steel热加工后降低硬度，加热至Ac3上30～50，缓慢冷却after hot working reducing hardness，slowly cooling

等温退火constant temperature annealing

快速冷却至A1下珠光体温度，等温至转换完全，快速降温，提高速度quickly cooling to temperature of pearlite，until transformation finished，then cooling to room temperature

球化退火spheroidizing annealing

过共析钢hypereutectoid steel得到球状渗碳体，降低硬度，提高塑性，改善切削性能，Acm上20～30get spherical cementite，reduce hardness，improve machinability

再结晶退火recrystallization annealing

去除加工硬化，加热至0.4Tmeliminate work hardness

去应力退火stress relief annealing

去除内应力，加热至0.3Tmeliminate inner force

正火normalizing

空冷 cooling in the air获得索氏体，中碳钢作为最终热处理，提高力学性能get Sorbite ，finial thermal process for medium carbon steel，improve mechanical property打碎网状渗碳体break secondary network cementite

淬火quenching／hardening

加热到Ac3、Ac1以上，以一定速度冷却，获得B或M，以提高硬度、耐磨性cooling with certain speed to require B、martensite，improve hardness、abrasion performance

单液淬火single stage quenching

碳钢用水，合金用油carbon steel use wateralloy use oil内应力大 inner stress is big

双液淬火double stage quenching

为了减少内应力to reduce inner stress

分级淬火 interrupted quenching

在贝氏体温度停留，待温度均匀后继续降温，减少内应力when temperature is uniform then continue cooling to reduce inner stress

等温淬火constant temperature quenching

产生贝氏体

回火tempering

淬火后，马氏体存在较大应力、不稳定，脆性大，回火提高塑性，降低内应力，获得回火马氏体、回火屈氏体、回火索氏体after quenching，martensite have large inner stress and it's unstable，fragility is bigtempering improve plasticity、reduce inner stress，get tempered martensite、troostite、sorbite

车刀、量具 淬火+低温回火turing tool、measure tool／quenching +low temperature tempering弹簧 淬火+中温回火spring／quenching + middle temperature tempering轴、齿轮 淬火+高温回火shaft gear／quenching and high temperature tempering

表面淬火+低温回火surface quenching

为了提高表面硬度、强度、耐磨性to improve surface‘s strength and hardness、abrasion performance

感应加热eddy-current heating

频率越低，深度越大，高频为200KHz，0.5～2mm

火焰加热flame heating

表面化学热处理Surface chemical heat treatment

渗碳carburization

低碳钢

渗氮nitridation

热处理影响因素thermal treatment‘s factor

脆硬性hardenability

淬透性quenching degree