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第1/54页上一页下一页机电专业英语徐存善主编TextHeatTreatment&HotWorkingofMetalsUnit4金属的热处理和热加工第2/54页上一页下一页机电专业英语徐存善主编TextHeatTreatmentandWorkingEquipment第3/54页上一页下一页机电专业英语徐存善主编TextTestingBeforeClass：Whatthemeaningof“Shaping”?(radio)“shaping”是什么意思？(单选)：提交第4/54页上一页下一页机电专业英语徐存善主编TextHeatTreatment&HotWorkingofMetals第5/54页上一页下一页机电专业英语徐存善主编TextWecanalterthecharacteristicsofsteelinvariousways.Inthefirstplace,steelwhichcontainsverylittlecarbon,willbemilderthansteel,whichcontainsahigherpercentageofcarbon,uptothelimitofabout1.5％.Secondly,wecanheatthesteelaboveacertaincriticaltemperature,andthenallowittocoolatdifferentrates.Atthiscriticaltemperature,changesbegintotakeplaceinthemolecularstructureofthemeta1.Intheprocessknownasannealingweheatthesteelabovethecriticaltemperatureandpermitittocoolveryslowly.Thiscausesthemetaltobecomesofterthanbefore,andmucheasiertomachine.第6/54页上一页下一页机电专业英语徐存善主编TextAnnealinghasasecondadvantage.Ithelpstorelieveanyinternalstresseswhichexistinthemetal.Thesestressesareliabletooccurthroughhammeringorworkingthemetal,orthroughrapidcooling.Metalwhichwecausetocoolrapidlycontractsmorerapidlyontheoutsidethanontheinside.Thisproducesunequalcontraction,whichmaygiverisetodistortionorcracking.Metalwhichcoolsslowlyislessliabletohavetheseinternalstressesthanmetal,whichcoolsquickly.第7/54页上一页下一页机电专业英语徐存善主编TextOntheotherhand,wecanmakesteelharderbyrapidcooling.Weheatitupbeyondthecriticaltemperature,andthenquenchitinwaterorsomeotherliquid.Therapidtemperaturedropfixesthestructuralchangeinthesteel,whichoccurredatthecriticaltemperature,andmakesitveryhard.Butabarofthishardenedsteelismoreliabletofracturethannormalsteel.Wethereforeheatitagaintoatemperaturebelowthecriticaltemperature,andcoolitslowly.Thistreatmentiscalledtempering.Ithelpstorelievetheinternalstresses,andmakesthesteellessbrittlethanbefore.ThepropertiesoftemperedsteelenableUStouseitinthemanufactureoftools,whichneedafairlyhardsteel.Highcarbonsteelisharderthantemperedsteel,butitismuchmoredifficulttowork.第8/54页上一页下一页机电专业英语徐存善主编TextTheseheattreatmentstakeplaceduringthevariousshapingoperations.Wecanobtainbarsandsheetsofsteelbyrollingthemetalthroughhugerollsinarollingmill.Therollpressuresmustbemuchgreaterforcoldrollingthanforhotrolling,butcoldrollingenablestheoperatorstoproducerollsofgreataccuracyanduniformity,andwithabettersurfacefinish.Othershapingoperationsincludedrawingintowire,castinginmoulds,andforging.第9/54页上一页下一页机电专业英语徐存善主编TextThemechanicalworkingofmetalistheshapingofmetalineitheracoldorahotstatebysomemechanicalmeans.Thisdoesnotincludetheshapingofmetalsbymachiningorgrinding,inwhichprocessesmetalisactuallymachinedoff,nordoesitincludethecastingofmoltenmetalintosomeformbyuseofmolds.Inmechanicalworkingprocesses,themetalisshapedbypressure---acutelyforging,bending,squeezing,drawing,orshearingittoitsfinalshape.Intheseprocessesthemetalmaybeeithercoldorhotworked.Althoughnormalroomtemperaturesareordinarilyusedforcoldworkingofsteel,temperaturesuptothere-crystallizationrangearesometimesused.Hotworkingofmetalstakesplaceabovethere-crystallizationorwork—hardeningrange.第10/54页上一页下一页机电专业英语徐存善主编TextForsteel,re-crystallizationstartsaround650to700~C,althoughmosthotworkonsteelisdoneattemperaturesconsiderablyabovethisrange.Thereisnotendencyforhardeningbymechanicalworkuntilthelowerlimitofthere-crystallinerangeisreached.Somemetals,suchasleadandtin,havealowre-crystallinerangeandcanbehotworkedatroomtemperature,butmostcommercialmetalsrequiresomeheating.Alloycompositionhasagreatinfluenceupontheproperworkingrange,theusualresultbeingtoraisethere-crystallinerangetemperature.Thisrangemayalsobeincreasedbypriorcoldworking.第11/54页上一页下一页机电专业英语徐存善主编Textmolecular[mə'lekjələ]a.由分子组成的,分子的annealing[ə'ni:liŋ]n.(低温)退火，焖火，磨炼relieve[ri'li:v]v.解除，减轻，使不单调乏味liable['laiəbl]a.有责任的，有义务的，应受罚的，有…倾向的contract['kən'trækt]v.收缩，缩紧，感染，订约rise[raiz]v.上升，增强，起立，高耸shaping[ʃeipiŋ]n.成形，造型，塑造mechanical[mi'kænikəl]a.机械的，呆板的，力学的machining[mə'ʃi:niŋ]n.切肖，制造，机械加工grinding[ɡraindiŋ]n.磨肖力工machined[mə'ʃi:nd]a.机械加工的pressure['preʃə]n.压力，压强bend[bend]v.使弯曲，使屈服，使致力，使朝向bending['bendiŋ]n.弯曲(度)，扭曲(度)Newwordsandphrases第12/54页上一页下一页机电专业英语徐存善主编Textsqueeze[skwi:z]v.挤(压，干)，压榨，勒索，紧握prior['praiə]a.在先的，在前的，优先的distortion[dis'tɔ:ʃən]n.变形，扭曲，曲解，失真crack[kræk]v.&n．破裂，裂纹，打开beyond[bi'jɔnd]prep.超过……的范围,超过,越过quench[kwentʃ]v.&n．熄灭，[机]淬火,解渴；fix[fiks]v.&n.安装,修理，使固定，准备tempering['tempəriŋ]v.回火rolls[rəuls]n.薄板卷，泛指钢材draw[drɔ:]v.拉,画,吸引drawing['drɔ:iŋ]n.冲压成形shear[ʃiə]v.剪断，切断，修剪，剥夺recrystallization[ri:,kristəlai'zeiʃən]n.再结晶hardening['hɑ:dəniŋ]n.硬化，淬火,锻炼crystalline['kristəlain]a.结晶的凡．结晶体influence['influəns]n.影响，作用Newwordsandphrases第13/54页上一页下一页机电专业英语徐存善主编Textmechanicalmeans机械设备(工具)beknownas…称为……work—hardeningrange淬火温度区TechnicalTerms第14/54页上一页下一页机电专业英语徐存善主编Text1.Thisproducesunequalcontractions，whichmaygiverisetodistortionorcracking．译文：这将引起不均匀压缩，增加其出现畸变和破裂的可能。说明：此句为非限定性定语从句。“Which”引导的从句时对“unequalcontractions”的进一步解释说明。Languagepoints第15/54页上一页下一页机电专业英语徐存善主编Text2.Thisdoesnotincludetheshapingofmetalsbymachiningorgrinding，inwhichprocessesmetalisactuallymachinedoff，nordoesitincludethecastingo