上游充通大率 SHANGHAI JIAO TONG UNIVERSITY Principles of Materials Processing Part Ill 全属材料热处理原理 Heat Treatment Principles of Metals Lecturer:Ke Chen 2017-05-18
Principles of Materials Processing Part III - 金属材料热处理原理 Heat Treatment Principles of Metals Lecturer: Ke Chen 2017-05-18
Outline for Chapter 10 上游充道大粤 SHANGHAI JIAO TONG UNIVERSITY Chapter 10:Shear Transformation 10.1 Martensite Transformations 10.1.1 Characteristics 10.1.2 Thermodynamics 10.1.3 Crystallographic Theory 10.1.4 Kinetics 10.2 Martensite Transformations in Steels 10.3 Bainite Transformations K.Chen 2
K. Chen Chapter 10: Shear Transformation 10.1 Martensite Transformations 10.1.1 Characteristics 10.1.2 Thermodynamics 10.1.3 Crystallographic Theory 10.1.4 Kinetics 10.2 Martensite Transformations in Steels 10.3 Bainite Transformations Outline for Chapter 10 2
Intro 上游充道大粤 SHANGHAI JIAO TONG UNIVERSITY Heat treatment process for hardening of steel? √Quenching! Rapid enough from the austenitic phase field> insufficient time for diffusion-controlled decomposition processes to occur Transform to martensite!>Diffusionless transformation! NG UNN Where will be the C atoms? > Solid solution of C in fcc y-Fe>Solid solution of C in a-Fe (Supersaturated!) K.Chen 3
K. Chen Heat treatment process for hardening of steel? Quenching! Rapid enough from the austenitic phase field insufficient time for diffusion-controlled decomposition processes to occur Transform to martensite! Diffusionless transformation! Where will be the C atoms? Solid solution of C in fcc γ-Fe Solid solution of C in α-Fe (Supersaturated!) 3 Intro
上游气通大粤 SHANGHAI JIAO TONG UNIVERSITY Shear/Displacive Transformation: In this transformation,atoms change position(lattice reconstruction)in an ordered military manner,by a shear mechanism. Military: The regimented/coordinated manner in which atoms change position In contrast to diffusion-controlled transformations which are termed civilian Two types of shear transformations: Diffusionless:individual atomic movements less than one interatomic spacing >Martensite transformation Diffusional:Bainite transformation (Fe:shear;C:diffuse) K.Chen 4
K. Chen Shear/Displacive Transformation: In this transformation, atoms change position (lattice reconstruction) in an ordered military manner, by a shear mechanism. Military: The regimented/coordinated manner in which atoms change position In contrast to diffusion-controlled transformations which are termed civilian Two types of shear transformations: Diffusionless: individual atomic movements less than one interatomic spacing Martensite transformation Diffusional: Bainite transformation (Fe: shear; C: diffuse) 4
上游充通大粤 Martensite transformation SHANGHAI JIAO TONG UNIVERSITY Any diffusionless transformation in which from start to completion of the transformation individual atomic movements are less than one interatomic spacing ■Only in steel? 层月 In principle,all metals and alloys,even ceramics can be made to undergo this transformation Complex process;the mechanism is not properly understood Growth of martensite with increasing cooling below M. K.Chen 5
K. Chen Martensite transformation Any diffusionless transformation in which from start to completion of the transformation individual atomic movements are less than one interatomic spacing Only in steel? • In principle, all metals and alloys, even ceramics can be made to undergo this transformation Complex process; the mechanism is not properly understood 5 Growth of martensite with increasing cooling below Ms