材料科學(xué)基礎(chǔ)英文版課件_(4)(1)-全文預(yù)覽
【正文】 mperature can be predicted. 2022/2/15 2022/2/15 Outline (1) ? Equilibrium grain boundary segregation – Segregation of phosphorus and molybdenum ? Introduction, experiment, results and discussion, summary – Relationship between phosphorus boundary concentration and ductiletobrittle transition temperature (DBTT) ? Introduction, experiment, results and discussion, summary – Effect of phosphorus grain boundary segregation on intergranular fracture ? Introduction, experiment, results and discussion, summary 2022/2/15 Introduction (1) 2022/2/15 Introduction (2) ? Does low temperature facilitate intergranular fracture? ? Christien’s results in 174 PH martensitic stainless steel: – The specimen experienced ductile fracture, intergranular fracture, cleavage fracture when impactfractured from 300oC to 196oC. (Christien, 2022) 2022/2/15 Experiment Pretreated samples Experimental procedure Aging at different temperatures for different times and quenching Boundary concentration Fraction of Intergranular fracture SEM Impact test Machining DBTT Hardness test Metallographic analysis Hardness Microstructure, Grain size AES 2022/2/15 Results and discussion (1) 2 0 0 1 6 0 1 2 0 8 0 4 0 0 40020406080100 % intergranular fractureI m pa ct t emperat ure (oC)480oC 1200h 650oC 2h Intergranular fracture is not observed at all test temperatures 2022/2/15 Results and discussion (2) Stress Temperature O Intergranular fracture stress Cleavage fracture stress Yield strength Tc Ta Tb 2022/2/15 Summary ? Phosphorus grain boundary segregation facilitates intergranular fracture. ? The specimen experienced ductile fracture, intergranular fracture, and cleavage fracture when impactfractured from high to low temperature. 2022/2/15 2022/2/15 Outline ? Stressinduced nonequilibrium grain boundary segregation – Introduction, experiment, results and discussion, summary ? Conclusions 2022/2/15 Introduction (1) 343 MPa (Shinoda and Nakamura, 1981) (Misra, 1996) 2022/2/15 Introduction (2) ? Diffusional creep Grain interior Grain boundary Solute atoms σ σ 2022/2/15 Introduction (3) σ σ ? Xu’s model Grain interior Grain boundary Solute atoms Vacancy Vacancysolute plex V ac an c y So l ute Com ple x??2022/2/15 Experiment (1) Creep test Pretreated samples Experimental procedure Ageing without stress for 1000 h and quenching Creep curves Stress ageing Machining Segregation kiics Tensile test Yield strength AES analysis 2022/2/15 920℃ 50min Time 980℃ 30min 650℃ 2h (Normalization) (Austeniz
教學(xué)課件相關(guān)推薦
鄂ICP備17016276號(hào)-1