近些年來(lái),汽車廠商在汽車上越來(lái)越多的使用熱成形件。熱成形件擁有很好的碰撞性能并能降低能耗。22MnB5熱成形QP鋼最有望達(dá)到此目的,其成分及多相組織特點(diǎn)能提高汽車服役性能�；诖�,對(duì)熱成形QP鋼的研發(fā)需要弄清其性能及生產(chǎn)技術(shù)。對(duì)此鋼種的制造工藝包括淬火配分熱處理,使其增加強(qiáng)度同時(shí)不降低鋼構(gòu)件的塑性。經(jīng)HS-QP處理后組織為馬氏體基體和富碳的殘余奧氏體。目前,研究者們致力于尋找生產(chǎn)低成本HS-QP鋼的最合適的生產(chǎn)參數(shù)。本研究使用Galerkin有限元方法分析淬火配分（QP）過(guò)程中碳從馬氏體擴(kuò)散到奧氏體的過(guò)程。不同于經(jīng)典的或復(fù)雜的擴(kuò)散場(chǎng)模型,本研究選用基于化學(xué)勢(shì)和成分的非線性控制方程。此模型被用于模擬1步法和2步法QP處理過(guò)程中的碳擴(kuò)散行為。模擬中設(shè)定奧氏體與馬氏體相界面不移動(dòng)。模擬結(jié)果與0.8 Si-22MnB5淬火配分處理后的用磁性法測(cè)的殘余奧氏體量（RA）的實(shí)驗(yàn)結(jié)果進(jìn)行了對(duì)比。模擬結(jié)果預(yù)測(cè)并揭示了碳和硅的含量對(duì)最終淬火組織中的殘余奧氏體含量的影響。 

【文章頁(yè)數(shù)】：55 頁(yè)

【學(xué)位級(jí)別】：碩士

【文章目錄】：
摘要
ABSTRACT
Nomenclature
CHAPTER 1: INTRODUCTION
    1.1 Motivation
    1.2 Aim and objectives of the current research
    1.3 Outline
CHAPTER 2: COMPREHENSIVE REVIEW OF LITERATURE
    2.1 Theory of Quenching & Partitioning in steels
        2.1.1 Martensite
        2.1.2 Retained austenite
        2.1.3 Governing equation
        2.1.4 Initial, boundary conditions and assumptions
CHAPTER 3: MODELLING IMPLEMENTATION
    3.1 Finite element method
    3.2 Finite difference time stepping
    3.3 Numerical simulation
        3.3.1 Finite element implementation
        3.3.2 The time stepping scheme
    3.4 Methodology to determine the Volume fraction of RA
        3.4.1 Simulation conditions
    3.5 Verification of the model
CHAPTER 4: EXPERIMENTAL WORK
    4.1 Microscopy
        4.1.1 Light Optical Microscopy (LOM)
        4.1.2 Scanning Electron Microscopy (SEM)
        4.1.3 Electron Backscatter Diffraction (EBSD)
    4.2 Magnetisation measurements
    4.3 X-Ray Diffraction (XRD)
    4.4 Microindentation hardness testing
    4.5 Tensile testing
    4.6 Microstructure characterization
    4.7 Mechanical properties
CHAPTER 5: RESULTS AND DISCUSSION
    5.1 Computational results
        5.1.1 Effect of Si content
        5.1.2 Effect of C content
    5.2 Model validation
        5.2.1 Comparison with Thermo-Calc (DICTRA)
        5.2.2 Comparison with experimental data
CHAPTER 6: CONCLUSIONS AND PERSPECTIVES
    6.1 Conclusions
    6.2 Further research
REFERENCES
ACKNOWLEDGEMENT
LIST OF PUBLICATIONS


【參考文獻(xiàn)】：
期刊論文
[1]Q＆P鋼配分過(guò)程中的組織演變[J]. 莊寶潼,唐荻,江海濤,米振莉.  北京科技大學(xué)學(xué)報(bào). 2012(11)



本文編號(hào)：3667541