焊条电弧焊奥氏体不锈钢焊缝微观组织对疲劳寿命和冲击韧性的影响
发布时间：2021-06-17 17:23
奥氏体不锈钢是应用最广泛的不锈钢,由于其优异的机械性能、耐腐蚀性和可加工性,几乎覆盖了不锈钢结构应用范围的60-70%。焊条电弧焊（SMAW）因其成本低、适应性强和便携性好,是不同AISI等级不锈钢系列最常用的焊接方法。巴基斯坦的主要工业中（特别是Heavy Mechanical Complex和Heavy Industries Taxila）,大部分的制造都依赖SMAW。这种焊接方法在巴基斯坦的其他行业（制糖厂、水泥厂等）的维修部门中也很常用。因此,本文作者采用SMAW方法制备奥氏体不锈钢接头,并对其焊接接头进行研究。在循环和冲击载荷的条件下,焊接接头易产生疲劳和韧性失效。不同焊接条件下的焊缝组织演变对于焊接接头的最终寿命产生很大的影响。本研究对于揭示显微组织演变对奥氏体不锈钢SMAW接头疲劳寿命和冲击韧性的影响机理有着重要的意义。多层多道焊缝中不同焊接区域的凝固和再凝固以及随后的相变对于焊接接头的力学性能起着至关重要的作用。本研究目的之一是研究多层多道焊对焊缝显微组织和接头力学性能的影响。使用金相显微镜测定了奥氏体中的δ铁素体相。不同于传统的依赖于一般铁素体数（F.N.）的方法,本...
【文章来源】：山东大学山东省 211工程院校 985工程院校 教育部直属院校
【文章页数】：208 页
【学位级别】：博士
【文章目录】：
Abstract
摘要
Chapter 1 Introduction
1.1 Significance of Research
1.2 Scientific Objectives
1.3 Research Methodology
Chapter 2 Literature Review
2.1 Welding zones generation
2.2 Overview of different welding techniques
2.3 Current status of Shielded Metal Arc Welding (SMAW) process
2.3.1 Consumable electrodes
2.3.2 Weld heat input
2.3.3 Chemical Composition
2.3.4 Influence of welding parameters
2.4 Current status of evolved microstructure in steel weldments
2.4.1 Grain nucleation
2.4.2 Solidification process
2.4.3 Microstructure and weldment properties
2.5 Current status of impact toughness of steel weldments
2.5.1 Impact toughness at weld interfaces
2.5.2 Chemical composition influence on Impact toughness
2.6 Current status of Fatigue life of steel weldments
2.6.1 Fatigue crack propagation rate FCPR in steel
2.6.2 Numerical Simulation of Fatigue
Chapter 3 Welding experiments and tensile testing
3.1 Selection of material
3.2 Chemical compositions of BM used to produces different specimens
3.2.1 Chemical composition of base metal
3.2.2 Mechanical properties of as-received base metal
3.2.3 Austenitization of as-received base metal
3.3 SMAW welding for different specimens
3.3.1 Welding conditions for weldments used to study impact toughness
3.3.2 Welding conditions for weldments used to study cooling rate effect on fatigue life
3.3.3 Welding conditions for weldments used to study chemical composition effect on fatigue life
3.3.4 Welding conditions for weldments used to study multipass welding effect on fatigue life
3.4 Procedure to measure the cooling rate of pre-heated welded plates
3.5 Tensile testing of weldments
3.5.1 Tensile test specimen preparation
3.5.2 Samples for hardness tests
3.6 Experimental procedure for different testing
3.6.1 Tensile test
3.6.2 Hardness test
3.7 Tensile tests results
3.7.1 Multipass weldments
3.7.2 Variation in cooling rate
3.7.3 Variation in chemical composition
3.7.4 Force-displacement curves
3.8 Hardness tests results
3.8.1 Multipass weldments
3.8.2 Effect of cooling rate
Chapter 4 Effect of microstructure on impact toughness
4.1 Impact toughness testing procedure
4.2 Impact toughness results
4.2.1 Effect of chemical composition and cooling rate
4.3 Quantitative Analysis of microstructure
4.3.1 Schaeffler Diagram: Estimation of delta ferrite percentage
4.3.2 Determination of localized δ-ferrites
4.4 Effect of microstructure on impact toughness
4.4.1 Impact energy based on δ/γ ratio
4.4.2 Effect of chemical composition on microstructure evolution, ferrite number and impact toughness
4.4.3 Effect of multipass welding on impact toughness
Chapter 5 Fatigue test specimens and results
5.1 Details of specimens used in fatigue test
5.1.1 Compact Tension (CT) specimen
5.1.2 Bend test specimen
5.1.3 Specimens for metallographic study
5.1.4 Specimens for fractographic study
5.2 Experimental procedure
5.2.1 Fatigue crack length measuring
5.2.2 Fatigue tests on CT specimen
5.2.3 Bend fatigue tests
5.2.4 Metallography of weldment
5.2.5 Fractography of Fracture Surfaces
5.3 Effect of Multipass welding on Fatigue Test
5.3.1 Microstructure evolution and its effect on FCPR in single pass welding
5.3.2 Microstructure evolution and its effect on FCPR in double pass welding
5.3.3 Microstructure evolution and its effect on FCPR in triple pass welding
5.4 Microstructural evolution due to variation in chemical compositions and its effect on fatigue life
5.4.1 Fatigue results of weldments W4, W5 and W6
5.4.2 Microstructural evolution of weldments W4, W5 and W6
5.4.3 Discussion on microstructural evolution effect on fatigue life of weldments W4, W5 and W6
5.5 Effect of cooling rate of pre-heated plates on microstructural evolution and fatigue life of weldments
Chapter 6 Numerical calculation of COD, SIF and analytical modeling of crack tip plasticity
6.1 Stress intensity factor calculation
6.1.1 Displacement method
6.1.2 Singular finite element method
6.1.3 Energy release rate criteria
6.2 Numerical model
6.2.1 J-Integral and COD as damage parameters
6.2.2 Finite element model (Based on J-integral singularity)
6.2.3 Working equations developing relationship between COD (δ_t) and stressintensity factor (K)
6.2.4 Assumption made while adopting this model
6.2.5 Limitations of the model
6.3 Numerical simulation procedure
6.3.1 Material
6.3.2 Boundary conditions
6.3.3 Meshing
6.3.4 J-Integral calculations
6.4 Simulation results
6.4.1 Stress intensity factor calculation by COD and J-integral
6.4.2 Effect of loading range on COD
6.5 Plastic zone size calculation
6.5.1 Plastic zone calculation through numerical values of J-integral
6.5.2 Plastic zone calculation through analytical modeling
Chapter 7 Conclusion and Future work
7.1 Conclusion
7.2 Future work
References
Acknowledgement
List of Publications
学位论文评阅及答辩情况表
【参考文献】：
期刊论文
[1]Welding of nickel free high nitrogen stainless steel: Microstructure and mechanical properties[J]. Raffi Mohammed,G.Madhusudhan Reddy,K.Srinivasa Rao. Defence Technology. 2017(02)
[2]Effect of welding processes on mechanical and microstructural characteristics of high strength low alloy naval grade steel joints[J]. S.RAGU NATHAN,V.BALASUBRAMANIAN,S.MALARVIZHI,A.G.RAO. Defence Technology. 2015(03)
[3]Numerical Simulation and Experimental Verification of CMOD in SENT Specimen: Application on FCGR of Welded Tool Steel[J]. Amir SULTAN,Riffat Asim PASHA,Mifrah ALI,Muhammad Zubair KHAN,Muhammad Afzal KHAN,Naeem Ullah DAR,Masood SHAH. Acta Metallurgica Sinica（English Letters）. 2013(01)
[4]Effect of Aging on the Toughness of Austenitic and Duplex Stainless Steel Weldments[J]. Omyma Hassan Ibrahim,Ibrahim Soliman Ibrahim,Tarek Ahmed Fouad Khalifa. Journal of Materials Science & Technology. 2010(09)
本文编号：3235606
【文章来源】：山东大学山东省 211工程院校 985工程院校 教育部直属院校
【文章页数】：208 页
【学位级别】：博士
【文章目录】：
Abstract
摘要
Chapter 1 Introduction
1.1 Significance of Research
1.2 Scientific Objectives
1.3 Research Methodology
Chapter 2 Literature Review
2.1 Welding zones generation
2.2 Overview of different welding techniques
2.3 Current status of Shielded Metal Arc Welding (SMAW) process
2.3.1 Consumable electrodes
2.3.2 Weld heat input
2.3.3 Chemical Composition
2.3.4 Influence of welding parameters
2.4 Current status of evolved microstructure in steel weldments
2.4.1 Grain nucleation
2.4.2 Solidification process
2.4.3 Microstructure and weldment properties
2.5 Current status of impact toughness of steel weldments
2.5.1 Impact toughness at weld interfaces
2.5.2 Chemical composition influence on Impact toughness
2.6 Current status of Fatigue life of steel weldments
2.6.1 Fatigue crack propagation rate FCPR in steel
2.6.2 Numerical Simulation of Fatigue
Chapter 3 Welding experiments and tensile testing
3.1 Selection of material
3.2 Chemical compositions of BM used to produces different specimens
3.2.1 Chemical composition of base metal
3.2.2 Mechanical properties of as-received base metal
3.2.3 Austenitization of as-received base metal
3.3 SMAW welding for different specimens
3.3.1 Welding conditions for weldments used to study impact toughness
3.3.2 Welding conditions for weldments used to study cooling rate effect on fatigue life
3.3.3 Welding conditions for weldments used to study chemical composition effect on fatigue life
3.3.4 Welding conditions for weldments used to study multipass welding effect on fatigue life
3.4 Procedure to measure the cooling rate of pre-heated welded plates
3.5 Tensile testing of weldments
3.5.1 Tensile test specimen preparation
3.5.2 Samples for hardness tests
3.6 Experimental procedure for different testing
3.6.1 Tensile test
3.6.2 Hardness test
3.7 Tensile tests results
3.7.1 Multipass weldments
3.7.2 Variation in cooling rate
3.7.3 Variation in chemical composition
3.7.4 Force-displacement curves
3.8 Hardness tests results
3.8.1 Multipass weldments
3.8.2 Effect of cooling rate
Chapter 4 Effect of microstructure on impact toughness
4.1 Impact toughness testing procedure
4.2 Impact toughness results
4.2.1 Effect of chemical composition and cooling rate
4.3 Quantitative Analysis of microstructure
4.3.1 Schaeffler Diagram: Estimation of delta ferrite percentage
4.3.2 Determination of localized δ-ferrites
4.4 Effect of microstructure on impact toughness
4.4.1 Impact energy based on δ/γ ratio
4.4.2 Effect of chemical composition on microstructure evolution, ferrite number and impact toughness
4.4.3 Effect of multipass welding on impact toughness
Chapter 5 Fatigue test specimens and results
5.1 Details of specimens used in fatigue test
5.1.1 Compact Tension (CT) specimen
5.1.2 Bend test specimen
5.1.3 Specimens for metallographic study
5.1.4 Specimens for fractographic study
5.2 Experimental procedure
5.2.1 Fatigue crack length measuring
5.2.2 Fatigue tests on CT specimen
5.2.3 Bend fatigue tests
5.2.4 Metallography of weldment
5.2.5 Fractography of Fracture Surfaces
5.3 Effect of Multipass welding on Fatigue Test
5.3.1 Microstructure evolution and its effect on FCPR in single pass welding
5.3.2 Microstructure evolution and its effect on FCPR in double pass welding
5.3.3 Microstructure evolution and its effect on FCPR in triple pass welding
5.4 Microstructural evolution due to variation in chemical compositions and its effect on fatigue life
5.4.1 Fatigue results of weldments W4, W5 and W6
5.4.2 Microstructural evolution of weldments W4, W5 and W6
5.4.3 Discussion on microstructural evolution effect on fatigue life of weldments W4, W5 and W6
5.5 Effect of cooling rate of pre-heated plates on microstructural evolution and fatigue life of weldments
Chapter 6 Numerical calculation of COD, SIF and analytical modeling of crack tip plasticity
6.1 Stress intensity factor calculation
6.1.1 Displacement method
6.1.2 Singular finite element method
6.1.3 Energy release rate criteria
6.2 Numerical model
6.2.1 J-Integral and COD as damage parameters
6.2.2 Finite element model (Based on J-integral singularity)
6.2.3 Working equations developing relationship between COD (δ_t) and stressintensity factor (K)
6.2.4 Assumption made while adopting this model
6.2.5 Limitations of the model
6.3 Numerical simulation procedure
6.3.1 Material
6.3.2 Boundary conditions
6.3.3 Meshing
6.3.4 J-Integral calculations
6.4 Simulation results
6.4.1 Stress intensity factor calculation by COD and J-integral
6.4.2 Effect of loading range on COD
6.5 Plastic zone size calculation
6.5.1 Plastic zone calculation through numerical values of J-integral
6.5.2 Plastic zone calculation through analytical modeling
Chapter 7 Conclusion and Future work
7.1 Conclusion
7.2 Future work
References
Acknowledgement
List of Publications
学位论文评阅及答辩情况表
【参考文献】：
期刊论文
[1]Welding of nickel free high nitrogen stainless steel: Microstructure and mechanical properties[J]. Raffi Mohammed,G.Madhusudhan Reddy,K.Srinivasa Rao. Defence Technology. 2017(02)
[2]Effect of welding processes on mechanical and microstructural characteristics of high strength low alloy naval grade steel joints[J]. S.RAGU NATHAN,V.BALASUBRAMANIAN,S.MALARVIZHI,A.G.RAO. Defence Technology. 2015(03)
[3]Numerical Simulation and Experimental Verification of CMOD in SENT Specimen: Application on FCGR of Welded Tool Steel[J]. Amir SULTAN,Riffat Asim PASHA,Mifrah ALI,Muhammad Zubair KHAN,Muhammad Afzal KHAN,Naeem Ullah DAR,Masood SHAH. Acta Metallurgica Sinica（English Letters）. 2013(01)
[4]Effect of Aging on the Toughness of Austenitic and Duplex Stainless Steel Weldments[J]. Omyma Hassan Ibrahim,Ibrahim Soliman Ibrahim,Tarek Ahmed Fouad Khalifa. Journal of Materials Science & Technology. 2010(09)
本文编号：3235606
本文链接：https://www.wllwen.com/kejilunwen/jiagonggongyi/3235606.html
