关于低碳钢屈服延伸现象的研究现状
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摘要
低碳钢因其优良的塑性常被用于家电和汽车面板。在低碳钢工业生产中,节能、高效的连续退火工艺取代能耗高、效率低的罩式退火工艺后,低碳钢在使用过程中遇到了严重的质量问题——因时效而产生的屈服延伸现象。屈服延伸现象是指低碳钢经人工时效或长时间的自然时效后,钢板表面在变形过程产生不均匀塑性变形而出现褶皱的现象,又称吕德斯带,该现象对钢板的表面质量和性能造成严重的损害。屈服延伸现象受碳氮含量、晶粒尺寸、合金元素、工艺参数和应变等因素影响,在明确屈服延伸现象发生的微观机理前提下,选择适当的成分和工艺参数能够在一定程度上减少或消除屈服延伸现象。关于屈服延伸的出现一般认为与晶体内间隙原子(碳原子和氮原子)的偏聚有关:经典理论认为屈服延伸现象是由于间隙原子在晶体内位错周围偏聚(也称柯氏气团),柯氏气团对位错的反复钉扎和解钉扎过程导致了屈服延伸;但是部分学者认为屈服延伸现象是偏聚在晶界上的间隙原子对位错运动的反复钉扎和解钉扎引起;也有部分学者认为是两者共同作用的结果。因此,关于出现屈服延伸现象的原因的争议在于间隙原子偏聚的位置,即偏聚于位错周围形成柯氏气团或偏聚于晶界。为了有效消除屈服延伸现象带来的危害,近些年来除研究屈服延伸现象发生的微观机理,即探究屈服延伸发生过程间隙原子偏聚的位置外,研究者们也探索了屈服延伸现象发生的微观力学行为。针对屈服延伸现象的研究引入了内耗、三维原子探针、聚焦离子束等先进技术手段,可实现对基体、晶界和位错等位置上各元素含量的表征,为进一步明确屈服延伸现象产生机制奠定基础;纳米压痕和扫描电镜原位拉伸等技术可用来研究屈服延伸发生过程的微观形变机理。其中采用纳米压痕技术研究屈服延伸现象时所得载荷-位移曲线上出现的晶界pop-in现象已被证实与屈服延伸现象存在联系,否定了较早认为初始pop-in现象与屈服延伸现象存在联系的观点。本文对屈服延伸的影响因素、机理和研究方法等方面进行了系统的综述,以期为低碳钢连续退火工业生产工艺中消除屈服延伸现象提供一定的线索,在降低生产成本、提高低碳钢表面成形质量方面有重要意义。
Low carbon steel is usually used for household appliance and automotive panel steel thanks to its excellent plasticity.Nevertheless,low carbon steel has encountered serious quality problem,namely the yield point elongation(YPE)phenomenon,in its application,since the high-energy consumption and low-efficiency batch annealing process was replaced by energy-saving and efficient continuous annealing process in low carbon steel industrial production.YPE refers to the wrinkles caused by uneven plastic deformation on the surface of the steel plate after artificial aging or long time natural aging,also known as the Lüders band,which causes severe damage to the surface quality and performance of the steel plate.Factors like carbon and nitrogen content,grain size,alloying elements,process parameters and strain can affect the formation of YPE.The phenomenon of YPE could be reduced or eliminated by choosing appropriate composition and process parameters on condition that the microscopic mechanism of YPE is clear and definite.It is generally recognized that YPE is usually associated with the segregation of interstitial atoms(carbon and nitrogen atoms).Classical theory suggests that YPE is attributed to the segregation of interstitial atoms around the dislocations within the crystal(also known as Cottrell atmosphere).The pinning and unpinning of dislocations caused by the Cottrell atmosphere lead to the YPE phenomenon.While some researchers believe that YPE is related to the segregation of interstitial atoms on the grain boundaries.The other researchers hold the opinion that YPE is resulted from the both.Therefore,the dispute in formation mechanism for YPE lies in the segregation position of interstitial atoms.In order to effectively eliminate the damage caused by the phenomenon of YPE,in recent years,some researchers have studied the distribution of interstitial atoms and the micro-mechanism of YPE,aiming to explore the segregation position of interstitial atoms during the occurrence of YPE.Besides,researchers have also studied the micro-mechanical behavior of YPE.Advanced methods including internal friction,3 DAP and focused ion beam(FIB)have been introduced into the research of micro-mechanism of YPE,and realized the characterization of the content of elements in matrix,grain boundary and dislocations,which contribute to the verification of the formation mechanism for YPE.Nano-indentation techniques and scanning electron microscopy in-situ tensile techniques can be adopted to explore the micro-deformation mechanism of the YPE.It is worth mentioning that the phenomenon of pop-in at the grain boundary in the load-displacement curve obtained through nano-indentation technique has been confirmed to be related to YPE,which negates the earlier view that the initial pop-in phenomenon is related to YPE.In this article,the factors affect YPE and the micro-mechanism of YPE in low carbon steel are summarized.Meanwhile,several research techniques applied in YPE study are introduced in detail.We hope that this review can provide some clues for the eliminate of YPE in industrial production of low carbon steel,which is of great significance in reducing production cost and improving the surface quality of mild carbon steel.
Low carbon steel is usually used for household appliance and automotive panel steel thanks to its excellent plasticity.Nevertheless,low carbon steel has encountered serious quality problem,namely the yield point elongation(YPE)phenomenon,in its application,since the high-energy consumption and low-efficiency batch annealing process was replaced by energy-saving and efficient continuous annealing process in low carbon steel industrial production.YPE refers to the wrinkles caused by uneven plastic deformation on the surface of the steel plate after artificial aging or long time natural aging,also known as the Lüders band,which causes severe damage to the surface quality and performance of the steel plate.Factors like carbon and nitrogen content,grain size,alloying elements,process parameters and strain can affect the formation of YPE.The phenomenon of YPE could be reduced or eliminated by choosing appropriate composition and process parameters on condition that the microscopic mechanism of YPE is clear and definite.It is generally recognized that YPE is usually associated with the segregation of interstitial atoms(carbon and nitrogen atoms).Classical theory suggests that YPE is attributed to the segregation of interstitial atoms around the dislocations within the crystal(also known as Cottrell atmosphere).The pinning and unpinning of dislocations caused by the Cottrell atmosphere lead to the YPE phenomenon.While some researchers believe that YPE is related to the segregation of interstitial atoms on the grain boundaries.The other researchers hold the opinion that YPE is resulted from the both.Therefore,the dispute in formation mechanism for YPE lies in the segregation position of interstitial atoms.In order to effectively eliminate the damage caused by the phenomenon of YPE,in recent years,some researchers have studied the distribution of interstitial atoms and the micro-mechanism of YPE,aiming to explore the segregation position of interstitial atoms during the occurrence of YPE.Besides,researchers have also studied the micro-mechanical behavior of YPE.Advanced methods including internal friction,3 DAP and focused ion beam(FIB)have been introduced into the research of micro-mechanism of YPE,and realized the characterization of the content of elements in matrix,grain boundary and dislocations,which contribute to the verification of the formation mechanism for YPE.Nano-indentation techniques and scanning electron microscopy in-situ tensile techniques can be adopted to explore the micro-deformation mechanism of the YPE.It is worth mentioning that the phenomenon of pop-in at the grain boundary in the load-displacement curve obtained through nano-indentation technique has been confirmed to be related to YPE,which negates the earlier view that the initial pop-in phenomenon is related to YPE.In this article,the factors affect YPE and the micro-mechanism of YPE in low carbon steel are summarized.Meanwhile,several research techniques applied in YPE study are introduced in detail.We hope that this review can provide some clues for the eliminate of YPE in industrial production of low carbon steel,which is of great significance in reducing production cost and improving the surface quality of mild carbon steel.
引文
1 Baker L J,Daniel S R,Paker J D.Metallurgy and processing of ultralow bake hardening steels[J].Material Science and Technology,2013,18(4):355.
2 Mangonon P L,Bramfitt B L.The metallurgy of continuous-annealed draw-quality sheet steel[J].JOM,2013,35(5):27.
3 MouldP P.Overview of continuous-annealing technology for steel sheet products[J].JOM,2013,34(5):18.
4 Lüders W.ber dieusserung der elasticitt an stahlartigen eisenstaben und stahlstben,undüber eine beim biegen solcher stbe beobachtete molecularbewegung[J].Dinglers Polytechnische Journal,1860,155:8.
5 Song R,Ponge D,Raabe D.Improvement of the work hardening rate of ultrafine grained steels through second phase particles[J].Scripta Materialia,2005,52(11):1075.
6 Tsuchida N,Tomota Y,Nagai K,et al.A simple relationship between Lüders elongation and work-hardening rate at lower yield stress[J].Scripta Materialia,2006,54(1):57.
7 Kim S,Hong M H,Chin K G,et al.Influence of carbon on mechanical properties of Cu bearing extra low carbon steel sheets[J].Steel Research International,2011,82(6):734.
8 Charit I,Seok C S,Murty K L.Synergistic effects of interstitial impurities and radiation defects on mechanical characteristics of ferritic steels[J].Journal of Nuclear Materials,2007,361(2):262.
9 Hall E O.The deformation of low-carbon steel in the blue-brittle range[J].Journal of the Iron and Steel Institute,1952,170:331.
10 Morrison W B.The effect of grain size on the stress-strain relationship in low-carbon steel[J].Translation ASM,1966,59(4):824.
11 Butler J F.Lüders front propagation in low carbon steels[J].Journal of the Mechanics and Physics of Solids,1962,10(4):313.
12 Johnson D H,Edwards M R,Chard-Tuckey P.Microstructure effects on the magnitude of Lüders strains in a low alloy steel[J].Materials Science and Engnieering:A,2015,625:36.
13 Clark D S,Russell T L,Wood D S.The influence of grain size on the yield phenomenon in steel[J].Acta Metallurgica,1961,9(12):1054.
14 Massardier V,Merlin J.Analysis of the parameters influencing the quench-aging behavior of ultra-low-carbon steels[J].Metallurgical and Materials Transactions A,2009,40(5):1100.
15 Hsun H.Effect of solutes on the Lüders strain in low-carbon sheet steels[J].Metallurgical and Materials Transactions A,1983,14(1):85.
16 Turkdogan E T,Barisic B.Causes and effects of nitride and carbonitride precipitation during continuous casting[J].Iron Steelmaker,1989,16(5):61.
17 Takahashi J,Kawakami K,Ushioda K,et al.Quantitative analysis of grain boundaries in carbon-and nitrogen-added ferritic steels by atom probe tomography[J].Scripta Materialia,2012,66(5):201.
18 Wilson D V.Role of grain boundaries in the discontinuous yielding of low-carbon steels[J].Metal Science Journal,1967,1(1):40.
19 Cottrell A H,Billy B A.Dislocation theory of yielding and strain aging of iron[J].Proceedings of the Physical Society:Section A,1948,62(1):49.
20 Nobuo N,Fujihara M,Tsuchiyama T,et al.Effect of phosphorus on Hall-Petch coefficient in ferritic steel[J].ISIJ international,2011,51(7):1169.
21 Morrison W B,Leslie W C.The yield stress-grain size relation in iron substitutional alloys[J].Metallurgical Transactions,1973,4:379.
22 Akama D,Nakada N,Tsuchiyama T,et al.Discontinuous yielding induced by the addition of nickel to interstitial-free steel[J].Scripta Materialia,2014,82(3):13.
23 Chang S K,Kwak J H.Effect of manganese on aging in low carbon sheet steels[J].ISIJ International,2007,37(1):74.
24 Souza T O D,Buono V T L.Optimization of the strain aging resistance in aluminum killed steels produced by continuous annealing[J].Materials Science and Engineering A,2003,354(1):212.
25 Mizui N,Okamoto A.Recrystallization texture control in ultra-low carbon Ti-added sheet steels containing Mn and P[J].ISIJ International,1990,76(3):422.
26 Pereloma E V,Bata V,Scott R I,et al.Effect of Cr and Mo on strain ageing behavior of low carbon steel[J].Materials Science and Engineering A,2010,527(10):2538.
27 Riccardo R,Carlo M,Roberto V.Effect of coiling temperature on formability and mechanical properties of mild low carbon and HSLA steels processed by thin slab casting and direct rolling[J].ISIJ International,2007,47(8):1204.
28 Lips K,Yang X H,Mols K.The effect of coiling temperature and continuous annealing on the properties of bake hardenable IF steels[J].Steel Research,1996,67(9):357.
29 Baird J D.The effects of strain-ageing due to interstitial solutes on the mechanical properties of metals[J].International Materials Reviews,1971,16(1):1.
30 Merin J,Merle P,Garnier S,et al.Experimental determination of the carbon solubility limit in ferritic steels[J].Metallurgical and Materials Transactions A,2004,35(6):1655.
31 Richard M D,Drexler E S,Fekete J R.Aging-induced anisotropy of mechanical properties in steel products:Implications for the measurement of engineering properties[J].Materials Science and Engineering A,2011,529:184.
32 Okamoto A,Koichi T.A mechanism of paint bake-hardening[J].Sumitomo Metals,1989,41:321.
33 Cui Y,Hu Y P,Wang R Z,et al.Effect of temper rolling and natural aging on properties of ultra-low carbon bake-hardening steel[J].Special Steel,2010,31(4):49(in Chinese).崔岩,胡吟萍,王瑞珍等.平整和自然时效对超低碳烘烤硬化钢板性能的影响[J].特殊钢,2010,31(4):49.
34 Hui Y J,Yu Y,Wang L,et al.Strain-induced precipitation in Ti micro-alloyed interstitial-free steel[J].Journal of Iron and Steel Research,International,2016,23(4):385.
35 Soenen B,De A K,Vandeputte S,et al.Competition between grain boundary segregation and Cottrell atmosphere formation during static strain aging in ultra-low carbon bake hardening steels[J].Acta Materialia,2004,52(12):3483.
36 De A K,Vandeputte S,Cooman B C D.Static strain aging behavior of ultra low carbon bake hardening steel[J].Scripta Materialia,1999,41(8):831.
37 Hanai S,Takmoto N.Effect of grain size and solid solution strengthening elements on the bake hardenability of low carbon aluminumkilled steel[J].ISIJ International,1984,24(1):17.
38 Bailon J P,Dorlot J M.Thermal-treatment effects on the Hall-Petch relation for armco-iron[J].Acta Materialia,1971,19:71.
39 Takaki S,et al.Effect of grain boundary segregation of interstitial elements on Hall-Petch coefficient in steels[J].Materials Transactions,2014,55(1):28.
40 Ono Y,et al.Roles of solute C and grain boundary in strain aging behaviour of fine-grained ultra-low carbon steel sheets[J].ISIJ International,2017,57(7):1273.
41 Zhao J Z,De A K,De C B C.A model for the Cottrell atmosphere formation during aging of ultra-low carbon bake hardening steels[J].ISIJ International,2000,40(7):725.
42 Zhou B X,Liu W Q.The appication of 3DAP in the study of materials science[J].Materials Science and Technology,2007,15(3):405(in Chinese).周邦新,刘文庆.三维原子探针及其在材料科学研究中的应用[J].材料科学与工艺,2007,15(3):405.
43 Chang L,et al.Fundamentals of aging and tempering in bainitic and martensitic steel products[J].Iron and Steel Society,1992,20:215.
44 Wilde J,Cerezo A,Smith G D W.Three-dimensional atomic-scale mapping of a cottrell atmosphere around a dislocation in iron[J].Scripta Materialia,2000,43(1):39.
45 Seto K,Larson D J,Warren P J,et al.Grain boundary segregation in boron added interstitial free steels studied by 3-dimensional atom probe[J].Scripta Materialia,1999,40(9):1029.
46 Fang Q F,Wang X P,Wu X B,et al.The basic principles and applications of internal friction and mechanical spectroscopy[J].Physics,2011,12(40):786(in Chinese).方前锋,王先平,吴学邦,等.内耗与力学谱基本原理及其应用[J].物理,2011,12(40):786.
47 Sekido K,Ohmura T,Hara T,et al.Effect of dislocation density on the initiation of plastic deformation on Fe-C steels[J].Materials Transactions,2012,53(5):907.
48 Wang M G,Ngan A H W.Indentation strain burst phenomenon induced by grain boundaries in niobium[J].Journal of Materials Research,2004,19(8):2478.
49 Kalidindi S R,Vachhani S J.Mechanical characterization of grain boundaries using nanoindentation[J].Current Opinion in Solid State and Materials Science,2014,18(4):196.
50 Ahn H,Oh C S,Lee K,et al.Relationship between yield point phenomena and the nanoindentation pop-in behavior of steel[J].Journal of Materials Research,2012,27(1):39.
51 Shen Z Y,Wang B L,Liang G F,et al.Grain boundary pop-in,yield point phenomenonand carbon segregation in aged low carbon steel[J].ISIJ International,2018,58(2):373.
52 Li D M,Su M.On the plastic deformation mechanism of a thin-fine specimen of mild steel[J].Metal Science and Technology,1987,6(8):31(in Chinese).李道明,苏梅.低碳钢微型试样塑性变形机制的研究[J].金属科学与工艺,1987,6(8):31.
2 Mangonon P L,Bramfitt B L.The metallurgy of continuous-annealed draw-quality sheet steel[J].JOM,2013,35(5):27.
3 MouldP P.Overview of continuous-annealing technology for steel sheet products[J].JOM,2013,34(5):18.
4 Lüders W.ber dieusserung der elasticitt an stahlartigen eisenstaben und stahlstben,undüber eine beim biegen solcher stbe beobachtete molecularbewegung[J].Dinglers Polytechnische Journal,1860,155:8.
5 Song R,Ponge D,Raabe D.Improvement of the work hardening rate of ultrafine grained steels through second phase particles[J].Scripta Materialia,2005,52(11):1075.
6 Tsuchida N,Tomota Y,Nagai K,et al.A simple relationship between Lüders elongation and work-hardening rate at lower yield stress[J].Scripta Materialia,2006,54(1):57.
7 Kim S,Hong M H,Chin K G,et al.Influence of carbon on mechanical properties of Cu bearing extra low carbon steel sheets[J].Steel Research International,2011,82(6):734.
8 Charit I,Seok C S,Murty K L.Synergistic effects of interstitial impurities and radiation defects on mechanical characteristics of ferritic steels[J].Journal of Nuclear Materials,2007,361(2):262.
9 Hall E O.The deformation of low-carbon steel in the blue-brittle range[J].Journal of the Iron and Steel Institute,1952,170:331.
10 Morrison W B.The effect of grain size on the stress-strain relationship in low-carbon steel[J].Translation ASM,1966,59(4):824.
11 Butler J F.Lüders front propagation in low carbon steels[J].Journal of the Mechanics and Physics of Solids,1962,10(4):313.
12 Johnson D H,Edwards M R,Chard-Tuckey P.Microstructure effects on the magnitude of Lüders strains in a low alloy steel[J].Materials Science and Engnieering:A,2015,625:36.
13 Clark D S,Russell T L,Wood D S.The influence of grain size on the yield phenomenon in steel[J].Acta Metallurgica,1961,9(12):1054.
14 Massardier V,Merlin J.Analysis of the parameters influencing the quench-aging behavior of ultra-low-carbon steels[J].Metallurgical and Materials Transactions A,2009,40(5):1100.
15 Hsun H.Effect of solutes on the Lüders strain in low-carbon sheet steels[J].Metallurgical and Materials Transactions A,1983,14(1):85.
16 Turkdogan E T,Barisic B.Causes and effects of nitride and carbonitride precipitation during continuous casting[J].Iron Steelmaker,1989,16(5):61.
17 Takahashi J,Kawakami K,Ushioda K,et al.Quantitative analysis of grain boundaries in carbon-and nitrogen-added ferritic steels by atom probe tomography[J].Scripta Materialia,2012,66(5):201.
18 Wilson D V.Role of grain boundaries in the discontinuous yielding of low-carbon steels[J].Metal Science Journal,1967,1(1):40.
19 Cottrell A H,Billy B A.Dislocation theory of yielding and strain aging of iron[J].Proceedings of the Physical Society:Section A,1948,62(1):49.
20 Nobuo N,Fujihara M,Tsuchiyama T,et al.Effect of phosphorus on Hall-Petch coefficient in ferritic steel[J].ISIJ international,2011,51(7):1169.
21 Morrison W B,Leslie W C.The yield stress-grain size relation in iron substitutional alloys[J].Metallurgical Transactions,1973,4:379.
22 Akama D,Nakada N,Tsuchiyama T,et al.Discontinuous yielding induced by the addition of nickel to interstitial-free steel[J].Scripta Materialia,2014,82(3):13.
23 Chang S K,Kwak J H.Effect of manganese on aging in low carbon sheet steels[J].ISIJ International,2007,37(1):74.
24 Souza T O D,Buono V T L.Optimization of the strain aging resistance in aluminum killed steels produced by continuous annealing[J].Materials Science and Engineering A,2003,354(1):212.
25 Mizui N,Okamoto A.Recrystallization texture control in ultra-low carbon Ti-added sheet steels containing Mn and P[J].ISIJ International,1990,76(3):422.
26 Pereloma E V,Bata V,Scott R I,et al.Effect of Cr and Mo on strain ageing behavior of low carbon steel[J].Materials Science and Engineering A,2010,527(10):2538.
27 Riccardo R,Carlo M,Roberto V.Effect of coiling temperature on formability and mechanical properties of mild low carbon and HSLA steels processed by thin slab casting and direct rolling[J].ISIJ International,2007,47(8):1204.
28 Lips K,Yang X H,Mols K.The effect of coiling temperature and continuous annealing on the properties of bake hardenable IF steels[J].Steel Research,1996,67(9):357.
29 Baird J D.The effects of strain-ageing due to interstitial solutes on the mechanical properties of metals[J].International Materials Reviews,1971,16(1):1.
30 Merin J,Merle P,Garnier S,et al.Experimental determination of the carbon solubility limit in ferritic steels[J].Metallurgical and Materials Transactions A,2004,35(6):1655.
31 Richard M D,Drexler E S,Fekete J R.Aging-induced anisotropy of mechanical properties in steel products:Implications for the measurement of engineering properties[J].Materials Science and Engineering A,2011,529:184.
32 Okamoto A,Koichi T.A mechanism of paint bake-hardening[J].Sumitomo Metals,1989,41:321.
33 Cui Y,Hu Y P,Wang R Z,et al.Effect of temper rolling and natural aging on properties of ultra-low carbon bake-hardening steel[J].Special Steel,2010,31(4):49(in Chinese).崔岩,胡吟萍,王瑞珍等.平整和自然时效对超低碳烘烤硬化钢板性能的影响[J].特殊钢,2010,31(4):49.
34 Hui Y J,Yu Y,Wang L,et al.Strain-induced precipitation in Ti micro-alloyed interstitial-free steel[J].Journal of Iron and Steel Research,International,2016,23(4):385.
35 Soenen B,De A K,Vandeputte S,et al.Competition between grain boundary segregation and Cottrell atmosphere formation during static strain aging in ultra-low carbon bake hardening steels[J].Acta Materialia,2004,52(12):3483.
36 De A K,Vandeputte S,Cooman B C D.Static strain aging behavior of ultra low carbon bake hardening steel[J].Scripta Materialia,1999,41(8):831.
37 Hanai S,Takmoto N.Effect of grain size and solid solution strengthening elements on the bake hardenability of low carbon aluminumkilled steel[J].ISIJ International,1984,24(1):17.
38 Bailon J P,Dorlot J M.Thermal-treatment effects on the Hall-Petch relation for armco-iron[J].Acta Materialia,1971,19:71.
39 Takaki S,et al.Effect of grain boundary segregation of interstitial elements on Hall-Petch coefficient in steels[J].Materials Transactions,2014,55(1):28.
40 Ono Y,et al.Roles of solute C and grain boundary in strain aging behaviour of fine-grained ultra-low carbon steel sheets[J].ISIJ International,2017,57(7):1273.
41 Zhao J Z,De A K,De C B C.A model for the Cottrell atmosphere formation during aging of ultra-low carbon bake hardening steels[J].ISIJ International,2000,40(7):725.
42 Zhou B X,Liu W Q.The appication of 3DAP in the study of materials science[J].Materials Science and Technology,2007,15(3):405(in Chinese).周邦新,刘文庆.三维原子探针及其在材料科学研究中的应用[J].材料科学与工艺,2007,15(3):405.
43 Chang L,et al.Fundamentals of aging and tempering in bainitic and martensitic steel products[J].Iron and Steel Society,1992,20:215.
44 Wilde J,Cerezo A,Smith G D W.Three-dimensional atomic-scale mapping of a cottrell atmosphere around a dislocation in iron[J].Scripta Materialia,2000,43(1):39.
45 Seto K,Larson D J,Warren P J,et al.Grain boundary segregation in boron added interstitial free steels studied by 3-dimensional atom probe[J].Scripta Materialia,1999,40(9):1029.
46 Fang Q F,Wang X P,Wu X B,et al.The basic principles and applications of internal friction and mechanical spectroscopy[J].Physics,2011,12(40):786(in Chinese).方前锋,王先平,吴学邦,等.内耗与力学谱基本原理及其应用[J].物理,2011,12(40):786.
47 Sekido K,Ohmura T,Hara T,et al.Effect of dislocation density on the initiation of plastic deformation on Fe-C steels[J].Materials Transactions,2012,53(5):907.
48 Wang M G,Ngan A H W.Indentation strain burst phenomenon induced by grain boundaries in niobium[J].Journal of Materials Research,2004,19(8):2478.
49 Kalidindi S R,Vachhani S J.Mechanical characterization of grain boundaries using nanoindentation[J].Current Opinion in Solid State and Materials Science,2014,18(4):196.
50 Ahn H,Oh C S,Lee K,et al.Relationship between yield point phenomena and the nanoindentation pop-in behavior of steel[J].Journal of Materials Research,2012,27(1):39.
51 Shen Z Y,Wang B L,Liang G F,et al.Grain boundary pop-in,yield point phenomenonand carbon segregation in aged low carbon steel[J].ISIJ International,2018,58(2):373.
52 Li D M,Su M.On the plastic deformation mechanism of a thin-fine specimen of mild steel[J].Metal Science and Technology,1987,6(8):31(in Chinese).李道明,苏梅.低碳钢微型试样塑性变形机制的研究[J].金属科学与工艺,1987,6(8):31.