Please wait a minute...
Acta Metall Sin  2017, Vol. 53 Issue (5): 549-558    DOI: 10.11900/0412.1961.2016.00316
Orginal Article Current Issue | Archive | Adv Search |
Effect of Surface Layer with Ultrafine Grains on Crack Arrestability of Heavy Plate
Jiangnan MA1,Ruizhen WANG2(),Caifu YANG2,Xiaoqin ZHA1,Lijuan ZHANG1
1 Luoyang Ship Material Research Institute, Luoyang 471023, China
2 Department of Engineering Steels, Central Iron and Steel Research Institute, Beijing 100081, China
Download:  HTML  PDF(10594KB) 
Export:  BibTeX | EndNote (RIS)      

Temperature reverting rolling process (TRRP) is a newly developed technology for producing heavy steel plate with ultrafine grained surface layer. With hybrid structures along thickness direction, TRRP steel plate has excellent fracture toughness with crack arrestability which arouses interest recently. However, the crack arrest mechanism of the surface layer is still unclear to date. In this work, two types of steel plate produced by TRRP and traditional thermo mechanical control process (TMCP) were studied in order to get a comprehensive understanding of the crack arrest mechanism. The mechanical property tests demonstrate that the toughness of surface layer of TRRP steel is significantly higher than that of TMCP steel, while the mechanical properties at 1/4 thickness position of the two types are quite close. It's worth noting that ductile-brittle transition temperature of the TRRP steel surface layer is as low as -100 ℃. Microstructure analysis of the TRRP surface layer shows a coexistence of equiaxed ferrite grains with grain sizes of about 2 μm and dispersed M-A constituent. Numerical simulation of the temperature field of TRRP intermediate slab reveals the microstructure forming process. First, the surface layer is cooled lower than phase transformation temperature, which results in the generation of bainite ferrite. Subsequently, dynamic recrystallization of ferrite takes place in rolling process and leads to the formation of ultrafine grains. Instrumental impact test at -60 ℃ shows that the crack propagation of TRRP steel is effectively inhibited after a steady developing stage. The morphological analysis of the cross section of fracture shows significant plastic deformation in the surface layer, which means crack propagation energy is absorbed. As a result, the crack propagation is efficiently arrested. The statistical study of the grain orientations in the surface layer of TRRP steel indicates a randomly distribution of the ultrafine grains, which can hinder the crack propagation effectively. The nano indentation test shows that the hardness distributions of TRRP steel are mainly below 2.0 GPa. This means the microstructure is characterized by a small amount of hard phase dispersing in soft matrix, thus the crack initiated at the interface of phases can hardly propagate.

Key words:  heavy plate      temperature-reverting rolling process      surface layer with ultrafine grain      crack arrest      instrumental impact     
Received:  20 July 2016     

Cite this article: 

Jiangnan MA,Ruizhen WANG,Caifu YANG,Xiaoqin ZHA,Lijuan ZHANG. Effect of Surface Layer with Ultrafine Grains on Crack Arrestability of Heavy Plate. Acta Metall Sin, 2017, 53(5): 549-558.

URL:     OR

Fig.1  OM images of temperature reverting rolling process (TRRP) steel((a) macrostructure (b) microstructure of region I in Fig.1a(c) microstructure of region II in Fig.1a (d) microstructure of region III in Fig.1a)
Fig.2  SEM images of surface layer (a, c) and t/4 (b, d) of TRRP (a, b) and TMCP (c, d) steels (UF—ultrafine ferrite, M-A—martensite-austenite, AF—acicular ferrite, QPF—quasipolygonal ferrite, UB—upper bainite, PF—polygonal ferrite, TMCP—thermo mechanical control process, t—thickness)
Steel Rm / MPa Rel / MPa A / %
Surface t/4 Surface t/4 Surface t/4
TRRP 621 600 545 520 21.0 25.5
TMCP 652 610 609 545 13.0 25.5
Table1  Tensile properties of surface layer and t/4 of TRRP and TMCP steels
Fig.3  Charpy absorbed energy vs temperature of TRRP (a) and TMCP (b) steels
Fig.4  Phase transformation behavior of microstructure through thickness of TRRP steel intermediate slab during water cooling and reverting (SUF—surface layer with ultrafine-grained microstructure, A—austenite, B—bainite, F—ferrite, P—pearlite, Ac1—austenite transformation beginning temperature during calefaction, Ac3—austenite transformation finish temperature during calefaction, Tuf—critical temperature for ultra-fine grain forming)
Fig.5  Temperature distribution along thickness of TRRP steel intermediate slab at the end of water cooling
Fig.6  Curves of load and absorbed energy vs hammer displacement at -60 ℃ (E1—crack initiation absorbed energy, E2—crack steady propagation absorbed energy, E3—crack arrest/collapse absorbed energy, E4—post crack arrest/collapse absorbed energy, Pm—max load, Pf—load at the beginning of crack arrest/collapse, Pa—load at the end of crack arrest/collapse)((a) surface layer of TRRP steel (b) surface layer of TMCP steel (c) t/2 of TMCP steel)
Fig.7  Fractographs of instrumented impact samples (Figs.7b, e and h are magnified images of marked area in Figs.7a, d and g. Figs.7c, f and i are cross section images of fracture)((a~c) surface layer of TRRP steel (d~f) surface layer of TMCP steel (g~i) t/2 of TMCP steel)
Fig.8  Inverse pole figure (IPF) maps of surface layer of TRRP (a) and TMCP (b) steels
Fig.9  Orientation distribution function (ODF) maps of surface layer of TRRP (a) and TMCP (b) steels (Φ, φ1, φ2—Euler angles)
Fig.10  Misorientation maps (a, c) and misorientation angle distribution diagrams (b, d) of surface layer of TRRP (a, b) and TMCP (c, d) steels (In Figs.10a and c, black lines show grain boundaries larger than 15°, red lines show grain boundaries between 2°and 15°)
Fig.11  SEM images of nanoindentations of surface layer of TRRP (a) and TMCP (b) steels
Fig.12  Statistics of the nanoindentation hardness of surface layer of TRRP (a) and TMCP (b) steels
Fig.13  Secondary crack in cross section of Charpy impacted fracture at -140 ℃ of TMCP steel
[1] Weng Y Q, Yang C F, Shang C J.State-of-the-art and development trends of HSLA steels in China[J]. Iron Steel, 2011, 46(9): 1
[1] (翁宇庆, 杨才福, 尚成嘉. 低合金钢在中国的发展现状与趋势[J]. 钢铁, 2011, 46(9): 1)
[2] Komizo Y I.Status & prospects of shipbuilding steel and its weldability[J]. Trans. JWRI, 2007, 36: 1
[3] Ishikawa T, Nomiyama Y, Yoshikawa H, et al.Ultra-high crack-arresting steel plate (HIAREST) with super-refined grains in surface layers[J]. Nippon Steel Tech. Rep., 1997, 75(11): 31
[4] Yao L D, Li Z G, Zhang P J.Research on ultra-fine grain and ultra-high toughness steel plate[J]. Iron Steel Vanadium Titanium, 2005, 26(1): 20
[4] (姚连登, 李自刚, 张丕军. 超细晶粒及超高韧性厚板的研究[J]. 钢铁钒钛, 2005, 26(1): 20)
[5] Mabuchi H, Hasegawa T, Ishikawa T.Metallurgical features of steel plates with ultra fine grains in surface layers and their formation mechanism[J]. ISIJ Int., 1999, 39: 477
[6] Zhao S X, Yao L D, Zhao X T.Development of heavy plate with ultra fine grained surface layer[J]. World Iron Steel, 2009, (5): 18
[6] (赵四新, 姚连登, 赵小婷. 表层超细晶厚钢板的研制[J]. 世界钢铁, 2009, (5): 18)
[7] Du H J, Li C, Zhao D W, et al.Development of Nb microalloyed low carbon steel plate with ultra-fine grains in surface layer[J]. J. Mech. Eng., 2011, 47(2): 58
[7] (杜海军, 栗春, 赵德文等. Nb微合金低碳钢表层超细晶中厚板的研制[J]. 机械工程学报, 2011, 47(2): 58)
[8] Ma J N, Yang C F, Wang R Z.Microstructure transformation and ferrite dynamic recrystallization behavior of microalloyed steel during temperature-reversion deforming[J]. J. Mater. Eng., 2015, 43(11): 24(马江南, 杨才福, 王瑞珍. 微合金钢回温变形时的组织转变和铁素体动态再结晶行为 [J]. 材料工程, 2015, 43(11): 24)
[9] Ishikawa T, Mabuchi H, Hasegawa T, et al.High crack arrestability-endowed steel plate with surface-layer of ultra fine grain microstructure[J]. Tetsu Hagané, 1999, 85: 544
[9] (石川忠, 間渕秀里, 長谷川俊永など. 脆性き裂伝播停止性能の優れた表層超細粒鋼板[J]. 鉄と鋼, 1999, 85: 544)
[10] He Q Z, Li Z N.Engineering Fracture Mechanics [M]. Beijing: Beijing University of Aeronautics and Astronautics Press, 1993: 55(何庆芝, 郦正能. 工程断裂力学 [M]. 北京: 北京航空航天大学出版社, 1993: 55)
[11] Ma J N, Yang C F, Wang R Z.Numerical simulation of temperature field and experiment during temperature-reverting rolling process of heavy steel plate[J]. Trans. Mater. Heat Treat., 2015, 36(3): 220
[11] (马江南, 杨才福, 王瑞珍. 中厚钢板回温轧制温度场的数值模拟和试验[J]. 材料热处理学报, 2015, 36(3): 220)
[12] Wang R Z, Lei T C.Dynamic recrystallization of ferrite in a low carbon steel during hot rolling in the (F+A) two-phase range[J]. Scr. Metall. Mater., 1994, 31: 1193
[13] Hales S J, Mcnelley T R.Microstructural evolution by continuous recrystallization in a superplastic Al-Mg alloy[J]. Acta Metall., 1988, 36: 1229
[14] Yang C F, Zhang Y Q, Liu T J.Low temperature impact fracture behavior of 10Ni5CrMoV steel[J]. Dev. Appl. Mater., 1997, 12(6): 2
[14] (杨才福, 张永权, 刘天军. 10Ni5CrMoV钢低温冲击断裂行为研究[J]. 材料开发与应用, 1997, 12(6): 2)
[15] Liu D Y, Xu H, Yang K, et al.Effect of bainite/martensite mixed microstructure on the strength and toughness of low carbon alloy steels[J]. Acta Metall. Sin., 2004, 40: 882
[15] (刘东雨, 徐鸿, 杨昆等. 贝氏体/马氏体复相组织对低碳合金钢强韧性的影响[J]. 金属学报, 2004, 40: 882)
[16] Zhang Y Q, Liu T J, Yang C F.Effect of melting methods on low temperature brittleness of steel 10CrSiNiCu[J]. J. Iron Steel Res., 1998, 10(5): 36
[16] (张永权, 刘天军, 杨才福. 不同冶炼方法对10CrSiNiCu钢低温脆性的影响[J]. 钢铁研究学报, 1998, 10(5): 36)
[17] Liu D S, Cheng B G, Luo M.Microstructure and impact fracture behaviour of HAZ of F460 heavy ship plate with high strength and toughness[J]. Acta Metall. Sin., 2011, 47: 1233
[17] (刘东升, 程丙贵, 罗咪. F460高强韧厚船板焊接热影响区的组织和冲击断裂行为[J]. 金属学报, 2011, 47: 1233)
[18] Hashemi S H.Apportion of Charpy energy in API 5L grade X70 pipeline steel[J]. Int. J. Pressure Vessels Piping, 2008, 85: 879
[19] Deng W, Gao X H, Qin X M, et al.Impact fracture behavior of X80 pipeline steel[J]. Acta Metall. Sin., 2010, 46: 533
[19] (邓伟, 高秀华, 秦小梅等. X80管线钢的冲击断裂行为[J]. 金属学报, 2010, 46: 533)
[20] Liu D S, Cheng B G, Luo M.Effect of heat-treatment processes on microstructure and properties of a NV-F690 shipbuilding plate steel[J]. Trans. Mater. Heat Treat., 2011, 32(9): 125
[20] (刘东升, 程丙贵, 罗咪. 热处理工艺对NV-F690船板钢组织和性能的影响[J]. 材料热处理学报, 2011, 32(9): 125)
[21] Yang P, Fu Y Y, Cui F E, et al.Orientational inspection of ferrite grains during strain enhanced transformation in plain carbon steel Q235[J]. Acta Metall. Sin., 2001, 37: 900
[21] (杨平, 傅云义, 崔凤娥等. Q235碳素钢应变强化相变过程中铁素体晶粒取向分析[J]. 金属学报, 2001, 37: 900)
[22] Lv Q G, Chen G N, Zhou J C, et al.Textures in hot rolled steel sheet[J]. Iron Steel Vanadium Titanium, 2001, 22(2): 1
[22] (吕庆功, 陈光南, 周家琮等. 热轧钢板的织构[J]. 钢铁钒钛, 2001, 22(2): 1)
[23] Liu D S, Cheng B G, Luo M.F460 heavy steel plates for offshore structure and shipbuilding produced by thermomechanical control process[J]. ISIJ Int., 2011, 51: 603
[24] Gao G H, Zhang H, Bai B Z.Effect of tempering temperature on low temperature impact toughness of a low carbon Mn-series bainitic steel[J]. Acta Metall. Sin., 2011, 47: 513
[24] (高古辉, 张寒, 白秉哲. 回火温度对Mn系低碳贝氏体钢的低温韧性的影响[J]. 金属学报, 2011, 47: 513)
[25] Liu D S, Li Q L, Emi T.Microstructure and mechanical properties in hot-rolled extra high-yield-strength steel plates for offshore structure and shipbuilding[J]. Metall. Mater. Trans., 2011, 42A: 1349
[26] Liu Z X, Li D Z, Qiao G W.Investigation on deformation induced ferrite (a kind of martensite) transformation above Ae3 temperature in a low carbon steel[J]. Acta Metall. Sin., 2005, 41: 1127
[26] (刘朝霞, 李殿中, 乔桂文. 低碳钢在Ae3温度之上的形变诱导铁素体(一种马氏体)的相变研究[J]. 金属学报, 2005, 41: 1127)
[4] HUANG Zheng;YAO Mei Institute of Physics; Academia Sinica; Beijing Harbin Institute of Technology Institute of Physics;Academia Sinica;Beijing 100080. CHARACTERISTIC TRANSITION TEMPERATURE OF BRITTLENESS OF LOW CARBON STEEL[J]. 金属学报, 1990, 26(2): 31-36.
No Suggested Reading articles found!