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RELATIONSHIP BETWEEN M-A CONSTITUENT AND CLEAVAGE FRACTURE BEHAVIOUR OF GRANULAR BAINITIC WELD METAL
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作者 XU Xiangxing SU Yi ZHOU Wei Tsinghua University,Beijing,ChinaCAI Qigong Central Iron and Steel Research Institute,Ministry of Metallurgical Industry,Beijing,China XU Xiangxing,Dept.of Mechanical Engineering,Tsinghua University,Beijing,100084,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1989年第2期143-146,共4页
The cleavage fracture mechanism of granular bainitie weld metal in 15MnVN steel has been investigated.SEM observation of a special specimen for revealing simultaneously fracture sur- face and microstructure shows that... The cleavage fracture mechanism of granular bainitie weld metal in 15MnVN steel has been investigated.SEM observation of a special specimen for revealing simultaneously fracture sur- face and microstructure shows that the cleavage of the weld is initiated by M-A constituent. The 95th percentile equivalent diameter of M-A constituent controls the cleavage fracture stress of the weld metal. 展开更多
关键词 granular bainite M-A constituent WELD cleavage fracture
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Effect of Microstructure Refinement on the Strength and Toughness of Low Alloy Martensitic Steel 被引量:52
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作者 Chunfang WANG Maoqiu WANG Jie SHI Weijun HUI Han DONG 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2007年第5期659-664,共6页
Martensitic microstructure in quenched and tempered 17CrNiMo6 steel with the prior austenite grain size ranging from 6 μm to 199 μm has been characterized by optical metallography (OM), scanning electron microsco... Martensitic microstructure in quenched and tempered 17CrNiMo6 steel with the prior austenite grain size ranging from 6 μm to 199 μm has been characterized by optical metallography (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The yield strength and the toughness of the steel with various prior austenite grain sizes were tested and correlated with microstructure characteristics. Results show that both the prior austenite grain size and the martensitic packet size in the 17CrNiMo6 steel follow a HalI-Petch relation with the yield strength. When the prior austenite grain size was refined from 199 μm to 6 μm , the yield strength increased by 235 MPa, while the Charpy U-notch impact energy at 77 K improved more than 8 times, indicating that microstructure refinement is more effective in improving the resistance to cleavage fracture than in increasing the strength. The fracture surfaces implied that the unit crack path for cleavage fracture is identified as being the packet. 展开更多
关键词 Martensitic steel Grain refinement STRENGTH Impact toughness cleavage fracture
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Deformation behavior and plastic instability of boronized Al0.25CoCrFeNi high-entropy alloys 被引量:3
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作者 Jin-xiong Hou Jing Fan +2 位作者 Hui-jun Yang Zhong Wang Jun-wei Qiao 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2020年第10期1363-1370,共8页
Using thermochemical treatments,boronized layers were successfully prepared on Al0.25CoCrFeNi high-entropy alloys(HEAs).The thickness of the boronized layers ranged widely from 20 to 50μm,depending on the heat treatm... Using thermochemical treatments,boronized layers were successfully prepared on Al0.25CoCrFeNi high-entropy alloys(HEAs).The thickness of the boronized layers ranged widely from 20 to 50μm,depending on the heat treatment time.Boronizing remarkably improved the surface hardness from HV 188 to HV 1265 after treating at 900°C for 9 h.Moreover,boronizing enhanced the yield strength of HEAs from 195 to 265 MPa but deteriorated the tensile ductility.Multiple crackings in the boride layers significantly decreased the plasticity.The insufficient work-hardening capacity essentially facilitated the plastic instability of the boronized HEAs.With decreasing substrate thickness,the fracture modes gradually transformed from dimples to quasi-cleavage and eventually to cleavage. 展开更多
关键词 BORONIZING high-entropy alloys boride layers tensile strength cleavage fracture
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Impact Toughness Scattering of Bainitic Steel in the Ductile-brittle Transition Temperature Region 被引量:1
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作者 石昆 CHEN Jiangbiao +3 位作者 HOU Hong KONG Lingti LI Jinfu 张汉谦 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2016年第3期636-643,共8页
The impact toughness scattering in the ductile-brittle transition temperature (DBTT) region was experimentally examined on mixed and homogeneous grains of low alloy high strength bainitic steel under dynamic loading... The impact toughness scattering in the ductile-brittle transition temperature (DBTT) region was experimentally examined on mixed and homogeneous grains of low alloy high strength bainitic steel under dynamic loading conditions. The results revealed that the mixed grain microstructure had larger impact toughness scattering than the homogeneous one, and the impact toughness scattering was mainly caused by the scattering in the cleavage fractttre stress σf. The value of σf. is related to the size of the microcrack formed in the bainitic packet. When a bainitic packet-sized microcrack propagates from one bainitic packet into the adjacent packet, cleavage fracture occurs. The cleavage fracture is controlled by the few coarse packets in the microstructures, and the σf scattering is influenced by the varied distances/relative locations between these coarse packets, and homogenizing the distribution of fine bainitic packet sizes is an effective way to reduce the impact toughness scattering in the DBTT region. 展开更多
关键词 bainitic steel low temperature impact toughness scatter cleavage fracture stress
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Impact toughness of a gradient hardened layer of Cr5Mo1V steel treated by laser shock peening 被引量:1
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作者 Weiguang Xia Lei Li +5 位作者 Yanpeng Wei Aimin Zhao Yacong Guo Chenguang Huang Hongxiang Yin Lingchen Zhang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2016年第2期301-308,共8页
Laser shock peening(LSP) is a widely used surface treatment technique that can effectively improve the fatigue life and impact toughness of metal parts.Cr5Mo1 V steel exhibits a gradient hardened layer after a LSP p... Laser shock peening(LSP) is a widely used surface treatment technique that can effectively improve the fatigue life and impact toughness of metal parts.Cr5Mo1 V steel exhibits a gradient hardened layer after a LSP process.A new method is proposed to estimate the impact toughness that considers the changing mechanical properties in the gradient hardened layer.Assuming a linearly gradient distribution of impact toughness,the parameters controlling the impact toughness of the gradient hardened layer were given.The influence of laser power densities and the number of laser shots on the impact toughness were investigated.The impact toughness of the laser peened layer improves compared with an untreated specimen,and the impact toughness increases with the laser power densities and decreases with the number of laser shots.Through the fracture morphology analysis by a scanning electron microscope,we established that the Cr5Mo1 V steel was fractured by the cleavage fracture mechanism combined with a few dimples.The increase in the impact toughness of the material after LSP is observed because of the decreased dimension and increased fraction of the cleavage fracture in the gradient hardened layer. 展开更多
关键词 Laser shock peening Gradient hardened layer Plastically affected depth Impact toughness cleavage fracture
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CHARACTERISTIC TRANSITION TEMPERATURE OF BRITTLENESS OF LOW CARBON STEEL
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作者 HUANG Zheng Institute of Physics,Academia Sinica,Beijing,ChinaYAO Mei Harbin Institute of Technology,Harbin,China Institute of Physics,Academia Sinica,Beijing 100080,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1990年第5期332-337,共6页
On the basis of analysis of low carbon steel fracture macro-features and micro-processes at low temperature,the definition was given of the characteristic transition temperature of brittleness,T_(pm),and its physical ... On the basis of analysis of low carbon steel fracture macro-features and micro-processes at low temperature,the definition was given of the characteristic transition temperature of brittleness,T_(pm),and its physical meaning was expounded.Discussion was carried out of phys- ical characteristic of variation at T_(pm) in respect of the fracture toughness and property of crack arrest.In addition,research was made on the application of T_(pm),which can give infor- mation about the transition of the fracture toughness,the property of crack arrest and critical crack size,to estimation the brittleness of low carbon steel at low temperatures. 展开更多
关键词 low carbon steel low temperature brittleness transition temperature cleavage fracture fracture toughness craek arrest
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Investigation of separation phenomenon in high-toughness X70 thick-walled linepipe steel
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作者 DING Jianhua LIANG Xiaojun JIAO Sihai 《Baosteel Technical Research》 CAS 2015年第3期35-40,共6页
Separation is a commonly observed phenomenon during drop weight tear testing in high-toughness linepipe steels. Severe separation is harmful because it may cause fracturing or bursting of pipes. In this study, a quant... Separation is a commonly observed phenomenon during drop weight tear testing in high-toughness linepipe steels. Severe separation is harmful because it may cause fracturing or bursting of pipes. In this study, a quantitative measurement of separation was proposed, and using this new method, a relationship between the separation and microstructure was determined and discussed. The microstructures observed using optical and scanning electron microscopy revealed that the separation was related to the mixed ferfitic and bainitic microstructures, or rather,it was related to the carbon enrichment in bainite. 展开更多
关键词 linepipe steel DWTT SEPARATION BAINITE thermomechanical processing cleavage fracture
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Fracture in sintered Sm-Co permanent magnetic materials 被引量:2
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作者 李安华 董生智 李卫 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2003年第3期241-247,共7页
The bending strength and fracture toughness of sintered Sm-Co permanent magnetic materials are measured. A scanning electron microscope equipped with an energy dispersive X-ray analysis system is employed to investiga... The bending strength and fracture toughness of sintered Sm-Co permanent magnetic materials are measured. A scanning electron microscope equipped with an energy dispersive X-ray analysis system is employed to investigate the bending fractography. The fracture behavior and micromechanism are discussed. The fracture behavior of sintered Sm-Co permanent magnetic materials exhibits cleavage fracture. Some Sm-rich impurities are found in fracture plane, suggesting that the Sm-rich impurities help reduce the cleavage brittleness of sintered Sm-Co permanent magnetic materials. The possible methods for improving the strength and toughness are also proposed. 展开更多
关键词 Sm-Co permanent magnents bending strength cleavage fracture
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Low Temperature Impact Toughness and Fracture Analysis of EN-GJS-400-18-LT Ductile Iron under Instrumented Impact Load 被引量:2
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作者 Xin-ning ZHANG Ying-dong QU Rong-de LI 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2015年第9期864-869,共6页
The impact toughness of EN-GJS-400-18-LT ductile iron was measured by Charpy V-notch impact test at temperature between-80 and 20℃.The fracture properties were tested under instrumented impact loading.Total impact fr... The impact toughness of EN-GJS-400-18-LT ductile iron was measured by Charpy V-notch impact test at temperature between-80 and 20℃.The fracture properties were tested under instrumented impact loading.Total impact fracture energy,crack initiation and propagation energy,dynamic loads and the ductile to brittle temperature were measured.Three-dimensional reconstruction of impact fracture morphology was accomplished by confocal laser scanning microscope.The results of quantitative fractography indicate that cleavage fracture produces flatter fracture surfaces accompanying with less absorbed energy during the impact fracture process.It indicates that fracture roughness has a close relationship with crack propagation energy at low temperature. 展开更多
关键词 graphite nodule ductile to brittle transition cleavage fracture deformation twin three-dimensional reconstruction
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Punchability and Punching Fracture Behavior of High Silicon Steel Sheets 被引量:1
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作者 Jing QIN Ping YANG +1 位作者 Wei-min MAO Feng YE 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2015年第9期852-857,共6页
The 0.2-0.3mm thick cold-rolled sheets and annealed sheets of high silicon steel were produced by rolling process,then punching tests were carried out at room temperature to 150℃.The punchability and punching fractur... The 0.2-0.3mm thick cold-rolled sheets and annealed sheets of high silicon steel were produced by rolling process,then punching tests were carried out at room temperature to 150℃.The punchability and punching fracture behavior were investigated by means of scanning electron microscope(SEM)and electron back-scattered diffraction(EBSD).It is found that cold-rolled sheets of high silicon steel show good punchability under the condition of 0.01 mm punch-die clearance and at the temperature of 100℃;the punchability of annealed sheets with fine grain size is better than that of annealed sheets with coarse grain size;the punching temperature of 150℃is suitable for annealed high silicon steel sheets especially with coarse grain size on account of punching edge quality.The major cleavage planes of annealed high silicon steel sheets are{100}crystallographic planes on which brittle fracture occurs at low temperatures.The cleavage systems include{100}〈110〉and{100}〈100〉,and cleavage fracture is completed by one or both of them.The punchability of high silicon steel sheets is related with punching temperature,grain size and ordering degree.Reducing ordering degree,increasing punching temperature,as well as refining grain size can improve the ductility and punchability of high silicon steel sheets. 展开更多
关键词 high silicon steel punch-die clearance punchability cleavage fracture dimple fracture
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Effect of Heat Input on Cleavage Crack Initiation of Simulated Coarse Grain Heat-affected Zone in Microalloyed Offshore Platform Steel
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作者 Feng LU Guang-ping CHENG +4 位作者 Feng CHAI Tao PAN Zhong-ran SHI Hang SU Cai-fu YANG 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2016年第10期1086-1095,共10页
The combined effects of martensite-austenite(MA)constituent and pearlite colony on cleavage crack initiation in the simulated coarse-grained heat-affected zone(CGHAZ)of V-N-Ti microalloyed offshore platform steel ... The combined effects of martensite-austenite(MA)constituent and pearlite colony on cleavage crack initiation in the simulated coarse-grained heat-affected zone(CGHAZ)of V-N-Ti microalloyed offshore platform steel under different heat inputs were investigated.The results of welding simulation,instrumented impact test,and quantitative analysis indicated that the size of the MA constituent decreased with the increase in cooling time,and by contrast,the size of the pearlite colony increased.According to Griffith theory,the critical sizes of cleavage microcracks were calculated.With the increase of cooling time,the calculated microcrack size could be characterized by the size of the MA constituent first,and then fitted with the size of the pearlite colony.Moreover,the calculated microcrack size variation was opposite to the microcrack initiation energy.This phenomenon is probably due to the combined effects of the MA constituent and pearlite colony with increasing the cooling time of the specimen′s temperature from800 to 500 ℃. 展开更多
关键词 simulated coarse-grained heat-affected zone martensite-austenite constituent pearlite colony cleavage fracture V-N-Ti microaltoying
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Effect of coarse TiN inclusions and microstructure on impact toughness fluctuation in Ti micro-alloyed steel 被引量:6
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作者 Tao Liu Mu-jun Long +6 位作者 Deng-fu Chen Hua-mei Duan Lin-tao Gui Sheng Yu Jun-sheng Cao Hua-biao Chen He-lin Fan 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2018年第10期1043-1053,共11页
Toughness is an important property for steels used in engineering applications. However, recent toughness testing has shown the existence of a significant fluctuation in toughness in a single rolled plate of titanium ... Toughness is an important property for steels used in engineering applications. However, recent toughness testing has shown the existence of a significant fluctuation in toughness in a single rolled plate of titanium micro-alloyed steel. The underlying causes of this fluctuation were investigated by fractography, analysis of microstructure and measurement of inclusions. Coarse and distributed TiN inclusions were responsible for the toughness variation, as they tended to act as the potential cleavage initiators to form micro-cracks. From a calculation of the local fracture stress, the critical size of coarse TiN inclusions for dominating micro-crack propagation was 4.93 μm, and similarly that of ferrite grains was 36.6μm. Under current casting and thermo-mechanically controlled processing schedules, the toughness fluctuation of rolled steel plates can be primarily attributed to the fraction of coarse TiN inclusions larger than 5μm. A corresponding relationship between impact energy and the proportion of coarse TiN inclusions was established. Finally, a normalizing treatment was applied to refine the ferrite grains of rolled steel plates. Despite the presence of coarse TiN inclusions, this refinement in ferrite grains minimized the toughness fluctuation and improved the uniformity of the impact properties of the steel plates. 展开更多
关键词 Impact toughness fluctuation Ti micro-alloyed steel cleavage fracture Coarse TiN inclusion Grain refinement
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A novel linear microprobe array for the fabrication of neural microelectrodes 被引量:3
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作者 ZHAO Shan Shan PEI Wei Hua +7 位作者 ZHAO Hui WANG Yi Jun CHEN San Yuan CHEN Yuan Fang ZHANG He GUO Dong Mei GUI Qiang CHEN Hong Da 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2015年第2期346-351,共6页
A novel linear microprobe array(LMPA)has been developed by a conventional microfabrication method from silicon.The LMPA leverages the properties of conventional microwire with additional features of naturally formed r... A novel linear microprobe array(LMPA)has been developed by a conventional microfabrication method from silicon.The LMPA leverages the properties of conventional microwire with additional features of naturally formed regular spacing.With the help of periodic microprobe arrays and double-side V-grooves fabricated in advance between each pair of the two microprobes’rear ends,the number of microprobe units for assembly in one array can be flexibly chosen by cleavage fracture from the LMPA.The fabrication method was demonstrated and the prototype device was assessed by electrochemical impedance spectroscopy(EIS)and in vivo test.The SNR of the spikes recorded was 6. 展开更多
关键词 LMPA regular spacing cleavage fracture V-groove
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Mechanical Behavior of CrMo4 Steel With Dual-Phase Microstructure
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作者 A Salemi A-H Golestaneh E Moosavi-Khoonsari 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2011年第S1期862-868,共7页
Multi-phase microstructures having good ductility may replace the conventional microstructures in different technological applications such as pressure vessels.Mechanical properties including the fracture behavior and... Multi-phase microstructures having good ductility may replace the conventional microstructures in different technological applications such as pressure vessels.Mechanical properties including the fracture behavior and the service life of pressure vessels are strongly affected by the microstructure.The objective of this study was to investigate the correlation between different dual-phase microstructures and mechanical properties of 42CrMo4 (AISI 4140) steel.To produce the martensite-bainite (M-B),the martensite-ferrite (M-F),and the ferrite-bainite (F-B) microstructures,the step quenching heat treatment was used.Mechanical properties of heat treated samples including the strength,ductility,and impact energy were measured.Tensile experiments revealed a discontinuous yielding in the F-B specimen with ferritic matrix.Fracto\graphic results showed high concentration bright facets (BFs) on broken specimen surfaces indicating the brittle cleavage fracture was the predominant mechanism in the dual-phase microstructures. 展开更多
关键词 42CrMo4 steel dual-phase microstructures cleavage fracture
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