共查询到20条相似文献,搜索用时 15 毫秒
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通过成分设计、相变规律研究、工业规模试制,分别获得了(PF+B)双相组织及AF组织的管线钢钢板。二者的试验研究结果表明,当弛豫终止温度低于相变开始温度后,组织中将出现多边形铁素体(PF)。弛豫终止后以20℃/s左右的冷速加速冷却时,未转变的奥氏体转变为由粒状铁素体(GF)及贝氏体铁素体(BF)组成的贝氏体B组织。相比于AF组织管线钢,(PF+B)组织管线钢具有较低的屈强比及较高的伸长率。试验获得的(PF+B)组织管线钢的轧板厚度达30.8mm,强度级别达到X70级,拥有较低的屈强比和较高的伸长率,满足海底管线对抗变形性能的要求。 相似文献
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《钢铁研究学报(英文版)》2011,(Z1):707-711
A low carbon Nb-microalloyed high deformability pipeline steel with X100 grade has been processed by TMCP and followed two-stage cooling process.The microstructure is characterized by ferrite/bainite multiphase.The effective grain size is 1.85μm in average.The volume of ferrite is about 10-15% and the grains sizes are mostly less than 5μm.The bainite consists of granular-bainite and lath-bainite,with M/A islands finely dispersed.The longitudinal tensile yield strength,uniform elongation,yield ratio are 647MPa,7.6% and 0.78,respectively.Ferrite/bainite multiphase have large strain hardenability that resulting high strength and high deformability combination.Precipitation of Nb also improves the strength and uniform deformability by precipitation strengthening and grain refinement. 相似文献
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Effect of Cooling Start Temperature on Microstructure and Mechanical Properties of X80 High Deformability Pipeline Steel 总被引:1,自引:0,他引:1
The effect of cooling (laminar cooling) start temperature on the phase constitution was analyzed by quantitative metallography. The martensite/austenite (M/A) island distribution was fixed by colour metallography. The strength and uniform elongation of the steels were tested with quasi-static tensile testing machine. The in-coordinate deformation of the soft and hard phases was analyzed using FEM. The results indicate that when the cooling start temperature is 690 ℃, the mechanical properties are the best, meeting the requirements of X80 high deformability pipeline steel. 相似文献
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In order to ensure the safety of long-distance oil and natural gas transmission pipeline installed in seismic and/or permafrost region, high strength pipeline steel with excellent deformability has been developed. The ferrite and bainite dual phase pipeline steel is a very important kind of high deformability pipeline steel. Polygonal ferrite is a key microstructure in ferrite and bainite dual phase deformability pipeline steel. Ferrite evolution during isothermal process at 700 ℃ after 50% deformation at 800 ℃ was conducted by using a Gleeble-3800 thermal simulator, and microstructure was characterized by using an optical microscope, a scanning electron microscope and a transmission electron microscope. There are two types of ferrite, ferrite with high density dislocation and ferrite with a little dislocation. There is about 7% (volume percent) deformation induced ferrite (DIF) for compression of 50% at 800 ℃ and strain rate of 1 s-1. During the isothermal process at 700 ℃, with the holding time increasing, ferrite volume percent, ferrite grain number and average ferrite grain size increase. As the holding time is prolonged, dislocation recovery occurs in DIF. There are secondary phases in ferrite when the holding time is too long, and secondary phases and dislocation formation in dislocation pinning. 相似文献
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The stress oriented hydrogen induced cracking (SOHIC) is a typical hydrogen embrittlement phenomenon occurring in the linepipe steels exposed to sour environment containing H 2 S gas.However,even recently,the cracking mechanism of SOHIC has not been clarified because of lacking in the empirical data on the actual failure mode of SOHIC cracking.The factors affecting SOHIC are discussed in terms of metallurgy of high strength linepipe steel and hydrogen electrochemistry.The cracking mechanisms of SOHIC are examined by comparing them with the empirical failure mode of SOHIC which is developed by observation of the actual fracture sites of the hydrogen induced blister cracking (HIBC) and secondary cracks.Finally,the correlation between SOHIC and HIC is discussed. 相似文献
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Bruce D. Craig 《Metallurgical and Materials Transactions A》1982,13(5):907-912
A series of four 4130 base steels with various phosphorus concentrations was subjected to cathodic charging to determine the
effect of P on hydrogen stress cracking resistance. Static fatigue curves for several different yield strengths were obtained
for each alloy. At high yield strengths under applied loads of 60 to 80 pct of the yield, 50 ppm P (bulk concentration) was
enough to provide sufficient grain boundary P for an impurity-hydrogen interaction which produced intergranular fracture along
prior austenite grain boundaries. Decreasing yield strength and applied stress caused a transition in fracture mode to transgranular
while the resistance to hydrogen stress cracking increased with decreasing P. Microhardness measurements of prior austenite
grain boundaries were made to establish the role of P. The role of P is not apparently related to its capacity as a strengthening
element but more probably as a hydrogen recombination poison. Grain boundary hardness measurements for low temperature tempers
(200 °C) appear to be valid while those at 500 °C were not. 相似文献
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应变速率对管线钢在碱性溶液中应力腐蚀行为的影响 总被引:1,自引:0,他引:1
主要研究了不同应变速率对X70管线钢在库尔勒土壤模拟溶液中应力腐蚀行为的影响.采用慢应变速率拉伸实验(SSRT)研究了不同应变速率下X70管线钢在模拟溶液中应力腐蚀开裂行为,并利用扫描电镜分析了不同应变速率下的断面形貌.结果表明,应变速率(特别是局部应变速率)对X70管线钢在库尔勒土壤模拟溶液中应力腐蚀行为有重要影响,应变速率在5×10-7~5×10-6s-1之间有较强的应力腐蚀开裂敏感性,在裂纹扩展不同阶段氢和阳极溶解交互作用相对贡献大小不同. 相似文献
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Jesus Israel Barraza-Fierro Bernardo Campillo-Illanes Ximing Li Homero Castaneda 《Metallurgical and Materials Transactions A》2014,45(9):3981-3994
Different thermomechanical treatments were applied to a high strength low carbon steel with a novel chemical composition. As a result, three different microstructures were produced with dissimilar mechanical and corrosion properties. Subsequently, a tempering heat treatment was applied to redistribute the phases in the steel. Microstructure A with 56 pct martensite and 32 pct bainite presented high strength but medium ductility; microstructure C with 95 pct ferrite and 3 pct martensite/austenite resulted in low strength and high ductility, and finally microstructure B with 98 pct bainite and 2 pct martensite/austenite resulted in high strength and ductility. Alternatively the corrosion behavior obtained by polarization curves was characterized in 0.1 M H2SO4, 3 M H2SO4, 3.5 wt pct NaCl, and NS4 solutions resulting in similar magnitudes, while the corrosion behavior acquired by electrochemical impedance spectroscopy had slightly differences in 3 M H2SO4. 相似文献
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《钢铁研究学报(英文版)》2011,(Z1):625-628
The correlation among finish rolling temperature (FRT),microstructure and mechanical property of the high grade pipeline steel was investigated in this study.The microstructure of the steels with different finish rolling temperatures was observed with scanning electronic microscope (SEM) and transmission electronic microscope (TEM).The martensite/austenite (M/A) islands distribution was fixed by colour metallography,and the mechanical properties of the steels were tested with quasi-static tensile testing machine.The result shows that the fraction of M/A island increased with the finish rolling temperature decreasing,and when the finish rolling temperature is 800℃,the mechanical properties are the best. 相似文献
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Thestudies[1,2 ] havestatedthatretainedausteniteinadual phasesteelistransformedtomartensiteundertensilestrain .Suchstrain inducedtransformationofretainedaustenitecanenhanceductilityofsteelwhentheretainedausteniteisratherstableagainststraining[3 ] .Basedonthi… 相似文献
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Xie Fei Wang Dan Wu Ming Yu Chengxiang Sun Dongxu Yang Xu Xu Changhao 《Metallurgical and Materials Transactions A》2018,49(4):1372-1382
Metallurgical and Materials Transactions A - The stress corrosion cracking (SCC) of X80 pipeline steel in simulated alkaline soil solution under different temperatures was investigated by... 相似文献
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分析了X100管线钢动态再结晶规律,并绘制了X100管线钢的奥氏体动态再结晶图。在实验室进行了X100管线钢的试制,结果表明:在实验室试制的X100管线钢,屈服强度达到了800MPa,抗拉强度达到了925MPa,并且冲击性能优良,各项性能指标均超过了API标准要求。用SEM对X100管线钢的金相组织进行观察,发现其典型组织为粒状贝氏体,并有少量的贝氏体铁素体。用TEM对其M-A岛形貌进行观察,发现M-A岛宽度约为300nm。 相似文献