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为了揭示1 000 MPa级低碳加铌钒钛微合金钢的高强韧机制,研究了S1(w(C)=0.09%)与S2(w(C)=0.17%)两种合金成分的油井管钢成分-工艺-组织-性能关系。试验表明,两种成分试验钢经水淬后的组织分别为板条贝氏体加少量马氏体和马氏体加少量贝氏体的复相组织。两种成分钢经过450~600 ℃、30 min的中温回火后,组织中均出现碳化物析出,且S1试验钢回火后的屈服强度基本不变,抗拉强度下降了约70 MPa,S2试验钢回火后的屈服强度与抗拉强度迅速升高170 MPa左右。溶度积公式的计算结果表明,两种钢的水淬组织中铌、钛元素析出彻底且析出物的体积分数都很小,因此回火铁素体基体中的VC析出强化对S1试验钢回火后屈服强度保持不变以及S2试验钢回火后屈服、抗拉强度提高起到重要作用。 相似文献
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铌钒微合金中碳钢的微观组织与强度的关系 总被引:7,自引:1,他引:6
介绍了工业试制铌钒微合金中碳钢的微观组织与强度的关系。在Gladman中碳钢方程和实验结果的基础上,提出了屈服强度和抗拉强度的新方程。该方程与钢的成分、晶粒尺寸、铁素体体积百分数、珠光体片间距和析出物颗粒有关,理论计算的屈服强度和抗拉强度值与实验结果吻合。该方程不仅适合微合金中碳钢的铁素体和珠光体组织,而且也适合高碳微合金钢的珠光体组织和低碳微合金钢的铁素体组织。 相似文献
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在22MnB5钢中添加不同含量的合金元素钛,制备了钛微合金化汽车用钢试样,并进行了试样显微组织、力学性能和耐腐蚀性能的测试与分析.结果表明:添加合金元素钛,有利于细化试样的内部晶粒、提高试样的力学性能和耐腐蚀性能.随钛含量从0逐渐增加至0.08%,试样内部晶粒先细化后粗化,其抗拉强度和屈服强度均先增大后减小、断后伸长率... 相似文献
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试验低碳贝氏体钢(/%:0.08C,0.11~0.13Si,1.10~1.20Mn,0.008~0.009P,0.002S,0.21~0.23Ni,0.020~0.021Ti,0.003~0.004Nb,0~0.0010B,0.000 7~0.0008O,0.0031~0.0033N)由50kg真空感应炉熔炼,轧成45mm钢板,并经930℃淬火,610℃回火。研究了0.0010%硼对780 MPa低碳贝氏体钢45mm板组织和力学性能的影响。结果表明,硼可显著提高试验钢的淬透性,不含硼试验钢淬火后得到粒状贝氏体,0.0010%硼试验钢淬火后得到板条贝氏体。硼明显改善试验低碳贝氏体钢的力学性能,含0.0010%硼试验钢淬、回火后的抗拉强度834MPa和屈服强度771MPa远高于不含硼试验钢的抗拉强度702MPa和屈服强度591MPa,实际生产中应加入适量硼可使低碳贝氏体钢得到板条贝氏体。 相似文献
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为阐明钢中常用合金元素对大线能量焊接热影响区粗晶区(CGHAZ)的影响规律,设计了不同合金质量分数的试验钢,并进行氧化物冶金工艺处理,考察了各试验钢模拟焊接CGHAZ冲击韧性和组织特征。结果表明,低碳高锰有利于韧性的改善,但存在合适的碳质量分数范围,极低碳时需抑制晶界铁素体生成;添加质量分数为0.01%的铌时可保持较高的CGHAZ韧性,但过量的铌促进贝氏体生成而导致韧性恶化;添加质量分数为0.05%的钒时能提高基体强度并保持优良CGHAZ韧性,更高质量分数时因碳化物大量析出导致韧性下降;在一定范围内提高镍和铜质量分数可综合改善钢板强度和CGHAZ韧性;铬和钼的添加可抑制晶界转变产物,促进微细针状铁素体组织生成,但在试验钢成分下较多的M/A使得CGHAZ韧性未得到有效改善。 相似文献
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采用热膨胀法测定6种不同成分低碳贝氏体钢的连续冷却转变(CCT)曲线。CCT曲线表明,加入微量硼能使含钒低碳贝氏体钢在大于03℃/s的冷速下获得贝氏体组织,而V-N微合金化的低碳贝氏体获得全贝氏体的临界冷速要高于V-B钢,且贝氏体转变的开始温度也要较V-B钢高20℃左右。在含钒、氮低碳贝氏体钢中加入钼、铬将会促进钢的贝氏体相变,但钼的作用要优于铬;钼、铬的加入可使含钒、氮低碳贝氏体钢的贝氏体转变温度降低至少30℃,且贝氏体组织得到了细化,钢的维氏硬度也提高了HV10~30。 相似文献
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Effects of alloying with combinations of the elements Mo, Cr and B on the bainite transformation behaviour and microstructure of hot‐rolled high strength sheet steels microalloyed with mass contents of Ti and Nb, 0.05 or 0.15 % C and 1.5 % Mn have been studied. The relationships between microstructures formed in the steels coiled at various temperatures and their mechanical properties have been investigated. The 0.15 % C microalloyed steel alloyed with Mo,Cr and B with a complex bainitic microstructure was found to have distinctive high performance behaviour combining continuous yielding, high tensile strength and plasticity after coiling in a wide temperature region. The strain hardening of the micro‐constituents typical for the investigated steels has been analysed to have a better understanding of the mechanical properties of complex phase microstructures in low alloy ferrous alloys. It was found that bainitic ferrite with austenitemartensite islands as a second phase leads to high strength and adequate elongation. The features of the bainite formation in the Mo, Cr and B alloyed CMn steel microalloyed with Ti and Nb during slow cooling from temperatures between 650 and 550 °C was studied by dilatometry. 相似文献
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The superiorities of air-cooled bainitic steels were described. A series of air-cooled bainitic steels containing manganese were developed and presented, which include low carbon granular bainitic steels, low carbon grain-boundary allotriomorphic ferrite/granular bainite dual phase steels, medium and medium high carbon bainite/martensite dual phase steel, low carbon carbide free bainite/martensite dual phase steels and casting bainitic steels.The development of ultra-low carbon bainitic steels in China was also introduced. 相似文献
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The nano-bainitic microstructures were compared in a 0.79C-1.5Si-1.98Mn-0.24Mo-1.06Al (wt%) steel after isothermal heat-treatment and a Fe-0.2C-1.5Mn-1.2Si-0.3Mo-0.6Al-0.02Nb (wt%) steel after controlled thermomechanical processing.The microstructure for both steels consisted of bainite.The microstructural characteristics of bainite,such as the morphology of the nano-bainite and thicknesses of bainitic ferrite and retained austenite layers,as a function of steel composition and processing was studied using transmission electron microscopy (TEM).It was found that the nano-bainitic structure can be formed in the low alloy steel through thermomechanical processing.Atom probe tomography (APT) was employed as a powerful technique to determine local composition distributions in three dimensions with atomic resolution.The important conclusions from the APT research were that the carbon content of bainitic ferrite is higher than expected from paraequilibrium level of carbon in ferrite for both steels and that Fe-C clusters and fine particles are formed in the bainitic ferrite in both steels despite the high level of Si. 相似文献
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摘要:设计了3种不同Si含量的低碳贝氏体钢,进行了不同温度下等温淬火热处理热模拟实验、X-射线衍射和拉伸实验等,研究Si含量对贝氏体相变动力学和贝氏体钢性能的影响。结果表明,随Si含量增加,贝氏体相变量降低,动力学方程参数b减小,n增大。另外,随贝氏体相变温度增加,参数b减小,n增大。而且在较低相变温度下,因Si含量不同造成参数b和n的值的差异更大,说明低温下Si含量对贝氏体相变动力学的影响更大。此外,Si含量越低,因相变温度不同造成贝氏体相变孕育期和完成时间的差异逐渐增大,表明随Si含量的增加,Si对贝氏体相变动力学的影响降低。最后,随着Si含量的增加,试样抗拉强度和伸长率均逐渐增加。研究结果为优化低碳贝氏体钢成分设计、调控其力学性能提供了参考。 相似文献
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采用不同V、Cr含量,结合Nb、Ti、Mo等微合金化的成分设计,控轧控冷、离线回火工艺生产了30 mm厚度规格的低碳贝氏体钢板,钢板的组织为粒状贝氏体、少量针状铁素体以及少量多边形铁素体,钢板的力学性能满足交货需要.使用透射电镜结合能谱仪分析了钢板的析出相情况,结果表明钢板的析出相主要是Nb、Ti的碳氮化物,析出相含有微乎其微的V,而没有Cr;Nb、Ti通过析出对钢板起到析出强化作用,V、Cr在钢中起固溶强化作用,对强度贡献较小. 相似文献
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Dong-Jun Choi Tae-Yeong Kim Hyun-Uk Hong Joonoh Moon Chang-Hoon Lee Dong-Ik Kim Jae-Hyeok Shim Heung Nam Han Young-Su Lee 《国际钢铁研究》2023,94(2):2200103
Herein, a series of low-Mo (0.2 wt%) fire-resistant steels with varying amounts of Ti (0.008–0.13 wt%) are investigated to study the effects of Ti on yield strength at elevated temperatures. At room temperature (RT), precipitation strengthening by nanoscale TiC precipitates is found to be the major factor for the enhanced strength. The amount of TiC precipitates and both the yield and tensile strengths increase monotonically with the Ti content. However, the yield strength ratio (YS at 600 °C divided by YS at RT) of the steel with the highest Ti content (0.13 wt%) is significantly reduced to 0.6. In contrast, the YS ratio of the steels with Ti content in the range of 0.008–0.087 wt% remains above 0.7 and increases with Ti content. The difference between the steels lies in the B content and the resultant bainite volume fraction. The steel with 0.13 wt% Ti does not contain B and has only 4% bainite, whereas the other steels contain 20 ppm B and approximately 60% bainite. Hence, a microstructure with a sufficient fraction of bainite is required to ensure strength at elevated temperatures. The properties can be further improved by Ti precipitation strengthening. 相似文献
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P. S. Bandyopadhyay S. K. Ghosh S. Kundu S. Chatterjee 《Metallurgical and Materials Transactions A》2011,42(9):2742-2752
In the present study, low carbon microalloyed ultrahigh-strength steel was manufactured on a pilot scale. Transformation of
the aforesaid steel during continuous cooling was assessed. The steel sample was thermomechanically processed followed by
air cooling and water quenching. Variation in microstructure and mechanical properties at different finish rolling temperatures
(FRTs) was studied. A mixture of granular bainite and bainitic ferrite along with interlath and intralath precipitation of
(Ti, Nb)CN particles is the characteristic microstructural feature of air-cooled steel. On the other hand, lath martensitic
structure along with a similar type of microalloying precipitates of air-cooled steels is obtained in the case of water-quenched
steel also. The best combination of strength (1440 to 1538 MPa) and ductility (11 to 16 pct) was achieved for the selected
range of FRTs of water-quenched steel. 相似文献