共查询到17条相似文献,搜索用时 140 毫秒
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摘要:连铸过程中铌的氮化物、碳化物和碳氮化物在奥氏体晶界的析出对铸坯的质量产生严重的影响。分析了500MPa级高强度抗震钢筋(HRB500E)中铌的氮化物、碳化物和碳氮化物在液相、凝固过程以及奥氏体相等不同阶段的析出热力学,计算了不同温度下NbN和NbC的平衡/实际浓度积,得到NbN和NbC在微合金钢连铸过程中的析出规律。计算结果表明:在HRB500E钢中,NbN、NbC在钢液成分均质状态和凝固过程中难以析出;在奥氏体相中,随着温度的降低,NbC、NbN及NbC0.85N0.15具备析出热力学条件,析出温度分别为1377、1229 和1378K,析出顺序依次为:NbC0.85N0.15、NbC、NbN。 相似文献
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《钢铁研究学报》2020,(8)
连铸过程中铌的氮化物、碳化物和碳氮化物在奥氏体晶界的析出对铸坯的质量产生严重的影响。分析了500 MPa级高强度抗震钢筋(HRB500E)中铌的氮化物、碳化物和碳氮化物在液相、凝固过程以及奥氏体相等不同阶段的析出热力学,计算了不同温度下NbN和NbC的平衡/实际浓度积,得到NbN和NbC在微合金钢连铸过程中的析出规律。计算结果表明:在HRB500E钢中,NbN、NbC在钢液成分均质状态和凝固过程中难以析出;在奥氏体相中,随着温度的降低,NbC、NbN及NbC_(0.85)N_(0.15)具备析出热力学条件,析出温度分别为1 377、1 229和1 378 K,析出顺序依次为:NbC_(0.85)N_(0.15)、NbC、NbN。 相似文献
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针对Fe-Nb-Ti-C-N系统, 利用双亚点阵模型对DH36钢中碳氮析出物析出条件进行热力学计算.计算结果表明, 钛的碳氮化物析出温度为1 380 ℃, 铌的碳氮化物析出温度为1 100 ℃.其中在1 100~1 400 ℃的高温区, TiN为影响奥氏体均热阶段晶粒长大的主要因素.在1 100 ℃以下的低温区NbC、TiC是抑制DH36钢中奥氏体再结晶及再结晶后奥氏体长大的重要因素. 相似文献
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HRB500E抗震钢筋中钛化物析出热力学分析 总被引:1,自引:0,他引:1
钢液凝固过程中钛化物在液相、固相的存在形态对固相组织的性能有着重要的影响,其第二相析出起到细化晶粒的作用。为分析HRB500E抗震钢筋钢中TiN、TiC、Ti(C,N)析出物的析出规律,对TiN、TiC、Ti(C,N)析出物进行热力学计算。结果表明,TiN、TiC在钢液成分均质状态下难以析出,TiC0.19N0.81在温度为1 843 K时析出;在凝固过程中,由于Ti、N在凝固前沿富集,TiN在凝固过程中具备析出的热力学条件,析出温度为1 745 K;在固相奥氏体中,TiN和TiC粒子具备析出热力学条件,TiC析出温度比TiN的低,铁素体中有TiC的析出。 相似文献
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一种Nb-Ti微合金钢微合金碳氮化物析出行为的研究 总被引:8,自引:1,他引:7
利用热模拟和TEM技术研究了Nb—Ti微合金钢中微合金碳氮化物的析出行为,研究结果表明,高温奥氏体区析出的微合金碳氮化物数量随变形量的增大而增加,尺寸随着变形温度的升高稍有增大。铁素体区析出的微合金碳氮化物尺寸比在形变奥氏体中析出的更为细小,数量随着保温时间的增加而增多,但尺寸变化不大;当温度较低的时候,微合金碳氮化物主要在位错线等晶内缺陷处析出。 相似文献
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P. S. Bandyopadhyay S. Kundu S. K. Ghosh S. Chatterjee 《Metallurgical and Materials Transactions A》2011,42(4):1051-1061
The current study concerns the development of a low-carbon, microalloyed ultra-high-strength steel on a pilot scale. The continuous
cooling transformation has been evaluated, and a flat top “C” curve with a mixed microstructure of bainite and martensite
has been obtained at a lower transformation temperature. The steel has been processed thermomechanically, followed by air
cooling and water quenching. In addition, a variation in microstructure and mechanical properties at different finish rolling
temperatures has been studied. Although a mixture of granular bainite and bainitic ferrite with interlath and intralath precipitation
of NbC/NbC(N)/TiC(N) particles are the characteristic microstructural feature of air-cooled steel, the lath martensitic structure
along the fine NbC/NbC(N)/TiC(N) precipitate is obtained in case of a water-quenched steel. The high-strength value obtained
in the current steel is caused by the accumulated contribution of fine-grained, pancaked austenite, highly dislocated fine
lath martensitic structure along with the presence of tiny precipitates of microalloy carbide/carbonitride. 相似文献
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Transmission electron microscopy was used to investigate the particle size distribution, morphology, composition, and crystallography of microalloy (Ti, Nb) precipitates in 4130 steels between 900 to 1250 °C. Considering the Ti fraction, the size and the morphology, two types of precipitates were identified: cuboidal coarse TiNbMo carbonitrides, rich in TiN and a fine dispersion between 2 to 25 nm of TiNbMo carbides. The progressive formation of higher soluble phases, such as NbC and MoC, was observed on the pre‐existent, TiN and TiC precipitates. In the studied conditions, nitrides were found to be insoluble and quite resistant to coarsening. On the contrary, carbides not only began dissolution in the range of 960 ‐ 1000 °C according to the microalloy content in the steel, but also produced abnormal grain growth. 相似文献
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The formation of precipitates during thermal processing of microalloyed steels greatly influences their mechanical properties.
Precipitation behavior varies with steel composition and temperature history and can lead to beneficial grain refinement or
detrimental transverse surface cracks. This work presents an efficient computational model of equilibrium precipitation of
oxides, sulfides, nitrides, and carbides in steels, based on satisfying solubility limits including Wagner interaction between
elements, mutual solubility between precipitates, and mass conservation of alloying elements. The model predicts the compositions
and amounts of stable precipitates for multicomponent microalloyed steels in liquid, ferrite, and austenite phases at any
temperature. The model is first validated by comparing with analytical solutions of simple cases, predictions using the commercial
package JMat-PRO, and previous experimental observations. Then it is applied to track the evolution of precipitate amounts
during continuous casting of two commercial steels (1004 LCAK and 1006Nb HSLA) at two different casting speeds. This model
is easy to modify to incorporate other precipitates, or new thermodynamic data, and is a useful tool for equilibrium precipitation
analysis. 相似文献
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Fanjun Ma Guanghua Wen Ping Tang Guodong Xu Feng Mei Wanlin Wang 《Metallurgical and Materials Transactions B》2011,42(1):81-86
In the continuous casting of the microalloyed steel, the slab surface transversal cracking could be prevented through the
control of the slab surface microstructure, which correlates with the precipitation behavior of carbonitrides in the microalloyed
steel. Therefore, the cooling rate is the key factor to determine the precipitation behavior of carbonitrides. This article
used confocal laser scanning microscopy to study the effect of different cooling rates on the precipitation behavior of the
carbonitrides in the microalloyed steel slab. When the cooling rate is less than 3 K·s−1, the precipitates in the steel are coarse, growing out along the austenite grain boundaries, and form a chain-like distribution.
These precipitates seriously reduced the hot ductility of slab. Quantitative study between the cooling rate and the precipitation
behavior of carbonitrides in microalloyed steel also has been developed. The results of this study could be used to improve
the understanding of the slab surface microstructure controlling to enhance the hot ductility of the slab and avoid the surface
crack of the slab. 相似文献
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氮在非调质钢中的作用 总被引:10,自引:1,他引:9
了氮在非调质钢中所起的有益作用。在Nb,V,Ti三咱微合金化元素中,钒有较高的溶解度,钒有较高的溶解度,是非调质钢最常用也是最有效的强化元素。钒在钢中通过形成细小析出相起细化晶粒和沉淀强化作用。与碳相比,氮与钒有更强的亲和力,且氮化物更稳定,因此,氮对控制钒的析出起更重要的作用。大量研究结果表明,非调质钢中增氮改变了钒在相间的分布,促进V(C,N)析出,使析出相的颗粒尺寸明显减小。因而氮增强了非调 相似文献