热轧态Cr、Ni微合金化高强度耐候钢组织与耐蚀性能

采用电化学测试、浸泡实验及SEM、XRD等方法研究了热轧态Cr、Ni微合金化高强度耐候钢组织及耐蚀性能。结果表明:热轧态高强度耐候钢试样组织均由珠光体和铁素体组成,Cr在两相中均匀分布,Ni在铁素体相中含量更多。Cr、Ni含量较高的Q700H耐候钢在3.5%(质量分数)NaCl溶液中具有较低的年腐蚀速率。浸泡60 d后,两种钢自腐蚀电流密度增加,但Q700H钢具有较高的电荷转移电阻和较小的自腐蚀电流密度。浸泡150 d后,Q700H钢表面的点蚀坑较Q500H钢表面的更细小。Cr、Ni含量的增加促进了锈层中致密α-FeOOH的生成;Cr、Ni在锈层中发生富集,Cr集中在内锈层,Ni富集于基体和锈层界面处,且随Cr、Ni含量增加,富集越明显。

Phase-field study on competition precipitation process of Ni-Al-V alloy

With microscopic phase-field kinetic model, atomic-scale computer simulation program for the precipitation sequence and microstructure evolution of the ordered intermetallic compound γ＇ and θ in ternary Ni75AlxV25-x alloy were studied. The simulation results show that Al concentration has important effects on the precipitation sequence. When Al concentration in Ni75AlxV25-x alloy is low, 0（Ni3V） ordered phase will be firstly precipitated, followed by γ＇（Ni3Al） ordered phase. With Al concentration increasing, θ and γ＇ ordered phases are simultaneously precipitated. With A1 concentration further increasing, γ＇ ordered phase is firstly precipitated, followed by θ ordered phase. There is a competition relationship between θ and γ＇ ordered phases during growth and coarsening process. No matter which first precipitates, θ ordered phase always occupies advantage in the competition process of coarsening, thus, the microstructure with preferred orientation is formed.

Microstructure and microtexture evolution of undercooled Ni-15%Cu alloy

Rapid solidification of undercooled Ni-15%Cu （mole fraction） alloy was studied using glass fluxing and cyclic superheating. To show the effect of cooling history on the microstrucyure and microtexture evolution, the as-solidified samples were either cooled naturally or quenched into water after recalescence. At low undercooling, grain-refined microstructure has a random texture and a highly oriented texture without annealing twins for the case of naturally cooling and quenching, respectively. At high undercooling, a fully random texture as well as a number of annealing twins are observed, and recrystallization and grain growth independently happen on the cooling history. Fluid flow and recrystallization play an important role in the microtexture formation for grain refinement at both low and high undercooling.

Q420D热轧高强耐低温叉车门架槽钢的研究开发

采用钒、镍微合金化技术思路设计出Q420D热轧高强耐低温叉车门架槽钢的化学成分,并制定合适的冶炼、轧制工艺进行工业化试验。结果表明:屈服强度、抗拉强度、冲击韧性、疲劳性能等完全满足工业使用要求。

高强度风电螺栓用钢的材料选择与性能研究

承德建龙生产的风电螺栓用钢,根据质量要求、使用规格、生产成本选择最合适材料42CrMoA;采用不同成分配比、不同热处理工艺优化淬火设备,显著改善风电紧固件用钢的内部质量,保证回火索氏体级别为1级~2级,进而提高力学性能至抗拉强度1080Mpa~1140Mpa,-40℃冲击功≥50J,成本最优的前提下满足10.9级风电螺栓的质量要求。

石油钻采平台用Q390E耐低温热轧H型钢的研究开发

采用铌镍微合金化设计出Q390E耐低温H型钢的化学成分,通过合理的冶炼轧制工艺控制铌镍微合金化过程,避免腹板裂纹的产生及粗大晶粒的出现。实验结果表明屈服强度达到430Mpa,抗拉强度达到552Mpa,伸长率达到22.6%,-40℃的冲击韧性Akv>72J。