355 MPa级转向架构架用钢连续冷却转变行为

高速动车组转向架构架对高速动车组的运行品质、行车安全起到至关重要的作用。为向355 MPa级转向架构架用钢的工业试制提供指导，在Gleeble-3800热模拟试验机上进行了热模拟试验，结合热膨胀法和金相-硬度法，绘制了355 MPa级转向架构架用钢动态连续冷却转变曲线，研究了试验钢在连续冷却条件下的显微组织演变规律。结果表明，冷速小于1 ℃/s时，其组织主要为多边形铁素体和珠光体；冷速大于5 ℃/s时，贝氏体类组织快速增加；冷速达到50 ℃/s时，为板条贝氏体组织。因此，对于355 MPa级转向架构架用钢，冷速控制在1~5 ℃/s较为适宜，其组织主要由比例适中软硬性相结合的铁素体、珠光体和贝氏体构成，可以获得优良的强韧性匹配。     

1 200 MPa级冷轧先进高强钢轧制稳定性的分析及控制

针对1 200 MPa级冷轧先进高强钢轧制不稳定问题,对热轧原料组织性能均匀性、冷轧压缩比、冷连轧机组轧制策略等进行了分析。结果表明,热轧工序投入边部加热器,采用分段冷却等手段,可有效降低热轧原料头尾部组织性能差异,保证通卷性能均匀,进而保证通卷轧制过程稳定;通过优化冷连轧机组压缩比,可有效降低材料本身的加工硬化强度,进而避免连轧机组后面机架的轧制超负荷情况;通过优化冷连轧机组轧制策略,可保证轧制过程中各机架均匀变形,避免出现轧制力差异较大的情况,进而保证轧制过程稳定。采用上述措施,1 200 MPa级冷轧先进高强钢轧制力控制在约15 000 kN,厚度精度控制在±0.06 mm以内,可保证该级别高强钢的稳定轧制。     

Effect of Indirect Transformation of Retained Austenite During Tempering on the Charpy Impact Toughness of a Low-Alloy Cr-Mo-V Steel

A modified tempering treatment has been designed in order to avoid the direct transformation of retained austenite (Ar) during tempering of a low-alloy Cr-Mo-V steel. Instead of the direct transformation of Ar into ferrite and M₂₃C₆ carbides during conventional tempering at 700 °C, transformation into aggregate of ferrite and cementite has been forced by a pre-tempering at 455 °C before conventional tempering. Experiments have been performed on specimens quenched with cooling rates 1.5, 3 and 12 °C/s, providing different types of Ar within the as-quenched microstructures. The results show that the tempering modification does not improve the Charpy impact toughness at the highest quenching rate of 12 °C/s, where the specimens cannot incur cleavage cracking induced from fine and discontinuous M₂₃C₆ carbides along lath interfaces. For the lowest quenching rate 1.5 °C/s, the Charpy impact toughness can be improved, and the failure is dominated by carbide aggregates, which originate from the decomposed products of blocky Ar. This is because the tempering modification effectively suppresses the formation of coarse M₂₃C₆ carbides at interfaces between the carbide aggregate and bainitic matrix, thereby resulting in a relatively homogeneous distribution of M₂₃C₆ carbides inside carbide aggregates. Therefore, the tempering modification is recommended for large-scale forgings, in which relatively high quenching rates are difficult to achieve.     

Ultra-thin Laminated Metal Composites with Ultra-high Strength and Excellent Soft Magnetic Properties

Structural metallic materials with excellent functional performance and lightweight features have always been the goal of material scientists' pursuit.In this work,laminated metal composites of different thicknesses(less than 0.4 mm) composed of structural materials with great differences in deformation ability were successfully fabricated via a novel processing procedure.Ultra-high strength and excellent soft magnetic properties were combined perfectly in the ultra-thin and super-light laminated metal composite strips due to unique structural design and essential attributes of the initial materials.These results emphasize the significant potential application value of the ultra-thin laminated metal composites in the field of structural and functional integration.     

中锰Q&P钢连续退火过程碳元素分配行为

采用扫描电镜、X射线衍射等研究了连续退火工艺中退火、淬火和配分等关键过程参数对中锰Q&P钢碳元素分配行为的影响,并分析了相应工艺条件下残留奥氏体量与碳含量的关系。结果表明:两相区退火温度的提高会导致奥氏体中的碳含量下降,微观组织表现为奥氏体含量增加,渗碳体量减少;退火时间10~60 s时,随着退火时间的延长,奥氏体含量和碳含量急剧增加,60 s后基本保持稳定;试验条件下淬火温度对残留奥氏体及碳含量的影响不显著;配分温度350~500℃时,随着配分温度的提高,奥氏体含量和碳含量呈现先增加后减小的趋势,配分温度450℃时均达到最大值;延长配分时间,残留奥氏体含量呈现先减少后增大再减少的趋势,残留奥氏体中的碳含量先减小后增加。     

铁素体/贝氏体双相钢循环载荷作用下变形行为的模拟研究

为了避免铁素体/贝氏体双相钢管线管在服役过程中的交变载荷作用下引起的塑性损伤，采用有限元模拟方法，建立了Chaboche随动强化模型，研究了铁素体/贝氏体双相钢在循环应变载荷作用下的变形行为。结果显示，在循环应变作用下，应变优先在铁素体中形成累积，并在铁素体、贝氏体界面集中；随应变幅的增大，应变带在铁素体中形成，而贝氏体内累积应变增加不大，两相界面应变差增大。研究表明，铁素体内应变和两相应变差的增加将降低双相钢的塑性变形能力。     

热变形工艺对含硫非调质钢流变应力及组织的影响

在变形温度950~1150 ℃和应变速率0.01~5 s^-1下,通过Gleeble-3500热模拟试验机进行单道次压缩试验,研究了热变形工艺对含硫非调质钢F45MnVS流变应力及组织的影响。结果表明:随着应变速率的增大,热压缩过程中的峰值应力增加,随着温度的升高,峰值应力降低;动态再结晶平均晶粒尺寸随着应变速率、变形量的增加而减小,随着温度的提高而增大。     

不锈钢表面阻氢涂层研究进展

不锈钢是高压氢系统的常用材料，在氢能储输技术中发挥重要作用，但高压氢环境引起的塑性降低、疲劳裂纹扩展速率加快等不锈钢氢脆问题，严重阻碍了氢能的产业化发展，在不锈钢材料表面制备阻氢涂层是解决不锈钢氢损伤问题的重要手段之一。本文首先综合介绍了典型涂层材料的应用特点及阻氢性能，探讨了制备工艺对涂层阻氢性能的影响、不同涂层材料的阻氢机理，并分析了涂层阻氢性能影响因素，之后总结了涂层阻氢性能评价方法及各种评价方法的优势与不足，并根据各种评价方法的技术特点，指出每种方法的适用范围。最后，基于阻氢涂层研究进展，文章提出以开发新型涂层结构为研究重点，同时加快新型涂层材料的探索，并重点关注涂层氢环境原位性能评价方法的研究。     

铝碳质长水口用低铝抗氧化涂层的研制

为抑制铝碳质长水口使用过程中石墨的氧化，其表面会涂覆含 20%~30%Al₂O₃的抗氧化涂层，但切割丝钢等特种钢冶炼过程必须严格控制钢液中夹杂的 Al₂O₃的含量，因此需要制备低氧化铝含量的抗氧化涂层。本文通过调节涂料组成、加水量和水玻璃加入量制备了低铝抗氧化涂层，并利用扫描电镜分析了抗氧化实验后试样断口的显微结构。结果表明：以粘土粉、钾长石粉和硅砂为主要原料，添加 10%硼砂的涂料可在 800 ℃形成良好的釉层，此时涂料中 A12O3的含量可降至 12%，得到了低铝涂料；当加入占涂料质量 80%的水和 40%的水玻璃时，涂层具有最佳的涂覆性能和抗氧化性能，涂层和长水口基体结合致密，保护了长水口中的石墨不被氧化。     

Effect of microbial hydrogen consumption on the hydrogen permeation behaviour of AISI 4135 steel under cathodic protection

The feasibility of microbial hydrogen consumption to mitigate the hydrogen embrittlement (HE) under different cathodic potentials was evaluated using the Devanathan-Stachurski electrochemical test and the hydrogen permeation efficiency η. The hydrogen permeation efficiency η in the presence of strain GA-1 was lower than that in sterile medium. The cathodic potential inhibited the adherence of strain GA-1 to AISI 4135 steel surface, thereby reducing the hydrogen consumption of strain GA-1. The adherent GA-1 cells were capable of consuming ‘cathodic hydrogen’ and reducing the proportions of absorbed hydrogen, indicating that it is theoretically possible to control HE by hydrogen-consuming microbes.