轮缘润滑器安装座失效原因分析

轮缘润滑器安装座故检过程中,渗透检测发现T型焊缝处出现宏观裂纹,该结构材料为Q345钢。通过外观检测、裂纹宏观形貌观察、裂纹断口形貌观察、焊接微观组织观察、冲击断口观察等试验,对结构的开裂原因进行分析。试验结果表明：焊接接头微观组织良好,无明显焊接缺陷,可排除由于组织原因引起构件失效的可能;对比裂纹断口形貌与焊缝金属冲击断口形貌,两者存在较大差异,可排除由于承受较大冲击载荷开裂的可能;裂纹微观断口存在大量疲劳条带,表明结构为疲劳开裂;综合考虑裂纹启裂位置的受力情况,可以判定疲劳开裂的原因是承受载荷部位的应力集中问题。     

焊接工艺参数对超窄间隙焊接热裂纹的影响

超窄间隙焊接中热裂纹是一种很容易出现的缺陷,采用焊剂带约束电弧超窄间隙焊接试验,通过改变焊接工艺参数和间隙宽度,研究其对热裂纹的影响.结果表明,焊缝成形系数与热输入和焊缝成形系数与间隙宽度的匹配关系是决定热裂纹的主要因素.在较小的焊缝成形系数和较大的热输入量下热裂纹倾向较大,并且随着间隙宽度的减小,焊缝中热裂纹倾向明显增加.当焊缝成形系数增大到临界值时焊缝中不产生热裂纹,且临界值随热输入量的增大而逐渐增大,随间隙宽度的增大而逐渐减小.     

2205双相不锈钢在酸性H2S环境下的应力腐蚀行为及开裂机理研究

_{摘要:采用C型环实验研究了2205双相不锈钢在饱和H2S环境下的应力腐蚀行为及开裂机理。研究结果表明,2205双相不锈钢在NACE标准A溶液中有良好的抗应力腐蚀能力。通过OM}、_{SEM、EDS及电化学手段分析得出2205双相不锈钢的应力腐蚀开裂经历了表面点蚀,蚀坑形成,H2S解离,H原子吸附并从蚀坑位置扩散进入金属基体,在金属基体中聚集,通过氢致开裂机制导致裂纹萌生,并逐渐扩展。}     

方坯轧制在线感应加热数值模拟与设计优化

针对方坯感应加热轧制过程容易发生边角升温不均匀的问题,建立了轧件移动式感应加热工况的电磁-传热耦合模型,并进行了有限元数值模拟分析。基于感应加热轧制工业运行数据,验证了模型的合理性,并对感应线圈设计进行了结构优化改进。结果表明,改进设计的感应线圈在钢坯边角部位的磁通密度分布得以明显地改善,工件边角部位的温差得以显著地降低,这有利于解决合金钢方坯轧制过程中常见的边角开裂问题。     

大气环境下1180MPa级超高强钢延迟开裂寿命研究

通过对试验钢进行拉深成形模拟超高强钢实际应用时的应力、应变状态,研究了盐雾和大气环境下DP1180钢、MS1180钢和QP1180钢这3种1180 MPa级超高强汽车薄板钢拉深冲杯试样的延迟开裂寿命.试验结果表明:在盐雾条件下,DP1180钢的抗延迟开裂性能最好,QP1180钢的抗延迟开裂性能最差;但大气环境下,DP1...     

Stress corrosion cracking susceptibility of P285NH and API 5L X65 steel grades in the high-level radioactive waste repository cell concept

Since 2014, the concept developed for the disposal of high-level radioactive waste in the French deep geological repository project Cigéo includes a cement-based grout material. This cement-based grout material will be injected between the casing and the claystone to neutralize the potential acidity resulting from the claystone oxidation induced by the drilling process of the disposal cell. In these conditions of pH (around 10.5) and temperature (90°C, maximum expected during the disposal), the metallic materials could be sensitive to stress corrosion cracking (SCC). In this project, different environments (aerated or deaerated, at room temperature or at 90°C) and synthetic solutions are considered to reproduce the different periods expected during the long life repository. The project is based on electrochemical measurements (polarization curves to define the SCC critical domain of potentials), slow strain rate tensile tests, and long-term immersion for crack initiation and propagation tests.     

催化裂化装置分馏系统腐蚀与防护

催化裂化装置作为石油炼制工业中最重要的二次加工装置,随着原油开采程度的不断加深,加工原油性质的不断劣化,重质油品催化裂化的比例增加,造成催化裂化装置腐蚀趋势加重,影响装置的安全生产.作为重油催化的特有现象分馏塔结盐和顶循环系统腐蚀,已经成为影响装置平稳操作、产品质量和安全生产的重要因素之一.本文简要介绍了催化裂化装置分...     

Correlations among stress corrosion cracking,grain-boundary microchemistry,and Zn content in high Zn-containing Al–Zn–Mg–Cu alloys

The correlations among the corrosion behaviour, grain-boundary microchemistry, and Zn content in Al–Zn–Mg–Cu alloys were studied using stress corrosion cracking (SCC) and intergranular corrosion (IGC) tests, combined with scanning electron microscopy (SEM) and high-angle angular dark field scanning transmission electron microscopy (HAADF-STEM) microstructural examinations. The results showed that the tensile strength enhancement of high Zn-containing Al–Zn–Mg–Cu alloys was mainly attributed to the high density nano-scale matrix precipitates. The SCC plateau velocity for the alloy with 11.0 wt.% Zn was about an order of magnitude greater than that of the alloy with 7.9 wt.% Zn, which was mainly associated with Zn enrichment in grain boundary precipitates and wide precipitates-free zones. The SCC mechanisms of different Zn-containing alloys were discussed based on fracture features, grain-boundary microchemistry, and electrochemical properties.     

一级行星架内孔淬火开裂原因分析

一批风电齿轮箱中42CrMo4钢一级行星架调质后机加工过程中发现内孔开裂。从成分偏析分析、淬火工艺验证、机加工表面磁粉探伤检测、金相分析等方面,对一级行星架进行了分析。结果表明,淬火冷却过于激烈是导致开裂的直接原因,严重的成分偏析是导致淬火开裂的主要原因。