Electrochemical and analytical study of corrosion inhibition on carbon steel in HCl medium by 1,12-bis(1,2,4-triazolyl)dodecane

1,12-bis(1,2,4-triazolyl)dodecane (dTC12) is an excellent corrosion inhibitor for carbon steel in deaerated 1 M HCl solution. In this work electrochemical and analytical techniques were used to study the inhibition of corrosion on carbon steel in acidic medium. The carbon steel corrosion inhibition of dTC12 was attributed to the synergistic effect between chloride anion and quaternary ammonium ion. The protective efficiency of the film was higher than 90%, indicating that corrosion of carbon steel in 1 M HCl is reduced by dTC12.The effect of dissolved oxygen on the inhibition efficiency was also investigated. The results show that the inhibition efficiency increases in early stage and decreases for a long immersion time.     

Hydrogen embrittlement of high strength steel electroplated with zinc-cobalt alloys

Slow strain rate tests were performed on quenched and tempered AISI 4340 steel to measure the extent of hydrogen embrittlement caused by electroplating with zinc-cobalt alloys. The effects of bath composition and pH were studied and compared with results for electrodeposited cadmium and zinc-10%nickel. It was found that zinc-1%cobalt alloy coatings caused serious hydrogen embrittlement (EI 0.63); almost as severe as that of cadmium (EI 0.78). Baking cadmium plated steel for 24 h at 200 °C gave full recovery of mechanical properties but specimens plated with zinc-1%cobalt and then baked still failed in 89% of the time of unplated controls. It was shown that hydrogen uptake and embrittlement could be controlled by depositing thin layers of cobalt or nickel at the steel/coating interface. For example, the least embrittlement was caused by zinc-10%nickel (EI 0.037) due to a nickel rich layer with very low hydrogen diffusion coefficient that formed during the initial stages of electroplating. Similarly, a 0.5 μm nickel layer was effective in lowering the embrittlement caused by zinc-1%cobalt to that of zinc-10%nickel. Furthermore, a 0.5 μm cobalt layer deposited before a zinc-1%cobalt coating gave virtually 100% recovery of mechanical properties after baking.     

不锈钢复合板热疲劳性能分析

利用冷热疲劳试验机模拟分析了冷热循环对不锈钢复合板热疲劳性能的影响,并采用扫描电镜、电子探针和电子背散射衍射仪对热疲劳试样V形缺口及裂纹区域的形貌和成分进行了深入分析。结果表明,不锈钢复合板热疲劳试样经 20~550 ℃ 7 500次冷热循环后,结合界面处V形缺口区出现微裂纹,且微裂纹起裂于V形缺口尖端基层侧。随着冷热循环的继续进行,微裂纹向基层内扩展,但并非沿着结合界面处扩展,而是沿着基层侧扩展。此外,热疲劳裂纹的起裂和扩展与氧化和应力作用有关,微裂纹起裂于热疲劳试样 V 形缺口区域基层侧表层局部氧化孔洞,并在冷热循环的应力作用下向基层内扩展,同时加剧氧化。随着冷热循环的继续进行,晶界氧化逐渐加剧,导致微裂纹扩展成更为明显的裂纹。     

Q390高强抗震钢板残余应力检测方法对比及分析

利用盲孔法、X-Ray法、中子衍射法和超声法对Q390高强抗震板及U形弯曲件进行残余应力检测,并对这4种方法测试得到的应力结果进行分析研究。结果表明,以上4种检测方法均要考虑其特定的检测应用范围,X-Ray法针对钢板表面下微米级深度的微米级晶格尺度范围局部点应力进行检测,中子衍射法可在毫米级尺度局部区域进行应力检测,盲孔法反映的是因毫米尺度钻孔导致的钢板表面孔周边的应力变化,超声法则可以通过连续扫描检测整个钢板残余应力的宏观分布变化。因此,对于工业钢板,超声法测试残余应力更加科学、合理、准确。同时,通过U形试样建立稳定的应力应变场,利用超声设备使用不同参考态对Q390高强抗震板弯曲件及退火弯曲件进行测试,结果表明,测试参考态的选取对应力测试结果影响很大,材料各向异性的影响对应力测试结果不可忽视。     

含铜抗菌不锈钢的应用研究现状

含铜(Cu)抗菌不锈钢是一类结构/功能一体化金属新材料,目前已经具备稳定的工业规模生产能力。为应对日常生活、医疗领域和海洋工程装备领域所遇到的细菌微生物污染问题,已经开发出适用于相应领域的多种含Cu抗菌不锈钢新材料。为了探索新阶段含Cu抗菌不锈钢的研发方向,综合介绍了含Cu抗菌不锈钢关键性能的研究进展及在多领域的应用现状,并分析了时代发展给该领域所带来的新的问题与挑战。     

Ce对440C不锈轴承钢夹杂物演变的影响

为探究稀土Ce对440C不锈轴承钢中夹杂物的改性作用,利用实验室MoSi₂电阻炉对440C不锈轴承钢进行稀土Ce处理,采用OM、SEM等系统分析了Ce的添加对440C不锈轴承钢脱氧及夹杂物演变的影响。结果表明,随着Ce加入量的增加,其收得率逐渐升高。Ce的加入使钢中TO质量分数由0.002 5%降低至0.001 2%。未加入Ce的钢中夹杂物主要为Al₂O₃、MnS以及镁铝尖晶石;加入质量分数为0.011 5%的Ce后,夹杂物被改性为以Ce-Al-O为主的夹杂物;当Ce的添加量达到0.036 4%时,夹杂物被完全改性为Ce-O-S夹杂物。适量的Ce可以降低夹杂物尺寸及面积比例,但过量加入会使夹杂物尺寸变大。在本试验条件下,当Ce质量分数为0.011 5%时,钢中夹杂物细小弥散效果最明显。以上结论可为Ce在高碳铬不锈轴承钢中的应用提供参考。     

IF钢切边质量提升控制技术

针对 IF 钢经过连退或镀锌热处理,在切边过程中由于切边质量不佳,带钢边部容易产生毛刺等缺陷,进而影响带钢边部质量的问题,通过研究切边后带钢切断面各区域比例以及切边工艺参数对切边后切断面各区域比例的影响,对圆盘剪切边工艺参数进行了优化设计;同时通过研究去毛刺辊工作原理以及亮边缺陷产生原因,对去毛刺辊的涂层和底辊辊型进行了优化设计。采取优化措施后,IF 钢的切边质量得到了改善,并彻底消除了亮边缺陷。     

海洋工程用钢的大气腐蚀与耐候钢的发展

综述了海洋工程用钢的大气腐蚀行为与耐候钢发展方面的研究,特别是近十余年来国内外的相关成果。首先介绍了钢大气腐蚀的电化学模型,并从耐候钢特殊的锈层结构与合金元素作用两方面论述了耐候钢的锈层保护机制;然后分析了环境因素,包括相对湿度与污染物、光照、锈层损伤等,对耐候钢大气腐蚀行为的影响;最后总结了耐候钢的发展历程以及晶粒尺寸与显微组织等非合金因素在耐候钢发展中的作用,可为新型耐候钢的设计与应用提供指导。     

转炉炼钢出钢过程的数值模拟

不同直径的出钢口决定转炉出钢流场的分布,从而影响出钢过程的钢水温降,而钢水温降直接影响转炉出钢温度以及炼钢生产节奏。为掌握出钢过程中的温降规律以及设计合理的出钢口参数,利用Ansys软件包建立三维转炉及钢包模型,借助数值模拟方法,研究得到200 t转炉在不同尺寸出钢口下的出钢流场数据,进而针对出钢过程中的钢水注流,研究出钢口尺寸及钢包内壁温度对注流温降的影响规律。研究发现,钢水注流的温降与注流比表面积成正比;另外在出钢早期,内壁温度每提升100 K,注流温降平均减小0.4~0.7 K。后续将继续开展出钢过程中钢包及合金辅料对钢水温降影响规律的研究,以期为转炉出钢工艺提供数据支撑。     

Characterization of blasted austenitic stainless steel and its corrosion resistance

It is known that the corrosion resistance of stainless steel is deteriorated by blasting, but the reason for this deterioration is not clear. A blasted austenitic stainless steel plate (JIS-SUS304) has been characterized with comparison to the scraped and non-blasted specimens. The surface roughness of the blasted specimen is larger than that of materials finished with #180 paper. A martensite phase is formed in the surface layer of both blasted and scraped specimens. Compressive residual stress is generated in the blasted specimen and the maximum residual stress is formed at 50–100 μm from the surface. The corrosion potentials of the blasted specimen and subsequently solution treated specimen are lower than that of the non-blasted specimen. The passivation current densities of the blasted specimens are higher those of the non-blasted specimen. The blasted specimen and the subsequently solution treated specimen exhibit rust in 5% sodium chloride (NaCl) solution, while the non-blasted specimen and ground specimen do not rust in the solution. It is concluded that the deterioration of corrosion resistance of austenitic stainless steel through blasting is caused by the roughed morphology of the surface.