Corrosion-Electrochemical behavior of 13% chromium (Cr) martensitic stainless steel in hydrochloric acid (HCl) solutions

Corrosion-Electrochemical behavior of a commercial API5CT grade L80 type 13Cr tubing enriched with microalloying elements is studied in 6, 7.5, 9, 12 and 15% HCl solutions by electrochemical methods. The objective is to contribute to the comprehension of corrosion phenomena caused by HCl of similar concentrations, generally used in acidizing job. The corrosion morphology is examined by scanning electron microscopy (SEM) coupled with EDAX. The soluble corrosion products are analyzed by atomic absorption spectroscopy and colorimetric methods. General, as well as localized, corrosion is present. The severest general corrosion with a maximum rate of 26 mm/year is obtained at 15% HCl. The localized corrosion which morphologically differs as function of HCl concentrations is revealed by SEM investigation. In all the above HCl solutions, the commercial 13% Cr martensitic stainless steel tubing shows no passive state. Above 6% HCl, the microalloying elements promote forming a discontinuous film of the corrosion products. The corrosion rate slightly decreases in 15% HCl compared to the published data on a conventional 13% Cr martensitic stainless steel tubing. This is due to both the chemical composition (silicon, manganese and vanadium) and microstructural properties. Copper seems to additionally accelerate the corrosion of the alloy. Published in Russian in Zashchita Metallov, 2007, Vol. 43, No. 4, pp. 372–380. The article was translated by the authors in English.     

Thermal stability behaviors of Cr(N,O)/CrN double-layered coatings by TGA/DTA analysis

In this study, Cr(N,O)/CrN double-layered coatings were synthesized using the cathodic arc deposition (CAD) process. CrN film was first deposited onto a substrate as an interlayer to ensure better adhesion, and Cr(N,O) film was subsequently deposited on top of the CrN layer as the surface layer. Variation in the Cr(N,O) coating composition was achieved through changing the O₂/N₂ flow ratio during the last stage of processing. Phase structure, chemical composition, and morphology of the resulting coatings were analyzed and observed using the X-ray diffractometer, Auger electron spectrometer and SEM. In addition, oxidation behavior of the coatings was investigated using TGA/DTA methods. The tests were carried out by increasing temperature up to 1000 °C in ambient air. With the introduction of oxygen gas during the CAD process, a superficial layer was produced in the Cr(N,O) constituent containing CrN and Cr₂O₃ phases. The formation of the oxide phase attributed to the reaction of chromium and oxygen was more favorable than that of chromium and nitrogen. The results also showed that Cr(N,O)/CrN double-layered coatings exhibited superior oxidation resistance at elevated temperature than that of CrN single-layer coated specimen (870 °C vs. 750 °C).     

Ti-26高强钛合金斜轧穿孔工艺研究

研究了Ti-26高强钛合金斜轧穿孔制备管坯工艺。测试了穿制的Ti-26合金管坯的力学性能，用金相显微镜观察了管坯的显微组织，用扫描电镜分析了拉伸断口的形貌。结果表明，采用斜轧穿孔方式完全可以制备Ti-26高强钛合金管坯；在1050℃下，选择合适的轧辊转速和前进角可顺利穿制Ti-26高强钛合金管坯，其管坯的强度为815MPa，延伸率达到13％，断面收缩率达到45％，晶粒度按ASTME标准为6级，比穿孔前细化，断口呈明显的塑性断口，加工管材无需热处理可以直接进行轧制，道次加工率可达45．8％。     

3Cr2W8V钢锻件表面裂纹的成因及预防措施

通过对难变形钢3Cr2W8V进行实验,证明了合理地选择锻造工艺参数,也是解决表面裂纹的重要途径之一。     

GCr15钢激光淬火层的奥氏体晶粒尺寸

ＧＣｒ１５钢激光淬火层的晶粒尺寸可在很大范围内变化，从约３０μｍ到小于２μｍ。以激光光斑为中心，相距越远，晶粒尺寸越细小，晶粒尺寸的变化与激光加热时理论推导的温度场存在对应关系。激光扫描速度对激光淬火层的奥氏体晶粒尺寸有显著的影响，原始组淬火层体晶粒尺寸影响较小，ＧＣｒ１５钢激光淬火层奥氏体晶粒尺寸的研究为激光淬火工艺的制订提供了重要的参考依据。     

晶界碳化物对Fe-Cr15-Ni25合金蠕变裂纹扩展行为的影响SCIEI

在两种不同晶界状态下研究了Fe-Cr15-Ni25合金的蠕变裂纹扩展行为。单相合金的空洞在晶界三叉点处形核,而对晶界上有碳化物析出的合金,空洞在晶界碳化物上形核。晶界碳化物阻碍了空洞的长大和连接,因而大大提高了蠕变裂纹扩展抗力。     

金属型铸造高铬白口铸铁磨球的复合变质处理研究

研究了复合变质处理对金属型铸造的高铬格白口铸铁磨球组织及性能的影响。结果表明，采用ＲＥ、Ｂ、Ｖ、Ｔｉ元素复合变质处理，可有效细化磨球结晶组织，改善碳化物的形态与分布，并显著提高冲击韧性和耐磨性能。     

利用"正火液"作为高铬铸铁磨球淬火介质的生产实践

高铬铸铁件在没有添加贵重元素的条件下,利用"正火液"配入适量的水作为淬火介质进行了试验和生产.实践证明,产品在热处理淬火时从未发生炸裂现象,同时完全达到了要求的力学性能指标.生产的锤头其使用寿命为高锰钢的6～8倍,为低铬白口铸铁的4～6倍.     

00Cr17Ni14Mo2不锈钢的性能及应用研究

研究了00Crl7Nil4M02不锈钢材料的机械性能、焊接性能和耐腐蚀性能，从用户和研究开发的角度探讨了其在压力容器、化工装置、化肥装置、海洋装置和建筑业等领域的应用。     

ZG3Cr18Ni25Si2耐热钢熔炼工艺的改进

介绍了改进后的ZG3Cr18Ni25Si2耐热钢熔炼工艺及特点，它具有较高的合金元素收得率，铸件的使用寿命比改进前延长了35％－45％。