不锈钢裸表面在氯化物溶液中的点腐蚀

研究了不锈钢去膜表面在氯化镁介质中的点腐蚀现象。去膜表面发生点蚀的临界电位低于膜覆盖表面发生点蚀的临界电位。去膜表面的点蚀主要在晶界和夹杂起源。点蚀形貌是敏锐的条纹状花样。根据作者提出的裸表面与氯化物介质反应步骤模型讨论了点蚀特征电位的意义以及裸表面点蚀形成的过程。     

Pitting Corrosion Behavior of Stainless Steel 304 in Carbon Dioxide Environments

The pitting corrosion behavior of stainless steel (SS) 304 in aqueous CO2-H2S-CI-environment was investigated by potentiodynamic cyclic anodic polarization and electron probemicroanalysis (EPMA). The experimental results show that the pitting corrosion susceptivityof SS 304 increases with the increase of temperature. Chlorine ion is the prerequisite for pittingcorrosion of SS 304 in H2S-CO2 environments. There is a linear relatiotxship between the pittingcorrosion potential (Eb-100) and chlorine ion concentration, and Eb-00 becomes noble with in-creasing pH value of the solution with or without H2S. pH value has little effect on the protec-tion potential with the presence of Hz S. H2S increases strongly the pitting corrosion susceptivi-ty and deteriorates the pitting corrosion resistance of SS 304 in CO2 environments. The obser-vations by EPMA show that SS 304 in CO2-saturated NaCI solution (3%) with H2S sufferspitting corrosion accompanied with intergranular corrosion.     

钴元素对SUS304不锈钢耐点腐蚀性能的影响

开发红土镍矿是解决镍资源危机的重点,由于红土镍矿中钴和镍伴生,导致不锈钢中钴元素的存在。本文以SUS304不锈钢钢板和电解钴为原料,采用真空感应冶炼炉和三高石墨铸模浇铸不同钴含量试样,利用线切割机加工腐蚀试样,进行三氯化铁点腐蚀试验。试验结果表明：钴元素的加入增大了铸态SUS304不锈钢点腐蚀敏感性,降低了铸态SUS304不锈钢耐点腐蚀性能,当钴含量小于0．3％时,点腐蚀速率没有增加,当钴含量为0．4％和0．5％时,点腐蚀速率明显增大。     

节镍型不锈钢点状腐蚀缺陷分析及改进

采用SEM、EDS及电化学测试系统等手段,对节镍型不锈钢板表面腐蚀缺陷可能涉及的因素进行分析排查,从而制定了一系列的改进措施。改进后能够有效地抑制腐蚀的发生,保证了产品的表面质量。     

Effects of Cu Content on Inclusions and Pitting Corrosion in S32205 Duplex Stainless Steel

Cu is an austenite-forming element in duplex stainless steel, and the precipitation of Cu-rich phase can improve the strength of the alloy. However, the role of Cu element in the corrosion resistance of stainless steel is widely controversial. Herein, the effects of different Cu content on the formation of inclusions and the pitting resistance of duplex stainless steel are studied by using potentiodynamic anodic polarization test, immersion corrosion, scanning electron microscope, and electron probe microanalysis. The results show that the pitting potential decreases significantly with the increase of Cu content, which greatly reduces its ability to resist Cl⁻ corrosion. The reason is that Cu increases the driving force for the formation of Al-containing oxides, which increases the number and size of Al-containing inclusions formed in the process of melting and solidification. At the same time, Cu promotes the formation of Cr-depleted zone, which promotes the formation of microcracks and pitting corrosion between steel matrix and inclusions in duplex stainless steel.     

Effect of Solution Annealing Temperature on Pitting Behavior of Duplex Stainless Steel 2204 in Chloride Solutions

The effect of solution annealing temperature ranging from 950 to 1 200℃ on the microstructure and corrosion performance of duplex stainless steel(DSS)2204 were investigated.The proportion of the ferrite phase increased while the austenite phase decreased and the ferrite stabilizing elements diluted in the ferrite phase with the increase of annealing temperature.The critical pitting temperature(CPT)of specimens annealed at 1 000℃ was higher than those annealed at 950 ℃,whereas further increasing the annealing temperature to 1 200 ℃ decreased the CPT.The pitting initiation sites were observed in the austenite phase,at the boundary of ferrite/austenite phase and inside the ferrite phase for specimens annealed at 950,1 000℃ and exceeding 1 100℃,respectively.The evolution trend of the CPT and the pit initiation site were analyzed by the pitting resistance equivalent number.     

Phase Transformation and Its Effects on Mechanical Properties and Pitting Corrosion Resistance of 2205 Duplex Stainless Steel

The effects of phase transformation on mechanical properties and pitting corrosion of 2205 duplex stainless steel were investigated. The amount of σ phase in the test specimen varied up to a maximum of 6% by thermal treatment at 850 ℃ for up to 60 min. The results showed that σ phase markedly increased the hardness and decreased the impact toughness of the test steel. But the increasing tendency of the ultimate tensile strength and the yield strength was not obvious, while the total elongation abruptly decreased with the aging time from 5 to 60 min. SEM impact microfractograph analysis revealed that the types of impact fracture changed from ductile mode to transcrystalline mode when the specimens were aged for 5-60 min. Furthermore, the extent of pitting potential reducing was found to be strongly temperature dependent, more pronounced at the higher temperature. During the incubation period of σ phase nucleation, the pitting corrosion test temperature and the aging time had collaborative effects on evidently displacing the pitting potential towards less noble values. After 15 min, the higher temperature contributed more to decreasing the pitting potential than the aging time.     

奥氏体不锈钢302和304的轧制

由于奥氏体不锈钢加Ｔｉ后污染钢液,在钢中形成ＴｉＮ和Ｔｉ(ＣＮ)夹杂,国外含Ｔｉ奥氏体不锈钢的生产量很小(只占0.5%),所以不含Ｔｉ的302和304奥氏体不锈钢得到了广泛应用。302钢号相当于1Ｃｒ18Ｎｉ9,304钢号相当于0Ｃｒ18Ｎｉ9。1　302和304不锈钢的轧制特点(1)钢的导热性差,导热系数相当于低碳钢的27%,加热速度较慢,一般为130℃ｈ。(2)在900～1250℃时有良好的塑性,但热变形抗力很大,随着加工过程中温度的下降,变形抗力急剧增高,因而要控制终轧温度和变形程度,通常轧制时为使终轧温度不低于950℃,轧辊表面不浇冷却水,并控制最大相对压…     

Prediction of Pitting Corrosion Mass Loss for 304 Stainless Steel by Image Processing and BP Neural Network

Pittingcorrosionisafrequentphenomenonen counteredinchemical,petroleumandmechanicalen gineeringandmanyotherindustrialapplication processes.Itcancauseinnumerableenergycon sumptionandeconomicdamage.Inordertoprevent ordecreasethepittingcorrosionofmetallicmate…     

Effects of Mo and Mn on Pitting Behavior of Duplex Stainless Steel

Effects of Mo and Mn elements on pitting corrosion resistance of lean duplex stainless steel in Cl-media solution have been studied.Gravimetric tests in 6 mass% FeCl_3 at 35 ℃ and potentiodynamic analysis in 3.5 mass% Na Cl were carried out.The corrosion potential( Ecoor) and the pitting potential( Epit) are shifted to a more noble potential because of the presence of Mo around the pits.While the presence of Mn could sharply reduce the value of pitting resistance equivalent number( PREn) and the pits can be formed more easily.The pits are found generating at the phase with a lower PREn.The identical tendencies between the Epitand PREn of weaker phase are the same.A corrosion mechanism has been proposed to determinate pitting corrosion behavior based on microstructural observations.     

不锈钢焊缝腐蚀漏液的研究

从材料采购、结构设计、工艺措施、现场管理等方面探讨了不锈钢罐体锈蚀漏液的原因,提出了根除其锈蚀漏液的措施,实践证明效果良好。     

200系列不锈钢耐腐蚀性能研究

通过在3.5%NaCl溶液中动电位极化曲线测定及盐雾试验,对200系列不锈钢和304不锈钢的耐腐蚀性能进行了对比研究。结果发现:200系列不锈钢的耐点蚀及耐均匀腐蚀性能远低于304不锈钢,在3.5%NaCl溶液中,201、202及304不锈钢的点蚀电位分别为-32、-22、312 mV,腐蚀速率分别为0.007 1、0.006 2、0.002 6 mm/a。     

302HQ冷镦用不锈钢线材的研制

通过对钢种化学成分进行合理优化内控,经特定的生产工艺流程,成功开发研制了302HQ冷镦用不锈钢线材。并在研制过程开发出独特的脱氧脱硫工艺和精炼渣系,提高了钢水纯净度。按照相关标准检测,钢种的化学成分和日本同类产品基本一致,钢种冷镦性能良好,热塑性、无磁性已经达到了国内领先水平,完全满足制造标准件的要求,制成的线材表面质量优良。