碳钢及低合金钢点蚀性能的研究

选择三种典型的碳钢、低合金钢,通过极化试验比较了它们之间的点蚀诱发敏感性和模拟孔蚀的“闭塞腐蚀电池”,试验研究了它们之间的孔蚀扩展行为。结果表明,B钢的点蚀诱发能力小于A钢和C钢;在同样的阴极极化电位下,B钢的阳极溶解电流也明显小于后两者。电子探针分析了不同夹杂物在诱发点蚀过程的腐蚀特征,夹杂物是钢中主要的点蚀诱发源。显微分析“闭塞腐蚀电池”腐蚀形貌,发现腐蚀形貌具有平行沟槽状。初步分析原因是沿轧向延伸的磷偏析带及夹杂物所导致的。扫描电镜和能谱仪对腐蚀产物的形貌、成分分析结果表明：B钢的锈层均匀致密,而A钢的锈层呈网状、疏松且有大量裂纹和孔洞。     

几种典型耐海水钢耐点蚀性能的比较

选择了三种典型的耐海水腐蚀钢,在pH为10的3%(wt.%)NaCl溶液中进行了极化试验,比较了钢的点蚀诱发敏感性;在3%(wt.%)海盐水和人造海水中分别进行了间浸挂片试验和模拟闭塞腐蚀电池试验,评价了钢的点蚀扩展速度;利用金相显微镜、电子探针(EPMA)、扫描电镜(SEM)和X射线衍射(XRD)分析了钢中夹杂物、腐蚀形貌和锈层的特征。结果表明,Ni-Cu-P钢的点蚀诱发敏感性比Cr-Cu-Ni钢强,Cr-Cu-P钢最弱。在相同条件下,Cr-Cu-P和Cr-Cu-Ni钢的点蚀扩展速度接近,但都明显大于Ni-Cu-P钢。四种钢的内锈层主要组成均为Fe3O4、α-FeOOH和和少量的非晶化合物,但Cr-Cu-P和Cr-Cu-Ni钢的内锈层明显比Ni-Cu-P钢致密。在酸化的蚀坑内,Cr可降低钢基体的电位,从而促进蚀坑的扩展;而Ni的添加则提高钢基体的电位,从而有助于降低钢的点蚀扩展速度。     

冶金因素对钢点蚀诱发敏感性的影响

选取有代表性冶金元素的几种低碳钢和低合金钢,通过在3%NaCl（pH=10）溶液中的极化实验比较它们之间的点蚀诱发敏感性,用电子探针（EPMA）分析钢中夹杂物诱发点蚀的腐蚀特征。结果表明,脱氧程度较差的沸腾钢的抗点蚀诱发能力明显优于脱氧程度完全的镇静钢,经过稀土处理的镇静钢的抗点蚀诱发能力有所改善,介于两者之间。镍铬系低合金钢的抗点蚀诱发能力优于锰系低合金钢,说明钢中合金元素对点蚀诱发敏感性有重要影响钢中夹杂物是最主要的点蚀诱发源,夹杂物边界钢基体表面的氧化膜最薄弱,夹杂物诱发点蚀的最初腐蚀均始于该基体处。     

不同低碳钢的点蚀诱发敏感性及诱发机理研究

选择4种冶金因素有代表性的低碳钢,通过极化试验比较了它们之间的点蚀诱发敏感性。电子探针分析了不同夹杂物在诱发点蚀过程中的腐蚀特征,显微腐蚀试验确定了点蚀诱发初期溶解产物的性质。结果表明,沸腾钢的点蚀敏感性显著低于镇静钢,稀土处理镇静钢则介于前两者之间。夹杂物是钢中主要点蚀诱发源,紧靠夹杂物的钢基体处的钝化膜保护作用最弱,点蚀均从该处基体诱发。同类杂物在不同类型钢中的点蚀诱发敏感性差异较大。同一钢中不同类型夹杂物的点蚀诱发敏感性差异很小,硫化物夹杂较其它夹杂物的点蚀诱发敏感性强。     

Cu-P-RE耐大气腐蚀钢的耐点蚀性能研究

通过电子探针、扫描电镜和能谱仪等物理手段和极化实验、交流阻抗等电化学方法研究了稀土耐候钢的耐点蚀性能。结果表明,稀土元素的加入提高了耐候钢的点蚀电位。普通Cu-P耐候钢的耐点蚀性和点蚀形貌与普碳钢相接近。耐候钢加入稀土后,稀土元素能使钢中长条状硫化锰或尖角链状的硅酸盐等有害夹杂物变质为细小球形的稀土夹杂,从而降低钢的点蚀敏感性,提高了钢的耐点蚀能力。且球状稀土夹杂物诱发的点蚀坑更加细小均匀,有利于腐蚀后期致密锈层的生成,能提高钢的耐蚀性。     

炼钢脱氧程度对钢材点蚀诱发敏感性的影响

选取不同脱氧程度的沸腾钢和镇静钢各两种，通过3％NaCl溶液中的极化试验测定了各自的点蚀电位，对其夹杂物形态和腐蚀形态进行观察，比较了它们的点蚀诱发敏感性。结果表明，钢中的夹杂物是主要的点蚀诱发源，而脱氧程度差的沸腾钢的点蚀电位明显高于镇静钢，腐蚀形态也有很大差异。综合分析认为，沸腾钢和镇静钢的点蚀诱发敏感性与脱氧程度和夹杂物类型、形态等因素有关。     

硫化物夹杂对钢点蚀行为的影响

通过控制冷却速率在钢中得到3种不同尺寸和分布的硫化物夹杂,采用在3%NaCl溶液中的极化实验比较点蚀诱发敏感性,并观察腐蚀后的形貌。结果表明：随着冷却速率增加,硫化物夹杂尺寸降低,聚集型硫化物增多;随硫化物夹杂平均尺寸减小,点蚀电位和极化电阻均先升高后降低;随着聚集型硫化物的增多,硫化物夹杂在分布上的关联性加大,夹杂物引起的蚀孔关联起来形成更大的蚀孔,使钢的点蚀敏感性升高。     

低碳钢点蚀诱发部位的实验研究

选择3种冶金因素有代表性的低碳钢,通过极化试验比较了它们之间的点蚀诱发敏感性,利用电子探针分析了不同夹杂物在诱发点蚀过程中的特征;并在利用琼脂涂封的条件下,研究了点蚀诱发时夹杂物溶解析出行为.结果表明,沸腾钢的点蚀诱发敏感性显著低于镇静钢,稀土处理镇静钢则介于前两类钢之间;夹杂物是钢中主要点蚀诱发源,钢基体与夹杂物交界处的钝化膜保护作用最弱,点蚀均从该处诱发;夹杂物的成分及形态的不同都会影响到产物的溢出位置和方式.     

硫化物夹杂对低碳钢孔蚀扩展的影响

选择两种具有不同类型硫化物夹杂的碳钢,通过模拟蚀孔的闭塞腐蚀电池试验,研究了它们在人工海水中的孔蚀扩展行为。结果表明,具有Ⅱ类硫化物的钢的零电流电位明显负于具有Ⅰ类硫化物的钢;在同样在阴极化电位下,前者的阳极腐蚀电流明显地大于后乾。通过显微分析考察了硫化物要对孔蚀扩展过程的影响。结果发现,硫化物夹杂处的腐蚀速度明显高于钢基体钢从而促进了也诉扩展。由于Ⅱ类硫化物的相界面积远大于类硫化物,前者对孔蚀扩     

夹杂物对低合金钢在酸性Cl~-溶液环境中点蚀行为的影响

为了探究低合金钢中夹杂物在低pH值,高浓度氯离子腐蚀环境下诱发点蚀的作用机理,利用pH为0.85的10%NaCl溶液,模拟货油舱下底板腐蚀环境,采用扫描电镜(SEM)、X射线能量色散谱(EDS)、夹杂物原位观察等手段,分析了不同类型、尺寸、形状的夹杂物对E36级船板钢点蚀行为的影响。结果表明:试验钢中存在MnS、TiO2等不同类型的夹杂,夹杂物在酸性溶液中最先被溶解,是点蚀的诱发源。夹杂物周围存在直径10μm左右的阴极保护区,在早期不易被腐蚀。此外,不同类型和形状的夹杂物诱发点蚀的优先顺序不同,MnS较TiO2优先诱发点蚀,长宽比大的夹杂较圆形夹杂优先诱发点蚀。     

Novel strategies for assessing the pitting corrosion resistance of stainless steel surfaces

Pitting corrosion is one of the most common mechanisms of surface damage on stainless steels. Electrochemical methods have been preferentially applied for the evaluation of the pitting corrosion resistance of stainless steels in the laboratory. Nevertheless, some of them are not reliable enough and in general the application of electrochemical methods in the field becomes difficult because of required deep understanding of corrosive phenomena and measurement technology. Therefore, new approaches for the evaluation of the pitting corrosion susceptibility of stainless steel surfaces in the laboratory as well as in the field are necessary. In the present paper two novel strategies including electrochemical noise measurements under anodic polarization for laboratory testing, and an indicator test to assess the susceptibility of stainless steel surfaces to pitting corrosion in the field are introduced. Experimental results concerning the influence of surface treatments on the pitting corrosion resistance on stainless steels have confirmed that final surface condition has a significant effect on their future pitting corrosion susceptibility. In addition, the pitting corrosion resistance of stainless steel surfaces was observed being specifically dependent on the achieved surface topography and in some cases independent on the roughness parameters of the surface.     

两种船体钢耐点蚀性能的电化学噪声评估

运用电化学噪声(EN)测量技术和极化曲线技术检测两种船体钢A和B在0.5mol/L NaHCO3+3%NaCl溶液中的腐蚀状况,结果表明,两种钢的噪声图谱都表现出了明显的点蚀特征;在点蚀诱导期,B钢电位噪声波动的幅度和暂态峰的密集程度均比A钢大,而且诱导期持续时间较短;对噪声电阻的分析也表明,在该试验体系中A钢表面状态更稳定。极化曲线的分析结果表明A钢的点蚀电位较高、极化电阻较大、腐蚀电流较小,耐点蚀性能更好,这与电化学噪声分析的结论一致。     

The effect of thermo-mechanical treatment on The pitting corrosion of reinforcing carbon steel bars

Steel reinforcing rods with varying amounts of cold work and carbon concentrations (0.06 to 0.45% C) exposed in soil embankments has shown various degrees of pitting corrosion. To understand this pitting process, laboratory investigations on residual stresses, microstructures and potentiodynamic cyclic polarization were undertaken. Analysis of residual stresses in the steels indicated low value of compressive stresses in hot rolled steels and high value of tensile stresses in the cold worked counterparts. Hot rolled steels displayed a slightly better pitting corrosion resistance than cold worked samples which is consistent with the above internal stress pattern. No definite correlation was obtained between the percentage of carbon in the steels and pitting susceptibility. An attempt has been made to define the role of the complex steel-soil system for pitting corrosion behavior.     

冶金因素对低合金钢点蚀诱发敏感性的影响

通过极化试验对4种低合金钢的点蚀诱发敏感性作了比较,并结合显微分析对4种钢点蚀诱发敏感性的差异机理做了探讨,结果表明：钢中夹杂物与合金元素是影响低合金钢点蚀诱发敏感性差异的主要原因。     

THE RELATIONSHIP BETWEEN PITTING SUSCEPTIBILITY AND INCLUSIONS IN CARBON STEELS IN ARTIFICIAL SEAWATER

1. IlltroductionMany studies have been conducted on the pitting of steels[1]. Actually3 pitting ofcarbon steels is less typical than that of stainless steels, and for the former the pits arewider and more shallow. For the pitting of carbon steels and the effect of inclusions on thepitting, there are some previous investigations. Wranglen[2] found a correlation betweensusceptibility to localized corrosion and the ratio of active to inactive sulfides; and onlyactive sulfide was believed to act a…