稀土对7085铝合金锻件组织和腐蚀性能的影响

采用晶间腐蚀和剥落腐蚀试验、硬度和电导率测试、慢应变速率拉伸试验、光学显微镜观察、透射电镜观察等试验方法,研究微量稀土对7085铝合金(Al-7.5Zn-1.5Mg-1.4Cu-0.15Zr)锻件组织和腐蚀性能的影响。结果表明,与未添加稀土的铝合金锻件相比,添加0.15wt%稀土使7085铝合金组织细化,时效后硬度提高,电导率略有降低,抗晶间腐蚀、剥落腐蚀性能显著提高。尤其加入Sc后,合金的硬度提高了21.3%,剥落腐蚀性能由EB提高为PA。     

微量稀土对7085铝合金强度和腐蚀性能的影响

采用慢应变速率拉伸试验、晶间腐蚀和剥落腐蚀试验、硬度和电导率测试、光学显微镜等分析方法,研究微量(0.15 mass%)稀土对7085铝合金(Al-7.5Zn-1.5Mg-1.4Cu-0.15Zr)强度和腐蚀性能的影响。结果表明,与未添加稀土的铝合金相比,添加微量(0.15 mass%)稀土使7085铝合金组织细化,时效后强度、硬度提高,电导率略有降低,抗晶间腐蚀、剥落腐蚀和应力腐蚀性能显著提高。     

Effect on marine immersion corrosion of carbon content of low alloy steels

This paper attempts to reconcile information from a number of different sources about the effect of small changes in carbon content on the immersion corrosion of specimens of normal commercial mild and low alloy steels. It does so through interpreting the data reported in the literature in terms of the recently proposed theoretically based phenomenological model for marine immersion corrosion. This model postulates different corrosion phases as corrosion progresses. When the experimental results are interpreted in terms of the model it is found that carbon content has minimal effect on the kinetically controlled corrosion phase. The next phase, when corrosion rate is controlled by oxygen diffusion, is also unaffected, in agreement with theoretical predictions. However, carbon content does affect the two anaerobic phases, with increased corrosion as the carbon content and the water temperature increase. The model allows apparently conflicting observations to be reconciled and shows that carbon content may be influential for longer-term corrosion and for corrosion in tropical waters.     

Effect of small compositional changes on marine immersion corrosion of low alloy steels

Small changes in the composition of mild and low alloy steels can effect their immersion corrosion behaviour. A number of comprehensive test programs for coupons immersed at different locations and recovered at different times have been reported. Comparison between them has also been attempted with modest success as well as leaving some apparent inconsistencies in the effect of some alloying elements.In this paper, a new comparative analysis of previously reported observations is reported. It employs a recently reported multi-phase phenomenological corrosion-time model, with different corrosion phases governing corrosion behaviour. Each phase is a function of time.The analysis shows that metal composition can influence the first, kinetically controlled corrosion phase and also the long-term anaerobic corrosion phases. However, during the phase controlled by oxygen diffusion through the corrosion product, metal composition is largely irrelevant, in agreement with theoretical predictions. It is shown that the several observations in the literature about the effect of particular alloys can be reconciled, including apparently conflicting observations about the effect of chromium content.     

微量稀土Sm对AZ80镁合金腐蚀性能的影响

通过静态失重法、电化学法、扫描电镜和XRD等手段研究微量Sm对AZ80镁合金的腐蚀性能和微观组织的影响.结果表明:Sm的加入使试验合金的自腐蚀电位升高,自腐蚀电流密度减小,合金的耐蚀性得到提高.当Sm含量为0.6％时合金的腐蚀速率下降为3.3g·m-2·d-1仅为原始合金的25％.同时Sm在合金中形成Al3Sm相,改变了AZ80镁合金中β相(Mg17Al12)的数量和分布,使镁合金的腐蚀行为由较严重的局部腐蚀向均匀腐蚀转变.     

The pitting corrosion of low alloy and mild steels

Electrochemical investigations and microscopical examinations of pitting corrosion of low alloy (weathering) steels, copper bearing steel and plain carbon steel have been performed. Higher inclination to pit formation in steels containing alloying elements were ascertained in corrosive environments containing chlorides. Scanning electron microscopy enabled the determination of differences in morphology of pits formed on the steels under study.     

稀土氧化物对低合金钢焊缝组织与韧性的影响

通过正交试验方法设计9组以稀土氧化物为添加剂的碱性焊条药皮成分,研究了在焊条药皮中添加的稀土氧化物种类和添加量对低合金钢焊缝组织与低温韧性的影响。试验结果表明,适量氧化镧、氧化铈和氧化钇的混合添加剂具有改善焊缝组织和提高焊缝低温冲击韧性的作用,在药皮中添加w(La2O3)0.7%,w(Ce2O3)1.0%和w(Y2O3)0.3%时,其焊缝低温韧性相对最好;氧化钇对焊缝低温韧性的影响程度明显高于氧化镧和氧化铈,而氧化镧和氧化铈对焊缝低温韧性的影响规律和作用程度基本相同。     

稀土在变形镁合金中的应用

综述了稀土在变形镁合金中的作用和应用情况。重点阐述了Mg-RE—Zr系变形镁合金的析出强化作用及塑性变形行为。稀土在变形镁合金中的应用具有十分广阔的前景。     

Effect of rare earth element Ce and La on corrosion behavior of AM60 magnesium alloy

New AM60-RE (RE = Ce or La) alloy was prepared and its corrosion behavior was evaluated by hydrogen evolution and electrochemical methods. New γ phase containing higher content of RE and Al elements has been found. The corrosion resistance of AM60 alloy improved with addition of RE, and this improvement could attribute to depression of the micro-galvanic couples, because the fraction of β was decreased, as well as the deposited RE-containing phases were less cathodic. Moreover, RE and Al enrichment in the corrosion product films on the RE-containing alloy surface was also a key factor to the inhibition of further corrosion.     

稀土改性6063铝合金的研究

严格控制镁、硅含量,向6063铝合金中添加一定量的混合稀土,采用工业生产设备熔炼稀土改性铝合金6063D-RE,研究其铸态组织和挤压性能.结果表明,添加稀土后,铝合金的挤压性能提高,挤压时所需挤压力减小,模具寿命提高,挤压速度变快,生产效率提高.稀土对铝合金组织有良好的改性作用,有少量的富含稀土相析出.     

The effect of sulfide inclusions on the susceptibility of steels to pitting,stress corrosion cracking and hydrogen embrittlement

Recent opinions on the effect of nonmetallic inclusions, especially sulfides, on the nucleation of pits, stress corrosion cracks, and hydrogen-induced cracks are reviewed. The nonmetallic inclusions present in steels as impurities adversely affect the corrosion resistance of steels. This is true for both the general and local corrosion mechanisms, like pitting corrosion, stress corrosion cracking (SCC), and hydrogen embrittlement (HE). The effect of nonmetallic inclusions (in particular that of sulfides) on the pitting corrosion mechanism has been the subject of numerous investigations. A fairly aboundant information can be found in vast original literature and in many review articles [1–3]. The role of nonmetallic inclusions in SCC is relatively less covered in the pertinent literature. Since, however, the nucleation of corrosion cracks frequently starts from pits, and pits nucleate at sulfides, the presence of sulfides is likely to affect the SCC process. Another corrosion mechanism that leads to a local cracking of a metal is the hydrogen embrittlement. The presence of nonmetallic inclusions enhances susceptibility of steel to hydrogen-induced cracking [4]. This review will be concerned with the effect of nonmetallic inclusions on the local corrosion types mentioned.     

The effects of water pollution on the immersion corrosion of mild and low alloy steels

The short-term immersion corrosion of mild and low alloy steels in seawaters is known to be proportional to the concentration of dissolved oxygen (DO) in the bulk water. Longer-term corrosion is a function of the activity of sulphate-reducing bacteria and is influenced by the concentration of nutrients in the bulk water. These influences are examined in more detail for the corrosion of steels in the brackish waters of the River Thames and for several immersion corrosion sites on the Eastern Australian seaboard and in the North Sea. The published data sources were supplemented with plausible assumptions about environmental conditions. New interpretations of the data are provided based on the previously published model for immersion corrosion. For waters with negligible salinity and sulphate levels early corrosion loss was shown to depend on the dissolved oxygen content of the waters, and later corrosion loss was a direct function of nitrogenous nutrient (pollution) levels. This also applies to longer-term corrosion.     

Influence of the alloy element on corrosion morphology of the low alloy steels exposed to the atmospheric environments

Morphology of the corroded surface of low alloy steels beneath rust after long-term exposure test in the atmospheric environment was analyzed. The form of the corroded surface was measured with the laser displacement sensor scanning the surface. The resultant height map was divided by the mesh and the maximum corrosion depth was calculated in each cell. The maximum depth was arranged by the extreme value analysis. From this analysis two kinds of corrosion patterns were distinguished; i.e., uniform corrosion and local corrosion. Electrolytic iron shows the only uniform corrosion pattern. The addition of Cu, Ni and Cr changed the form of the corroded surface from the uniform corrosion to the combined pattern (uniform corrosion + local corrosion). The addition of Cr has a marked effect in changing the corrosion pattern.