双相不锈钢中γ和α相对腐蚀开裂敏感性的影响

一、绪言由奥氏体(γ相)和铁素体(α相)共存的双相不锈钢,其与奥氏体系不锈钢相比,不仅具有屈服强度大,耐点蚀和缝隙腐蚀及抗BCC 性能良好的优点,而且节约镍;与铁素体系不锈钢相比,则其抗氢脆性能和焊接性能较之为好。因而双相钢受到各国的     

不锈钢管应力腐蚀开裂的评价方法

参考NACE TM 0177标准,通过模拟抗应力腐蚀开裂(SCC)性能评价试验,探讨了采用弯梁试验(B法)、C型环试验(C法)和双悬臂梁(DCB)试验(D法)法评价不锈钢油管应力腐蚀开裂性能的适用性。结果表明:B法不能反映不锈钢油管实际表面状态对其抗SCC性能的影响,D法评价不是很有效,C法则可以反映管材表面状态对其抗SCC性能的影响,故推荐使用C法评价不锈钢油管的抗SCC性能。     

渤中19-6气田封隔器金属材料的腐蚀适应性评价

在模拟渤中19-6气田井下工况环境中对35CrMo碳钢、42CrMo碳钢、HS110抗硫钢、13Cr不锈钢、13Cr超级不锈钢(13CrS)、2205双相不锈钢等6种金属材料进行了腐蚀试验,研究其腐蚀行为。通过失重法计算金属的腐蚀速率,采用扫描电镜(SEM)观察金属腐蚀形貌,采用X射线光电子能谱仪(XPS)分析腐蚀产物成分。结果表明：HS110抗硫钢、35CrMo碳钢、42CrMo碳钢、13Cr不锈钢、13Cr超级不锈钢、2205双相不锈钢的腐蚀速率依次降低,且所有钢在液相中的腐蚀速率高于其在气相中的腐蚀速率。渤中19-6气田封隔器的中心管推荐选用13Cr超级不锈钢和2205双相不锈钢,卡瓦等功能性部件推荐选用42CrMo碳钢。     

激光增材制造304不锈钢显微结构特征与性能研究

针对工业领域中大量304不锈钢关键零部件需要精密修复的问题,采用激光增材制造技术在304不锈钢基材表面制备304不锈钢零件,分析了其显微结构特征、物相结构、抗电化学腐蚀性能与力学性能。结果表明,激光增材制造304不锈钢主要由γ-(Fe,C)与马氏体C_(0.055)Fe_(1.945)组成,组织细小且致密,无气孔与裂纹;激光增材制造304不锈钢的抗电化学腐蚀性能优于传统制备304不锈钢;激光增材制造304不锈钢的屈服强度与抗拉强度约为传统制造304不锈钢的1.24倍与1.22倍;激光增材制造304不锈钢的伸长率相对传统制造304不锈钢提高了16.7%。     

《材料保护》2010年第9期

316L不锈钢非晶态Ni-W-P化学镀层的耐蚀性能 为了弄清316L不锈钢获得Ni—W—P非晶态化学镀层的耐蚀性能,以模拟人工汗液和5％硫酸溶液为腐蚀介质,对Ni—W-P非晶镀层的耐腐蚀性能进行了研究。结果发现：在镀层厚度10μm以上的情况下：（1）Ni—W-P非晶镀层阳极极化性能与316L不锈钢基本相当;（2）在前48小时,Ni—W—P非晶镀层耐汗液的抗变色能力与不锈钢相近,但随着浸泡时间的延长,其抗变色能力较不锈钢差。     

Al含量对316L不锈钢显微组织和力学性能的影响

研究了Al含量对316L不锈钢显微组织、力学性能和抗腐蚀性能的影响。结果表明,Al元素在热轧态316L不锈钢中的主要存在形式是固溶和第二相Al4C3。随着Al含量的增加,316L不锈钢的耐蚀性、屈服强度和抗拉强度升高,但其塑性降低。     

超细SiC粉体对304不锈钢抗Cl~-腐蚀性能影响

介绍了研究超细Si C粉体对304不锈钢抗Cl-腐蚀性能影响的背景。详细阐述了整个试验过程,在生产条件下采用冲入法,将改性超细Si C粉体加入到304不锈钢中,对添加Si C粉体前后的304不锈钢试样采用金相检验、静态浸泡试验和电化学分析的方法,讨论了Si C粉体对不锈钢的组织和抗Cl-腐蚀性能的影响。结果表明:经改性Si C粉体强化处理后的304不锈钢组织得到细化;抗Cl-腐蚀性提高;添加Si C粉体的304不锈钢自腐蚀电流密度从原不锈钢的1.535μA/cm2降为0.588μA/cm2。     

Cr-Mn-N奥氏体-铁素体不锈钢的空蚀行为

利用超声振荡空蚀实验机对Cr-Mn-N奥氏体－铁素体不锈钢进行了空蚀研究。结果表明，低硬度Cr-Mn-N不锈钢的抗空蚀性能高于高硬度的0Cr13Ni5Mo不锈钢。空蚀过程中，Cr-Mo-N奥氏体－铁素体不锈钢中的铁素体优先脱落，空蚀表面的铁素体含量由19％迅速降低到6．9％后保持稳定。奥氏体易于在铁素体脱离后形成的蚀坑处开始脱落，加工硬化是该不锈钢吸收空蚀冲击能量的一个重要途径，是其硬度较低却表面出良好抗空蚀性能的重要原因。     

不锈钢焊接接头的激光熔凝试验

对1Cr18Ni9Ti不锈钢焊接接头进行局部激光熔凝,观察激光熔凝后焊接接头组织的变化,并进行腐蚀试验。试验结果表明:在硫酸溶液中具有良好抗腐蚀性的不锈钢经焊接后,接头部位的抗腐蚀性较母材有所降低,但经激光熔凝后,抗腐蚀性可得到明显提高,这说明激光熔凝对改善不锈钢焊接接头的抗腐蚀性是有效的。     

氧化时间对不锈钢表面氧化铝膜硬度和耐腐蚀性的影响

通过高温氧化在建筑用不锈钢表面制备氧化铝膜,对其结构、形貌及硬度和抗腐蚀性能进行研究。结果表明:氧化铝层的抗腐蚀性能随着氧化时间的增加而提高。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.