不同屈服点钢筋混凝土柱耗能性能的试验研究

提出一种不同屈服点钢筋混凝土柱,共设计了4根柱：普通钢筋混凝土柱,配置低屈服点钢和高韧性混凝土柱,配置低屈服点钢、普通钢筋弯起和高韧性混凝土柱,低屈服点钢和普通钢筋并排的高韧性混凝土柱,通过对4根柱进行低周反复加载试验,研究了不同屈服点钢筋混凝土柱的破坏形态、滞回特性、耗能能力和刚度退化。研究表明：不同屈服点钢筋混凝土柱在弹性阶段时,由于低屈服点钢筋发生塑性变形可以有效吸收地震能量,阻尼系数较普通钢筋混凝土柱有较大提高,而高屈服点钢筋仍处于弹性阶段,刚度没有明显退化,可以保证结构的强度。     

含裂纹型缺陷压力容器用钢失效评定曲线研究

在力学性能测试的基础上．应用CEGB R6-Revison 4方法中的选择1和选择3曲线，对16MnR，20R和Q235B三种吉裂纹型缺陷压力容器用钢的失效评定曲线进行研究。结果表明．三种材料的失效评定曲线基本上均在Lr〈0.4后因试样结构不同而发生分散。而且均以是以Lr=0.7为分界线，在两侧分别出现不同的最为保守和最不保守曲线。给出了符合三种材料特性的失效评定曲线拟合方程，以便为工程应用提供依据。     

Effect of Varying Carbon Content and Shot Peening upon Fatigue Performance of Prealloyed Sintered Steels

The aim of the work was to find out how the modification of surface treatment and microstructures affect the fatigue characteristics of the considered sintered materials.Two different systems were prepared:as-sintered and shot peened prealloyed sintered(Astaloy CrL based)steels with addition of 0.5%and 0.7%C.Sintering was carried out in laboratory tube furnace in an atmosphere of pure gases 75%N2+25%H2.The sintering temperature was 1180-C and sintering time was 60 min.Heating and cooling rates were 10-C/min...     

高钢级管线钢的常规TMCP工艺与HTP工艺

介绍了常规TMCP工艺和HTP工艺在管线钢生产方面的发展历程和管线钢整体的化学成分设计情 况，对比分析了主要微合金元素Mo和Nb分别在常规TMCP工艺和HTP工艺中的作用，论述了常规TMCP工艺的机理，即通过奥氏体再结晶区粗轧来细化奥氏体组织和非再结晶区精轧来增加奥氏体内位错密度，提高铁素体的形核率细化相变后的组织，最后根据终轧厚度对钢板采用不同的冷却方式来获得良好性能。分析了HTP工艺与常规TMCP工艺的主要不同点,并指出HTP工艺经济效益优于TMCP工艺，已成为目前高强度管线钢生产的主要工艺。     

Materials for flexible riser systems: problems and solutions

Criteria to be satisfied in the selection of materials for unbonded flexible risers are first outlined. The paper then describes how three main types of thermoplastic and two classes of steel meet these requirements, and briefly discusses selection criteria and materials used for ancillary equipment for flexible riser systems     

Solving some key failure analysis problems using advanced methods for materials testing

A dilemma encountered in engineering practice is a proliferation of newly designed (mostly high-strength and/or corrosion-resistant) steels and alloys that are unusable in industry as they are highly susceptible to failure under operating conditions including environmentally assisted cracking. The problem of materials failure has several sources, the most significant of which is how engineers select which material to use in which industry. As a rule, selection is based solely on assessing the mechanical properties of materials with little or no consideration of how these mechanical properties will interface with specific operating parameters found within different industries. The functional design, selection and use of materials aimed at preventing in-service failures depends, therefore, on finding testing methods, standards and approaches appropriate to real operating conditions guided by analysis of material performance under those conditions.     

Effect of cathodic polarization and sulfate reducing bacteria on mechanical properties of different steels in synthetic sea water

At the slow strain rate tensile tests done using the specially designed facility, the decrease in the elongation to fracture, reduction of area, fracture energy and no effect on the strength have been stated for the low alloy ferrite‐pearlite and sorbite steels, polarized in synthetic sea water at potentials corresponding to the cathodic protection (? 800 to ? 1400 mV_SCE). Presence of SRB promotes the plasticity loss, being especially pronounced at potentials ? 1100 to ? 1200 mV_SCE. At higher cathodic polarization, the plasticity estimated in inoculated and in sterile water equalizes. The effects have been correlated with the contents of absorbed and of permeable hydrogen. The promotion of hydrogen charging and the plasticity loss by SRB at the low and medium applied cathodic polarization has been accounted for the observed production of S^?2 ions and inhibition of deposit formation. The negligible effect of SRB at the high cathodic polarization has been suggested to be a result of the suppression the SRB growth due to the high alkalization of the near surface solution. The same amount of hydrogen produces the less detrimental effect on the sorbite than on the ferrite‐pearlite steel. However, at the similar cathodic polarization, the sorbite steel absorbs the highest amount of hydrogen and reveals the most pronounced degradation. Cathodic protection of constructions subjected to the action of SRB in the sea water should provide the conditions, under which no fragment of marine construction could be polarized by potential corresponding to the maximum degradation of the plastic properties of steels (? 1100 to ? 1200 mV_SCE).     

Correlation between cyclic deformation behaviour and microstructure in a duplex steel between 300 and 773 K

Cyclic tests performed in the temperature range 300–773 K on duplex stainless steel DIN 1.4460 show that the cyclic stress–strain behaviour of this steel is strongly temperature dependent. At 300 and 473 K an almost constant peak tensile stress stage, is followed by a slight softening that continues up to failure in the case of 300 K, but by a secondary hardening at 473 K. Pronounced initial cyclic hardening followed by secondary hardening was the main feature of the temperature range between 573 and 723 K. At 773 K, after a weak hardening stage, a strong softening continues up to failure. The mechanical behaviour and the evolution of the microstructure were analysed, and the internal and the effective stresses were studied. It was found that the internal stress is responsible for the strong hardening that occurs in the intermediate temperature range and for the softening at 773 K.     

Metal dusting

This introductory review paper summarizes shortly the research on metal dusting, conducted in the MPI for Iron Research during the last dozen years. Metal dusting is a disintegration of metals and alloys to a dust of graphite and metal particles, occurring in carburizing atmospheres at a_C > 1 and caused by the tendency to graphite formation. The cause of destruction is inward growth of graphite planes into the metal phase, or in the case of iron and low alloy steels into cementite formed as an intermediate. The kinetics of metal dusting on iron and steels was elucidated concerning dependencies on time, temperature and partial pressures. High alloy steels and Ni‐base alloys are attacked through defects in the oxide scale which leads to pitting and outgrowth of coke protrusions, after initial internal formation of stable carbides M₂₃C₆, M₇C₃ and MC. A dense oxide layer prevents metal dusting, but formation of a protective Cr‐rich scale must be favored by a fine‐grain microstructure and/or surface deformation, providing fast diffusion paths for Cr. Additional protection is possible by sulfur from the atmosphere, since sulfur adsorbs on metal surfaces and suppresses carburization. Sulfur also interrupts the metal dusting mechanism on iron and steels, causing slow cementite growth. Under conditions where no sulfur addition is possible, the use of high Cr Nickelbase‐alloys is recommended, they are largely protected by an oxide scale and if metal dusting takes place, its rate is much slower than on steels.