Stored energy of a severely deformed interstitial free steel

A Ti-stabilised IF steel subjected to room temperature equal channel angular pressing (ECAP) for 8 passes, route B_C was further cold rolled to 25, 50 and 95% thickness reductions. The evolution of bulk stored energy (350–600 J mol⁻¹) and the associated thermal behaviour was investigated by differential scanning calorimetry (DSC). Local stored energy (5–140 J mol⁻¹) was measured using microhardness, electron back-scattering diffraction (EBSD) and X-ray line profile analysis. The higher stored energy values via calorimetry correspond to energy release from all sources of strain in the material volume as well as Ti precipitation during annealing. An apparent activation energy of 500–550 J mol⁻¹ suggests sluggish recrystallisation due to excess Ti in solid solution.     

Variation of the yield stress and latent strain energy in the course of plastic deformation of a neutron-irradiated chromium-nickel steel

The laws of variation of the flow stress (σ) and latent strain energy (E_s) in the course of plastic deformation have been studied in the samples of a titanium-doped chromium-nickel steel (12Kh18N10T grade) before and after neutron irradiation to a dose of 5×10²²m^?2 (neutron energy E>0.1 MeV). The E_s versus σ curve can be divided into several characteristic regions, the first of which is described by a relation of the type E_s～E₀+kσ² (E₀ and k being certain coefficients). It is established that neutron irradiation shifts the E_s versus σ curve toward smaller latent energies.     

Relationship of energy dissipation efficiency to microstructural evolution in hot working of AISI 304 steel

On the basis of dynamic materials, modeling maps of energy dissipation efficiency were evaluated for 304 stainless steel from synthesized stress-strain curves over the ranges 900–1200 °C and 10⁻³ to 10² s⁻¹. The constitutive equations as well as the ductility and microstructural evaluation were determined from torsion tests; these results were found to be in good agreement with the literature. High values of dissipation efficiency are obtained in association with the occurrence of flow curve peaks and flow softening resulting from dynamic recrystallization. However, the efficiency associated with the same softening mechanism during steady state at high strains is fairly low. In consequence, it seems an inadequate parameter to define the mechanism or to predict the ductility.     

新型组合耗能器耗能特性试验研究

提出了一种将增位型黏滞阻尼墙跨层布置的增效耗能减震结构体系。基于能量等效原理,并采用积分的方法建立了增位型阻尼墙的阻尼力和滞回耗能的计算公式,进行了普通黏滞阻尼墙和位移放大3倍的增位型阻尼墙的拟静力试验,在相同的位移幅值和加载频率下,增位型阻尼墙的阻尼力放大4.40倍,耗能平均放大4.41倍。进一步对某30层混凝土框架核心筒结构进行普通阻尼墙与增位型阻尼墙的地震响应对比分析。通过对比分析验证了增位型阻尼墙的减震效果,并且发现增位型阻尼墙跨层布置时的结构附加阻尼比倍数提高,结构响应进一步减小。将增位型阻尼墙跨层布置可取得更优的减震控制效果。     

Hydrogen permeation in plastically deformed steel membranes

We study the influence of plastic deformation on the electrochemical permeability of hydrogen. For this purpose, membrane specimens of FeE690T steel were deformed in the cold state by rolling or tension, and the diffusion of hydrogen in these specimens was measured by the classical Devanathan-Stachursky technique. The effective diffusion coefficients are determined according to the time dependences of the intensity of hydrogen flow from the back side of the membrane. They are characterized by the well-pronounced dependence on the level of strain. Moreover, the diffusion of hydrogen is simulated by taking into account the phenomenon of seizure of hydrogen atoms by traps formed in the presence of plastic strains. The linear diffusion equation is used to compute the time dependence of permeation of hydrogen for various densities of the traps. The effective coefficients of hydrogen diffusion are determined from the permeation curves. The accumulated results are in good agreement with the experimental data. Published in Fizyko-Khimichna Mekhanika Materialiv, Vol. 42, No. 1, pp. 77–81, January–February, 2006.     

位移放大型阻尼墙减震结构的模型试验与数值分析

提出一种凸轮式响应放大金属阻尼器,介绍其工作机理和恢复力计算公式,对安装该阻尼器的单自由度体系建立了运动方程和能量方程。以达到相同位移控制效果为目标,采用不同吨位的金属阻尼器,分别对无控结构、安装传统金属阻尼器和安装凸轮式响应放大金属阻尼器的单自由度体系进行了多遇、罕遇和极罕遇地震作用下的地震响应对比分析。结果表明：在各级地震作用下,串联小吨位金属阻尼器的凸轮式响应放大金属阻尼器均达到了与安装传统大吨位金属阻尼器相同的位移控制效果和耗能比例,基底剪力控制效果也得到了明显的提升,说明采用小吨位金属阻尼器通过响应放大便可达到直接安装大吨位阻尼器的相同位移控制效果,体现了其优越的经济性;另外,在极罕遇地震作用下,该装置能避免阻尼器发生位移失效的现象,体现了该消能装置在各级地震作用下均能保证结构和阻尼器的安全。     

Corrosion of deformed boiler steel in flushing solutions

The effect of work hardening of boiler steel on the kinetics of electrochemical reactions in acid flushing solutions was studied. It was shown that by selecting suitable corrosion inhibitors it is possible to counteract the corrosion accelerating effect of work hardening (the mechanicochemical effect) and to eliminate the electrochemical heterogeneity of steel due to work hardening.     

Effect of loading prehistory on phase transformations in chromium-nickel steel with plastic deformation

Results are given for a study of the kinetics of phase transformations in chromium-nickel austenitic steel with repeated plastic deformation including under conditions when prior and repeated loading differ in temperature and form of stressed state. It is established that prior low-temperature deformation intensifies the process of martensite formation at room temperature whereas deformation under room temperature conditions has almost no effect on martensitic transformation kinetics at low temperature.Translated from Problemy Prochnosti, No. 10, pp. 46–50, October, 1991.     

Controlling stage in the transfer of carbon in the system carbon steel/liquid sodium/chromium-nickel steel

The mechanism of transfer of carbon in sodium was studied. On the basis of experimental data the activation energy for carburizing type 18/8 steel was calculated. The activation energy for transfer of carbon in sodium calculated from experimental results agreed with published data. It was concluded that the main controlling stage in the transfer of carbon in the system studied is the diffusion of carbon in type 18/8 steel.     

An investigation of the relaxation of static stresses in chromium-nickel steel specimens in cyclic loading

A multifactorial experiment on relaxation of stresses in chromium-nickel steel specimens in static and asymmetric cyclic loading with frequencies of 35 Hz and 10 kHz is described. With use of the method of experiment planning mathematical models describing the reduction in stresses and accumulation of plastic deformation in relation to the maximum stress, frequency and amplitude of the cyclic load, and temperature were obtained. Certain practical recommendations on use of the results obtained in the process of technical action for the purpose of reducing residual stresses, particularly by the vibration method, are proposed.Translated from Problemy Prochnosti, No. 3, pp. 39–43, March, 1990.     

Influence of boron/steel/aluminium hybrid composite structure on the energy dissipation therein

The technological conditions for making polyreinforced composites by hot pressing stacks consisting of boron/aluminium monolayers and knitted nets of stainless steel have been studied. Improvement of mechanical properties, and especially behaviour under cyclic loading, was achieved as a result of introducing additional loop elements of thin steel wires into the macrostructure of the composite. It was found that the arrangement of net layers, the number of wires in a bundle and the steel content considerably affected the cyclic strength and energy dissipation factor.