HY440C热轧扁钢缺陷分析及控制

介绍了HY440C不锈钢的特点、"河冶品牌"HY440C不锈钢热轧扁钢的生产工艺,分析了HY440C不锈钢轧制过程中产生表面缺陷、裂纹等缺陷的原因,提出了解决措施。     

Residual strains in HY100 polycrystals: Comparisons of experiments and simulations

Residual stresses commonly arise in metallic components following plastic deformation and can have a significant effect on the mechanical properties. At the scale of the crystals, stresses are directly related to changes in lattice spacing. Neutron diffraction provides an effective method of measuring the spacing of atomic planes in crystal lattices with sufficient precision to determine the elastic (lattice) strains. In this work, tensile specimens were loaded and unloaded in situ to progressively larger amounts of plastic strain. Neutron diffraction measurements were taken at various points in the loading history, and the data were reduced to give the average elastic strains in subsets of the crystals characterized by common crystallographic directions. Using the finite element method, lattice strains were computed at the crystal level by modeling a polycrystal grain by grain. Elastic strains were extracted for sets of crystals corresponding to those sets examined by diffraction at comparable points in the loading history. Detailed comparisons for a steel (HY100) indicate that the model shows good agreement in predicting the lattice strains, both in the loaded and unloaded states. Further, the simulations elucidate aspects of the distributions of lattice strains that arise from the grain-to-grain interactions.     

Audiogenic epilepsy in 101/HY mice at different periods of postnatal development

It has been established that mice of strain 101/HY suffer from audiogenic epilepsy seizures, the frequency and severity of which depend on animal sex and age. Mice were subjected to high intensity sound (about 100 dB) at the age of 14-16, 30, 60, and 190-270 days (Groups I, II, III, and IV, respectively). The testing was done three times. Mice of Group I were tested twice. The duration of sound stimulus was 20 s. Mice of both sexes from Group I were most sensitive. During the first test, the so-called "wild-run" behavior developed in 90% of animals and 60% showed tonoclonic seizure. Lethal outcomes in animals of this group (26.7% of the males and 23.5% of the females) were observed mainly during the second test, conducted one day after the first one. Only 6.7% of the males died during the first test in Group I. Severity of audiogenic seizure in males decreased with age, whereas among females there was a decrease in the number of animals with sensitivity to the sound stimulus. Among females of Groups III and IV, we did not detect any animals responding to the audiogenic stimulus by seizure and there were no deaths. Mechanisms underlying the audiogenic sensitivity of 101/HY mice are reviewed in the light of other information about the development of this genetic trait in rodents and in connection with other biological characteristics of these animals.     

Ductile fracture in HY100 steel under mixed mode I/Mode II loading

A number of criteria have been proposed which predict the direction of cracking under mixed Mode I/Mode II loading. All have been evaluated for brittle materials, in which a crack subjected to tension and shear propagates normal to the maximum tensile stress (i.e. fracture is of the Mode I type). In a ductile material, however, a notch subjected to mixed Mode I/Mode II loading may initiate a crack in the direction of maximum shear. This paper shows that the profile of the notch tip changes with increasing mixed mode load in such a way that one side of the tip blunts while the other sharpens. Various specimens, subjected to the same mixed mode ratio, were unloaded from different points on the load-displacement curves to study the change in notch-tip profile. Studies under the Scanning Electron Microscope (SEM) have shown that cracks initiate at the sharpened end, along a microscopic shear band. Using a dislocation pile-up model for decohesion of the carbide-matrix interface, a micromechanical model has been proposed for crack initiation in the shear band. It is shown that a theoretical prediction of the shear strain required for decohesion gives a result that is, of magnitude similar to that of the shear strain at crack initiation measured in the experiments.     

HY沸石的脱铝改性及其对CO2/H2O的吸附性能

采用不同浓度的盐酸溶液对HY沸石进行脱铝改性,利用XRD、TGA等分析手段对所制备样品的物相、结构等进行表征分析,研究了样品对CO2/H2O的吸附性能.结果表明：采用浓度为0.5 mol/L的盐酸溶液对沸石HY进行脱铝改性后,材料仍然具有较完好的晶体结构,在保持较高CO2吸附能力的同时疏水性能得到明显改善.     

An investigation of environmental effects on fatigue crack growth in Q1N (HY80) steel

Fatigue threshold tests have been conducted on through-thickness and semielliptic cracks in laboratory air, vacuum, and salt water at stress ratios(R = K_min/K_max @#@) of 0.2 and 0.7. The effects of stress ratio are rationalized by crack closure concepts. Environmental effects are explained by considerations of the irreversibility of slip at the crack tip and the role of debris on the fracture surfaces. Differences in the fatigue crack growth rates in the three environments are attributed largely to the extent of the irreversibility of slip due to the chemisorption of water/ water vapor at the crack tip. Debris in saltwater solutions is also shown to significantly affect the near-threshold growth through its influence on crack closure and the transportation of environment to the crack tip. formerly Graduate Student, Department of Materials Science and Technology, Cambridge University formerly with the Department of Materials Science and Metallurgy, Cambridge University     

A comparison of the fracture behavior of two commercially produced heats of HY180 steel differing in sulfide type

The mechanical properties of two heats of HY180 steel are compared after aging at 425 °C or 510 °C. The two heats of material appear very similar microstructurally, except most of the sulfides in one are believed to be titanium carbosulfides, while the sulfides in the other heat appear to be manganese sulfides. At both aging temperatures, the crack tip opening displacement at fracture (δ_IC) of the heat containing the titanium carbosulfides is over twice that of the heat containing the manganese sulfides. Measurements of the void volume fracture as a function of strain indicate that the titanium carbosulfide particles are much more resistant to void nucleation than are the manganese sulfide particles. The unusually high toughness of the heat containing the titanium carbosulfides is attributed to this increased resistance to void nucleation. Formerly Graduate Student, Carnegie Mellon University Formerly Postdoctoral Student, Carnegie Mellon University     

Neonatal administration of ACTH(1-10) causes genotype-dependent changes in the level of brain monoamines and audiogenic sensitivity in adult CBA and 101/HY mice

We studied the haemodynamic response to cessation of mechanical ventilation and removal of the tracheal tube in 84 patients after coronary artery bypass grafting. Patients were sedated on the ICU with propofol 1-3 mg kg-1 h-1, and randomly allocated to extubation while awake or while still sedated. Systolic and diastolic blood pressures and heart rate increased significantly faster in the awake group as mechanical ventilation was stopped; systolic blood pressure 6.1 (3.0) vs 0.7 (1.8) mm Hg min-1, diastolic blood pressure 2.1 (1.6) vs 0.2 (0.9) mm Hg min-1, heart rate 2.1 (1.7) vs 0.2 (0.5) beats min-2; P < 0.01 in each case. Treatment was required for systolic hypertension during discontinuation of mechanical ventilation in 20 patients (53%) in the awake group and in three patients (7.5%) in the sedated group (P < 0.001). No patient in the sedated group had any new ischaemic ECG changes. Significant new ST segment changes did not occur in the sedated group but were present in five patients in the awake group (P = 0.013), one of whom suffered a perioperative myocardial infarction. Removal of the tracheal tube while patients are still sedated after coronary artery bypass grafting is safe, and reduces the incidences of haemodynamic disturbance and myocardial ischaemia during extubation.