Research on flow stress in ferrite deformation of a Ti-IF steel

The experiments of the ferrite warm deformation of ultra-low carbon (ULC) Ti-IF steel were carried out on a hot simulator and the influences of deformation temperature, strain, and strain rate on the flow stress were analyzed. New flow stress models suitable to ferrite warm forming of Ti-IF steel were given on the basis of analyzing the influence of deformation technology parameters on the flow stress.     

Intelligent Multilevel Knowledge Acquisition System for Product Design and Its Implementation

The characteristics of design process, design object and domain knowledge of complex product are analyzed. A kind of knowledge representation schema based o n integrated generalized rule is stated. An AND-OR tree based model of concept f or domain knowledge is set up. The strategy of multilevel domain knowledge acqui sition based on the model is presented. The intelligent multilevel knowledge acq uisition system (IMKAS) for product design is developed, and it is applied in th e intelligent decision support system of concept design of complex product.     

Relationship among wear-resistance of three-body abrasion,substructure and property in martensite steels

The effects of subsurface hardness on wear-resistance of martensitic steel 20Cr, 40CrSi, 60Mn, T8 and T10 in three-body abrasion under static load was investigated. It shows that the characteristic ofthe subsurface hardness distribution and the abrasive wear resistanceis related to the substructure near the worn surface. The substructure of the tested martensite steel has an apparent relationship with thecarbon content and steels with moderate carbon content and hardness exhibit good resistance to abrasive wear. The competition of the work-hardening effect and the temper softening effect, which resulted from deformation and friction heat generating during abrasive wear is considered to be a main reason for the relation among wear-resistance, hardness and substructure. At the test conditions, the wear-resistance of 40CrSi is the best.     

A new acid pickling process for copper alloys

The cleaning process of removing oxides on the surface of copper alloy sheets was investigated systematically. Through optimizing, a perfect process was selected that is fit for removing oxides on the surface. By acid pickling, all kinds of copper oxides are removed completely, furthermore, no poisonous gases are given out and a smooth and clean surface of copper alloys is obtained. At present, the process is applied successfully in the copper-processing industry.     

Surface-particle-emulsion heat transfer model between fluidized bed and horizontal immersed tube

A mathematical model, surface-particle-emulsion heat transfer model, is presented by considering voidage variance in emulsion in the vicinity of an immersed surface. Heat transfer near the surface is treated by dispersed particles touching the surface and through the emulsion when the distance from the surface is greater than the diameter of a particle. A film with an adjustable thickness which separates particles from the surface is not introduced in this model.The coverage ratio of particles on the surface is calculated by a stochastic model of particle packing density on a surface. By comparison of theoretical solutions with experimental data from some references, the mathematical model shows better qualitative and quantitative prediction for local heat transfer coefficients around a horizontal immersed tube in a fluidized bed.     

Metallurgical quality of CSP thin slabs

The casting structure, chemical composition segregation, dendrite arm space, inclusiona and during the CSP (compact strip production) rolling process were investigated. The results show that the CSP thin slab has a feature of uniform fme grains, more columnar crystals, less central porosity and segregation etc. There is no great difference in macrostructure between the CSP thin slab and conventional slab; however, the fine dendrite structure of the CSP slab is more uniform. Moreover, the central porosity and segregation are obviously improved after the first pass; and the dendrite is bent along the rolling direction rather than broken into pieces.Small inclusions with the diameter less than 10 μm in the CSP slab are dominantly consisted of aluminates formed by Al deoxidation and Ca treatment and not floating out of the melt. The large size inclusions found in the continuous casting slab are very few.     

Daughter minerals in fluid inclusions of garnet and diopside from Tongguanshan Copper Deposit by SEM/EDS and LRM

Tongguanshan copper deposit of Tongling large ore belt is one of the typical skarn copper deposits. Based on careful observation under microscope many daughter minerals including transparent ones and opaque ones have been distinguished in the fluid inclusions of garnet and diopside. The results of SEM/EDS (scanning electron microscope/energy dispersive spectrometer) and LRM (laser Raman microprobe) analysis show that these daughter minerals in garnet are sylvite, halite, sphalerite, chalcopyrite and carbonate. Sylvite daughter mineral is very popular in garnet and diopside. The existence of so much sylvite daughter mineral and other daughter minerals in the fluid inclusions indicates that the ore-forming fluid is of supper-high salinity and high potassium concentration. High potassium concentration in the fluid inclusions agrees with K-rich mesotype-acid rock and K-silicate alteration that occurred widely in this area. The daughter mineral assemblage in garnet and diopside is similar to the mineral assemblage of oreforming stage that followed skarn stage.     

Thermoelectric properties of porous (Bi0.15Sb0.85)2Te3 thermoelectric materials

In order to obtain thermoelectric materials with high figure of merit, the concept of Hollow (Vacuum) Quantum Structure or Effect and related thermoelectric materials design were proposed. To demonstrate the theory, the materials of (Bi_0.15Sb_0.85)₂Te₃ with porous structure have been fabricated. Their thermoelectric properties and the microstructure were investigated and compared with their density structure. It was found that the porous structure could improve their properties greatly.     

Interaction of fatigue and creep of GH33 under multi-axial stress at high temperature

Low-cycle fatigue experiments of tension-compression, torsion and tension-torsion with holding time were performed.The interaction law of creep and fatigue under multiaxial stress at high temperature was investigated, and the micro-mechanism of equilibrium diagrams was analyzed. A united equation of fatigue life under multiaxial stress was proposed.     

Longitudinal surface cracks on continuous casting slabs of P and Cu containing container steel

The fact that the amount of the mold flux components differs at different locations on the cracking surface indicates that the longitudinal surface cracks are initially formed in the mold and are enlarged in the secondary cooling zone. Based on the hot ductility measurement of two typical container used steels, it is known that the steels are in severe embrittlement state in the temperature range of 825-775℃. By means of increasing Cr/Ni plating thickness on the upper part of the mold, reducing mold heat flux, adopting new secondary cooling pattern, etc., the occurrence of the surface longitudinal cracks on the steel CC (continuous casting) slabs has been significantly reduced.