Advanced Materials Research Vol. 900

Abstract: Preliminary research has shown that red mud is a viable option to be used as a fluxing agent in the steelmaking process, as it is able to achieve similar results as fluxes currently used in steel refining. This research focused on how red mud can be used as a flux for refining steel. Desulfurization was conducted with aluminum additions and temperature variations. The results showed that experiments utilized waste residues from the aluminum industry as refining flux for steel refining; more than 95% sulfur reduction was achieved; increasing temperature and aluminum content can improve desulfurization.

Abstract: Titanium (Ti) alloy metal has been used for permanent implant in the human body. Its high strength and hardness take place due to the β phase formation at room temperature. Ti-6%Al-6%V alloy is most popular, of which vanadium (V) content is used as the β phase stabilizer. However V can induce allergic reaction from the body. V can be substituted by other element, such as Mo and Nb. Microstructure observations for Ti-6%Al-6%Mo and Ti-6%Al-6%Nb alloys show that β phase exists as matrix having good workability at room temperature. After preheat at 1000°C, no cracking failure occurs during forging and rolling treatment. Thermal spray method is used for CaPO₄ surface treatment. A CaPO₄ layer on the alloy substrate forms after the molten CaPO₄ is hot sprayed on to the alloy substrate surface. Corrosion test results indicate that the increase in Mo or Nb content up to 6% leads to the increase in corrosion resistance.

Abstract: Decomposition of austenite in steels from high to low temperatures is pearlite, bainite and martensite phase transformation. According to studies, magnetic field promotes the three transformations. The phenomenons indicate the three transformations have coherence in magnetics. There is a transformation from paramagnetism (γ) to ferromagnetism (α) among all these three. Magnetic drive ΔG_m plays an important role in the phase transition. The bainite transformation was carried out at 300°C during different isothermal time. Combining the results, it studied the relationship of bainite and pearlite transformation from characteristics of the nucleation of BF, microstructures etc. Even without magnetic field, spontaneous magnetization makes contributions to phase transformation driving force. Small deflections cause by spontaneous magnetization may promote the lattice reorganization from FCC to BCC in a certain extent, while promote the formation of the new phase with BCC cube.

Abstract: As one of the quenched and tempered steels, 40Cr steel is often used to manufacture the shaft in heavy-duty trucks. To adjust the working environment of the heavy-duty machines, 40Cr steel should have high impact property. In this study, different tempering cooling mediums were treated as critical influence on improving impact property of the steel. After heated under 520°C tempering temperature, the samples of 40Cr were cooled in air, oil and water, respectively. The experiments were carried out through charpy impact, metallographical and SEM analysis. The results has shown that 40Cr steel of high impact property and fine microstructure can be obtained when water is used for the tempering cooling medium.

Abstract: For a period of time, because of a steel factorys frequent breakout , through monitoring the breakout slab cover, One of the important reasons for breakout is unreasonable flow field distribution in the mold. Through simulation this thesis analyzes how the parameters such as draw speedsubmerged nozzle affect the condition of flow field in the continuous casting mold , optimizing submerged nozzles structure and size which are fit for slab continue caster craftwork.

Abstract: A new type mechanism of anti-loosening bolt has been developed on the basis of the recovery characteristics of Fe-Mn-Si shape memory alloy. Based on that, Fe-Mn-Si shape memory alloy (SMA) anti-loosening bolt was processed, and its loose torque was increased by axial and radial restoring force generated in the process of heating. The anti-loosening experiment of the Fe-Mn-Si SMA bolt matching the common nut shows that the loose torque of pre-strain bolt increases with the increment of temperature, when the temperature is up to 500°C, the loose torque is 3 times than that of common bolt, which fits in with the characteristics of Fe-Mn-Si SMA phase transition; According to the failure criterion of fasteners, 80% decrease of loose torque, the vibration failure time of Fe-Mn-Si SMA bolt is 7 times than common bolt, so its anti-loosening effect is remarkable.

Abstract: Incremental Sheet Forming (ISF) is a flexible technology for forming customized productions in small batch, and has received wide attention, especially in the automobile manufacturing industry, where TRIP(Transformation Induced Plasticity) steel is widely used for its great ductility and high strength. But the springback of TRIP steel products is more serious than that of common steel ones, which induce the low dimensional accuracy and block the industrial application. This work would illustrate the experimental research on the dimensional accuracy of TRIP steel products in ISF. To make a reasonable accuracy evaluation, square cone-shaped samples of 1060Al and 08F steel were formed by ISF as the reference. By comparing the outline unconformity and the dimensional deviation, it comes to the conclusion that dimensional accuracy of TRIP steel sheet products is much lower than that of other materials.

Abstract: GH169 was coated by hot-dipping in a molten aluminum bath, and then diffusing annealing at 950 °C for 2 h. The high temperature isothermal oxidation behavior of the hot-dipped aluminized alloy and GH169 was tested at 900 °C for 100 h using resistance furnace. The surface morphology and phase composition of the oxide scale were studied by SEM and EDS. The result of high temperature oxidation test showed that oxidation curves of hot-dipped aluminized steel and GH169 followed parabolic law at 900 °C for 100h and the hot-dipped aluminum present more excellent anti-oxidation. A dense film formed on GH169 mainly composed of Cr₂O₃ and TiO₂ while on hot-dipped aluminized steel is Al₂O₃.

Abstract: The effect of different tempering temperatures on microstructure and impact property of 20CrMnTi steel has been studied on Zwick/roell Amsler PKP 450 pendulum machine, SU-8020 scanning electron microscope (SEM) and optical microscope. The results shows that the impact property of 20CrMnTi steel is dramatically improved after high-temperature tempering. However, the minimum value occurs when it was tempered at 350°C because of low-temperature tempering brittlement at this degree. The SEM fracture morphology was typical dimples after high temperature tempering, and the type of fracture was ductile fracture; the type of cleavage characteristic and quasi cleavage characteristic were generated on the fracture morphology at low-temperature and medium-temperature tempering respectively, and the type of fracture was brittle.

Abstract: The casting Al-Si-Mg alloy can be strengthened by heat treatments. There are close relations between heat treatments and alloys mechanical properties and corrosion resistance. The effects of heat treatments condition on corrosion behavior of Al-Si-Mg alloy in NaCl solution were studied by electrochemistry tests and immersion corrosion tests in this paper. The morphology of alloys after immersion corrosion was observed by OM (optical microscopy) and SEM (scanning electron microscopy). The influences of heat treatments on the corrosion of casting Al-Si-Mg alloy were explained. Different microstructures could lead to variation of corrosion properties. The corrosion properties of Al-Si-Mg alloy after casting, ST (solution treatment) and different aging respectively were analyzed. The results show that corrosion properties under PA (peak aging) are the worst and the best ones with ST, at the same time the I_corr under PA are the highest case and the lowest ones with ST.