Advanced Materials Research Vols. 535-537

Abstract: Through the thermal simulation test of the Nb-Ti micro-alloyed steel austenite cooling process and microstructure observation & microhardness test, the tests indicate cooling rates have effect on the phase transition and microstructure of tested steel, the critical quenching speed of Nb-Ti micro-alloyed steel is about 23°C/s with very good hardenability. With the increasing of the cooling rate, the beginning and ending temperature of phase transformation decrease and the ferrite structure content was decreased at room temperature. It’s easy to happen Bainite transformation at the beginning, and make the M block or flake M fine, which is to increase the strength and toughness of the steel.

Abstract: High boron alloyed stainless steel(HBASS) with different Ti content were fabricated by vacuum induction furnace and their microstructure and boride phase were analyzed. The boride phase of HBASS do not contain Ti element is mainly (Fe,Cr)2B phase with slender rod-shape. After adding Ti into steel, because Ti and B preferentially combines into TiB2 phase with petals or small block shape which can stop the formation of hard and brittle (Fe,Cr)2B, so the number of (Fe,Cr)2B phase is reduced. And after adding Ti, many crisscross cracks appeared in internal large (Fe,Cr)2B phase, which will be effective to break into small pieces of boride to improve steel plasticity and shielding thermal neutron performance during hot rolling process.

Abstract: Laboratory research on the mineral processing technique of a specularite ore from Baxi was performed, while the processes including gravity separation, low intensity magnetic separation(LIMS) -high intensity magnetic separation(HIMS)-gravity separation was adopted. The run-of-mine ore was milled till the -0.074 mm range accounts for 50% and treated through a LIMS – HIMS process, with the magnetic field strength of LIMS being 95.52 kA/m and HIMS,1.2T. As a result, an iron concentrate grading about 67.58% at a recovery of 96.21% can be obtained, which are rather good metallurgical performances. The iron concentrate with high grade also could be beneficiated by table separation, but its recovery is lower than it obtained from intensive LIMS – HIMS dressing.

Abstract: Test was made on separating iron from a ultra-low-grade vanadium titanium magnetite ore by a process of tailing discarding at a coarser size，staged grinding and staged low intensity magnetic separation. The results show that when the raw ore is treated by permanent dry magnetic separator with low intensity magnetic separation at 12～0 mm size，qualified tailings of about 20% yield can be discarded．The coarse concentrate is grounded in two stages. With the first stage grinding size being 45% -200 mesh and the second stage，75% -200 mesh，and then treated by two stage low intensity magnetic separation．As a result，an iron concentrate with a TFe grade of 65.80%and an iron recovery of 47.74%can be achieved．

Abstract: Ilmenite is an economically important and interesting mineral. It is found as a by-product of tin mining in Bangka Indonesia. This mineral has can be used as the source of making titanium metal, titanium dioxide (TiO2) pigment and material for photo catalysts. However, the synthesis of TiO2 from ilmenite using both sulfate and chloride processes still has faced a major problem to obtain white pigment of high purity and lower operation cost. This is mainly due to Fe2O3 impurity in TiO2 pigment which cannot be easily decomposed. Therefore, this study is aimed at investigating the possibility of using Bangka ilmenite mineral to obtain TiO2 pigments and photocatalysts. For this purpose, , sodium hydroxide (NaOH) was used as decomposition solution via hydrothermal process in a teflon-lined autoclave equipment. The characterization results indicated that Bangka ilmenite contains a significant TiO2 level of more than 30 %, although there still remains some other impurities. Upon decomposition of dissolution using NaOH, was decrease in impurity elements down to 60 %. The decomposition process of ilmenite was optimum at NaOH concentration of 10 M where the ilmenite decomposes to form an intermediate phase of sodium titanate with the morphological shape of fine threads.

Abstract: High manganese steel is a wear-resisting steel. With the rapidly development of industry, it is very important to improve the wear resistance of high manganese steel. We do some experiments with cold asynchronous rolling technique on austenitic high manganese steel.The results show that hardness and impact abrasion resistance are enhanced greatly with the increase of deformation, and the toughness not decrease to very low.

Abstract: The law of phase change of bearing-B steel during continual cooling was studied by adopting dilatometer. The CCT curves of bearing-B steel were drawn, and the effects of RE on critical cooling rates were studied. The experimental results show that the start temperatures of martensite TM was decreased from 438 to 404°C. The critical cooling rate was simultaneously decreased from 33 to 15°C/s.

Abstract: SUS304 stainless steel samples were sputter-etched by a radio frequency (RF) magnetron sputtering apparatus. Correlations between the formation of conical protrusions on the steel surface and sputter parameters, such as sputter power, anode-to-substrate distance, argon gas flow ratio and sputter-etching time were discussed. The results show that the conical protrusion precipitates both uniformly and densely on the surface with the power being 600W, the anode-to-substrate distance being 50mm, the argon gas flow ratio being 50sccm and the sputter-etching time being 6h.

Abstract: Abstract:The microstructures and mechanical properties of 22Mn2SiVBS steel after austenitizing at 1280°C and then cooling in air and piled up after rolled were studied in this paper .the results show that when 22Mn2SiVBS steel cooling in air it can obtain the fine grain granular bainte and remain austenite,and piled up after rolled it can obtain granular bainte and proeutectoid ferrite. After heat treatment the strength and hardness is higher than the sample piled up after rolled, but the toughness is lower.

Abstract: The recrystallization texture in a rolled polycrystalline (Fe₈₁Ga₁₉)₉₉B₁ alloy sheet was investigated using X-ray and EBSD (Electron backscattering diffraction) methods. The η fiber (//RD) with dominant Goss ({110}) component was successfully obtained through sheet thickness after primary recrystallization. Goss remains the dominant texture component during further grain growth. The development of Goss can be attributed to the specific rolling induced favorable shear band morphology and deformation texture. The results provide a prospective route for the efficient recrystallization texture optimization and economical production of Fe-Ga sheets.