Advanced Materials Research Vols. 750-752

Abstract: The paper studied that effect of temperature on tribological performances of ion nitrocarburized layer of 42MnCr52 steel under CD15W-40 oil lubricating. It is found that the ion nitrocarburized layer has more excellent friction reduction and wear resistance performances than the plain surface under different temperatures, especially under the higher temperature 150°C, the friction factor and wear scar width of ion nitrocarburized layer is 36% and 77% less than that of the plain surface respectively, which indicates that ion nitrocarburized layer can play more excellent friction reduction, wear resistance and scuffing resistance performances under the relative higher temperature.

Abstract: The research about effects of Nb on martensite size and mechanics in B-bearing steel was completed. The results show that both steels have similar martensite due to high hardenability of B element which is responsible for high mechanical properties. However, there are differences in the microstructures between A steel (Nb-containing steel) and the B steel (Ti-containing steel). Microstructural observation of the quenched specimen shows that the formation of fine martensite is dominant in the A Steel than B steel due to Nb element. Martensite size in B-bearing steel was refined by Nb element for high fatigue property and toughness.

Abstract: The preparation of pellets with taking the iron concentrate and titanium concentrate as the raw materials, the pulverized coal as the reducing agent and the CMC as the binder were researched in this paper. It was deduced from the orthogonal experiment results that the impact of quantities of binders on the compressive strength is the greatest, carbon ratio takes the second place, water content takes the third place, and pressure the least; the impact of the water content on the drop numbers is the greatest, pressure takes the second place, carbon ratio takes the third place and quantities of binders the least. Suitable parameters of forming process are ore ratio is 1:1, quantities of binders is 2.5%, carbon ratio is 18%, water content is 8% and pressure is 16 MPa.

Abstract: As large flow rate of argon blowing in the process of bottom argon blowing ladle will cause severe fluctuations and sprays of molten steel, making the slags surface boiled and steel secondly oxidized, melting the refractory materials in the ladle, the flow rate of bottom argon blowing is limited, which will affect the efficiency of stirring. A 1:7 ratio ladle water model is established in the lab, and we will discuss how the diameter (d) of immersed tube, inserting depth (h) and the rate of bottom argon blowing affect the mixing time. The results show that the fluctuations on the steel surface can be diminished by the variations of diameters of immersed tube and inserting depth, the mixing time can be shorted by the increased flow rate of bottom argon blowing.

Abstract: The effect of power and tool rod position on inclusion removal was studied in the ladle refining cold model when the organic particles were used to imitate the inclusion. The mechanism of removing inclusion by cavitation bubbles was investigated. Both the transient bubbles and stable bubbles can promote the removal of inclusion; as the power increase, cavitation intensity increases, the number of cavitation bubbles increases, the collision probability of the cavitation bubbles increases with the inclusion, the efficiency of removing inclusion increases; as the wave source into the liquid is 1/2 H, the effect of removing inclusion is the best.

Abstract: In this paper, the latest research development on the heat treatment processes, microstructure and mechanical properties of low-carbon martensite steel was reviewed. And the effects of heat treatment processes on the microstructure and mechanical properties of low-carbon martensite steel were analyzed.

Abstract: Continuous cooling static transformation regularity of T700 was investigated by gleeble-3500, the results show when the cooling rate is small organization is mainly composed of ferrite and pearlite. With the increase of cooling rate, begin to appear granular bainite. When the cooling rate is 10-20 °C /s, microstructure is acicular ferrite and bainite. Along with the cooling speed further increasing, martensite begins to appear in organize, and with the increase of cooling rate, martensite content gradually increase.

Abstract: Continuous cooling dynamic transformation regularity of T700 was investigated by gleeble-3500. The results show when the cooling rate is small organization is mainly composed of polygonal ferrite and pearlite and has minor banded organization. With the increase of cooling rate, begin to appear granular bainite. When cooling rate reaches 3/s or more, ferrite changes to quasi polygon, and start to appear small amount of bainite. when the cooling rate is 7°C/s, pearlite is disappeared in structure, granular bainite increases, quasipolygonal ferrite content is gradually decreased. When the cooling rate is increased to 10°C/s or above, organization is granular bainite.

Abstract: High-temperature oxidation behaviors of super-clean 9CrMoV steel and 1CrMoV steel for HP steam turbine rotor materials were investigated. The super-clean 9CrMoV steel showed a superior high-temperature oxidation resistance with very small oxidation rates even though at 630°C, because the oxidation was restrained by the Cr-oxides formed near the base metal. On the other hand, the oxide scales formed on the 1CrMoV steel were composed of Fe-oxides, and the oxidation rate increased remarkably at the temperatures above 610°C.

Abstract: Fe-6.5wt%Si silicon steel has excellent soft magnetic properties, but its ductility in room temperature is near zero. A lot of researchers tried to improve the ductility by adding alloy elements. In this paper, we summarized the action mechanism and the content of these alloy elements according to the overseas and domestic research status. Al, B, Cr, RE, et al. improved the ductility of Fe-6.5wt%Si silicon steel in low temperature, but reduced its magnetic properties simultaneously. Ni, Ti, Mn, et al. improved the ductility of Fe-6.5wt%Si silicon steel inconspicuously.