The air cooling rate of the Low Carbon Mn-Si-Cr steel bar with different diameter after austenitizing at 910oC and 960oC was simulated by Formaster-F Phase transforming instrument and Gleeble-1500 thermal /mechanical simulating machine. Microstructure of the specimen was observed by OLYMPUS PME3 optical microscope and FEI QUANTA200F scanning electron microscope. The hardness and impact toughness of the steel was tested by HBRV-187.5 hardness tester and JCSJ300-I instrumented Charpy impact tester. The experimental result showed that with the amount of CFB in CFB+M mixed microstructure increasing the combination of strength and toughness of the steel was improved. The higher the austenitizing temperature of the steel, the wider the air-cooling rate range obtaining CFB+M mixed microstructure. However, the steel produces mixed grain after austenitizing at 960 oC. For obtaining fine prior austenite grain size, Ti and Nb alloying element need to be added.

No abstract

No abstract

We study noncommutative Chern-Simons mechanics and noncommutative Hall effect by Dirac theory in this paper. The magnetic field is introduced by means of minimal coupling. We show that the constraint set will enlarge when a dimensionless parameter takes zero value. In order to illustrate our idea, we study two specific models. One is noncommutative Chern-Simons mechanics which describes a charged particle on a noncommutative plane interacting with a perpendicular uniform magnetic field. The other is a charged particle on a noncommutative plane with a background uniform electromagnetic field. We show that when the dimensionless parameter tends to zero, the particle will live in a lower dimensional space in both models. Noncommutative Chern-Simons mechanics will reduce to a harmonic oscillator and the classical equations of motion of a charged particle in the background of a uniform electromagnetic field are governed by classical Hall law when the dimensionless parameter tends to zero.