Abstract: Mechanical properties, tensile strength and fracture strain of 0.11%C liquid-forged carbon steel in liquid-solid stage during solidification were determined for the first time by tensile test with the glenble-1500 thermo-mechanics analog machine. The experiment showed that the liquid-solid co-existing range of 0.11%C carbon steel can be divided into three zones, each of which has different mechanical behaviors. In zoneⅠ, the tensile strength equals zero, the fracture strain has a high level but reduces sharply in quantity with the declining of the temperature. In zone Ⅱ, with the declining of the temperature, the tensile strength develops gradually while the fracture strain reduces further to the lowest level. In zone Ⅲ, both the tensile strength and the fracture strain increase sharply in quantity as the temperature further declines. It is very clear that zone Ⅱ (1495～1505℃) is the hot brittleness zone where the hot crack occurs easily. Observation and analyzing of the fracture surfaces of the specimens has further testified the above result.

Key words: 力学性能, 热裂纹, 液态模锻, aerodynamic noise, high-speed train, large eddy simulation, Lighthill', pantograph