Optimization Design of Insert Hot Stamping Die’s Cooling System and Research on the Microstructural Uniformity Control of Martensitic Phase Transitions in Synchronous Quenching Process

Table 4

Basic thermal physical parameters of air (485°C).

Temperature (°C)	Density (kg/m^3)	Specific heat (J/kg·°C)	Thermal conductivity (W/m·K)	Viscosity (m^3/s)	Thermal expansion rate (1/K)
460	0.471	1087	0.055	3.48e^−6	1.32e^−3