Abstract
Bonding of low carbon steel and sintered steel to aluminum was carried out by means of squeeze casting technique. Influences of casting pressure and pouring temperature on the bonding strength between steel and aluminium was studied by using samples with different casting conditions, i.e.; with the pressure range from 250kg/cm2 to 1,000kg/cm2 and aluminium casting temperature from 700°C to 900°C. To measure bonding strength between steel and aluminium, as-cast ingots were mechanically cut into clad type tensile test specimens and were tensile tested at −196°C, 20°C and 180°C. The results indicated that bonding strength increased by increasing both the casting temperature and the pressure for both types of steels. Copper coating and a high heat content ratio between molten aluminium and low carbon steel were effective for improving bonding strength. In the case of the sintered steels, bonding strength changed remerkably by casting pressure and sintered density. SEM, EPMA and X-ray diffraction study revealed that the diffusion layers between steel and aluminium consisted of tongue-like Fe2Al5 at the steel side and FeAl3 at the aluminium side. Total thickness of the diffusion layer varied with casting pressure, temperature and the surface condition of the steels. Fracture occurred at the base of the Fe2Al5 layer in all the specimens at all the temperatures of tensile test. Under the optimum fabrication condition, bonding strength of about 3kg/mm2 in the temperature range from −196°C to 180°C was obtained.
