材料期刊网

Continuous extruding/extending forming process for A 2017 alloy in semi-solid state was proposed through installing extending die at the outlet of shearing-cooling-rolling (SCR) machine.A series of experiments to produce flat bar of A2017 alloy were carried out.The forming process, metal flow behavior in die and microstructure and mechanical property of products were investigated.It is shown that if the pouring temperature of melt was higher, the die was filled with semi- solid slurry with low solid fraction and periodical cracks would occur on the product surface; If its pouring temperature was lower or the preheating temperature of die was lower, semisolid slurry would solidify rapidly and block the die after entering the cavity.The analysis of mass flow trace shows that the semi-solid slurry moves forward layer by layer and fills the die extending cavity in radiation manner and the velocity of mass flow in the central area of extending cavity and exit of mould is the maximwn, and then decreases gradually from the center to both sides of die wall.By increasing the die extending angle, the velocityof mass flow becorned more homogeneous.Under rational process control and die design, the A2017 flat bar with transverse section of 10 × 50 mm and with good surface and fine equiaxed grains can be obtained by continuous extruding/extending forming process.The product's tensile strength and elongation are 420.5 MPa and 14.2% , respectively.