HOT DUCTILITY OF 304HC STAINLESS STEEL AND THE MODEL OF RESISTANCE TO DEFORMATION

The ductility map of 304HC stainless was determined by using the Gleeble-1500 dynamic thermal-mechanical simulator. The effect of Cu on the hot ductility of 304HC stainless steel was analyzed and the mathematical model of resistance to deformation was established. The microstructure, inclusion and fracture surface were studied by using the method of micro structure analysis, scanning, energy spectrum and electron microscope. The results show that Cu has effect on the hot ductility, and the hot ductility of 304HC stainless steel decrease with the increase of content of Cu. The deformation temperature also has much effect on the hot ductility, the suitable deformation temperature are 1100-1200℃. The reason of it is that the Cu rich chemical compounds were precipitated from austenite phase during cooling. The Cu rich chemical compounds are brittle substance such as Cu2S, Cu2O and ε-Cu etc.

Force analysis and experimental study of pure aluminum and Al-5%Ti-1%B alloy continuous expansion extrusion forming process

The deformation zone of CONFORM extrusion was divided into primary gripping zone,gripping zone,conical expansion chamber zone,cylindrical zone and sizing zone of die,and corresponding force equilibrium equations were established using the Slab method.The deformation force formulae of CONFORM machine at any wrapping angle with an expansion chamber were obtained.Experiment on pure aluminum and Al-5%Ti-1%B alloy was conducted on the CONFORM machine self-designed.The resistance to deformation of Al-5%Ti-1%B alloy at the deformation temperature of 400℃ and the strain rate of 3.07 s-1 was measured to be 50 MPa using Gleeble-1500 thermal simulation machine.The calculation results of deformation forces for CONFORM process with an expansion chamber for pure aluminum and Al-5%Ti-1%B alloy were given.The experimental CONFORM radial force is in agreement with the radial force obtained by theoretical formula.