The interrelation between mechanical properties and damping capacity of 316L stainless steel has been investigated and two factors, mechanical properties and damping capacity of 316L stainless steel with two phase of martensite and austenite, were also studied. Furthermore the effect of thermo-mechanical treatment on the mechanical properties and damping capacity of 316L stainless steel was studied to obtain good combination of mechanical properties and damping capacity.
The results obtained from this study are as follow:
The and -martensite were formed with surface relief, specific direction, and intersection by deformation. With increasing degree of deformation, the volume fraction of ε-martensite increased and then subsequently decreased, while -martensite rapidly increased. With increasing degree of deformation, tensile strength was increased, and elongation was decreased, however damping capacity increased and then subsequently decreased. Tensile strength and elongation were affected by the -martensite and damping capacity was influenced greatly by -martensite. Thus, there was no proportional relationship among strength, elongation, and damping capacity.
The two phase structures of deformation induced martensite and reverse austenite were obtained by deformation and reverse annealing treatment at given temperatures between 500℃ and 700℃. Austenite with ultra fine grain less than 0.5㎛ was obtained by reverse annealing treatment. Volume fraction of reverse austenite increased with an increase of annealing temperature and time. With an increase of volume fraction of reverse austenite, strength was decreased rapidly, while elongation was rapidly increased, and damping capacity was slowly decreased. Strength, elongation, and damping capacity of 316L stainless steel with two phases of martensite and austenite were strongly affected by reverse austenite.
Dislocation, martensite, and stacking faults were formation by thermo- mechanical treatment.
The and -martensite were formed by deformation, but only -martensite was formed by thermo-mechanical treatment. Volume fraction of stacking faults and ε-martensite were increased with increasing number of cycle of thermo- mechanical treatment. With an increase number of thermo-mechanical treatment, hardness, strength and damping capacity increased, while elongation decreased.
With increasing volume fraction of martensite formed by thermo-mechanical treatment, hardness and strength were rapidly increased, but elongation was rapidly decreased. Thus, hardness, strength, and elongation were influenced greatly by martensite. Damping capacity of thermo-mechanical treated 316L stainless steel was increased with an increase of stacking faults formed by thermo-mechanical treatment. Thus, damping capacity of thermo-mechanical treated 316L stainless steel was strongly affected by stacking faults. The results confirmed that the good combination of strength and damping capacity was obtained from thermo-mechanical treatment.