| To fabricate bulk stain-less steel with outstanding mechanical properties, stain lesssteel was firstly nano-crystallized by high energy ball-milling and subsequently SparkPlasma Sintered to obtain bulk stain less steel with high consistency and goodobdurability.304L power was milled and refined for a serious different milling time including1h,5h,10h,15h,20h, and25h. To investigate the effect of milling time, the grain size andqualitative/quantitative phase analysis on the milled power was conducted by X-RayDifference (XRD); Size and morphology of the particles were characterized by ScanningElectron Microscopy (SEM). Results show that martensite transformation was induced bythe milling, and grain size was refined to nano scale, the particles shows um-scale laminashaped structure that mainly consists of fine and flake partles.To fabricate bulk material, after high energy ball milling for1h,304L nanocrystallinepower was sintered at a various different temperature including850°C,900°C,950°C,1000°C, and1100°C for5min. Phase calibration of the sintered304L power wasconducted by XRD, microstructure was investigated by Transmission ElectronMicroscopy (TEM), and the fracture surface of tensile tested sample were analyzed bySEM. Density measurement was employed to indicate the consistency; mechanicalparameters such as Vickers hardness, Tensile Strength, Yield Strength and Elongation wereinvestigated by hardness and tensile test. Results show: anti-martensite transformationhappens during the SPS process of ball milled nanocrystalline power, and bulk stain-lesssteel in um-scale was obtained. The bulk steel sintered at950°C,which relative densityreached99.11%,has been nearly completely consistent. Compared with standard castedand subsequently annealed steel, the obtained sintered bulk steel shows a increase ofhardness, yield stress and tensile strength by21%,100%, and27%, respectively. |
PDF Full Text Request