Modification Of Biomedical Stainless Steel By High Current Pulsed Electron Beam

The 316 L stainless steels has been internationally recognized as the preferred material for medical stainless steel surgical implants at present and widely applied in the fields of orthopedics, dental, cardiac surgery for its excellent comprehensive mechanical properties,easy processing technology and controlled cost. Hence, enhancing mechanical properties and biocompatibility have present more and more significant meaning. Nevertheless, the corrosion of stainless steel could inevitably occurred in the complex organic environment and damaged by corrosion and wear corrosion. As the result, the material release harmful metal ions and the corrosion product that can disturb the normal physiology functions of human tissue, triggering malignant tissue reactions and host response, eventually meaning the invalidation of functional materials and biological incompatibility. Therefore, this paper takes enhancing the wear corrosion complex properties of stainless steel for biomedical application as a cut-in point, using SOLO-M pulsed electron beam source for material surface modification. By means of metallographic microscope, scanning electron microscopy(SEM), X-ray diffractometry(XRD) and Energy dispersive spectrometer(EDS), the paper has inquired the microstructure and surface morphology of the experimental materials. Furthermore, the samples surface microhardness, wear resistance, corrosion resistance and wear corrosion resistant test experimental have also been explored and analyzed. Finally, the optimum treatment technology, the material surface modification mechanism and the results were obtained. The experimental results show that:1、The original sample surface is smooth and flat, also the grain of sample is coarsenin.After HCPEB treatment it can be seen obviously that a large number of craters were formed on the surface, with the increase of pulse times the density of the crater increases first and then decreases, the size increases, the refining effect of grain also became much more obviously.2、The inclusions in 316 L stainless steel are Mn S particles, the overheated eruption of inclusion itself or substrate interface are the important reasons leading to the formation of craters. With the increase of pulse times the melt completely erupt and Mn S inclusions in the crater are eliminated, and the material surface had get the purification effect.3、The 316 L stainless steel treated multiple pulse on(111) crystal plane would occur preferred orientation, and find every diffraction peaks of treated samples deviate to large angle.4、The surface hardness is improved greatly after HCPEB treated and increased with the growth of pulse times, the hardness could reach to 180 Hv with 45 pulses, which is 15%higher than the hardness of original samples. Meanwhile, with the increase of pulse times the friction coefficients and width of wear track decrease, the wear resistance is improved significantly.5、The corrosion resistance of 316 L stainless steel is effectively enhanced by HCPEB. In this study 45-pulsed sample has optimal corrosion resistance, grain refining, preferred orientation and residual compressive stress are the basic reasons of improving corrosion resistant ability.6、The treated samples in saline environment to get lower friction coefficient and less wear mass loss. The increasing of wear resistance and corrosion resistance will reduces the influence of wear corrosion compound action,samples of wear corrosion were enhanced.7、The wettability of the treated sample surface was significantly improved, which is better than original, at the same time showed a good hemocompatibility.