论文部分内容阅读
奥氏体不锈钢用离子渗碳或离子渗氮能生成扩张的奥氏体。两种工艺得到的过饱和碳或氮的fcc晶体结构能很好地硬化,提高耐磨性,且保持原有的耐蚀性能。在本项研究中我们在AISI 316L SS不锈钢上在高温(225～504℃)和高能(30～500 keV),高通量(～1015cm-2),短时间保温(～400 ns),轻离子束(氘和氦)的辐射下,用离子渗碳和离子渗氮渗入N和C生成扩张的奥氏体,并研究它的稳定性。发现扩张的奥氏体在325℃以下是稳定的,在325℃和504℃之间,随温度升高它的晶格常数逐渐减小。我们观察到显微组织只和处理温度有关,由于热处理时间不长,没有观察到组织变化。超过504℃晶格常数回复到奥氏体材料原来的晶格常数。另一方面,观察到当用脉冲离子束时,随着脉冲数减少扩展奥氏体的晶格常数也减小。这种行为可以解释为通过由每束辐射作用在表面上因热振动,包括快速加热然后快速冷却引起N或C逐渐外扩散。然而发现经过20个离子脉冲后最终的晶格常数比原始奥氏体的略高一些,这是稳定的极限。这个残余的扩张量是由于在紧靠表面层的奥氏体晶体中产生应力引起几微米的部分非晶化的结果。
Austenitic stainless steel with ion carburizing or ion nitriding can generate expanded austenite. The fcc crystal structure of the supersaturated carbon or nitrogen obtained by the two processes can be well cured, improve the wear resistance, and maintain the original corrosion resistance. In this study, we incubated AISI 316L SS stainless steel at high temperature (225 ~ 504 ℃) and high energy (30 ~ 500 keV), high flux (~ 1015cm-2) Beam (deuterium and helium) radiation, with ion carburizing and ion nitriding into N and C to generate expanded austenite, and to study its stability. The expanded austenite is found to be stable below 325 ° C and its lattice constant decreases with increasing temperature between 325 ° C and 504 ° C. We observed that the microstructure was only related to the treatment temperature, and no tissue change was observed due to the short heat treatment time. The lattice constant of more than 504 ℃ reverts to the original lattice constant of the austenite material. On the other hand, it is observed that the lattice constant of expanded austenite decreases as the number of pulses decreases when pulsed ion beams are used. This behavior can be explained as the gradual out-diffusion of N or C by heat vibration on the surface by each beam of radiation, including rapid heating and then rapid cooling. However, it was found that the final lattice constant after 20 ion impulses was slightly higher than the original austenite, which is a stable limit. This residual amount of expansion is the result of partial amorphization of a few microns due to stressing in the austenitic crystals next to the surface layer.