MAGNETIC FREEZING BY USING THE TRANSFORMATION OF MATERIAL

提出了一种利用奥氏体不锈钢相变进行磁记录的新方法。从奥氏体到马氏体的转变是摩擦应力作用的结果。马氏体是铁磁性的，而奥氏体不是。观察了不锈钢中磁场的记忆现象。在磁场作用下，均匀拉伸应力产生不锈钢薄板相变后，测量了钢表面的磁力分布。其分布与励磁线圈产生的磁场分布相似。这一结果意味着有关外加磁场分布的信息被冻结在拉伸试样中。通过研究得到的冻结特性如下：1)拉伸不锈钢板所施加的应力与储存在板中的磁力大小之间存在良好的相关性。关系表现出良好的线性关系。2)随着塑性变形量的增加，冻结场的磁力和畸变都增大。这意味着存在一个最佳的冻结条件。这些条件取决于材料。sus304的最佳应力为410 MPa。3)冷冻磁场在不锈钢板内保存2个月以上。当磁场方向与冻结磁场方向一致时，磁场对外部磁场来说是相当稳定的。CO2激光器的辐照可以擦除冻结的磁场。CO2激光器的辐照具有触发磁场冻结的能力。

A new magnetic recording, which uses the phase-transformation of austenitic stainless steel, is proposed. The transformation from austenito to martensite occurs as a result of tribological stress. Martensite is ferromagnetic while austenite is not. memorizing phenomena of magnetic field in stainless steel were observed. After a uniform tensile stress generated the phase-transformation of a stainless steel thin plate in a magnetic field, the magnetic force distribution on the steel surface was measured. The distribution was similar to that of the magnetic field that was induced by the exciting coil. This result means that the information about the external magnetic field distribution was frozen in the tension test specimen. The freezing characteristics obtained by conducting the study were as follws ;1)There is a good correlation between the stress applied by stretching a stainless steel plate and the magnitude of the magnitic force, which is stored in the plate. And the relationship shows good linearity.2)As the amount of plastic deformation increases, both magnetic force and distortion of the frozen field increase. This means that there exists an optimal condition for the freezing. These conditions depend on materials. The optimal stress for SUS 304 is 410 MPa.3)The frozen magnetic field was contained in the stainless steel plate for more than 2 month. the magnetic field is quite stable for the external magnetic field wnen the direction coincides with that of the frozen magnetic field.4)The frozen magnetic field is erased by the irradiation of CO2 laser5)The irradiation of CO2 laser has a capability to be used as a trigger for the freezing of magnetic field.