EBSD技术在磁场下等温珠光体相变研究中的应用

Application of EBSD technique on pearlite transformation under high magnetic field

讨论了背散射电子衍射(EBSD)技术在获得有关Fe-2Si-3Mn(at%)铸钢磁诱发珠光体(MIP)相变的多相组织信息方面的实际应用。结果表明,面扫描中电子背散射衍射花样(EBSDP)的标定率与MIP的转变量关系极大,转变量越大则标定率越高,面扫描分析数据能更好地反映MIP的分布、取向和结构信息,相变初期形成的珠光体MIP存在微织构<100>//ND;相变早期形成的珠光体量较少,区域扫描中EBSDP标定率低,晶体学取向分析可用各个珠光体(P)团内铁素体片的点分析结果的集合来定性描述,有望获得磁场处理后多晶样品表面的微织构信息。对实际样品的分析还表明:同一P团可由多形核机制形成;相变的初期阶段在原奥氏体晶界上的不连续析出物为铁素体。

The practical application of electron backscatter diffraction （EBSD） technique in obtaining statistically relevant information from the multi-phase microstructure in a Fe-2Si-3Mn （at%） casting steel processed by isothermal transformation under high magnetic field was discussed. The results show that the indexing rate of electron backscatter diffraction pattern （EBSDP） has a close relationship with the transformed volume fraction of magnetic-induced pearlite （MIP） , the more the fraction, the higher the indexing rate of EBSDP, thus, a better reflection of the distribution, crystallographic orientation and structure of MIP colonies can be achieved with the data collected through area scanning. At quite early stage of phase transformation, the low transformed fraction of MIP will give a low indexing rate of EBSDP over the surface of sample, the crystallographic data collected by point analysis on a ferritc plate in a pearlite （P） colony can be used to represent qualitatively the crystallographic orientation of the P colony, therefore, micro-texture information of MIP over the surface of polycrystalline sample might be obtained from a large number of point measurements. It has also indicated that a P colony can be formed by the multi-nucleation mechanism; those discontinuous precipitated particles along prior austenite grain boundaries are ferrite.