择优取向对X射线法测定钢中Ar量的影响

The Effect of Preferred Orientation on the Determination of Ar Content in Steel by X—ray Diffraction

采用 X 射线法可以精确测定钢中残余奥氏体的含量,但是在测定时要考虑择优取向对测定精度的影响.本文采用能量色散衍射法,截取不同试样表面、选用多组衍射线、标准试样台、Rr 试样台等试验方法及设备,对不同钢种和具有不同程度择优取向的样品进行了对比分析测试得出:择优取向对奥氏体含量较少的钢种中的残余奥氏体量的测定精度具有较大影响.合理截取试样截面可部分消除择优取向对测定精度的影响.采用选择多组衍射线对和截取多组截面的方法可以精确测定残余奥氏体量.标准台和 Rr 台对测试结果没有明显作用.

The content of retained austenite(At)in steel can be determined by meta- llographic,maguetic and X-ray diffraction methods,etc.For smaller fraction of Ar,metallographie test result is not reliable,the magnetic test data is alw- ays the restilt of Ar of the whole specimen but the result of Ar of Selected ar- eas or volumes of the specimen with the standard contrast specimen is difficult to be made.However, the effect of prefered orientation on the precision of diffraction data needs to be considered.The author found by experiment that prefered orientation has greater effect on the precision of Ar content measur ing by X-ray diffraction for the steels containing less At.Proper heat treatment and diffracting at different sections of a specimen can partially eliminate the effect.The Ar content cart he accurately measured by choosing several couples of diffraction fringes diffracted at several sections of a specimen.