七、特征 X 射线波长及衍射晶面的选择微分布拉格公式得:式(45)说明,在一定的应力和弹性应变状态下,衍射线的布拉格角θ_0越大,弹性应变引起的衍射线的挪动量也越大。在2θ角测量准确度相同时,利用这样的线条进行应力测定,准确度就会较高。从式(31)也可以得到相同的结论,由该式可以看出,应力值σ_x 相同时,X 射线应力常数 K 越小,衍射角2θ_(?)随 sin~2Ψ的变化率就越大,如果2θ测量准确度相同,则所得2θ_(?)-sin~2Ψ直线斜率 M 的误差相同。K越小,显然该斜率误差所引起的应力值σ_x 的误差也越 Selective differential Bragg’s formula of characteristic X-ray wavelength and diffraction plane: Equation (45) shows that the larger the Bragg angle θ_0 of the diffraction line under certain stress and elastic strain, the more the diffraction line moves due to the elastic strain The greater the amount. In 2θ angle measurement accuracy of the same, the use of such lines for stress measurement, the accuracy will be higher. From equation (31), we can get the same conclusion. It can be seen from the formula that when the stress σ_x is the same, the smaller the X-ray stress constant K, the larger the change rate of diffraction angle 2θ_ (?) With sin ~ 2Ψ, If the 2θ measurement accuracy is the same, then the error of the slope 2 of the 2θ _ (?) - sin ~ 2Ψ line is the same. The smaller K is, the more obvious the error of the stress value σ_x caused by the slope error is