应变路径变化对纯镍组织和织构的影响

Effect of strain path change on microstructure and texture in nickel during cold rolling and annealing

摘要:

采用背散射电子衍射（EBSD）和X射线衍射（XRD）技术对比分析了两种应变方式（单向轧制和交叉轧制）对大变形量（厚度方向压下量90%）纯镍形变组织和织构以及随后热处理过程中组织和织构演变的影响。结果表明：单向与交叉轧制纯镍的形变微观组织均以层片状组织为主，但前者储存能高于后者；单向轧制纯镍的宏观织构是典型的铜型冷轧织构，而交叉轧制纯镍的主要织构组分是黄铜和旋转型黄铜织构，且前者的织构强度明显高于后者。对两种方式形变样品在不同温度下进行退火处理，发现单向轧制样品中形成了以立方织构为主的再结晶织构，且随着退火温度的升高，立方织构的强度逐渐增强；而交叉轧制样品则形成了弱的再结晶纤维织构，其强度远小于单向轧制样品的再结晶织构强度。另外，单向轧制样品在高温800°C保温处理后，出现了少量异常长大晶粒，这是由于取向相近的立方取向晶粒聚集形成团簇，使得微观取向分布不均匀造成的；而交叉轧制方式可以抑制热处理过程中的晶粒异常长大。

Abstract:

The effect of strain path (unidirectional rolling and cross rolling) on microstructure and texture in deformed and recrystallized state was investigated by electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). The results show that the lamellar structure is dominant in both of samples with two rolling mode, but the stored energy in the unidirectional rolled (UDR) sample is higher than that in the cross rolled (CR) sample. The deformation texture is significantly affected by the strain path. The UDR sample is characterized by the typical “copper type” rolling texture, while the CR counterpart is mainly composed of Brass (Bs) and ND-rotated Brass (BsND) texture components. In addition, the minor cube and rotated cube were found in both of deformed samples. When the two samples were simultaneously annealed at different temperatures for 1h, the different recrystallization textures were obtained. The cube texture was prevailed in the UDR sample, while the weakened fiber texture was dominant for the CR sample. In addition, the abnormal grain growth was observed in the UDR sample annealed at 800℃ for 1h, which was attributed to the formation of clustered grains with a preferred cube orientation leading to the inhomogeneous microtexture, while the cross rolling mode suppressed the occurrence of abnormal grain growth during annealing.