退火对Zr-Sn-Nb-Fe-Si新锆合金薄板带材组织性能的影响

Effect of annealing on microstructure and properties of Zr-Sn-Nb-Fe-Si novel zirconium alloy sheet strip

针对锆合金带材冲压成形时易破裂的问题,研究了再结晶退火对Zr-Sn-Nb-Fe-Si新锆合金薄板带材组织性能的影响。结果表明,随着退火温度的升高,新锆合金薄板带材的最大减薄率减小;第二相颗粒弥散分布于新锆合金晶粒内部及晶界,其形貌基本为球状,尺寸较大第二相为Zr(NbFe)_(2),较小为β-Nb;新锆合金带材具有<1010>//RD和<1120>//RD两类织构,其中<1120>//RD取向的晶粒与形变基体的取向差为30°/<0001>。随着再结晶退火温度的升高,第二相颗粒产生的钉扎作用不能阻碍锆合金重合点阵∑13晶界的快速迁移,导致<1120>//RD取向的再结晶晶粒择优长大,吞并形变基体,小角度晶界占比降低,大角度晶界占比升高,造成再结晶织构由<1010>//RD转变为<1120>//RD,改善晶粒变形的均匀性,提高带材冲压时塑性变形的均匀程度,因此再结晶退火有利于改善新锆合金薄板带材的冲压成形性能。

Aiming at the problem of strip cracking for zirconium alloy during the stamping forming process,the effect of recrystallization annealing on microstructure and properties of Zr-Sn-Nb-Fe-Si novel zirconium alloy sheet strip was investigated.The results show that with the increase of annealing temperature,the maximum thinning reduction rate of the novel zirconium alloy sheet strip decreases,in the grain and at the grain boundary of the novel zirconium alloy,the second phase particles are dispersed.The morphology of second phase particles is basically spherical,and the larger size second phase is Zr(NbFe)^(2),the smaller size second phase isβ-Nb.The novel zirconium alloy sheet strip has two kinds of textures:<1010>//RD and<1120>//RD.The misorientation between the grains of<1120>//RD and the deformed matrix is 30°/<0001>.With the raising of recrystallization annealing temperature,the pinning effect generated by the second phase cannot prevent the rapid migration of∑13 grain boundaries of the zirconium alloy superposition lattice,leading to the recrystallized grains of<1120>//RD orientation growing preferentially and annexing the deformed matrix,the proportion of small angle grain boundary decreases while the proportion of large angle grain boundary increases,resulting in the transformation of texture from<1010>//RD to<1120>//RD during recrystallization,which improves the uniformity of grain deformation,improves the uniformity of plastic deformation of the sheet strip during stamping forming.Therefore,the recrystallization annealing is in favor of improving the stamping properties of the novel zirconium alloy sheet strip.