Effect Of Annealing Process Of Microstructures And Properties Of Cold-Rolled Al-Fe Alloy Sheets

Al-Fe alloy has an attractive prospect in the fields of space,weapon and automobile due to its excellent heat resistance,wear resistance,corrosion resistance,anti-oxidation and vulcanization corrosion resistance under high temperature conditions.The shape of Al-Fe phase is generally needle-like or sheet-like,which will seriously split the matrix,resulting in stress concentration and greatly reducing the mechanical properties of Al-Fe alloy.And the metal deformation caused by cold rolling will cause work hardening,which is not conducive to the subsequent work.Therefore,it is essential to study the effect of rare earth element La on the microstructure and properties of cold-rolled Al-Fe alloy during annealing process.This subject mainly focused on coli-rolled Al-Fe alloy sheets produced by the Zhongtuo Aluminum Co.Ltd.A systematic research was carried out on the microstructure and mechanical properties of cold-rolled Al-Fe alloy with different La during recrystallization annealing process by means of microstructure characterization and mechanical properties,and the evolution of recrystallization texture was also investigated.The cold rolled Al-Fe alloys with 0,0.2 wt.%and 0.4 wt.%La are annealed at constant temperature and at constant time,respectively.The experimental results show that the morphology and size of Al-Fe phase are changed by the addition of La.The cold-rolled Al-Fe phase develops from thick strip to ball while the recrystallized Al-Fe phase has a significant decrease in the width dimension.The recrystallization is completed after holding at 315 ℃ for 3 hours under constant annealing condition.The tensile properties were different during partial recrystallization.The addition of rare earth La decreased the yield strength and tensile strength of the materials,and increased the elongation of the materials,meanwhile the tensile strength and elongation of the samples with 0.2 wt.%La are higher than that of 0.4 wt.%.After recrystallization,the tensile strength,yield strength and elongation of these three AI-Fe alloys are similar.At constant temperature,recrystallization was completed at 315 0C for 1 h and only 5min at 365 ℃.The tensile strength and yield strength of the three alloys were similar with the holding time while the tensile strength and yield strength of the Al-Fe alloy with 0.2 wt.%La content were slightly higher than those of the other two alloys.The macro-texture and micro-texture of the cold-rolled Al-Fe alloy with 0.2 wt.%La were measured,and the grain size and grain misorientation angle during recrystallization annealing process were statistically analyzed.The experimental results show that the macro-texture is mainly β orientation line in cold rolling state,and it changes from S{124}<211>to R{124}<211>during recrystallization annealing.The position of the resulting R texture appears as orientation line in Euler space is similar to that of β-line.There are many grain orientations in the cold-rolled Al-Fe alloy,which are mainly composed of<001>orientation and<111>orientation,and plenty of broken and sub-grains are distributed in the sample space,forming a large number of large angle grain boundaries.In the process of partial recrystallization,the<111>orientation grains almost occupy the whole microstructure space,showing a relatively single orientation mainly composed of small angle grain boundary and sub-crystal in the alloy.When recrystallized completely,the grain boundaries are getting clear and the<001>orientation and<111>orientation are dominant in the alloy,resulting the diversity of orientation increases and high angle grain boundaries increases slightly.In conclusion,the AI-Fe alloy with 0.2wt.%La content has good microstructure.better tensile strength and elongation after partial recrystallization and completed recrvstallization.Moreover,the effect of Fe element results in strong R{124}<211>after recrystallization in Al-Fe alloy.