Properties And Characterization Of Homogeneous Lamellate Heterogeneous Materials Processed By Accumulative Roll Bonding On The Al-Mg-Si Alloy

Aluminum(Al)alloys have great applications in automobile industry,which is of great significance to realize automobile light-weight and improve energy efficiency.Twin Roll Casting(TRC),as a novel casting method,can effectively reduce the alloy production process,reduce energy consumption and production costs.It is considered to be one of the most promising technologies in the metallurgical industry in the 21 st century.As an emerging structural material,heterogeneous layered heterogeneous materials have broad application prospects.It can be processed by the Accumulative Roll Bonding(ARB)process,and can break through the limitations of traditional strengthening mechanisms that are difficult to balance with strength and plasticity.In recent years,extensive research has been conducted on the heterogeneous lamellate materials processed by dissimilar metals,but there are few reports on the heterogeneous lamellate materials processed by similar metals.Therefore,in this study,based on TRC Al-Mg-Si alloy,the heterogeneous lamellate materials processed by similar metals has been designed.The microstructure evolution and mechanical properties were studied.The main research contents and conclusions are as follows:(1)Al-Mg-Si alloy strips were successfully processed by twin rolling cast combined with asymmetric casting technology.Two different thicknesses Al-Mg-Si alloy strips were processed by changed the roller gap.The TRC process parameters of the thick sample were determined:the casting temperature was 690 ?,the rolling speed is 8 m/min,the roller gap is 2.25 mm.The parameters of the thin sample were also determined:the casting temperature was 700 ?,the rolling speed is 10m/min,the roller gap is 0.3 mm.The differences in the microstructure and mechanical properties of two different thickness strips are studied.Due to the faster cooling rate during TRC process,the secondary dendrite arms are smaller and the central segregation zone is significantly reduced in the thin sample.The final yield strength and tensile strength of the thin sample were 184 MPa and 211 MPa,respectively,and the plasticity was8%,the yield strength and tensile strength of the thick sample were 90 MPa and 152 MPa,and the plasticity was 23%.(2)Based on the two different thicknesses Al-Mg-Si alloy strips processed by twin-roll casting process,the heterogeneous lamellate materials processed by similar metals has been fabricated by accumulative rolling bond at 300 ?.During ARB process,due to the difference in the initial properties,the thin TRC strip act as a single-sided lining plate in the first cycle,and the thick TRC strip bear more deformation.After the third pass,the deformation on both sides is relatively uniform.The mechanical properties of the compound sheets agree the mixing rule.After solution and artificial aging treatment,the compound sheet exhibits a better strong plastic combination,as a result of the difference in the the size and distribution of the precipitated phases on both sides.(3)To reduce production process,the heterogeneous lamellate materials were processed at 550 ?.The deformation combined with the quenching process replaces solution treatment through increasing the rolling temperature.There are differences in the solution and dynamic precipitation of the both sides during the ARB process.The cooling rate of the hot rolling-quenching production process is lower than that of water quenching,which leads to the occurrence of dynamic precipitation.The size of the dynamic precipitation phase is usually larger than 1(?)m,and the contribution to the strength is small.It will even impair the subsequent aging performance.Due to the difference in solution and precipitation phase of the both sides,the compound sheet has a better strong plastic combination.In summary,the heterogeneous lamellate materials processed by similar metals has been fabricated by the "two-roll casting +accumulative roll boding" technology,and its microstructure evolution and mechanical properties at different deformation temperatures were studied.The further research was carried out in the precipitates of the subsequent artificial aging treatment.A new method for processing heterogeneous lamellate materials has been proposed in this work.The results of this work can broaden the application fields of lightweight materials and provide a basis for developing Al-based heterogeneous lamellate materials and realizing high-efficiency production.