Study On Friction Stir Welding Of 6061-T6 Aluminum Alloy And PMMA Dissimilar Materials

With the continuous emergence of new materials and new structures,metal polymer composite structures are more and more widely used.Nowadays,Connection process has matured gradually.In the connection between polymer materials and metals,we mostly use mechanical connection and bonding process,but these have different flaws and defects.With the extensive application of aluminum alloy,friction stir welding is gradually on the stage of history.As a new welding method,friction stir welding has great potential in the preparation of composite materials and hybrid structures,and has gradually become a research hotspot in recent years.In this paper,6061?T6 aluminum alloy and polymer material PMMA are used as raw materials,we use friction stir welding to lap different materials,discuss the welding feasibility of two materials,test the mechanical properties of the well-formed joints for tensile and analysis the microstructure of welded joints.In order to study the feasibility of welding 6061?T6 aluminum alloy and polymer material PMMA,three different specifications of mixing heads with stirring pin lengths of 2.0mm,2.3mm and 3.0mm were used to weld the two materials by using different welding parameters Feasibility test.The results showed that when welding test is conducted with a mixing head with a needle length of 2.0mm,it is necessary to use a lower reduction of more than 2.0mm,which makes it impossible to form an effective connection between two plates due to the huge interaction force generated by the pressure of the mixing head.When using 2.3mm of that,multiple sets of parameters can form an effective connection.When using 3.0mm of that,an effective connection can also be formed between the two materials.In summary,the better parameter combination is a rotation speed of 1000 r / min,a welding speed of 300 mm / min,and a reduction of 3.0mm.In order to study and determine the optimal welding parameters,the tensile and metallographic specimens were made and observed for several groups of better process parameters.The test results show that in the tensile test,using a stirrer with a needle length of 2.3mm,the welded specimen has higher strength.Under the parameter combination of a rotation speed of 1200 r / min,a welding speed of 70 mm / min,and a reduction of 2.3mm,the maximum tensile strength of 38.24 MPa can be obtained.Metallographic microscopic observation of the cross section obtained under the test parameters,we found that the two materials were well mixed at the welded joint,and the "onion ring" in friction stir welding appeared.