Aluminum Alloy Side Research Articles

５０５２アルミニウム合金／純チタン摩擦圧接継手の機械的性質に及ぼすインサートメタルの影響

5052 aluminum alloy to pure titanium were friction welded using a continuous drive friction welding machine. Effect of using an insert metal on the microstructures and mechanical properties of the dissimilar friction welded joint was investigated. Friction welded joints without insert metal were observed compound layer and the thickness of intermetallic compound layer were irregular and thick. Friction welded joint with insert metal, its compound layer became thin and generated comparatively evenly. In spite of the existence in the friction welding of the use of the insert metal, the hardness of compound layer of both welded joints showed higher than those of the both base metals. Tensile strength of welded joint without insert metal showed 78% of 5052 aluminum alloy and it's fractured at weld interface. But, in case of welded joint using an insert metal, the tensile strength showed 92% of 5052 aluminum alloy. The elongation of welded joints with insert metal was improved. All the welded joints with insert metal were fractured at softened area of heat affected zone of 5052 aluminum alloy side in tensile test.

６０６１アルミニウム合金／Ｓ３５Ｃ炭素鋼摩擦圧接継手の引張および疲労強度特性

Welded joint performance of joints welded by the friction welding method has been studied for various material combinations because the method can more easily produce a combined shaft in comparison with other fusion welding method. In this study, 6061 aluminum alloy to S35C carbon steel were friction welded under three different friction welding conditions; and tensile and fatigue tests were conducted to obtain its strength characteristics in relation to the base material strength. As the result, the following were clarihed: Joint performance of friction welded joints is dependent on friction welding conditions; for this material, P2 (MPa) may be selected so that a friction welding condition for obtaining over 80% joint efficiency may exceed P2/P1=5 as P1=20 MPa. The HAZ region of low hardness exists by friction heat in the aluminum alloy side near the weld interface. Though it fractures in tensile tests from the softening region and in the fatigue test, there is a case in which it fractures in a weld interface. Therefore, fatigue strength decreases from the value estimated from tensile strength; attention to this fact is required when it is designed as a structural member. A particular structure near the weld interface exists, and since even if identical friction welding is adopted for all joints, the structure is delicately different so that the structure affects fatigue crack generation. Therefore, it seems that the scatter of fatigue strength of friction welded joints is larger than that of the base metal by fracture formation.

５０５２／２０１７アルミニウム合金摩擦圧接継手接合界面の機械的混合層と機械的性質

The mechanically mixed layer at a weld interface and the mechanical properties of dissimilar welded joints of 5052 aluminum alloy to 2017 aluminum alloy, which were made by using a brake type friction welding machine were examined with different welding conditions. The mechanically mixed layer is formed on the friction process, and it is observed at a weld interface all over. The thickness of the mechanically mixed layer decreased with increasing friction pressure, the mixed layer of the outside of joint became thinner than that at the center. The tensile strength of joints which were made with the friction pressure of above 45 MPa, which had an average thickness of 200 μm in mechanically mixed layer, showed 85% of 5052 aluminum alloy base metal. The breakage occurred at the softened area of 5052 aluminum alloy side. The impact strength of joints, which had an average thickness of 200 μm in mechanically mixed layer, were 70% of 5052 aluminum alloy base metal.

Friction welding of Al2O3P/6061 aluminium alloy composite to 5052 aluminium alloy

Summary 6061 aluminium alloy matrix composite containing 20.5 vol% particulate alumina and 5052 aluminium alloy were welded using a brake type friction welding machine. The microstructures and mechanical properties of the friction welded joints were investigated. The mechanically mixed regions and the alumina particles which had moved to the other part of the composite alloy were observed clearly on the weld interface. The hardness at the weld interface showed higher values than those of the base metals. The variation of hardness on the composite material side was not very significant, but a softened area could be seen in the heat affected zone of the 5052 aluminium alloy side and recovery to the same level of hardness as that of the 5052 aluminium alloy base metal could be found at about 20 mm from the weld interface. Regardless of the welding conditions, the joint efficiency in terms of tensile strength was 95–101% of that of the composite material base metal and the maximum elongation was 71% of that of the composite material base metal. Friction welded joints with good joint efficiency fractured near the weld interface of the heat affected zone of the composite base metal. The impact values of the welded joints with a notch in the weld interface were about 70% of those of the composite material base metal.