The Effect of Varying Process Parameters on the Microhardness and Microstructure of Cu–Steel and Al–Al2O3 Friction Joints

Abstract

Perbezaan dalam kelajuan putaran serta tekanan tempaan semasa kimpalan geseran mempengaruhi sifat–sifat sambungan yang terhasil. Sambungan geseran tembaga C11000 dan keluli lembut AISI 1030 (Cu–keluli) serta aluminium 6061 dan alumina (Al–Al₂O₃) disediakan dengan menggunakan mesin kimpalan geseran pacuan terus. Kekerasan mikro merentasi sambungan menunjukkan kekerasan tembaga yang lebih rendah dan kekerasan keluli yang lebih tinggi berbanding kekerasan bahan induk apabila kelajuan putaran 900 rpm digunakan. Pada kelajuan putaran 1800 rpm, keputusan yang sebaliknya diperolehi. Ubahbentuk ira terhad pada kawasan < 0.5 mm daripada garis sambungan. Kekerasan mikro merentasi sambungan untuk sambungan Al–Al₂O₃ tidak dapat memberi keputusan yang jelas disebabkan kesan liang terhadap kekerasan mikro yang diukur. Keputusan ini menunjukkan ujian kekerasan mikro tidak sesuai untuk pencirian sambungan Al–Al₂O₃. Kata kunci: Kimpalan geseran, tembaga, keluli, aluminium, alumina, kekerasan mikro Varying the rotational speed and forging pressures during friction welding affect the joint properties differently. C11000 copper to AISI 1030 mild steel (Cu–steel), and 6061 aluminum to alumina (Al–Al₂O₃) friction joints were fabricated on a direct drive friction welding machine. Microhardness traverses across the joint showed lower copper hardness, and higher steel hardness compared to the parent material, when 900 rpm rotational speed as used. This trend is reversed when the rotational speed is increased to 1800 rpm. Grain structure distortation was confined to an area of < 0.5 mm from the joint interface. Microhardness traverses across the Al–Al₂O₃ joint could not yield much information due to the influence of porosity on the microhardness readings. The results indicate that microhardness test is not appropriate for the characterization of Al–Al₂O₃ friction joints. Key words: Friction welding, copper, steel, aluminum, alumina, microhardness