The Thickness Distribution of Oxidation Film on Tapered Pipe Surface in Dieless Drawing

Abstract

The thickness distribution of oxidation film on the surface of AISI304 stainless steel tapered pipe, its influence factors, and the effect of metal matrix deformation on oxidation behavior during dieless drawing were studied in this paper. The results showed that oxidation rate was affected strongly by induction heating temperature and deformation degree. The thickness distribution of oxidation film was uneven and increased from the larger diameter end to the smaller diameter end along the axial direction of tapered pipe. When induction heating temperature raised or the distance between heat and cold sources was increased, or feed speed was decreased, oxidation rate was accelerated and oxidation film on the tapered pipe surface thickened significantly, due to massive cracks in oxidation film induced by deformation of metal matrix. The density and width of cracks in oxidation film were enlarged, and the thickness of oxidation film increased with the increase in deformation degree.

Formability Analysis and Oxidation Layer Effects in Dieless Drawing of Stainless Steel Wires

“…The diameter of the wire was so small that it is difficult to measure the surface roughness of the oxide layer. The thickness of the oxide layer exhibited some variation of about 1-7 μm, which is quite close to the results in Qin et al [20]. Generally the thickness of the oxide layer increased with the forming temperature and the surface color of the product became slightly darker as the forming temperature increased.…”

“…The oxides were very brittle and undergo fracture easily at the early stage of deformation, which usually resulted in the thickness variation of the oxide layer. According to Qin et al [20], the structures of the oxide layer are mainly Fe 3 O 4 and FeCr 2 O 4 . The diameter of the wire was so small that it is difficult to measure the surface roughness of the oxide layer.…”