Carburizing of Duplex Stainless Steel (DSS) Under Compression Superplastic Deformation

A new surface carburizing technique which combines superplastic deformation with superplastic carburizing (SPC) is introduced. SPC was conducted on duplex stainless steel under compression mode at a fixed 0.5 height reduction strain rates ranging from 6.25 x 10(-5) to 1 x 10(-3) s(-1) and temperature ranging from 1173 K to 1248 K (900 A degrees C to 975 A degrees C). The results are compared with those from conventional and non-superplastic carburizing. The results show that thick hard carburized layers are formed at a much faster rate compared with the other two processes. A more gradual hardness transition from the surface to the substrate is also obtained. The highest carburized layer thickness and surface hardness are attained under SPC process at 1248 K (975 A degrees C) and 6.25 x 10(-5) s(-1) with a value of (218.3 +/- A 0.5) mu m and (1581.0 +/- A 5.0) HV respectively. Other than that, SPC also has the highest scratch resistance.