| abstract |
By mass%, C: 1.00-2.30%, Si: 0.10-0.60%, Mn: 0.20-0.80%, P: 0.030% or less, S: 0.030% or less, Cr: 4.80-13.00%, the balance being iron and inevitable A substrate which is an impurity, a nitride layer (800 to 1200 Hv), a CrN film (800 to 2000 Hv), and a DLC film on the substrate (600 to 700 Hv), wherein the VLC hardness is In the region from the film surface to 0.20 t (where t is the film thickness), 3000 to 3500, and in the region from the interface with the CrN film to 0.20 t, 1500 to 3000, the wave number measured by Raman spectroscopy is 1380 cm − Absorption intensity ratio I 1380 / I 1540 at 1 and 1540 cm −1 is 0.5 to 0.7 in the region from the film surface to 0.3 to 0.5 in the region from the interface between the DLC film and the CrN film, The titanium tube forming roll is excellent in adhesion resistance, wear resistance, peel resistance, and coefficient of friction of the roll surface. |