COATED CUTTING TOOL

摘要

The present invention concerns a cutting tool insert for turning of steel at high cutting speeds. The cutting tool insert comprises a (006) textured alpha-Al2O3 coated cemented carbide grade. The cemented carbide body has about 4.5-6.5 wt-% Co and about 3-10 wt-% cubic carbide forming metals and an S-value of about 0.77-0.92 and a coercivity of about 10-20 kA/m. The alpha-Al2O3 layer has a thickness ranging from about 7 to 12 mum and is composed of columnar grains having a length/width ratio from about 2 to 12 and is deposited on an MTCVD Ti(C,N) layer having a thickness from about 4 to 12 mum. The alumina layer is characterised by a pronounced (006) growth texture. The alumina layer is the uppermost layer and is wet-blasted having an Ra value of less than 1 mum, giving the tool a black and shiny appearance.