SE513978C2 - Coated cemented carbide inserts for cutting metalworking - Google Patents

Abstract

The present invention relates to coated inserts for metal cutting applications containing at least one hard constituent of a carbide, nitride and/or carbonitride of the metals Ti, Ta, Hf, Nb, V, Zr and W or solid solutions thereof, in 3-20 weight-%, preferably 4-14 weight-%, binder phase. By using a binder phase comprising in solid solution: Co max 95 %, Ni max 95 % and Cr 3-25 % improved properties are obtained particularly in machining operations of intermittent character. Coatings comprising carbides and/or carbonitrides and/or oxicarbides and/or oxinitrides and/or oxicarbonitrides of titanium and/or Al2O3 are particularly useful.

Description

10 15 20 25 30 35 513 978 2 contains 3-20% by weight, preferably 4-14% by weight of binder phase, wherein the binder phase contains in solid solution expressed in% by weight: Co 20-80, Mo 1-6, added up to 5% by weight.

The carbon content should be between a lower value corresponding to the limit Cr 3-25, and the residue Ni. Vanadium can lb to the eta phase and an upper corresponding stoichiometric carbon slippery. In some embodiments, the carbon content may be lower than the limit to eta phase and thus the core metal will also contain eta phase or other understochiometric phases. 3-20 vol-% har found appropriate.

At too high a carbon or chromium content, brittle chromium is formed. carbide and therefore both the chromium and carbon contents must be chosen as such that the formation of chromium carbide is minimized.

The invention can be used in inserts with even binder phase distribution. or, preferably, in inserts with a binder phase-enriched surface zone with a depth of up to 50 pm. The degree of binder phase enrichment should be between 1.2 and 2.5 times, preferably between 1.4 and 1.8, higher than the binder phase content of the remainder of the insert. Such inserts can be manufactured e.g. by using the technique described in US 4,610,931.

The core metal is coated with durable layers of known types using known CVD, MTCVD or PVD technology. MTCVD is a CVD process at a slightly lower temperature where you use for example CH 3 CN gas and TiCl 4. If the total Ni content is more than about 1.5% by weight must be taken into account in order to avoid the the effects of Ni on the quality of the layer by e.g. an- at least at the beginning of the layering process, a rather low temperature temperature, preferably <960 ° C.

Layers comprising Ti carbides and / or carbonitrides and / or oxycarbides, and / or oxynitrides and / or carbonitrides and / or Al2O3 are particularly useful. In a suitable design, at least a 0.3-5 μm, intermediate layer is coated comprising TiCO or TiCON or TiON within a Ti-containing part of the layer, about 0.5-3 μm from the cemented carbide surface.

The layer thickness should be <30 μm, preferably 3-16 μm. = For milling applications, the total layer thickness should be oxy- be 3-7 pm and for turning applications it should be let the layer thickness be 5-16 pm. *in 10 15 20 25 513 978 The present invention is particularly useful in processing of steel and cast iron when the cuttings are subjected to relatively short, periodic stresses when the cutting edge is mechanical and thermally stressed for short periods accompanied by short pe- periods when it is unloaded and cooled and thus after one for some time cause thermal or mechanical fatigue in the cutting Gene. This is typical of milling operations but occurs also in certain turning operations of an intermittent nature.

The reason for the observed tool life for it the coated cemented carbide of the present invention is still not investigated in detail. It is believed that through the cracks that already present in the layer, or formed during processing in the cemented carbide or in the layer, the binder phase is oxidized and causes a weakening of areas closest to the layer. By use the more oxidation-resistant binder phase compositions significantly counteracts this type of disadvantage. The addition of chromium increases the oxidation resistance of the binder phase. Addition of nickel, on the other hand, both increases the oxidation resistance of the Co-binder phase but decreases its except the deformation hardening by stabilizing the Co-phase FCC structure.

The invention has been described with respect to cemented carbide inserts for cutting machining. It is obvious that the invention can be used for cutting metal applications in coated inserts containing at least one hard component of a carbide, nitride and / or carbonitride of the metals Ti, Ta, Hf, Nb, V, Zr and W, or solid solutions thereof, in a binder phase. 10 15 20 25 30 35 515 978 4 Example 1 Cuts for cutting machining according to the invention with composition in% by weight: 91.5 WC, 3.9 Co, 3.7 Ni, 0.8 Cr, 0.1 Mo was manufactured and coated with a layer consisting of 0.5 μm TiN, 5 μm Ti (C, N) and 3 μm Al 2 O 3. The TiN layer made up it the inner layer closest to the cemented carbide and it was coated at a temperature of 920 ° C. The Ti (C, N) layer was coated by MTCVD technique.

As references, inserts with the composition in% by weight were used: 91.5 WC and 8.5 Co and coated with the same layer.

Practical test: 50 inserts from each group were tested under the following conditions. looks: Operation: Face milling Pump housing in gray cast iron (SSOl25) 263 m / min 0.14 mm / tooth Workpiece: Cutting speed: Feed rate: Cutting depth: 2 mm Cutting fluid: Emulsion Cutting type: TNHF1204AN-65 Lifetime criterion: Cantilever breaks from the workpiece.

Lifespan: Cuts according to the invention: 29 minutes Reference insert: 16 minutes Example 2 Cuts for cutting machining according to the invention with composition in weight%: 94.5 WC, 3.3 Co, 1.1 Ni, 0.6 Cr, 0.1 Mo, 0.2 V was manufactured and coated with a layer consisting of of 1.5 μm TiC, 0.5 μm Ti (C, O), 7 μm Ti (C, N) The TiC layer formed the inner layer closest to the cemented carbide and and 6 μm Al 2 O 3.

The Al2O3 layer was the outermost layer.

As references, inserts with the composition in% by weight were used: 94.7 WC and 5.3 Co and coated with the same layer.

Practical test: Operation: Intermittent plane turning Working material: Ferrite-perlite nodular cast iron SS0727 Cutting speed: 150 m / min Feed rate: 0.1 mm / rev Cutting depth: 2.0 mm 11 '- 515 978 L'l Cutting fluid: None Cutting type: CNMAl204l2 Lifetime criterion: Phase wear Lifespan: Cuts according to the invention: Reference insert: 0.3 mm 75 minutes 41 minutes

Claims (3)

10 15 20 25 513 978 6 Krax Coated insert for cutting metalworking with a cemented carbide substrate containing a hard component of a carbide, nitride and / or carbonitride of the metals Ti, Ta, Hf, Nb, V, Zr and W or solid solutions thereof in 3-20 wt. %, preferably 4-14% by weight of binder phase and a surface layer containing Ti carbides and / or carbonitrides and / or oxycarbides and / or oxynitrides and / or oxycarbonitrides and / or alumina, characterized in that the binder phase consists of a solid solution , in% by weight, Co 20-80, Mo 1-6, Cr 3-25, V up to 5 and the remainder Ni, the chromium and carbon contents being adjusted so that the formation of chromium carbide is minimized. Coated insert according to the preceding claim, characterized in that the substrate has a binder phase-enriched surface zone up to 50 μm thick. Coated insert according to one of the preceding claims, characterized in that the substrate contains 3-20% by volume of eta phase or other understochiometric phase. Coated insert according to any one of the preceding claims, characterized in that the surface layer contains a 0.3-5 μm, preferably 0.5-1.5 μm, intermediate layer comprising TiCO, TiCON or TiON within a Ti-containing part of the layer about 0.5-3 μm from the surface of the insert. .