Powder Metallurgically Manufactured High Speed Steel

Abstract

The present invention relates to a high speed steel with a chemical composition that comprises, in % by weight: 0.6-2.1 C 3-5 Cr 4-14 Mo max 5 W max 15 Co 0.5-4 V, balance Fe and impurities from the manufacturing of the material, which steel is powder metallurgically manufactured and has a content of Si in the range of 0.7<Si≦2.

1 . Powder metallurgical manufactured high speed steel, which has been consolidated without presence of liquid phase, having a chemical composition that comprises, in % by weight:
 0.6-2.1C   3-5 Cr   4-14 Mo   max 5 W   max 15 Co   0.5-4 V,   balance Fe and impurities from the manufacturing of the material, characterised in that it has a content of Si in the range of 0.7<Si≦2.   
   
   
       2 . High speed steel according to  claim 1 , characterised in that it comprises not more than 1.5 Si, even more preferred not more than 1.0 Si. 
   
   
       3 . High speed steel according to  claim 2 , characterised in that it comprises 0.7-0.9 Si. 
   
   
       4 . High speed steel according to  claim 3 , characterised in that it comprises 0.75-0.85 Si. 
   
   
       5 . High speed steel according to  claim 4 , characterised in that it comprises 0.78-0.82 Si. 
   
   
       6 . High speed steel according to  claim 1 , characterised in that it comprises max 1.5 C. 
   
   
       7 . High speed steel according to  claim 6 , characterised in that it comprises 1.0-1.15 C. 
   
   
       8 . High speed steel according to  claim 1 , characterised in that it comprises 3.5-4.5 Cr. 
   
   
       9 . High speed steel according to  claim 8 , characterised in that it comprises 3.7-4.0 Cr. 
   
   
       10 . High speed steel according to  claim 1 , characterised in that it comprises 6-12 Mo. 
   
   
       11 . High speed steel according to  claim 10 , characterised in that it comprises 9-10 Mo. 
   
   
       12 . High speed steel according to  claim 11 , characterised in that it comprises 9.2 to 9.7 Mo. 
   
   
       13 . High speed steel according to  claim 1 , characterised in that it comprises 1-3 W. 
   
   
       14 . High speed steel according to  claim 13 , characterised in that it comprises 1.2-1.9, preferably 1.3-1.7 W. 
   
   
       15 . High speed steel according to  claim 1 , characterised in that it comprises max 12 Co. 
   
   
       16 . High speed steel according to  claim 15 , characterised in that it comprises 7.5-9.0 Co. 
   
   
       17 . High speed steel according to  claim 16 , characterised in that it comprises 7.7-8.2 Co. 
   
   
       18 . High speed steel according to  claim 1 , characterised in that it comprises 0.9-2.5 V. 
   
   
       19 . High speed steel according to  claim 18 , characterised in that it comprises max 1.5 V. 
   
   
       20 . High speed steel according to  claim 19 , characterised in that it comprises 1.1-1.2 V. 
   
   
       21 . High speed steel according to  claim 1 , characterised in that it has a content of MC-carbides of not more than 8% by volume, preferably not more than 5% by volume, and even more preferred not more than 3% by volume, where at least 80%, preferably at least 90%, and even more preferred at least 95% of the MC-carbides have a carbide size in the longest extension of the carbide of not more than 4 μm, preferably not more than 3.5 μm, and even more preferred not more than 3 μm, and that it has a content of M 6 C-carbides of not more than 25% by volume, preferably not more than 20% by volume and even more preferred not more than 17% by volume, where at least 80%, preferably 90%, and even more preferred at least 95% of the M 6 C-carbides have a carbide size in the longest extension of the carbide of not more than 9 μm, preferably not more than 7 μm, and even more preferred not more than 5 μm. 
   
   
       22 . High speed steel according to  claim 1 , characterised in that it has a content of MC-carbides of not more than 3% by volume, where at least 99% of the MC-carbides have a carbide size in the longest extension of the carbide of not more than 3.5 μm, and that it has a content of M 6 C-carbides of not more than 17% by volume, where at least 99% of the M 6 C-carbides have a carbide size in the longest extension of the carbide of not more than 7 μm, preferably not more than 5 μm. 
   
   
       23 . High speed steel according to  claim 1 , characterised in that it has been hardened at a temperature of 1100-1200° C. 
   
   
       24 . Use of high speed steel according to  claim 23 , in bimetallic saw blades characterised in that the steel has been tempered at a tempering temperature of 600-650° C. within a tempering time range of 0.5-10 mm. 
   
   
       25 . Use of a high speed steel according to  claim 23 , for the manufacturing of drills, milling cutters, saws or other solid tools for cutting operations characterised in that the steel has been tempered at a tempering temperature of 500-600° C. within a tempering time range of 0.5-4 h. 
   
   
       26 . Process for producing a powder metallurgical manufactured high speed steel having a chemical composition that comprises, in % by weight:
 0.6-2.1 C   3-5 Cr   4-14 Mo   max 5 W   max 15 Co   0.5-4 V   0.7-2 Si,   balance Fe and inevitable impurities   said process comprises the steps:   a) filling a capsule with metal powder comprising iron and the alloying elements accordingly with the chemical composition of the steel,   b) sealing the capsule,   c) hot isostatically pressing the capsule in a hot isostatic press, at a HIP temperature, consolidating the steel material without presence of liquid phase.   
   
   
       27 . Process according to  claim 26  wherein between step b) and step c) the capsule is cold isostatically pressed in a cold isostatic press. 
   
   
       28 . Process according to  claim 26  wherein prior to step c) the capsule is preheated in a preheating furnace, gradually increasing the furnace temperature to a temperature close to the HIP temperature used in step c).