| 摘要 |
1523926 Cutting tool UDDEHOLMS AB 12 Dec 1975 [18 Dec 1974] 51095/75 Heading C7A A cutting tool of composition:- the structure of the tool may consist of a martensitic matrix having a grain size of 5-70 Ám, determined austenite grain size, containing 5-15 volume per cent of an intracrystalline, homogeneously distributed, finely dispersed Fe, Co, W and/or Mo intermetallic compound and between the grains of the matrix 20-30 volume per cent of a primarily precipitated phase mainly consisting of the same intermetallic compound and having a predominant grain size of 1-2 Ám. The tool may be prepared by finely dividing and cooling a melt of the above composition under non- oxidizing conditions to produce a fine powder e.g. by atomizing a melt using nitrogen gas jets, hot compacting the powder to an ingot e.g. by hot isostatic pressing at 1200-1250‹C, hot working the ingot to a blank e.g. by rolling or forging at 1,000‹C to 1200‹C, cooling the blank slowly to 500‹C and then annealing at 875-910‹C for 10 to 15 hours, cooling, machining to form the cutting tool, solution annealing at 1200-1350‹C and quenching either to 250-350‹C followed by tempering at least once at a temperature of 550- 700‹C for 2-5 hours or quenching in oil to room temperature further working the tool and tempering at least once for 2-5 hours at 550-700‹C. |
