| 摘要 |
PURPOSE: A high speed tool steel is provided to obtain tempering hardness over HRC 60, able to satisfy the property of toughness and hardness reciprocal to each other and to offer bending intensity over 630 3.0kgf/mm2 and shock toughness over 14kgfm/cm¬2 via a new alloy design. CONSTITUTION: 0.55-0.75wt% of carbon, 1.0-2.0wt% of silicon, 0.2-0.8wt% of manganese, 3.8-5.8wt% of chrome, 2.0-4.0wt% of molybdenum, 0.08-0.5wt% of tungsten(tungsten+1/2molbdenum=1.1-2.5wt%), 0.01-0.2wt% of cobalt, less than 0.01wt% of aluminum, 0.002-0.02wt% of nitrogen, less than 0.008wt% of sulphur and less than 30ppm of oxygen are contained in a high speed tool steel for cool and hot rolling. One or two sorts among 0.6-2.6wt% of vanadium and 0,01-0.1wt% of niobium are contained(if two elements are selected, niobium+1/2vanadium is 0.3-1.4wt%). And remnants are iron and impurities.
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