Heat treatment of tool steelsCase studies
1. High Speed Steel (HS 6-5-2)
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General overview
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Comparison of properties
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Heat treatment (1)
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Heat treatment (2)
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Heat treatment (3)
Heat treatment sequence
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Immersiontime as
function ofsize and
austenisingtime
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Temperingfor optimum hardness.Precipita-tion ofcarbides.
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CCT diagram of HS 6-5-2
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Isothermal TTT diagram of HS 6-5-2
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2. Cold working tool steel (K11)
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Generaloverview
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Comparison of properties
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Heat treatment (1)
Heat treatment (2)
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Heat treatment (3)
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Heat treatment sequence
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CCT diagram of K11
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Isothermal TTT diagram of K11
3. Powder metallurgical (PM)cold working steel
(K390 MICROCLEAN)
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Comparison of conventional andPM steel structure
Comparison of toughness andwear resistance
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Powder metallurgy
• Production of metal powder• Mixing and blending• Compacting• Sintering• Forming• Final treatment• Tool production
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Powder processing
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Shape and size of powders
• Shape and size of powders depend on the method of production
• Particle size range: 0,001…1 mm• Shapes (one-, two, three dimensional):
– spherical– elongated– irregular– porous
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Blending metal powders
• Screening by screens of various meshsizes
• Mixing by size and by material to uniform distribution of components
• Lubrication• Objective:
– Favourable composition– Better properties– Lower friction at compaction
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Compaction• Blended powders are
pressed into shapes indies
• The pressed powder is known as greencompact (rigid, lowstrength)
• Tooling:– Single acting punch– Floating container– Two counteracting
punches
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Sintering (process)
• Compressed powder is heated in controlled atmosphere
• Variables: temperature, atmosphere and time
• Result: increasing strength and toughness, lowering porosity.
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Sintering (microstructure)
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Sintering (furnace)
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Heat treatment (1)
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Heat treatment (2)
CCT diagram of K390
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Applications (forming tools)
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Application: cutting tools
W- and Ti-carbide plates for high-speed cutting