Cold working die steel

a technology of working die steel and die steel, which is applied in the field of cold working die steel, can solve the problems of hardness degradation, hard to achieve difficulty in achieving a low level of hardness, so as to reduce the toughness or mechanical properties, increase the free cutting property, and reduce the hardness

US20060157163A1Inactive Publication Date: 2006-07-20DAIDO STEEL CO LTD
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2006-07-20
Estimated Expiration
Not applicable · inactive patent

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Abstract

This invention is aimed at providing a cold working die steel successfully reduced in the hardness, and increased in readiness in the cold workability (forging, pressing and so forth) and machinability (milling, drilling, endmilling processing, grinding and lathe turning). A cold working die steel aimed at solving the above-described subject consists essentially of, in % by mass, 0.6%≦C≦1.60%, 0.10%≦Si≦1.20%, 0.10%≦Mn≦0.60%, 5.5%≦Cr≦13.0%, 0.80%≦Mo+0.5W≦2.10%, 0.10%≦V≦0.40%, 0.0002%≦O≦0.0080%, 0.001%≦A1≦0.10%, and the balance of Fe and inevitable impurities; has transformation point Ar3 in the range from 750° C. to 850° C., with both ends inclusive; has a mean circle-equivalent diameter of a carbide, which belongs to a circle-equivalent diameter range from 0.1 μm to 3 μm observed in a section of a structure obtained after spherodizing a sample that was heated at a temperature of (Ar3+50° C.) or above and 1,050° C. or below, of 0.25 μm to 0.8 μm, with both ends inclusive; has a Brinell hardness attained after the spherodizing of HB179 to HB235, with both ends inclusive; has a steel cleanliness of (dB+dC)60×400 in the group C inclusion and the group B inclusion specified by JIS G0555 of 0.05% or less; and has a K value defined as Cr(%)−6.8×C(%) of 0.1 to 3.5, both ends inclusive.
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Description

FIELD OF THE INVENTION

[0001] This invention relates to a cold working die steel used for cold die and structural components processed by forging or pressing in cold working; mechanical components demanding wear resistance; punch and die for cold forging; mold die for high tensile steel sheets; bending dies; cold forging dies; swaging dies; thread rolling dies; punch components; slitter knives; punch dies for lead frames; gauges; deep-drawing punches; bender punches; shear blades; benders for stainless steel; drawing dies; tools for plastic working such as heading; punches for gears; cam components; press punch dies; progressive punch dies; seal plates for soil conveyers; screw components; rotary plates for concrete spraying machines; IC molding dies; precision press mold demanding high dimensional accuracy; and dies used for the above-described applications after being surface-treated by CVD, PVD or TD. BACKGROUND ART

[0002] SKD11, SKD12 and so forth, which are representative steel...

Examples

Embodiment Construction

[0048] First, 200 kg of each of the inventive and comparative steel materials having compositions listed in Table 1 were melted in a vacuum induction furnace, made into an ingot, and the obtained steel ingot was hot-forged so as to produce a 70 mm×70 mm square rod. The rod was then annealed at the temperature listed in Table 2 (cooling rate: 18° C. / h).

[0049] Of the compositions of comparative steels listed in Table 1, those departing from the compositional ranges specified by this invention are indicated by a downward arrow (↓) if they came short of the lower limits, by an upward arrow (↑) if they exceeded the upper limits.

[0050] [Table 1]

TABLE 1Components (wt %)No.CSiMnPSCuNiCrMoW 1Comparative steel0.710.38↑0.930.028↑1.320.117.030.84 2Inventive steel1.230.530.340.060.4310.321.44 3Comparative steel0.710.380.370.0280.0020.09↑1.557.030.84 4Comparative steel0.660.420.320.0130.0010.230.5310.50.32 5Inventive steel0.610.950.470.0040.0630.050.135.72.01 6Inventive steel0.780.750.210.0350....