Formed product and method for production thereof

a technology of formed products and products, applied in the field of formed products, can solve the problems of lowering the toughness of formed products, complicated and difficult refining process, etc., and achieve the effect of high strength, high strength and high strength

Inactive Publication Date: 2008-09-04
TORIZUKA SHIRO +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This approach enables the production of high-strength formed products with Vickers hardness of 200 or more and JIS strength classification of 8.8 or more, without the need for alloying elements or refining processes, enhancing both strength and toughness while simplifying the production method.

Problems solved by technology

In production of formed product, however, refining by hardening and tempering is a complicated and difficult process, and if produced without refining steps, the productivity is enhanced and it is very beneficial industrially.
However, addition of alloying elements often lowered the toughness of formed product, and was not always preferred means.

Method used

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  • Formed product and method for production thereof
  • Formed product and method for production thereof
  • Formed product and method for production thereof

Examples

Experimental program
Comparison scheme
Effect test

embodiments

Embodiments 1 to 4

[0052]By melting a steel material having chemical composition as shown in Table 1, and introducing a strain larger than a critical strain in warm working temperature region, a steel bar having an ultra fine structure of average grain diameter of 1 μm or less was prepared. The appearance image of the steel material and its scanning electron microscope (SEM) image are shown in FIG. 2.

TABLE 1[mass %]CSiMnPSs.AlN10.050.31.00.010.0010.0310.00220.100.31.00.010.0010.0310.00230.150.31.00.010.0010.0310.00240.301.01.00.010.0010.0310.00250.450.31.00.010.0010.0310.00260.760.31.00.010.0010.0310.00270.160.10.80.010.0010.0310.002(SWCH16A)

[0053]This steel having an ultra fine structure was formed into a wire material of φ1.3 mm in diameter, and the leading end was formed to form a screw head, cut to a specified length, and rolled to form a screw head, and a cross recessed pan head machine screw of M1.6 was produced (embodiments 1 to 4).

[0054]Top view and side view of obtained scre...

embodiments 5 to 9

[0060]Using a wire material of φ8 mm in diameter of a steel having an ultra fine structure in the composition in Table 1, the leading end was formed to form a bolt head, cut to a specified length, and rolled to form M8 bolts (embodiments 5, 7, 8). Using a wire material of φ3 mm in diameter of a steel having an ultra fine structure, the leading end was formed to form a head, cut to a specified length, and produced into rivets (embodiments 6, 9). FIG. 5 is a photograph showing the appearance of embodiment 6.

[0061]By way of comparison, using chemical compositions shown in Table 1, wire materials of ferrite grain diameter of 20 μm were used, and bolts and rivets were produced similarly (comparative examples 4 to 6). Using chemical composition 7 in Table 1, the material was cold formed, and refined by conventional method by hardening and tempering.

[0062]In these pressed products, the ferrite grain diameter of structure, tensile strength, and core hardness were measured, and results are s...

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Abstract

A formed product, characterized in that it is produced by using, as a material, a steel having an ultra fine structure comprising ferrite grains having an average grain diameter of 3 μm or less and by a method comprising only a forming step and including none of refining steps; and a method for producting the above formed product with ease. The formed product contains no alloying element and has been subjected to no refining step, and has been imparted with high strength and high toughness by the above ultra fine structure.

Description

[0001]This is a divisional of Ser. No. 10 / 531,386, filed Apr. 15, 2005, now abandoned, which is a 371 of PCT / JP03 / 13309, filed Oct. 17, 2003.TECHNICAL FIELD[0002]The present invention relates to a formed product, and a method for production thereof. More particularly, the invention relates to a formed product ensuring high strength and high toughness by ultra fine structure without resort to addition of alloying elements or refining steps, and a method of producting the same easily.BACKGROUND ART[0003]Hitherto, to product a formed product of metal or alloy, generally, a steel bar or wire is used as material, and formed in cold or warm working, and refined by hardening, carburizing or tempering. In production of formed product, however, refining by hardening and tempering is a complicated and difficult process, and if produced without refining steps, the productivity is enhanced and it is very beneficial industrially.[0004]Herein, formed products include screws, bolts, nuts, shafts, ...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): C21D9/00C22C38/02B21J1/04B21K1/46C22C38/00C22C38/04C22C38/06F16B35/00F16B35/04
CPCB21K1/46C22C38/04C22C38/02
InventorTORIZUKA, SHIRONAGAI, KOTOBUMURAMATSU, EIJIROSUZUKI, YOSHIYUKI
OwnerTORIZUKA SHIRO