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DEVELOPMENT OF ISOTHERMAL-TRANSFORMED
STEEL WIRE FOR NON-HEAT TREATED BOLTS
Heiji Sugita Susumu Kikuchi
Sugita Wire Ltd., 3-1-12, Higashisumida,
Sumida-ku, Tokyo |
Abstract: This study introduces the
development of steel wires for non-heat treated bolts through a
combination with the steel wires which are treated with
isothermal transformation under the lead patenting process, as
well as with the subsequent cold drawing. The main results are
follows: ⑴ Applicable tensile strength range of the steel wires
for non-heat treated bolts, is 700～1000MPa or above. ⑵ It was
found the developed steel wires were applicable to the mass
production of such non-heat treated bolts in an extremely severe
shape as upset head bolts, flanged head bolts, cross-recessed
head machine screws, hexagon socket head bolts, and so on. ⑶ The
non-heat treated bolts made of the developed steel wires are
more excellent both in the toughness and fatigue strength than
the conventional heat treated bolts.
Key words:
Non-heat treated bolt Cold heading
Isothermal transformation Steel wire Drawing Absorbed energy Fatigue strength
Manuscript received on March 15, 1993
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