We have developed a new method of improving the fatigue strength of the steel wire for automobile. Principle of the new method is thin surface layer annealing of the wire by using the high power density zone of the focused laser beam in the cone shaped focusing mirror. In this method, the laser beam was coaxially irradiated and focused on the wire the anneal it uniformly. Using this laser processing technique, up to 3μm depth of uniform annealing has been realized, which results in four times increase in fatigue strength of the wire without degrading the tensile strength. No defect was observed on the annealed surface of the wire. It should be possible to realize the effective manufacturing process of high performance steel wires using this method.

1.
Vector G.
Gregson
,
et al, “
Guide for material processing by lasers
,”
Laser material processing committee LIA
, p
52
–p
55
,
1977
.
2.
K.
Minamida
,
et al, “
Wedge shape welding multiple reflecting effect of high power CO2 laser beam
,”
Proc. of ICALEO’86
, p
97
–p
104
,
1986
.
3.
Y.
Yamada
,
et al, “
Wire Rod for Higher Breaking Strength Steel Cord
,”
Wire Journal International
, p
53
–p
65
,
1986
.
4.
H.
Kawasumi
,
et al, “
The effect of thermal sourse in laser hardening
,”
J. Japan Soc. Prec. Eng
., Vol.
47
, No. 6, p
669
,
1981
.
5.
Adolf
Rose
, et al,
Max Planck Inst. fur Eisenf.
“Atlas zur Warmebehandlung der Stahle”,
Verlag Stahleisen
, P.
II
–302E,
1954
.
This content is only available via PDF.
You do not currently have access to this content.