This article studies the laser weldability of 400MPa grade ultra-fined grained ferrite steel. By using a 3kW CO2 laser, the influence of heat input on the grain size, microstructure and toughness of the laser welded joint is investigated. The results show that the microstructure of the weld metal and HAZ mainly consists of lower bainite, mixed with low carbon martensite, pearlite and ferrite. Although both grain sizes of the weld metal and HAZ has largely grown up, the strength and toughness of the welded joint are much higher than that of base metal. The cleanness of 400MPa ultra steel has greater influence on the toughness of the welded joint than grain size, especially the lower S, Si and Mn content of ultra-steel base metal is contributed to the higher strength and toughness.

Topics
Lasers, Chemical elements, Alloys, Ferromagnetic materials, Metallurgy, Perlite
1.
A.
Sato
 (
2000
).
Research Project on Innovative Steels in Japan
. In
Proc. of ULTRA-STEEL
,
Tsukuba, Japan
1
–
10
Google Scholar
 
2.
Y.
Weng
 (
2000
).
New Generation of Iron and Steel Material in China
. In
Proc. of ULTRA-STEEL
,
Tsukuba, Japan
,
11
–
32
Google Scholar
 
3.
W. P.
Lee
 (
2000
).
Development of High Performance Structural Steels for 21st Century in Korea
. In
Proc. of ULTRA-STEEL
,
Tsukuba, Japan
,
33
–
63
Google Scholar
 
4.
N.
Yurioka
 (
1997
).
TMCP steels and their welding
.
Welding in the World
,
43
(
2
),
2
∼
17
Google Scholar
 
5.
K.S.
Bang
,
W.Y.
Kim
 (
2002
).
Estimation and prediction of HAZ softening in thermomechanically controlled-rolled and accelerated-cooled steel
.
Welding Journal.
174
–
179
Google Scholar
 
6.
W.
Chen
,
Y.
Peng
,
C.
Wang
,
G..
Bao
,
Z.
Tian
 (
2001
).
Welding thin plate of 400 MPa grade ultra-fine grained steel using CO2 laser
. In
Proc. of Int. Symposium on Ultrafine Grained Steels (ISUGS 2001)
,
Fukuoda, Japan
,
252
–
255
Google Scholar
 
7.
Y.
Peng
,
C.
Wang
,
W.
Chen
,
G..
Bao
,
L.
Zhao
,
Z.
Tian
 (
2001
).
Microstructure and mechanical properties CO2 laser welded joint of ferrite ultrafine grained steel
. In
Proc. of Int. Session of Workshop on New Generation Steel
,
Beijing, China
,
199
–
206
Google Scholar
 
8.
Y.
Peng
,
C.
Wang
,
W.
Chen
,
G..
Bao
,
L.
Zhao
,
Z.
Tian
 (
2002
).
The parameter-related microstructural characteristics of laser autogenously produced weld metal of ultrafine grained steel
. In
Proc. of the 4th Workshop on the Development of High Performance Structural Steels for 21st Century (HIPERS-21
),
Souel, Korea
,
299
–
302
Google Scholar
 
9.
C.
Wang
 (
2002
).
Study on Laser Welding of 400MPa Ultra Steel and its Weldability
. Ph.D Thesis,
Tsinghua University
,
China
.
This content is only available via PDF.
© 2004 Laser Institute of America.
2004
Laser Institute of America
You do not currently have access to this content.