Metal Solidification Research Group, Shanghai University

Effect of Pulsed Magnetic Field on Solidification Structures of Metals

Zhai Qi-Jie *, Gao Yu-Lai, Li Qiu-Shu

*Corresponding author, email: qjzhai@staff.shu.edu.cn

Personal website: http://www.foundrymate.com

October 11, 2004

Metal Solidification Research Group, Shanghai University

Four Parts:

Background

Experimental procedure

Results and discussion

Conclusions

Metal Solidification Research Group, Shanghai University

Background:

Can obviously refine the solidification structure

No research on pure metal, e.g. Al

No consensus is acquired about the effect of

magnetic field

Little information is available about the

refinement mechanism

Metal Solidification Research Group, Shanghai University

Experimental procedure:

High-voltage pulsed power source

and the solidification equipment

Materials choose: pure Al, gray iron and

stainless steel

Analysis methods: OM, TA

Metal Solidification Research Group, Shanghai University

Results and Discussions ——Effect on Al

(a) (b)

(c) (d)

10mm 10mm

10mm 10mm

Macrostructure of the

solidified samples under

the pulsed magnetic field

with different intensities

(a) B=0T

(b) B=0.3T

(c) B=0.38T

(d) B=0.51T

Metal Solidification Research Group, Shanghai University

0.0 0.1 0.2 0.3 0.4 0.5 0.60

1

2

3

4

5

6

Ave

rage

gra

in s

ize,

mm

Intensity of the pulsed magnetic filed, T

Results and Discussions ——Effect on Al

Relation between the intensity of the pulsed magnetic field and the average grain size

Metal Solidification Research Group, Shanghai University

Results and Discussions ——Effect on Al

Distribution of the magnetic induction intensity in the intense magnetic generator

-200 -150 -100 -50 0 50 100 150 2000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Lower end of the magnetic field

In

tens

ity o

f pu

lsed

mag

netic

fie

ld, T

Position of the coil axis, mm

Vol t age 50VVol t age 425VVol t age 850VVol t age 925VVol t age 1000V

Upper end of the magnetic field

Metal Solidification Research Group, Shanghai University

Results and Discussions ——Effect on Al

Relationship between the intensity of pulsed magnetic field and solidification temperature

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7600

620

640

660

680

700

Solid

ific

atio

n te

mpe

ratu

re, o C

Intensity of pulsed magnetic field, T

Results and Discussions ——Effect on gray iron

Metal Solidification Research Group, Shanghai University

Chemical composition of experimental gray iron

Metal Solidification Research Group, Shanghai University

Results and Discussions ——Effect on gray iron

Graphite morphology of hypoeutectic gray iron under different

pulsed magnetic field parameters

(c)

(b)(a)

75 μm

(d)

75 μm

75 μm 75 μm

(a) B=0T

(b) B=1.2T

(c) B=3.1T

(d) B=6.4T

Metal Solidification Research Group, Shanghai University

Results and Discussions ——Effect on gray iron

Graphite morphology of hypereutectic gray iron under different

pulsed magnetic field parameters

(a) B=0T

(b) B=0.3T

(c) B=1.2T

(d) B=2.6T

(a)

(c) (d)

(b)

75 μm 75 μm

75 μm 75 μm

Metal Solidification Research Group, Shanghai University

Results and Discussions ——Effect on gray iron

0.0 0.5 1.0 1.5 2.0 2.5 3.00

5

10

15

20

25

30

35

40

ave

rage

leng

th (

x102 )m

m

pulsed magnetic field intensity (T)0.0 0.5 1.0 1.5 2.0 2.5 3.0

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

av

erag

e th

ickn

ess,

(x1

02 )mm

pulsed magnetic field intensity (T)

Effect of the magnetic intensity on the length of the graphite

Effect of the magnetic intensity on the thickness of the graphite

Results and Discussions ——Effect on gray iron

Metal Solidification Research Group, Shanghai University

0 50 100 150 200 250 300 3500

100200300400500600700800900

10001100120013001400

1108oC

1233oC1114oC

Temp

erat

ure

(o C)

Time ( s )

0 50 100 150 200 250 300 3500

100200300400500600700800900

10001100120013001400

st ar t pr ocess

1125oC1245oC

Temp

erat

ure

(o C)

Time ( s )

B=0T B=3.1T

Relation between the temperature and time for solidification of gray iron

Metal Solidification Research Group, Shanghai University

Results and Discussions ——Effect on stainless steel

(h)(g)(f)(e)

(a) (b) (c) (d)

10mm10mm10mm10mm

10mm 10mm 10mm 10mm

(a)B=0T

(b)B=0.78T

(c)B=1.10T

(d) B=1.35T

(e)B=1.8T

(f)B=3.00T

(g) B=3.24T

(h) B=3.84T

Metal Solidification Research Group, Shanghai University

Conclusions:

1. The solidified structure of pure aluminum evolved from columnar

grains to equi-axed ones, and the grain size becomes smaller as

the augment of the intensity of pulsed magnetic field. The effect

of the pulsed magnetic field on the solidification temperature of

Al can be neglected.

2. The pulsed magnetic field can refine and improve the graphite

morphology of the gray iron. Also, the pulsed magnetic field can

decrease its undercooling of the eutectic transformation.

Metal Solidification Research Group, Shanghai University

Conclusions:

3. The solidification structures of austenitic stainless steel are changed

from coarse columnar crystals to narrow and thin ones after adding

pulsed magnetic field. However, equi-axed grains can’t be obtained.

Metal Solidification Research Group, Shanghai University

Acknowledgement:

Financially supported by

(1) National Natural Science Foundation of China, (2)

Science and Technology Committee of Shanghai

Municipality

The end. Thank you!

Metal Solidification Research Group, Shanghai University

Experimental equipments:

Metal Solidification Research Group, Shanghai University

Schematic of the solidification equipment:

1 － Magnetic field generator

2− Pouring cup

3−Liquid metal

4−Mould

5−Cooling System

6−Computer-controlled

thermometric system

7−Pad

8−Mobile platform

9 － Thermal couples

10 － Pulse power source

7

10

1 3 42

65

8

9