中国工业检验检测网www.industryinspection.c

http://www.industryinspection.com QQ:1781054143
25 7
2 0 0 3 7
NDT
Vol . 25 No . 7
July 2 0 0 3
(
, 210037)
:
,
,
,
: ; ; ;
:TG115. 28
:A
:100026656 (2003) 0720349202
THE CAUSE OF FORMATION FOR ANOTHER ABNORMAL INDICATION
IN MAGNETIC PARTICLE INSPECTION
ZHONG Wei2chang
(Nanjing Gas Turbine Research Institute , Nanjing 210037 , China)
中 国 工 业 检 验 检 测 网
Abstract : According to Coulombπs law of magnetism and the principle of minimum magnetic free energy , the magnetic charge
distribution along the edges of a longitudinal slot on work piece surface was given when it was longitudinally magnetized. It was
demonstrated that a longitudinal crack would also attract magnetic particles sometimes to form abnormal indication when the work
piece was longitudinally magnetized. Furthermore , it was inferred that a transverse crack circumferentially magnetized would ad2
sorb magnetic particles sometimes too. The above had been verified by practical experience of magnetic particle inspection.
Keywords :Magnetic particle inspection ; Longitudinal magnetization ; Longitudinal crack ; Abnormal indication
www.industryinspecti
[6 ,7
(
] ,
ml (Wb/ m) [10 ] (1a)
,
) ,
w hC
ml =
() , l + 2 w + h m 0 H 0 (1)
,
2 l ,2 w , h ,m
[14
,
] m
,
,
0
,
0 = 4 10 - 7 H/ m
[5
] ,
,
H 0
,A/ m
C
,
,
[69 ] ,
1
[8 ,9 ]
(1b ,c) ,
m= m0 sin (2)
:2002205220
:
(59571064)
m
,Wb/ m
349
© 1995-2003 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved.

http://www.industryinspection.com QQ:1781054143
:
1
m0
,
Wb/ m
2
(2a) 2b
, H 0
2b ,
,
,
2a [10 ] 中 国 工 业 检 验 检 测 网
www.industryinspecti
, 2
,
3
5
[11
]
, ,
() [12 ,13
] ,
( )
(3 A
(5) ,
) ,
(3 B ()
)
,
(4a)
(4b) ,
6
(
)
, ( )
(4c ,d)
4a ,b
;c ,d
4
4
4c , d ,
,
( )
3
5
350
© 1995-2003 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved.

http://www.industryinspection.com QQ:1781054143
25 7
2 0 0 3 7
NDT
Vol . 25 No . 7
July 2 0 0 3
2003
,
2003
11 1417
2003
,
2003 ,
,
,
13
, ,
,
,
,
(
)
8
, 6
22
8
,
8 19
(
)
中 国 工 业 检 验 检 测 网
www.industryinspect
[14
,
]
,1997 ,19(4) :95 - 98.
, [7 ] Wei Chang Zhong. Theoretical
fundamentals of magnetic
dipole for longitudinal magnetization of a square steel
,
com2
ponent[J ]. Materials Evaluation ,1999 ,57(9) :937 - 939.
,
[8 ] .
[A ]. ()
MT PT
() [ C]. :1996.
,
[9 ] Wei Chang Zhong. Non2relevant indications along the base
apex lines of work pieces magnetized circumferentially[ A ].
10th Asia2Pacific Conference on Non2Destructive Testing[M/
:
CD]. Brisbane Australia :2001.
[10 ] .
[J ]. [1 ]
. ,2002 ,24(8) :332 - 335.
[M]. :
,1975.
[11 ] .
[A]. [2 ]
. [M].
:
,1987.
[ C]. :2002. 248 - 254.
[12 ]
.
[M]. :
,1985.
[4 ]
.
[13 ] , . [M]. :
.
[M]. : ,1987.
,1994.
[14 ] .
[A ]. [5 ]
. [ Z].
:
,1985.
[M/ CD]. :2003.
[6 ] .
[J ]. 351
© 1995-2003 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved.