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00:49 May-10-1999

Ishbel Macdonald

Consultant, Engineering Consultant - NDT
Subsea 7,
Norway,
Joined Nov 1998
11
Magnetic permeabilities

Hello therr

Does anyone out there have any idea where I can find values for the magnetic permeabilities of steels such as duplex and super duplex? I am looking into the possibility of carrying out MPI, and so would like to know how "magnetic" these materials are. I know that there are methods to carry out such evaluations, but unfortunately, I do not have access to the equipment.

Regards

Ishbel




 
04:23 May-10-1999
Kåre Johansson
Re: Magnetic permeabilities : Hello therr

: Does anyone out there have any idea where I can find values for the magnetic permeabilities of steels such as duplex and super duplex? I am looking into the possibility of carrying out MPI, and so would like to know how "magnetic" these materials are. I know that there are methods to carry out such evaluations, but unfortunately, I do not have access to the equipment.

: Regards

: Ishbel
We did some MPI of 2205 some years back with good result. We assumed a permeability of 60% of carbon steel and it worked reasonably well. This is not theoretically correct as
the permeability will depend on both the amount of ferrite and the chemical composition of the ferrite. Watch for false indications in the HAZ due to changes in ferrite content. If you want more exact values yu could look into the proceedings of some of the duplex conferences which have been held. Maastricht (1997), Glasgow (1994), Baune (1991).Steel producers like Sandvik and Creusot Loire should also be able to help.
Kåre


 
19:24 Jan-11-2012

LK

NDT Inspector,
Norway,
Joined May 2008
104
Re: Magnetic permeabilities In Reply to Kåre Johansson at 04:23 May-10-1999 .

Good afternoon.

Any changes within last 12 years ? :)
Anybody have more information about MPI of duplex bars?
One customer requested both PT and MT on them.
I have some doubts about efficiency of mag particle testing.

Looking forward for your comments.
LK

 
20:24 Nov-14-2012

John H

NDT Inspector,
Norway,
Joined Nov 2012
1
Re: Magnetic permeabilities In Reply to LK at 19:24 Jan-11-2012 .

I look forward to more information on this subject.

 
02:14 Nov-15-2012
John
Re: Magnetic permeabilities In Reply to John H at 20:24 Nov-14-2012 .

All u can think of is a lift test of the material

 
01:30 Nov-22-2012

Michel Couture

NDT Inspector,
consultant,
Canada,
Joined Sep 2006
806
Re: Magnetic permeabilities In Reply to Ishbel Macdonald at 00:49 May-10-1999 (Opening).

Ishbel,

You're not saying wht type of equipment you have or which MPI method you will be using (yoke or mag bench).

Regardless, what you have to remember is that your magnetic field should be strong enough to magnetise your part and show the indication you are seeking. ASTM E709 talks about two way to ensure your magnetic inspection will be succesful is to use a pie gauge and see the artificial defects in it or with a Gauss meter tha will indicate a field of 30 - 60 gauss in the part.

 
02:22 Nov-22-2012

Jianjun Wu

Engineering, NDE
China,
Joined Nov 2012
20
Re: Magnetic permeabilities In Reply to Michel Couture at 01:30 Nov-22-2012 .

Recently, I read a book regarding the permeaility of steel materials.

This book specifies the Magnetic characteristic curve of the material which will help us to determine the proper parameters in MT techinque selection. But this book is written in Chinese. However, the symbols and curves could be easily understood. If any one want this book, please leave your mail. Br, Hc are indicated in the curve.

 
02:29 Nov-22-2012

Jianjun Wu

Engineering, NDE
China,
Joined Nov 2012
20
Re: Magnetic permeabilities In Reply to Ishbel Macdonald at 00:49 May-10-1999 (Opening).

zoom image[zoom]

According to the Curve, if Br>0.8T, Hc>1000A/m or (H*B)max>0.4kJ/m3, residual method would be better for this material; otherwise, continuous method will be applied.

Hope this will do some help to you.
 


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