AISI 1005 vs AISI 1008 2

[mbfree]

We were using AISI 1008 low carbon steel for an electromagnetic application. We didnt have any problems yet, until recently when we switched vendors and started getting AISI 1005. The magentic properties are very worse and I was wondering what could be the contributor to this. We ran a lab test for the new material vs the old one and heres what we came up with.

AISI 1008
C-> 0.06
Mn-> 0.32
P-> 0.011
S-> 0.012
Al-> 0.07
B-> less than 0.001
Cr-> 0.03
Cu-> 0.02
Mo-> less than 0.01
Ni-> 0.01
Si-> 0.01

AISI 1005 (with added Boron)
C-> 0.04
Mn-> 0.17
P-> 0.003
S-> 0.012
Al-> 0.03
B-> 0.0025
Cr-> 0.01
Cu-> 0.03
Mo-> 0.01
Ni-> 0.01
Si-> 0.01

All values are in weight percent.

The basic difference I noted is in Mn content. Could anyone have anything, to confirm its Mn. Or is it one of the other elements.

I only have this much information with me now. I dont have values for the exact amoutnt of electromagentic property deviation, but I know it was really bad for the 1005 compared to 1008.

 

[sreid]

When you say worse magnetic properties;

Less residual magnatism.

Lower saturation.

Lower permeability.

?

 

[mbfree]

As far I know for now, it was bad in the Magnetic Strength along with a noted decline in almost all the properties.

 

[israelkk]

Maybe it is cold rolled compared to annealed? But without more details on the application and measured magnetic values it is difficult to answer. As a rule the lower the carbon content the better the magnetic properties. Therefore 1005 should have been better than 1008.

 

[MagMike]

Manganese is antiferromagnetic, but at the levels shown in your test report it won't make much of a difference.

Most likely the differences are due to cold-rolling and/or heat treat condition (as israelkk mentioned). I'd suggest sending the 1005 out for annealing.

EdStainless mentioned in an earlier thread: Steels are generally not processed with magnetic properties in mind. One needs to be very careful specifying important parameters if magnetic properties are important.

 

[mbfree]

Thanks for your replies guys. Yeah I was just thinking of the composition difference and not about the heat treatment. May be that is the reason...

 

[mbfree]

Again, Magmike, I just got information that we already sent it out for Annealing, but it didnt have any difference.
Specifically the B-H curve for 1005 is considerably lower than that of 1008.

 

[sreid]

I wonder if the 1005 could be Free Machining with a high lead content?

 

[MagMike]

Was there any machining done on the material after annealing?

The B-H curve for 1005 should be slightly higher than 1008, assuming they both were processed exactly the same way.

 

[israelkk]

This is odd. For the last 30 years I was used 1010, 1018, 1020, 1113, 1117, 12L14 cold rolled and hot rolled bars for solenoids and electromagnets with no noticeable difference in magnetic forces.

We never needed to anneal the parts after machining.

For solenoids made from sheet or strip metal we used annealed because the stamping and bending radius requirements.

 

[EdStainless]

mbfree, you need to have a sample fully annealed. I would use 2,200F in pure hydrogen for a couple of hours. This will tell you what the material is capable of.
The saturation magnetization of the 1005 has to be as goo or better than the 1008. It may have different permiability and hysterisis.
Can you get the test conditions and data? Did you measure resistivity also?

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[mbfree]

Magmike, yeah thats exactly what bothers me too...The parts were annealed after machining and was basically the same size and shape as that of 1008.
We have been using low-carbon steels for the application for quite some years now and didnt expect 1005 to behave this badly.
Edstainless, I am not sure how far they went with the annealing process, but I will try to get the data.

Originally we tested for hardness values for both and 1008 came up with HR B 50-60 and 1005 had HR B 30-40, which is way lower than the former, but could be attributed to the lower carbon content.
Anyways, the saturation point of 1005 is way lower than 1008 and seems to be the crux of the problem. It could be something which is inherent to 1005, but I am not sure.

After all, you would expect both the materials to behave almost the same way without spending any additional investment on 1005.

 

[EdStainless]

Did your own lab do the chemistries? If not then send a piece of each to your own (or local) lab. There is something amiss. I suspect that they overlooked something. Make sure that Pb, Sn, Sb, N, and Bi are included.
I can see that the perm could be screwed up, but not the sat.

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Neither should your protection

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[dgallup]

We use 1005 all the time for magnetic applications, it should have a very high saturation flux density. All your elements are within our specification. We anneal at 1346 to 1382 deg F for 2 to 4 hours.

 

[mbfree]

Thanks for all the replies....
I have to ask this, Does annealing temperature have that much of an effect on the magnetic property???

 

[EdStainless]

It will have a huge effect on perm. It should have almost no effect on saturation.
Except, if you use annealing to purify the material. But that is 1400C fro 18 hours in pure hydrogen.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

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[mbfree]

Ed Stainless, thank you for your response. I might sent the samples again for an analysis report. Could you/anyone just quickly familiarize me how Pb, Sn, Sb, N, and Bi would affect the perm. and/or saturation. How about Oxygen content too?

 

[mbfree]

Also, to let you guys know, the annealing temperature we used was around 1600 F and was for around 2.5 hrs.

 

[EdStainless]

Those impurities are mostly just filler. they would only reduce the B in that they would take up space in place of Fe.
It is only when elements exceed their solubility and for secondary phases that they really mess up the properties.

Sounds like a good anneal. Was it in a reducing atmosphere?

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

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[sreid]

Is it possibe that the added Boron is the culprit?