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Metallurgy/carbon steel magnetism

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QUESTION: Hello,
I have a question that I have been asking online for weeks only to get conflicting answers and or complicated magnetism and physics lessons. I have a project that requires that I shape a piece of carbon steel and then permanently magnetize it. Machining the piece,  heating and magnetizing I've got covered.The material I need to use is carbon steel.I know there are better materials that can be used to make a strong permanent magnet like neodymium, boron, silicon etc, but my project calls for iron carbon alloy ONLY. My question simply is- What percentage of carbon in the steel would  make the strongest permanent magnet? And with that- What specific grade of carbon steel do I need to purchase. If you could help me with this question, it would be so much appreciated. If this isn't your expertise them maybe you can direct me to some who can give me a straight answer. Thank you

ANSWER: Dear Mathew,
How can you get straight answer as you know straightly what are you searching, not me or anyone else.Following guidelines will surely help you in selecting one of the best option suiting your taste.All the best.
Neodymium magnets are by far the strongest type of permanent magnet available. It depends on the application.  If you need the highest strength in the smallest possible package at room temperature, grade N52 is the strongest available.
Many of our magnets are offered in grade N42, which is a great balance between cost, strength and performance at higher operating temperatures.  You can get the same strength as an N52 magnet by using a slightly larger N42 magnet.
If you have slightly elevated temperatures, in the 140F to 176F range (60C -80C), N42 magnets might actually be stronger than N52.
Neodymium Magnet Physical Properties
Magnet Summary Table - Click this link for the pull force and surface field of each of our stock magnets listed in table format


Magnetic Characteristics
Material Type   Residual Flux Density
(Br)   Coercive Force
(Hc)   Intrinsic Coercive Force (Hci)   Max.Energy Product
(BH)max
N35   11.7-12.1 KGs   >11.0 KOe   >12 KOe   33-35 MGOe
N38   12.2-12.6 KGs   >11.0 KOe   >12 KOe   36-38 MGOe
N40   12.6-12.9 KGs   >11.0 KOe   >12 KOe   38-40 MGOe
N42   13.0-13.2 KGs   >11.0 KOe   >12 KOe   40-42 MGOe
N45   13.3-13.7 KGs   >11.0 KOe   >12 KOe   43-45 MGOe
N48   13.8-14.2 KGs   >11.0 KOe   >12 KOe   45-48 MGOe
N50   14.1-14.5 KGs   >11.0 KOe   >11 KOe   48-50 MGOe
N52   14.5-14.8 KGs   >11.2 KOe   >11 KOe   49.5-52 MGOe
N35M   11.7-12.1 KGs   >11.4 KOe   >14 KOe   33-35 MGOe
N38M   12.2-12.6 KGs   >11.4 KOe   >14 KOe   36-38 MGOe
N40M   12.6-12.9 KGs   >11.4 KOe   >14 KOe   38-40 MGOe
N42M   13.0-13.3 KGs   >11.4 KOe   >14 KOe   40-42 MGOe
N45M   13.3-13.7 KGs   >11.4 KOe   >14 KOe   42-45 MGOe
N48M   13.6-14.2 KGs   >11.4 KOe   >14 KOe   45-48 MGOe
N50M   14.1-14.5 KGs   >11.4 KOe   >14 KOe   48-50 MGOe
N33H   11.4-11.7 KGs   >10.3 KOe   >17 KOe   31-33 MGOe
N35H   11.7-12.1 KGs   >10.8 KOe   >17 KOe   33-35 MGOe
N38H   12.2-12.6 KGs   >11.4 KOe   >17 KOe   36-38 MGOe
N40H   12.6-12.9 KGs   >11.4 KOe   >17 KOe   38-40 MGOe
N42H   13.0-13.3 KGs   >11.4 KOe   >17 KOe   40-42 MGOe
N45H   13.3-13.7 KGs   >11.4 KOe   >17 KOe   42-45 MGOe
N48H   13.6-14.2 KGs   >11.4 KOe   >16 KOe   45-48 MGOe
N30SH   10.8-11.2 KGs   >10.1 KOe   >20 KOe   28-30 MGOe
N33SH   11.4-11.7 KGs   >10.3 KOe   >20 KOe   31-33 MGOe
N35SH   11.7-12.1 KGs   >10.8 KOe   >20 KOe   33-35 MGOe
N38SH   12.2-12.6 KGs   >11.4 KOe   >20 KOe   36-38 MGOe
N40SH   12.6-12.9 KGs   >11.4 KOe   >20 KOe   38-40 MGOe
N42SH   13.0-13.3 KGs   >11.4 KOe   >20 KOe   40-42 MGOe
N45SH   13.3-13.7 KGs   >11.4 KOe   >19 KOe   43-45 MGOe
N28UH   10.4-10.8 KGs   >9.8 KOe   >25 KOe   26-28 MGOe
N30UH   10.8-11.2 KGs   >10.1 KOe   >25 KOe   28-30 MGOe
N33UH   11.4-11.7 KGs   >10.3 KOe   >25 KOe   31-33 MGOe
N35UH   11.7-12.1 KGs   >10.8 KOe   >25 KOe   33-35 MGOe
N38UH   12.2-12.6 KGs   >11.4 KOe   >25 KOe   36-38 MGOe
N40UH   12.6-12.9 KGs   >11.4 KOe   >25 KOe   38-40 MGOe
N30EH   10.8-11.2 KGs   >10.1 KOe   >30 KOe   28-30 MGOe
N33EH   11.4-11.7 KGs   >10.3 KOe   >30 KOe   31-33 MGOe
N35EH   11.7-12.1 KGs   >10.8 KOe   >30 KOe   33-35 MGOe
N38EH   12.2-12.6 KGs   >10.8 KOe   >30 KOe   36-38 MGOe

Thermal Characteristics
Neodymium Material Type   Maximum Operating Temp   Curie Temp
  C (F)   C (F)
N   176F (80C)   590F (310C)
NM   212F (100C)   644F (340C)
NH   248F (120C)   644F (340C)
NSH   302F (150C)   644F (340C)
NUH   356F (180C)   662F (350C)
NEH   392F (200C)   662F (350C)
The Thermal Characteristics listed above are values commonly associated with each magnet'sgrade or material.  Actual performance in your application may vary with other factors, including the shape of the magnet, the Permeance Coefficient or load line, and how it is used in a circuit.  See our in-depth article on Temperature and Neodymium Magnets for more details.


Physical and Mechanical Characteristics
Density   7.4-7.5 g/cm3
Compression Strength   950 MPa (137,800 psi)
Tensile Strength   80 MPa (11,600 psi)
Vickers Hardness (Hv)   560-600
Young's Modulus   160 GPa (23,200 psi)
Recoil Permeability   1.05 μrec
Electrical Resistance (R)   160 μ-ohm-cm
Heat Capacity   350-500 J/(kg.C)
Thermal Expansion Coefficient (0 to 100C)
parallel to magnetization direction   5.2 x 10-6 /C
Thermal Expansion Coefficient (0 to 100C)
perpendicular to magnetization direction   -0.8 x 10-6 /C

Plating Characteristics
Plating Type   Overall Thickness   Salt Spray Test   Pressure Cooker Test
NiCuNi (Nickel Copper Nickel)   15-21 μm   24 hours   48 hours
NiCu + Black Nickel   15-21 μm   24 hours   48 hours
NiCuNi + Epoxy   20-28 μm   48 hours   72 hours
NiCuNi + Gold   16-23 μm   36 hours   72 hours
NiCuNi + Silver   16-23 μm   24 hours   48 hours
Zinc   7-15 μm   12 hours   24 hours
Each individual layer of Nickel and Copper are 5-7 μm thick. The Gold and Silver plating layers are 1-2 μm thick.
Test results shown to allow comparison between plating options. Performance in your application under your specific test conditions may vary. Salt Spray testing conducted with a 5% NaCl solution, at 35C. Pressure Cooker Test (PCT) conducted at 2 atm, 120C at 100% RH.
SELECT MATERIAL AS PER YOUR SPECS/STANDARD.
Regards,
R.P.SHARMA


---------- FOLLOW-UP ----------

QUESTION: I don't understand what is wrong with my question. I need to make a magnet out of carbon steel. Steel which only has iron and carbon. What percentage of carbon does the steel need to make a strong permanent magnet. If I have pure iron and want to make it into a permanent magnet how much carbon do I need to add.

Answer
Surely, there is a serious problem with your question- you want to make permanent magnet from plane carbon steel (iron+carbon) without understanding the basic requirement of permanent magnetic steel.
Neodymium-Boron-Iron makes a grade for your target alloy.These are popular as NIB steels.
Still if you want to know carbon contents, answer is 0.003%.
You can't make strong permanent magnet from iron+carbon alloy(plain carbon steel).
Trust your query remains plugged, all the best for making "impossible" a "possible" as the word "Impossible says---I M POSSIBLE"
Regards,
RP SHARMA

Metallurgy

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RAJINDER PRASAD SHARMA

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Questions that i can answer:- 1-sand casting of cast iron,S.G. iron,steel and aluminium alloys 2-Gravity die casting of aluminium 3-Low pressure die casting of aluminium 4-High pressure die casting of aluminium 5-Failure analysis of ferrous and non-ferrous castings Questions that i can`t answer:- 1-testing of iron and steel 2-Problem related to welding 3-Problems related to corrosion 4-Amorphous metals,rubbers,nylon,plastics and plastic moulding

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1-Sand casting and ferrous and non-ferrous alloys 2-Gravity die casting,low pressure die casting,high pressure die casting of aluminium alloys.With a specialisation in auto-mobile components castings. 3-Alloy steel making on arc furnace,AOD,VOD,Con-cast root of alloy steel making. I have been working as Foundry man since last 27 years.

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Hindustan motors Ltd.

Education/Credentials
I am a Metallurgical Engineer graduated from National institute of Technology,warangal(India) in 1984 and in 1991 i completed my masters degree in business administration(M.B.A.) from Institute of Management Technology,Ghaziabad(India).

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