Microphone Pendant 316 Stainless Steel Fashion
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"Can type 316 stainless steel become magnetic?"
2001
Q. I have been using some type 316 stainless steel threaded pipe fittings in a system containing sulphuric acrid. A city inspector came to my site and put a magnet up to the pipe fittings and information technology stuck. Although the fittings had type 316 cast into the body, he stated that they could non be stainless steel because they are magnetic. I have been told that the machining of the fittings, such as cutting the threads, can crusade them to become magnetic. Is this true, and if so where can I find something in writing to prove the inspector ?
Thank you,
David Hathaway
- Pico Rivera, California, USA
^
2001
A. We've seen this question in this forum earlier [letters 7136, 21171 ... ].
Blazon 316 stainless can be fabricated magnetic by working the metal.
George Brackett 3
- Utica, New York
^
2001
A. Hi David!
The magnet test is commonly a proficient one, every bit it is necessary to impart enough piece of work into the steel to go information technology to alter the arrangement of the atoms to get ferromagnetic properties. (You got to get from the standard face up centered cubic to a trunk centered tetragonal blueprint.) It hasn't been my experience that this happens with mere machining in 316- I've always had to go cold rolling, or bending, or some sort of forming to go the magnet to stick. Some of the things that could touch on this include composition- higher chromium, carbon, or molybdenum contents, or lower nickel contents, will brand the transformation occur a lower amounts of common cold piece of work. Possibly your casting is a bit off in composition?
Is it as magnetic even away from the cut threads?
Regarding references, I oddly enough don't find anything in the Mil Handbook on this, and while in that location is likely something in ane of the many publications the Nickel Development Constitute offers, I can't guarantee it without spending some time searching (just be sure to pick up your gratis copy of #9014!) .
Then, I'll recommend what Peter Moore of Atlas Steels in Australia has put together: a dainty handbook on stainless steels, at
www.atlas-steels.com.au/techinfo/
www.atlassteels.com.au/site/pages/technical-handbooks-of-stainless-steel.php
[link updated by editor Dec. 2013].
At that place'due south a section in the Technical Handbook on magnetic properties you might find interesting.
Good luck!
Lee Gearhart
metallurgist - Eastward. Aurora, New York
^
2001
A. David,
I thought that 316 was non-magnetic (strictly speaking a magnetometer is influenced by 316!) but that the 400 series, which had more fe, is magnetic...only how magnetic information technology is, I don't know ...
All the same, if your acid concentration of Sulphuric is fairly high,(say 90% or more) and so fifty-fifty Fe or any grade of stainless @ R.T. should exist OK. And if that is and then, tell that inspector to go have a running jump!
It would have been more helpful if you had mentioned the concentration & the temperature.
Listen you lot, PVC is better than 316 stainless and can take any concentration of sulphuric up to 93% commercial... merely there are other and better plastics which cost far more if you wanted a higher temperature resistance.
Freeman Newton [dec]
(It is our distressing duty to suggest that Freeman passed away
April 21, 2012. R.I.P. former friend).
^
2001
A. The fundamental to the respond is that the fittings are said to be castings. Stainless steel coming together "316" is actually a rolled or forged textile simply the proper name is used for shorthand even for castings. The "equivalent" casting specification is CF-8M, which is like but non identical in composition and properties. And so why is it magnetic? When cast, steels similar to 304 and 316 stainless have small amounts of the magnetic phase referred to as ferrite in the microstructure. (Welds used for these materials also have small-scale amounts of ferrite.) Depending on the corporeality of ferrite, stainless castings vary from slightly to substantially magnetic. If you compare the pull of the magnet to something that is fully magnetic, such as 400 series stainless or carbon steel, yous'll see a big difference, since the ferrite amount in the casting is only between 5 and 25 percentage.
Any textbook on stainless castings will explain this. Few Spider web pages go into this sort of detail, but I found a clarification at
www.sfsa.org/sfsa/pubs/cvf/ecs.html
--the Steel Founder'southward Society of America, that at to the lowest degree documents it in relatively simple language. All yous have to know is that the ferrite is the magnetic portion.
gas & electrical
Paul Tibbals, P.E.
San Ramon, California, The states
(My opinions are not related to nor a statement of my employer'south)
^
2001
A. Lee: The casting composition would be a bit off typical if the casting was NOT slightly magnetic.
Paul: Well stated.
316 for wrought product has its chemistry balanced and then that it is fully austenitic (and hence incidentally nonmagnetic) because that microstructure requires least power when rolling the steel into bar/sheet/rod/whatever, whether that rolling is being done hot or cold.
CF-8M for castings has its chemistry counterbalanced and then that it is predominantly austenite with unremarkably 5 to xv pct ferrite. This is done to enhance hot strength and reduce the possibility of complex cast shapes tearing every bit they absurd in the mold. Since the casting isn't going to be rolled, the increased hot strength doesn't cause any inconvenience. The increase in strength is maintained downwardly to room temperature.
A beneficial side effect is that the ferrite in CF-8M is induced past employ of higher chromium content than is used in 316 (usually eighteen-19 per centum for CF-8M against 17-17.5 for 316) and this gives the casting course meliorate resistance to general corrosion as well every bit to pitting corrosion.
If CF-8M castings are required to exist nonmagnetic, they can be made so, past using a different balance of the constituent elements while still property each element within its specified range. For instance, CF-8M or any other stainless class which is for components to be used on pot lines in an aluminium smelter, are fabricated nonmagnetic so that they are not attracted to the potline busbars that are carrying massive electric currents and thus generating massive magnetic attractions. Simply where CF-8M castings are required to be nonmagnetic, the purchaser/specifier MUST SAY SO otherwise the foundry steelmaker will ordinarily choose to have a few percent ferrite present.
As Paul notes, it is regrettable that many design engineers remember 316 for castings. Castings fabricated to the typical wrought 316 chemical composition have corrosion resistance and mechanical properties that are junior to those made to the typical casting CF-8M chemical limerick.
Nib Reynolds [dec.]
consultant metallurgist - Ballarat, Victoria, Australia
Nosotros sadly relate the news that Beak passed away on January. 29, 2010.
^
2003
A. I have recently experienced that Stainless does non mean non magnetic. In my case it is very important the material in the component is non magnetic since I am using information technology in a particle detector with a magnetic field of max 4 Tesla.
I suggest that you take a expect at this accost for a fantabulous explanation:
www.physlink.com/Education/AskExperts/ae546.cfm
Best regards,
Lasse Isaksen
CERN - Geneva, Switzerland
^
2004
A. I found this information helpful:
Background:
Magnetic permeability is the power of a material to carry magnetism, indicated by the degree to which information technology is attracted to a magnet. All stainless steels, with the exception of the austenitic group, are strongly attracted to a magnet.
Austenitic Grades:
All austenitic grades have very depression magnetic permeabilities and hence show almost no response to a magnet when in the annealed status; the situation is, nevertheless, far less articulate when these steels have been cold worked by wire cartoon, rolling or even centerless grinding, shot blasting or heavy polishing. Later substantial cold working Form 304 may exhibit quite strong response to a magnet, whereas Grades 310 and 316 will in nigh instances still exist near totally non-responsive. The alter in magnetic response is due to diminutive lattice straining and germination of martensite. In general, the higher the nickel to chromium ratio the more than stable is the austenitic structure and the less magnetic response that will exist induced by common cold work. Magnetic response tin therefore be used equally a method for sorting grades of stainless steel, just considerable caution needs to be exercised.
Stress Relieving:
Any austenitic (300 series) stainless steel which has developed magnetic response due to cold work can be returned to a non-magnetic status by stress relieving. In general this can exist readily achieved by briefly heating to approximately 700 - 800 °C (this can be conveniently carried out past careful utilize of an oxy-acetylene torch). Note, nonetheless, unless the steel is a stabilized grade it could become sensitized to carbide precipitation. Total solution treatment at 1000 - 1150 °C will remove all magnetic response without danger of reduced corrosion resistance due to carbides. If magnetic permeability is a cistron of design or is incorporated into a specification, this should be conspicuously indicated when purchasing the stainless steel from a supplier.
Cold Working:
Many cold fatigued and/or polished confined have a noticeable corporeality of magnetism equally a result of the previous common cold work. This is specially the instance with grades 304 and 303, and much less so for the higher nickel grades such as 310 and 316. Even within the chemic limitations of a unmarried standard analysis range in that location tin be a pronounced variation in the rate of inducement of magnetic response from cold piece of work.
Magnetically Soft Stainless Steels:
In some applications at that place is a requirement for a steel to exist "magnetically soft". This is often required for solenoid shafts, where information technology is necessary for the plunger to respond efficiently to the magnetic field from the surrounding coil when the current is switched on, but when the electric current is switched off the magnetic field induced in the steel must rapidly collapse, allowing the plunger to return to its original position. Steels which comport in this way are said to be magnetically soft. For corrosion resisting applications in that location are ferritic stainless steels which are magnetically soft, usually variants of a grade "18/two" (xviii% chromium and 2% molybdenum) but with very tightly controlled additions of silicon and oftentimes with sulphur added to make them costless machining. Special mill processing guarantees the magnetic properties of the steels.
Source: Atlas Steels Commonwealth of australia
Robert Cullen
- Milford, New Hampshire
^
December 18, 2013
A. This is an age old question. The reasons are that common cold working of AISI316 tin can produce the martensitic phase in the asutenite matrix, known equally epsilon martensite, which of course is magnetic. Just mere thread cut will not produce this degree of cold work although thread rolling instead of cutting could. Its a case of ascertaining if information technology was thread cut or rolled. Also casting grades are usually inferior in central elements to forming grades, to assist with casting, so a skilful solution is to use thread cut formed tube 316 rather than cast 316. I accept been involved in many years of applications of these materials into power stations cooling systems, gas pipelines systems, hot h2o systems and domestic products in solar technology; and I accept witnessed the inferior operation of cast 316 in warm applications in regard to corrosion resistance. I would not use the casting alloys in such applications.
Geoff C Grace
Geoff Grace Contract Consulting - Bundoora, Victoria, Australia
^
2007 -- this entry appended to this thread past editor in lieu of spawning a duplicative thread
Q. I am checking some screws that are 316 or equivalent Stainless Steel. Someone checked them with a magnet and assumed they are steel rather than stainless steel because they are magnetic. Is this necessarily truthful?
Cheers!
Marker Arnett
Quality Inspector - Elwood, Indiana, USA
^
2007
A. Such things tin exist determined at a cost, Mark. At that place are costly (well-nigh $40K) hand-held X-ray fluorescence machines called "scrap sorters" which will almost instantly identify the alloy in complete detail.
But as for the nigh likely scenario, I'd say the screws are probably stainless but not 316 -- mayhap 4xx series. Good luck.
Ted Mooney , P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Bailiwick of jersey
^
June 22, 2010
A. The chemical spot test method is inexpensive and constructive at determining stainless steel 316. Spot test kits are available and more than reliable than magnetic backdrop because alterations in the physical properties will not effect composition of the alloy. The Moly Test is such a test for verifying stainless steel 316.
Wolf Koslow
Koslow Scientific Company
Englewood, New Bailiwick of jersey
^
January 29, 2009
A. Nowadays some companies decrease Ni and increment Mn content of austenitic stainless steels to make them cheaper! Mn, like Ni, is a austenite stabilizer meaning that we tin can maintain austenite phase stable in room temperature with cheaper-Mn instead of expensive Ni.
Refer to austenitic stainless steels standards (similar Russian GOST standards for 08X18H10T, east.g.,. AISI 321), the ferrite content upwardly to 10% is permissible. Up to this ferrite content there is no severe change in corrosion properties of stainless steel particularly general corrosion behavior, simply in more ferrite content, the stainless steels may be susceptible to intergranular corrosion (depends on environs).
Ok, Ideally the 300 serial stainless steels shall not show whatever magnetic properties Just practically the magnetic properties of 300 series are not so uncommon!
Morteza Dehghani
- Academy of Tehran, Islamic republic of iran
^
July 6, 2011 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q.
ane. Please how can I identify an original stainless steel pipe and fittings.
2. And how tin can I place a 316 stainless steel pipe and fittings
alex faith
buyer - port harcourt, Nigeria
^
July 7, 2011
A. Hello, Alex.
Yous may know something that I don't, merely as far as I know there is no accepted meaning for "original" stainless.
10-ray fluorescence can determine the type of stainless steel exactly, merely the equipment is expensive. A spot exam was previously mentioned by Wolf Koslow. Good luck.
Regards,
Ted Mooney , P.E. RET
Striving to live Aloha
finishing.com - Pino Beach, New Jersey
^
September 12, 2011 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. How-do-you-do My name is Tom Winter. Nosotros accept a customer is Taiwan with a problem with 316 stainless steel corrosion on 316 bolts and pipe hangers, castings. They are corroding, probably due to body of water air. They are exposed. They don't they they are stainless steel because they are magnetic, only their vender assures them they are 316. Could the corrosion form the salts turn the 316 magnetic? I have heard that piece of work hardening can make 316 become magnetic. Anyone have have whatsoever experience with this? Thanks
Tom Wintertime
We process tubing and fittings - St. Louis, Missouri, The states
^
September xx, 2011
A. Cast 316 cloth is more magnetic than other forms, as explained in numerous cloth texts. Regardless of the ferrite content, stainless steel can corrode if exposed to the right conditions. We see it with 316L and in super duplex which have different ferrite contents. Common salt air will definitely contribute to corrosion. I don't know if salt would arrive more than magnetic. Either way, we prevent corrosion (or significantly delay it) in our marine applications past either painting our SS products or electropolishing them. A reduction in surface roughness vastly increases the ability of material to withstand corrosion.
A positive cloth identification (PMI) test can be performed to determine various types of steel. Nosotros use it to distinguish betwixt 316L and 304 grades of stainless.
I'm sure the equipment is expensive, but I've also seen companies that hire or lease information technology. Alternatively, discover a exam lab that makes house calls.
Hope this helps!
Mathew Heidmous
- Boulder, Colorado, US
^
November 8, 2011
A. The reference you are looking for is in "Metals Handbook" (c) 1985 published past the American Society for Metals.
Peter Orr
- Colorado Springs, Colorado, United states of america
^
July 6, 2012
Q. Our company uses transmission oil seals (lip seals) in its marine products. We accept used the same supplier for nearly 20 years. Upon receipt of these lip seals, our staff removes each 316 stainless steel garter spring from the lip seal. We inspect spring length and general condition. In addition, we pass a magnet over each spring.
Recently, these 316 stainless springs began to stick firmly to our magnet.
Our product (containing these lip seals) operates in salt h2o. In an try to reduce the effects of corrosion and electrolysis, nosotros have requested 316 stainless from our vendor for years.
My business organisation is that they now receive these springs from a different supplier and the quality of the stainless has diminished.
Heating the springs to 700-800 °C is not possible.
We practice take other SS parts passivated (locally) earlier putting into inventory. Would passivation eliminate some / all of this increase in magnetic characteristics?
Any other suggestions?
Thanks.
Jeff Potent
- Deerfield Beach, Florida, USA
^
August 13, 2012
A. Jeff,
I very much doubt that passivation would touch on the magnetism, it's merely a surface treatment. There are ways that normally non-magnetic stainless grades tin can end upwards magnetic, but I would as well worry that your 316 is not up to par.
Ray Kremer
Stellar Solutions, Inc.
McHenry, Illinois
^
August xiv, 2012
A. Degaussing is the process that you are looking for. Follow the instructions to the letter or you could brand the problem worse rather than better. Do frequent checks on the product that the floor produces. It tin can become s hands.
James Watts
- Navarre, Florida
^
June 2015
Howdy James. Aye, degaussing can certainly remove magnetism (the piece will no longer act as a magnet and attract steel to itself) but I'thousand non so sure information technology does anything to right a piece of stainless steel that has become ferromagnetic (the stainless steel being attracted past a magnet). It clearly doesn't remove ferromagnetism from steel parts.
Regards,
Ted Mooney , P.Eastward. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^
Oct sixteen, 2012
A. If you are looking for 316 Non Magnetic so you lot demand to be ordering 316 to the AMS5360 [affil. link to spec at Techstreet] spec which does not overlap with the normal 316/316L grades. AMS5360 has lower chrome and college nickel. This is what I sell to my aerospace accounts and other industry foundries requiring a truly non magnetic 316 alloy.
Rod Guyton
- Torrance, California, United states
^
February 24, 2013
Q. Dear Sir,
Very recently I have taken a 8" dia. stainless steel weir strainer sample. It's attracted by magnet; and then I sank the sample into 33% hydrochloric acid (commercial) solution. I have seen after 48 hours, the stainless steel became highly colorless & severely corroded.
In these circumstances, let me know, is the stainless steel sample pure stainless steel? And why has it has severely corroded? And how tin can be tested for justification as a pure stainless steel.
Your early on response volition be highly appreciated.
Thanks
Tapash
Tapash Chandra Das
- Narayangonj, Dhaka, Bangladesh
^
February 24, 2013
A. Howdy Tapash. "Stainless steel" describes dozens or hundreds of different steel alloys which are somewhat corrosion resistant. Most are alloys of steel with chromium, ofttimes with nickel, and smaller amounts of other materials like molybdenum. Some are strongly magnetic, some are non-magnetic. Just very few stainless steels could exist expected to stand up up to 33% hydrochloric acid.
Regards,
Ted Mooney , P.Due east. RET
Striving to live Aloha
finishing.com - Pino Beach, New Jersey
^
June 10, 2015
Q. Hello
What is the way to return the not-magnetic feature of 316 stainless steel?
I have stainless steel sail (specification ane.4571 - three.00 mm - 1D) that has been prepared. Only later cut by light amplification by stimulated emission of radiation the anti-magnetic feature is somewhat lost. What do you advise?
Majid Turkan
- MAZANDARAN,Iran
^
How to tell if 316SS cloth is a casting or not?
Nov 1, 2015
Q. How tin can I tell the manufacturing process of SS316 cloth, we are trying to determine if it is cast material or not?
We did micro assessment and it revealed a non-twinned grain structure, notwithstanding hardness was fine and chemical analysis was within range (with no actress carbon detected)
David Robinson
- dubai, uae
^
Nov 2015
Hullo David. Why does it matter? I'one thousand not implying that it doesn't matter; rather, I'm saying that knowing why it matters tin can sometimes propose an easier, improve, or more direct test.
Generally, things are cast only when that's the most applied way to obtain the desired shape; so sometimes only looking at it will give you ninety% odds how it was made. If it looks similar a casting, it almost surely is; if it doesn't look like a casting, it probably isn't :-)
Regards,
Ted Mooney , P.Eastward. RET
Striving to live Aloha
finishing.com - Pino Beach, New Bailiwick of jersey
^
November 3, 2015
Q. Hi,
Thanks for the answer.
The reason information technology matters is my client specifically asked their provider to ensure that product was non made from cast material. At present it's difficult to assess equally the component is fully machined, merely on 1 section the cloth looked cast. The manufacturer claims that this was due to shot/sand blasting of the material to aid machining.
This is why the question was asked.
Hence nosotros did the assessments bachelor to united states of america and I'thou left with the results published on my original post.
David Robinson [returning]
- dubai, uae
^
adv. 
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