Thread: Any way to understand if a straight is stainless steel?

I think Sailor was talking about unmagnetic, not demagnetised steel.

The fact that 3-second thingamabling magnetises/demagnetises the screwdriver is an indication that it is a magnetic object whose properties can be changed with magnetic field (as that thing does). If that thing works on a tool, 100% guarantee it sticks to magnet. What that changes is whether the magnetic field is aligned so it attracts other similar objects.

Unmagnetic steel, one which could as well be plastic for all that thingy or a magnet cares, has a different structure of the steel. I'm not even sure it can be changed on pre-existing object - Most probable it will have to be made that way.

Originally Posted by ursus

I think Sailor was talking about unmagnetic, not demagnetised steel.

Unmagnetic steel, one which could as well be plastic for all that thingy or a magnet cares, has a different structure of the steel. I'm not even sure it can be changed on pre-existing object - Most probable it will have to be made that way.

Yes i was thinking with maybe too large levels. I've been with as we have demagnetized ships. They consist of both carbon and ss steel materials.
However demagnetizing affects to DC magnetism only (not AC). Do not ask about the details as i do not know.
For what i've studied is that carbon steel, when left untouched in it's place, will reach some amount of magnetism because of the magnetic field of the earth. When at work, we turn objects we do not want to get magnetized, 180 degrees few times a year.

Originally Posted by Sailor

Yes i was thinking with maybe too large levels. I've been with as we have demagnetized ships. They consist of both carbon and ss steel materials.
However demagnetizing affects to DC magnetism only (not AC). Do not ask about the details as i do not know.
For what i've studied is that carbon steel, when left untouched in it's place, will reach some amount of magnetism because of the magnetic field of the earth. When at work, we turn objects we do not want to get magnetized, 180 degrees few times a year.

Interesting

Carbon steel is magnetic, but not necessarily a magnet. A demagnetized steel screwdriver will still cling to a magnet (and become magnetized to some degree again by doing so).

Things that benefit from demagnetiziation are ships that want to avoid mines that detect magnetic fields - and it's useful for files to be degmagnetized so that steel filings don't cling to it. Things that are useful to be magnetized would be a screwdriver so that good steel screws will cling to the tip. Cheap 302 stainless will not, of course, because it doesn't react to magnetism.

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The magnetic properties of stainless steels vary considerably, ranging from paramagnetic, non-magnetic, in fully austenitic grades to hard or permanent magnetic behavior in the hardened martensitic grades.

Austenitic (non-magnetic) Stainless Steels

All austenitic stainless steels are paramagnetic, non-magnetic, in the fully austenitic condition as occurs in well-annealed alloys. The DC magnetic permeabilities range from 1.003 to 1.005 when measured with magnetizing forces of 200 Oersteds (16 kA/m). The permeability increases with cold work due to deformation-induced martensite, a ferromagnetic phase. For certain grades such as Types 302 and 304, the increase in magnetic permeability can be appreciable, resulting in these grades being weakly ferromagnetic in the heavily cold-worked state. For example, Type 302 and 304 increase in permeability by ten fold when the cold reduction is 80%.

The magnetic permeabilities achievable in austenitic stainless steels are very low as compared to conventional magnetic materials. Consequentialy, their non-magnetic behavior is of more concern. In the event that the magnetic property of an austenitic stainless steel is of particular concern, it can be measured by relatively simple means as described in ASTM Standard Method A342.

Austenitic stainless steels are not hardenable by heat treatment. If the application requires that the steel be hardenable, consider using Martensitic and precipitation hardenable stainless steels (see below); however, note that these are ferromagnetic. It is important to consider the effects of using ferromagnetic materials in magnetic circuits if the circuit was originally designed using paramagnetic steels.

Examples of austenitic stainless steels are Type 302, 303, 304, 316 and 316L.

Ferritic Stainless Steels

Ferritic stainless steels are ferromagnetic and have been used as soft magnetic components such as solenoid cores, pole pieces and return paths. Although their magnetic properties are not generally as good as conventional soft magnetic alloys, they are successfully used for magnetic components that must withstand corrosive environments. As such, they offer a cost-effective alternative to plated iron and silicon-iron components. Additionally, the relatively high electrical resistivity of Ferritic stainless steels has resulted in excellent AC performance.

These stainless steels have soft magnetic properties: high magnetic permeability, low coercive force, Hc, and low residual induction Br, which depend on alloy chemistry. In particular, impurities such as carbon, sulfur, and non-metallic inclusions, and stresses due to cold working. Magnetic permeability decreases and the coercive force increases; the behavior is less magnetically soft with increasing amounts of impurities and stress. Hence, optimum magnetic performance is obtained with well-annealed, high-purity alloys. Carpenter 430F and 430FR (Solenoid Quality) is an excellent choice for soft magnetic alloy applications. Note that if the material has been cold worked, its coercivity, Hc, will increase, and when exposed to magnetic fields, it will retain some magnetic effects, hence acting as a weak permanent magnet.

Examples of Ferritic stainless steel are Type 430F Solenoid Quality, Type 430FR Solenoid Quality, and Type 446

Martensitic and Precipitation Hardenable Stainless Steels

All Martensitic and most precipitation Hardenable stainless steels are ferromagnetic. Due to the stresses induced by the hardening transformation, these grades exhibit permanent magnetic properties if magnetized in the hardened condition. For a given grade, the coercive force, Hc, tends to increase with increasing hardening, rendering these alloys more difficult to demagnetize.

Examples of martensitic stainless steels are Type 410, 416, 420, 440B and 17-4.

Thanks for that, Robert. Have you got the reference for that quote? Thanks again.

So cheap stainless razors are non-magnetic whereas all others are magnetic I guess.