Both grades have similar amounts of iron, chromium, nickel, manganese, silicon, and carbon, but the presence of molybdenum gives 316 stainless steel superior corrosion resistance properties compared to 304 stainless steel, particularly in harsh environments.
The iron content of both 304 and 316 is pretty close, and I don't think that's the reason for the different magnetic properties. It's more to do with what types of crystal matrix a given alloy forms, namely ferritic vs austentitic. (feritic matrices are ferromagnetic while austentitic ones generally aren't) From the data I'm seeing, 304 is generally close to 69% iron and 316 is close to 67%. 304 also has slightly more chromium, but the biggest differrence is the 2~3% Molybdenum content. The latter might be what has a more darmatic effect on the crystal structure, and maybe some impact on corrosion resistance, but is mostly there to increase strength, especially at high temperatures. (molybdenum content greatly improves creep strength) 304 is also supposed to be an austentitic, and many sources say it's not ferromagnetic, but obviously it's at least slightly ferromagnetic (I've seen this in person too, and was at one point concerned I'd been cheated on the grade of steel I'd purchased). 304 stainless is still much less magnetic than carbon steel or ferritic stainless steel grades, so it seems like it's at least mostly austentitic. Pure nickel is also ferromagnetic (as is Cobalt), while chromium, manganese, and nickel are not. Iron-nickel-cobalt alloys tend to be ferromagnetic, but the percent of non-ferromagnetic components doesn't directly correspond to the final properties, and alloys with considerably fractions of nonmagnetic components can still end up ferromagnetic, while additions of relatively small percentages of certain components can have significant impact on the final crystal matrix. (as does the annealed or heat treated condition of the material) I'm pretty sure 304 is reasonably suited for being in contact with most strong, oxidizing acids (like sulphuric acid), while 316 is slightly better at this, too, it still shouldn't be the main problem in this case. The fact carbon steel welding rod seems to have been used on that fitting is the main problem. 316 is rated to be better for long term exposure to seawater, road salt, or other long term salt exposure, and more generally is more corrosion resistant to chlorides. (Though I'm seeing info that even 316 steel is considered non-resistant to hydrochloric acid, while both 304 and 316 are suitable for sulfuric acid, though 316 is slightly more resistant to corrosion in general)
Correction: specific combinations of magnetic metals in an alloy can also lead to a reduction or elimination of ferromagnetism. Straight nickel-iron alloys still tend to be ferromagnetic at room temperature, both at the >50% nickel and >50% iron range, as do stainless steels like the 400 series with no nickel but significant amounts of chromium. But the interaction of iron, nickel, and chromium in 300 series stainless leads to a dramatic reduction in ferromagnetic properties. (obviously moreso with small additions of certain other metals) Iron-cobalt alloys also tend to be ferromagnetic, and at least some iron-nickel-cobalt ones are, too, but I'm not sure whether that's true for all proportions of the three. (and addition of other metals would change that further) So there's more complex interactions going on here in general and a somewhat limited rule of thumb.
None ferromagnetic stainless steel (304, 316, etc) become ferromagnetic after being cold worked, so your joint could just be cold worked stainless steel, same with your 304 steel. To truly test/remove ferromagnetism you need to heat treat them first
Can a magnet work _through_ stainless steel 304 plate? I realise you showed it was slightly affected by the magnet, but I'n more interested on the magnet on the other side. In other words, supposing I'm able to fix a magnet onto one side of the 304 plate, can I get a magnet to stick to it and hold the plate?
Yes it can, you could have a thick steel plate covered with thin stainless steel to get a magnet to stick. Or even a magnet glued etc to the back side, but it also depends on the thickness of stainless steel and the power of the magnet.
#304 and #316 are generally non-magnetic but can become mildly magnetic through being cold-worked. ie bending, deforming. There is no simple method for identifying a stainless with a magnet. That drain fitting in the video, however, is strongly magnetic and could be a martensitic stainless.
@@paulmaxwell8851 You are correct. I have some 316 grade steel ratchet buckles that were manufactured to my specs and due too all the bending in the manufacturing process they are slightly magnetic. Magnet tests should not be used to test stainless steel.
"stainless steel should be non-magnetic" martensitic stainless steel: "are you sure about that?" Still, the corrosion resistance on martensitic stainless is nowhere near as good as in austenitic stainless like 304 and 316, so yeah for vinegar you definitely want non-magnetic/austenitic stainless
It depends on the weight of the magnet to the magnetic strength ratio. Most refrigerator magnets are very weak and relatively heavy for its size. We use either magnet fragments or very small/very strong neodymium magnets to perform our quick tests.
Both grades have similar amounts of iron, chromium, nickel, manganese, silicon, and carbon, but the presence of molybdenum gives 316 stainless steel superior corrosion resistance properties compared to 304 stainless steel, particularly in harsh environments.
Nope. 304 has 18% Cr, the 316 has 16%
Nickel % also 8% in 304 vs 10% in 316
Also the general use is for hot water in 316...big difference in corrosion resistance
@@osher87which one is better
@@osher87 Yes. They're similar as you wrote. Mo makes the significant difference.
The iron content of both 304 and 316 is pretty close, and I don't think that's the reason for the different magnetic properties. It's more to do with what types of crystal matrix a given alloy forms, namely ferritic vs austentitic. (feritic matrices are ferromagnetic while austentitic ones generally aren't)
From the data I'm seeing, 304 is generally close to 69% iron and 316 is close to 67%. 304 also has slightly more chromium, but the biggest differrence is the 2~3% Molybdenum content. The latter might be what has a more darmatic effect on the crystal structure, and maybe some impact on corrosion resistance, but is mostly there to increase strength, especially at high temperatures. (molybdenum content greatly improves creep strength)
304 is also supposed to be an austentitic, and many sources say it's not ferromagnetic, but obviously it's at least slightly ferromagnetic (I've seen this in person too, and was at one point concerned I'd been cheated on the grade of steel I'd purchased).
304 stainless is still much less magnetic than carbon steel or ferritic stainless steel grades, so it seems like it's at least mostly austentitic.
Pure nickel is also ferromagnetic (as is Cobalt), while chromium, manganese, and nickel are not. Iron-nickel-cobalt alloys tend to be ferromagnetic, but the percent of non-ferromagnetic components doesn't directly correspond to the final properties, and alloys with considerably fractions of nonmagnetic components can still end up ferromagnetic, while additions of relatively small percentages of certain components can have significant impact on the final crystal matrix. (as does the annealed or heat treated condition of the material)
I'm pretty sure 304 is reasonably suited for being in contact with most strong, oxidizing acids (like sulphuric acid), while 316 is slightly better at this, too, it still shouldn't be the main problem in this case. The fact carbon steel welding rod seems to have been used on that fitting is the main problem. 316 is rated to be better for long term exposure to seawater, road salt, or other long term salt exposure, and more generally is more corrosion resistant to chlorides. (Though I'm seeing info that even 316 steel is considered non-resistant to hydrochloric acid, while both 304 and 316 are suitable for sulfuric acid, though 316 is slightly more resistant to corrosion in general)
Correction: specific combinations of magnetic metals in an alloy can also lead to a reduction or elimination of ferromagnetism. Straight nickel-iron alloys still tend to be ferromagnetic at room temperature, both at the >50% nickel and >50% iron range, as do stainless steels like the 400 series with no nickel but significant amounts of chromium.
But the interaction of iron, nickel, and chromium in 300 series stainless leads to a dramatic reduction in ferromagnetic properties. (obviously moreso with small additions of certain other metals)
Iron-cobalt alloys also tend to be ferromagnetic, and at least some iron-nickel-cobalt ones are, too, but I'm not sure whether that's true for all proportions of the three. (and addition of other metals would change that further)
So there's more complex interactions going on here in general and a somewhat limited rule of thumb.
Any chemical is available to check the ss grade 304 vs 316 like 202 vs 304?
Thanks 👌👍
None ferromagnetic stainless steel (304, 316, etc) become ferromagnetic after being cold worked, so your joint could just be cold worked stainless steel, same with your 304 steel. To truly test/remove ferromagnetism you need to heat treat them first
"Stainless steel should be non-magnetic."
*stops video* 🤦 Certain types of stainless steel are magnetic, and others aren't.
I think what he meant is the stainless steel for the vinegar tank.
Thank boss
Which one should I choose for perfume storing tank?
I assume perfume is alcohol based so 304 Stainless Steel should be fine.
@@UnsanctionedFabrication Yes, oil & alcohol.
Can a magnet work _through_ stainless steel 304 plate? I realise you showed it was slightly affected by the magnet, but I'n more interested on the magnet on the other side. In other words, supposing I'm able to fix a magnet onto one side of the 304 plate, can I get a magnet to stick to it and hold the plate?
Yes it can, you could have a thick steel plate covered with thin stainless steel to get a magnet to stick. Or even a magnet glued etc to the back side, but it also depends on the thickness of stainless steel and the power of the magnet.
thank you. I learned a lot. I thought 304 is not magnetic
#304 and #316 are generally non-magnetic but can become mildly magnetic through being cold-worked. ie bending, deforming. There is no simple method for identifying a stainless with a magnet. That drain fitting in the video, however, is strongly magnetic and could be a martensitic stainless.
@@paulmaxwell8851 You are correct. I have some 316 grade steel ratchet buckles that were manufactured to my specs and due too all the bending in the manufacturing process they are slightly magnetic. Magnet tests should not be used to test stainless steel.
🔥🔥Best test is with POTASSIUM TIOSANATE + 9V BATTERY.
Old fashiooonnnn
"stainless steel should be non-magnetic"
martensitic stainless steel: "are you sure about that?"
Still, the corrosion resistance on martensitic stainless is nowhere near as good as in austenitic stainless like 304 and 316, so yeah for vinegar you definitely want non-magnetic/austenitic stainless
This didn't prove to be true I just tried. 304 that I have in the house is also non-magnetic.
It depends on the weight of the magnet to the magnetic strength ratio. Most refrigerator magnets are very weak and relatively heavy for its size. We use either magnet fragments or very small/very strong neodymium magnets to perform our quick tests.
It could be cheap Chinese stainless steel most 304 is not magnetic at all
That's what I thought 40 yrs ago. We used 17-4 and it was magnetic AND corrodes (slightly) but was tougher than the back of Superman's head.
😎 PЯӨMӨƧM