Type 304 vs. type 202 stainless steel

A. The major differences between 202 and 304 stainless steels are in the nickel and chromium contents. 202 has 16-18% chromium and 0.5-4.0% nickel, whilst 304 has 18-20% chromium and 8-10.5% nickel. There are other minor differences in the amount of carbon (0.08% in 304 and 0.12% in 202), manganese (2% in 304 and 5.5-7.5% in 202), as well as slight differences in the silicon, phosphorus and molybdenum contents. Both are austenitic steels and are essentially non-magnetic, but will become temporarily magnetic by working them. The manganese helps preserve the austenitic phase in the steels, as does the nickel. I can see an attraction in some people for using the 202 steel as it contains less nickel, and there is concern amongst some folk that they are sensitive to nickel. However. as far as I am aware, nickel containing stainless steels have not been shown to cause nickel sensitivity - however, I am willing to be shown to be wrong here.

A. Hi Deepa. The short answer is that type 304 contains 8% nickel which is much more expensive than iron, so it will cost more than nickel-free or low-nickel stainless steels while being more corrosion resistant.

Regards,

A. Hi Abdul. I'm confident that there are educational/trade organizations in India which serve the baking industry and can warn you about sanitary codes, food & drug manufacturing rules, etc. Lacking such info, type 316SS is the only construction material which I would have confidence in as being fully approved. Although even 4xx grades are used by major suppliers of flatware these days

I would specifically not go into a cost-cutting program from 304 to 202 in the food industry. Just a personal opinion from someone on a different continent :-)

Readers: a great way to learn is to try to teach. You'll learn far more, far quicker, by attempting to answer an open question here than by adding yours to the list :-)

Good luck and Regards,

A. Hi Sirisha. This page is only opinion & non-official, and the pages age & get out of date, so it cannot substitute for a "code check", but I don't know why SS202 or 4XX couldn't be used although they are not as corrosion resistant as SS304, and will rust quicker.

Luck & Regards,

A. Hi cousin. I answered that question to the best of my ability as someone from the metal finishing industry in the USA. But hopefully someone from the food service industry in India will do a code check and chime in with a better answer for you.

Regards,

A. Hi Cindy. Although I suppose it might be possible to find stainless steels that aren't 'food grade', most stainless steel is. Your flatware may be type 304, your steak knives type 420 or 440A, your pots & pans type 316 for example. If you are selling these, then good stewardship demands that you know exactly what kind of stainless you intend to use; but if it's for yourself and gifts to a few family & friends it will probably be alright.

Regards,

Thanks Ted for your answer to my question re. SS cake testers. I get the impression I won't kill anybody with my homemade testers. (After all, they're just for family!)

A. Hi Juhi. 202 stainless seems to be a relatively new composition for many applications which have traditionally used 304 stainless steel. I think there is little doubt that 304 is "better" thanks to its higher nickel content, but more expensive for the same reason.

BPA is related to plastics manufacturing & composition and as far as I know has nothing to do with steel or stainless steel ... but I imagine that some baby flatware products are made of plastic or have plastics on their handles.

Some flatware today is made of nickel-free type 4xx stainless steels, and although it is not as corrosion-resistant as type 304 or type 202 stainless, apparently those manufacturers feel it is good enough.
Luck & Regards,

A. You can use magnetic stainless steels if you want to, but the most usual stainless steels are 304 and 316 grades

A. True, but knives are usually some variant of 400 SS which is magnetic. So, what is a utensil?

A. Hi Dr. Abbas. Some major suppliers of flatware have switched from 18/8 stainless to 18/0. It is not as corrosion resistant but quite a bit less expensive.

Luck & Regards,

A. Hi Dr. Abbas. 4xx stainless steels are less expensive than type 304 because they contain no nickel. They are less corrosion resistant and more prone to rusting, but they are sometimes used for kitchen utensils. Type 304 work hardens, so it is probably harder to press complicated shapes; I don't really know about type 410, but it probably doesn't work harden. (Please search the site for "polishing SS410" or similar search terms so readers can more easily follow all the discussions on that topic).

Regards,

A. Hi Parimal,
Nickel makes stainless more resistant to rust in certain conditions, but more than that, it is the responsible for its austenitic structure. Nickel makes austenite stable and improves speed of self-passivation, and makes all the part non-magnetic.

200-series replaces nickel with manganese, and this element doesn't stabilize austenite as nickel, so you can find other structures after or during cold-forming. You can find more sulfur in the alloy, if it is not informed in some certificate you should ask for it AND measure the raw material, you could be surprised what you can find in these low cost alloys.

Well, keep us posted! Best of luck!

Thank you Daniel for your comment that "you could be surprised what you can find in these low cost alloys". You have reminded me, and probably other readers, of the truism that when you are shopping for low price, the low priced supplier most certainly is as well :-)

Luck & Regards,

A. Hi, Ajaz. X-ray fluorescence is fast and non-destructive, but the instruments are quite costly ($35,000+ USD)

There may be spark tests or chemical spot tests, but the widespread use of SS202 is relatively new, it is apparently intended to be hard to tell from 304 but be cheaper, and I haven't seen any real easy cheap tests yet, sorry.

Regards,

A. Hi Abhilash. Your question appears to be similar to Ajaz Peerzade's. A hand-held x-ray fluorescence alloy sorter / scrap sorter ⇦ this on eBay or Amazon [affil links] should do the job quickly & easily ... but they are very expensive. If you have a friend in a junk yard, he probably has one. Good luck.

Regards,

Hi Anand. An x-ray fluorescence alloy sorter is a very 'simple' method. But it's very costly. See if a nearby scrap yard can sort them for you. Good luck.

Regards,

A. Hi Amit. If stainless steel is strongly magnetic, it's not austenitic stainless steel (202, 304, 316, 347) unless it has been so strongly cold-worked that it lost much of its austenitic structure. That's all the information that can be gleaned from a single binary digit of information like magnetic vs. non-magnetic. Apologies but you need more data; you cannot tell what grade of stainless steel you have from this one single quality.

Regards,

A. 202 is actually easier to weld than 304. although it might be more prone to corrosion at the welded joints whereas 304 is not very prone to rusting at the welded joints.

Hi Biranchi. That question hasn't attracted enough interest to get an answer yet :-(

But you can improve that by telling us if you've you tried welding it, what welding rod you tried and what results you got that make you hope/think there's a better rod. Thanks!

Luck & Regards,

A. Hi Vivek. I believe that SS202 is non-magnetic but can become somewhat magnetic through cold-working like SS304. This sounds to me like an application where true and complete freedom from magnetism is essential. Is there a good reason you can't use aluminum railings?

Regards,

A. Hi Dinesh. The short answer is that 202 is an austenitic, non-magnetic, stainless steel. But please detail your situation ... because the longer answer starts with "Why do you want to know?"
Although it is non-magnetic as annealed, cold working can introduce various degrees of magnetic effects. Due to it's lack of molybdenum, it is more subject to magnetism from cold-working than type 316; I think it's perhaps slightly less subject to such effects than type 304 -- but such answers aren't yes or no. A neodymium magnet may attract it too. If your situation is like Vivek's, I'd say 202 is NOT safely non-magnetic. Good luck.

Regards,

A. For an interior handrail, I'd consider 304 and 202 to be pretty identical, because I'm thinking of corrosion resistance in that application (both acceptable) and strength (again, both acceptable). I'm not sufficiently familiar with the formability of 202 to know if it's good, but I'd bet that would be reflected in the price. If the price was right, I'd go with the 202.

Good luck!

A. Hello friends ...

I am working last 5 years in stainless steel fabrication.
Just I want to say that 304 and 316 grade is best of all ... for furniture, railing, etc.  

But don't forget about gauge (thickness) -- 16 gauge is better.

A. S/S 304 type is better economically although it's quality is in the middle of 316 and 202, the cost also lies between the prices of 316 and 202.

Basically, S/S 202 is more prone to corrosion when exposed to water and acid solutions. The longevity of S/S 304 is longer than that of 202 although both will corrode over time. But still there are ways to prevent S/S from rusting such as grinding sand paper and buffing.

A. In all of these stainless steels, Cr is trying to form ferrite while the austen-itizing elements, Ni, N, Mn and Cu, are trying to form austenite. The higher the Cr content, the more austen-itising elements are needed to change all the ferrite to austenite. J4 is a good example -- in order to get the Ni level down to 1% Ni, and so minimize the price, it has been necessary to reduce the Cr content to 15-16%. This is much lower than the 18.0 - 20.0% Cr specified for grade 304 and it is Cr which makes the greatest contribution towards corrosion resistance.

This means that such 200-series grades have lower corrosion resistance and are suitable for a much narrower range of applications than grade 304. This has not been well understood and there are many instances where 200-series grades have failed due to corrosion, such as when they have been used for components like handrails in exterior applications.

A. Hi Subi. The answer has been offered that SS202 is cheaper than SS304 but not as corrosion resistant, not as reliable & consistent, and failures have been noted. It might prove okay or it may not; unfortunately I doubt that anyone will assure you that all will be fine nor claim that failure is certain.

Luck & Regards,

A. Hi Pawan. Please tell us who you are and what you do because ... if you are an engineer designing such gates, my answer would be that 304 is a more robustly dependable material. But if you are a consumer buying such a gate my answer is that unfortunately you will not be able to predict the quality of an item from its sales pap, only from the reputation of the supplier :-)

Regards,

A. Hi Negi. Assuming that you are the contractor offering & installing these railings, a frequent answer for 12 years on this thread is that SS304 is more expensive, more corrosion resistant, and 'better' than SS202 -- and thus it's a safer choice for you. Some participants talked specifically about stairways, window grills, and railings and felt that only SS304 or SS316 should be used. Ammit Gulati has stated that "there are many instances where 200-series grades have failed due to corrosion, such as when they have been used for components like handrails in exterior applications"

Whether the difference will be demonstrable in any one given case, or whether SS202 will be 'good enough', is hard to say. Readers are welcome to quote exposure studies to support or refute Amit's claim but I'm not aware of any.

If you are the owner of the residence, choosing between bids, it's a different question entirely, however, because I personally feel that it is impossible to judge quality & durability from sales pap about raw materials ... you must instead choose a reputable contractor. Good luck!

Regards,

A. Hi Md Azam. Sorry I don't know what a "VCB structure" is. Google suggests that you might be talking about a "vacuum circuit breaker" or a "visitor & convention bureau" :-(

But it's pretty clear that 304 is more expensive and corrosion resistant. Whether to take a chance on 202 is actually going to depend on how severe the consequences of doing so are if corrosion comes quicker than customary.

Regards,

A. Hi Raj, Modular kitchen are available in MS Steel & Stainless Steel, either 202 or 304 grade. For Bangalore weather conditions 202 grade of SS is more than sufficient; however, there is no debate in the fact that SS 304 is better.

A. Hi Singh. My reading of the above is that 304 is more expensive because of its nickel content, and somewhat superior in corrosion resistance. Abhishek Kashikar, a modular kitchen dealer, stated fairly strongly his opinion that 202 is good enough but clearly not as good as 304. I doubt that anyone will be able to offer more quantitative data comparing their life in modular kitchens, but we'll see.

Regards,

A. Hi Vikram. SS440 is razor blade steel and seems to me to offer strengths you wouldn't need in a range hood while not offering the corrosion resistance of the austenitics. I personally think that 304SS has proven itself over the decades and would prefer it, but yes the 2xx stainless steels are a bit cheaper.

Still, I think you may find that the logistics may end up being more important than the theoreticals. If you find one composition well-stocked locally in the needed gauges, with the finish you want, with protective paper or plastic that will suit your shears and brakes and other handling, that may be what you want -- you obviously don't want to have two hundred range hoods 99% finished in your work-in-progress only to have to wait 6 weeks for a piece not readily available in that material to finish them up :-)

Regards,

A. Hi Raj. Assuming that these are for indoor use, SS 202 sounds fine. CR has no corrosion resistance so you would need proper pretreatment followed by a paint or coating that would not be damaged by the heat.

Regards,

A. Hello Vinit. I'm not versed in threading, but SS202 is known as 'gummy' rather than easily machinable. If you stay with SS202 you must select tools & methods that are up to the job.

Luck & Regards,

A. Hi Vinit,

You should check the material of the flat dies of the rolling machine, it's quite different from the ones used for carbon steel. And die material is vital for service life.

I didn't work with SS202, but SS302 and SS304L have nearly the same conformability and they can be threaded by flat die rolling machines provided the right materials for the dies and hardness of the raw material is not too high.

Hope it helps! Regards,

A. Hi Jenny. Unfortunately, it is generally hopeless for a purchaser to select small appliances based on their supposed composition of stainless steel :-(

As you've read on this page, type 304 stainless steel is in theory more corrosion resistant -- but that's something for manufacturers to weigh when deciding how to make their products. It's probably not a valid point for a purchaser since the designs might be different, with one or the other more likely to stay wet or be more difficult to clean ... or one may be passivated and the other not. If the one made of SS202 seems more elegant to you and thicker in finish, and you can't find trustable reviews for comparison, that's the one you should probably buy. Perhaps the two manufacturers are trying to meet the same price point and one elected to do so by using thin SS304 while the other decided to go with a heavier gauge of the less expensive SS202. Good luck.

Regards,

A. Hello Naeem,

It could either be SUS302, SUS303 or SUS304, but I don't see SUS303 with an elongation of 60% because of the addition of sulfur (which you didn't measure or inform). SUS303 elongation is usually near 35%.

Hope you can solve this!

Regards,

A. Hi Jatin. Induction cooktops are usually made of glass or ceramic, not metal, so your question is probably about the pots & pans used on an induction cooktop. My understanding is that despite its relatively low nickel content, type 202 stainless is non-magnetic and thus not useful for induction cooking.

Regards,

A. Hi Ramakrishna. I would expect that those materials are satisfactory for oil storage; and your inquiry will hopefully draw some additional responses.

But note that materials that will be in contact with foodstuffs tend to be highly regulated by bodies like NSFA and the FDA, and there are situations where only SS316 is allowed. I would suggest doing a code check not just relying on personal opinions. Good luck.

Regards,

A. Hi cousin Larry. Please introduce yourself and your situation so we don't accidentally give you a misleading answer. A homeowner might have no trouble storing rice in their kitchen canister, but that doesn't necessarily mean that SS202 is suitable for a silo farm holding grains or nuts, for example. Help us help you. Thanks, and good luck!

Regards,

A. Hi Tomas. SS304 is better than SS202 which is better than SS430. But unfortunately, I think the only way to know if this particular SS202 barbecue will be satisfactory is to check better business bureau reports, Amazon reviews, references from other buyers, Yelp reviews, or reports from friends & neighbors. Sales pap never constitutes a good manufacturing process review; you won't learn whether the stainless was properly passivated, whether some of it has a clear coat on it, if the burners cause hot spots on the cover which will discolor it, whether the screws, rivets, and hinge pins are 202SS, etc.

I hope someone else can help you, but I have zero confidence in my own ability to determine good purchases from sales pap even after 50 years in metal finishing :-(
For example, I've owned many stainless gas grills in my life and the only thing I can say with confidence is that people will likely be happy with a Weber grill but unhappy with nearly any other brand.

Read the warranty carefully -- it will tell you whether the grill manufacturer promises to meet your aesthetic requirements or not. And when you clean the grill, use only what the manufacturer suggests; never use any product that has acid or bleach in it. Best of luck!

Regards,

Many thanks for your advice and above all, many thanks for taking the time to share your expertise and experiences!
All the best, Tomas

A. Hi Vaki. Your question is a bit vague. I think you are asking whether the appearance will be satisfactory vs. whether it will be rusty? You are quite near the sea, and I've never been to the area. Personally, I would use properly passivated 304 SS, maybe even 316 SS unless I already saw a good range of examples of 202 SS successfully employed on buildings in the area.

Hopefully an architect or HVAC engineer from the area will offer a comment.

Regards,

A. SS 316 is preferable near sea.

A.
AISI 202 should be better, but for better corrosion resistance for that temperature range you should seek for a refractory SS, as AISI 310/314.

Regards,