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  • STAIN-less steel?

    Hey all,

    I recently made some parts from what I had assumed were two bars of 303 ('cause that's what I'd ordered)....two parts from two bars of different diameter, 3/4" and 7/8".

    Now I turned down the parts and thoroughly cleaned each...then I put them in the autoclave (steam sterilizer) for thirty minutes and when I removed them I found that one was spotless, and one was covered in blackish-brownish spots.

    Needless to say I wasn't able to use the crappy one.

    My question (which sounds really stupid as I write this) is, did they send me one SS and one mild steel, or do some grades of stainless actually rust easier than others....I mean they both seemed to cut with the same degree of difficulty that I usually find with SS.....it didn't seem like I was cutting 1018 or the like.

    Thanks for any input.

    I feel like an idiot for asking.

    John

  • #2
    ZINOM,

    First test, is the spotted one magnetic?

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    • #3
      At work we use a lot of 303 for cleanroom use. When machining it, small pieces of the cutter get lodged in the 303 and you must passivate (mild acid) the finished part to eat out the rustable pieces of tooling.

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      • #4
        My guess is that if the one piece that has rust spots is lightly magnetic, it is a 400 series SS.
        Duke Reno / Yankee Metallic Metalcraft

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        • #5
          Just passed a magnet over various known pieces of stainless around here.

          Have a frying pan, with a matching lid. Bought it new.

          The lid is magnetic the pan is not.

          Just curious, where did you get your metal?
          Gene

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          • #6
            Yes, the spotted one IS magnetic....I checked it after all this happened....I also did a spark test, (not that I know what I'm looking for) and the book I was going by described the differences between low carbon, high carbon and tool steel.....it didn't go into specifics among the different grades of SS.

            I have since immersed the part in water just to see what'd happen and it produces a lot of rust......I don't know, I guess I gotta suck it up and order again and hope they send the right thing.....it's not like the visable difference between aluminum and brass.

            Thanks guys,

            John

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            • #7
              If you planned on using 303 Su or Se for the ease of machining, you may have gotten 416 stainless instead. If it is in the 'A' state it means it is annealed and easy to machine. Easier to machine (110%) even than the 303 su/se (78%). The 416 is also stronger and more expensive than the 303. You can easily prevent it from rusting when it is at the final product by immersing it in a acid bath for a short duration. The acid will dissolve the ferrite (iron) on the surface without pitting the nickel and other alloys. When you buff the surface after the acid bath you are creating a water tight seal against further rusting under normal atmospheric conditions.
              Try machining it to see what you think. If it is a bitch to machine, it is probably in a hardended state, or on the high side of being pump shaft grade. Use only carbide or cobalt to machine it because it will eat up HSS bits even with coolant. I hope this helps.
              Duke Reno / Yankee Metallic Metalcraft

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              • #8
                Topct, I got it from Nolan supply (now Abrasive Tool).

                I just want to get some bar stock and turn down a couple cylindrical parts...I don't have any acid, I don't even know what "su" or "se" means.

                Jeez, I thought this would be slightly simpler hahaha(actually, the other rod required no extra work)....AND, it will need to be sterilized at 15-20 psi at 270 degrees for a half hour each time it is used....which would be often.

                Is there a secret handshake or at least a way to let them know that I want regular 303 in a "normal" state....so I can just turn, drill, tap and GO!?

                I'm just a guy in his basement with limited knowledge of materials and techniques....so acid baths and annealing are a little beyond my regular practices.

                Thanks again for the help thus far.....seriously.

                John

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                • #9
                  <font face="Verdana, Arial" size="2">Originally posted by ZINOM:
                  ...I don't have any acid, I don't even know what "su" or "se" means.</font>
                  I'm sorry about the tech talk. I was where you were not long ago. You will see letter designations with some alloys, steel, aluminum, stainless, brass etc. In this case they add some alloy to help the principle metal machine better. The "se" stands for Selenium and the "su" stands for Sulpher. The addition of either one allows for easier machining but in some cases, the addition of the alloy makes the principle metal less conducive to welding, and may affect its final strength. Using an example for aluminum, 2024 aluminum is great to machine, but it does not weld easily due to an alloy that is mixed in to help it machine better. 6061 aluminum (commonly referred to as 'Aircraft quality aluminum') does not machine as easily as 2024, but 6061 welds easier than 2024.
                  <font face="Verdana, Arial" size="2">
                  Is there a secret handshake or at least a way to let them know that I want regular 303 in a "normal" state....so I can just turn, drill, tap and GO!? John
                  </font>
                  Uh Oh. If you don't know the handshake just forget about everything I just told you.
                  Actually its all about telling the metal retailer what you want the material for. They should either know it off the top of their head, or they have a book that will tell them the machinabilty, weldability. work hardening, characteristics of the basic type of metal you want.
                  I just went to a metal supplier today looking for some 416 annealed that I need for a job. Well there is more than one type of 416 annealed. So you learn somthing new everyday. Usually the retailer guys are willing to help and don't mind you asking questions. If I need something I'm not sure of, I start by saying," I'm just a hobbyist and this is what I want to make out of (insert metal), what's the best alloy for my application?
                  {Edited 'cause o' spellin'}


                  [This message has been edited by YankeeMetallic (edited 03-07-2006).]
                  Duke Reno / Yankee Metallic Metalcraft

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                  • #10
                    All you have to take with you is one of those pocket screw drivers with a magnet in the end. When they bring the metal, see if the magnet sticks to it, all 300ss series is non magnetic 303 & 304 has a very little trace of magnetizem. Just noticable, but not enough to hold the little screw driver to the metal.

                    ------------------
                    Doug
                    Doug

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                    • #11
                      &gt;&gt;&gt;or do some grades of stainless actually rust easier than others....


                      Some stainless can be very bad with rust, I've found 440 to rust like crazy. If you fart near it it rusts.

                      &gt;&gt;&gt;I mean they both seemed to cut with the same degree of difficulty that I usually find with SS.....

                      don't think of it all as just SS. The propertied vary so widely. The scrapper around the corner gets all cranky when I bring in barells of "SS" thats magnetic, so I bring out the book and show him, no its not all non-magnetic, then I show him the certs for the material. Then he gets really cranky when the barrel is full of yellow chips, well its not blue, must be stainless, out with the certs.

                      Seriously though, the category of stainless is so widely varied when it comes to machining properties. A simple Stainless designation means almost nothing, magnetic means nothing, some of its fun, some of it sucks. Ever mess with 13-8, horrible sound, beautiful cut but it sounds like hell. 440C, eats tools, crappy finish and has a very unique smell, 440F same smell, same crappy finish, cuts like butter. 17-4 acts just like a heat treated alloy steel, but shinier(my personal favorite). 303, cuts real easy, tough to get a good finish. 304, gummy sticky nasty crap, responds well to aluminum type geometries, sometimes. get into the super alloys(inconel, waspaloy, hasteloy, a286, hp-9-4-30) they respond well to aluminum type tools also. Then you get into the ceramic tools and big fire balls, and it just gets more fun.

                      I would suggest getting your hands on as many catalogs as you can, from both metal suppliers and tool makers. The ones from the metal supplier will give you all kinds of info on available conditions, heat treat specs, properties of various materials and the tooling catalogs will flood your mind with how to go about cutting all those various materials. fun stuff.

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                      • #12
                        John
                        what were the chips like?
                        My guess is that one is PG C1045
                        Looks much like stainless, but you get blue chips when machined with a carbide tool.
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                        http://motorworks88.webs.com/

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                        • #13
                          my suggestion for what its worth.
                          test both what is left if any with a magnet as machihing(cold working) can cause a slight amount of magnetism and it will pick up irorn for hss tools. If both prove to be non-magnetic you have your answer and both are likely what you ordered. If this is the case you can get muratic acid at harware store, degrease the part and disolve rust in probably 1/2 hour. If one bar is magnetic and one is not then send the other(mag one) back and ask them to replace. Most (90%) of 303 sold is regular annealed and unless you asked for the se or b grade you probaly wouln't get them. You might also check the color on the ends of the bar and see if they are the same. Again if different material is probaly also differnt.

                          Good luck

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                          • #14
                            Hey Guys,

                            Well I went and got some muriatic acid
                            (I wasn't aware of it's ease of availability), and I soaked the part in about a half-cup, in a plastic container.

                            The acid did it's work I'd say, (about ten miutes) then I thoroughly rinsed it in cold water and buffed it.....now I will put it in the ultrasonic and then autoclave it tomorrow....we'll see how it goes then (or maybe after the ultrasonic if all goes poorly).

                            My question now is what do I do with the acid?.....the guy at the hardware store said to put it in a five gallon bucket of water and I could then pour it in my backyard...the water and bucket part sounded fine....but the pouring out part....??

                            Any further input is appreciated (and needed at this point).

                            Thanks all,

                            John

                            Fishfrnzy, the entire bar that the part was cut from is magnetic...and not just slightly either......something seems a tad off to me.

                            Comment


                            • #15
                              My refernce material states that type 303 in the annealed condition should be non magnetic. It is possible you have 303 condition "B" which is cold worked to increase stregth but since you aslo have the rusting problem and cond B is rare stuff I would say you did not get what you wanted. You could ask for certification which, if they accurately kept track of their stock would tell you.

                              As for the acid someone out there surely knows more but 5 gals water would be about 100/1 and should be ok to dispose of. Or if it makes you feel better dump a box of baking soda in bucket first.

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