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  • Shaanxi Tonghui Steel Co., Ltd.

  • E-mail: sxthsteel@sxth-group.com

  • Tel: +86-29-89636557

  • Add: 1st Building Of Jinqiao International, Xi'an, Shaanxi,China

  • How Do You Identify Which Grades Stainless Steel You Have?
    May 03, 2018


    stainless steel pipe/coil/sheet/bar

    Do you find that stainless steels is hard to identify?

    Once you unknown the steel grade, we can based on the physical and chemical properties of the steel, with the help of simple tools to determine if it is stainless steel and what kind of stainless steel it is. Here we will tell some simple identification methods for you to do:


    1.  Observing the color of the item after picking process

    Generally speaking, the color of stainless steel after pickling will change on the surface:

    Grade of steel

    Color after pickling

    Color before pickling

    Cr-Ni stainless steel



    Cr stainless steel


    Dark brown

    Cr-Mn-N stainless steel



    2.  Testing with Magnet

    The alloy make-up of the stainless steel will determine if it is magnetic or non-magnetic. Although the magnet can basically distinguish the Cr stainless steel and the Cr-N stainless steel, it cannot distinguish the specific steel grades and concrete steel number accurately. 400 series are magnetic, 304,316, 201,202 is the the only stainless steel that is not attracted by magnet, However, 304 could become magnetic when cold worked. Because Cr stainless steel can be magnetized in any condition; Cr-Ni stainless steel is generally nonmagnetic in annealing, and some will be magnetic after cold processing; The magnetic condition of Cr-Ni-N stainless steel is more complicated: some are non-magnetic, some are magnetic, some are non-magnetic and the horizontal surface is magnetic. High manganese steel is completely nonmagnetic.  

    3. Testing with copper sulfate

    copper sulfate test often come with good results. Dissolve about 8 grams of copper sulfate in about 500 ml of water. Swab that on to the item you tests. Carbon steel surfaces will immediately show a copper color as the iron dissolves and the copper replaces it. 300 series stainless shows no reaction, and 400 series usually won't show a reaction, or it'll be very limited.

    4.  For special types of steel, more sophisticated methods are needed to identify them:

     1) Spark testing

    If you grind a bit of the item on a grinding wheel and it gives off sparks, the item is most likely made of a 300-series grade of Cr stainless steel. If it throws a “glow” of intensive sparks, then it is high manganese steel or Mn-N steel.

     2) Acid testing 

    Place a drop of strong Nitric acid/ Sulfuric acid on the steel surface, or the steel in acid solution at room temperature. Observing the changes of the surface color of the item: Strong attack , green crystals and dark surface:302,304; Slow attack, tan surface turns brown:316.

    We stock and supply stainless steel pipes for many different application and segments according to ASTM,EN,DIN ,JIS requirements.Any SS pipe deeds

    Call for us or email sxthsteel@sxth-group.com for more!