The difference between 201 and 304 stainless steel

How to distinguish the difference between 201 and 304 stainless steel - This information is provided by Chongqing Peng Gan Trading Co., Ltd.: 1. To identify stainless steel imported or ordered by a steel mill, it is generally sufficient to check the steel or packaging mark based on the quality certificate of the imported or steel mill.
The certificate of quality is the supplier's confirmation and assurance of the inspection results of the batch of products. Therefore, the quality certificate not only describes the name of the material, the specifications, the number of deliveries, the weight, and the delivery status, but also all the inspection results of the specified guarantee items.
Similarly, for ease of management, avoidance of confusion, and prevention of accidents caused by confusion, manufacturers place markings such as grades, batch numbers, status, specifications, quantities, and manufacturer codes on materials or packaging. The marked mark and the quality certificate should be consistent. The commonly used marking methods mainly include the following three methods: painting (applying the color indicating the grade of the material at the specified position) and printing (stencil printing or jet printing at the specified position of the material to indicate the material's grade, specification, furnace number, etc.) , It is often used on thick steel plates or large and medium-sized steels) and listed (in the case of bundled or boxed materials, tags with marked numbers, batch numbers, specifications, quantities, etc.).
Stainless steel signs are generally printed and tagged.
2. The society has overstocked stainless steel. Depending on the length of the overstock time and the quality of the storage, there are generally two situations:
The first is that the overstocking time is not long and the storage is good. The processing unit not only keeps the original quality certificate or transcript, but also the markings on steel or packaging are all available and clear. For the identification of this type of stainless steel, it is also sufficient to check the mark on the steel or packaging based on the quality certificate.
The other is the long backlog, the custody is not perfect, there is no quality certificate, and the marks on steel or packaging are not obvious or fall off. For the identification of such stainless steel materials, it is mainly necessary to carry out in-depth investigation and study, and consult the processing unit for the original documents. In general, the steel bills, etc., are marked on the original invoices and other documents. If there is no steel record, it is also necessary to check the local price information at that time to determine the steel number by price. This is a relatively effective method of determining the steel number, but it is often easy to wear it. Therefore, it is necessary to grasp the method of identification of physical objects.
Physical identification means that, in the case of unknown steel grades, based on the inherent physical and chemical properties of commodities (including solids, remnants, and waste, etc.), with a simple instrument, it is sensed to determine whether it is stainless steel. And what kind of stainless steel is the specific method.
It should be pointed out that the sensory identification can not distinguish the specific steel (species) number, can only basically distinguish between chromium stainless steel, chromium nickel stainless steel and chromium manganese nitrogen stainless steel three major categories, the identification method is as follows:
Color identification After pickling stainless steel, the surface color silver and white smooth: Chrome nickel stainless steel color silvery white jade; Chrome stainless steel color white slightly gray shiny weak; Chrome manganese nitrogen stainless steel color and chromium nickel stainless steel is slightly lighter. The surface color of stainless steel that has not been pickled: Chrome-nickel steel is brownish white, chrome steel is brownish black, and chromium-manganese nitrogen is black (these three shades are heavily oxidized). Cold-rolled unannealed chromium-nickel stainless steel with silver-white surface.
Discriminating magnets with magnets can basically distinguish two types of stainless steels. Because the chromium stainless steel can be attracted by the magnet in any state; the chromium nickel stainless steel is generally non-magnetic in the annealed state, and after the cold working, some are magnetic. However, manganese-rich steels with higher manganese content are non-magnetic; chromium-nickel-nitrogen-based stainless steels have more complex magnetic properties: some are non-magnetic, some are magnetic, and some have a non-magnetic vertical surface and a magnetic surface. Therefore, although magnets can basically distinguish between chromium stainless steel and chromium-nickel stainless steel, they cannot correctly distinguish some special-purpose steel grades, let alone distinguish specific steel grades.
Identification of copper sulfate will remove the oxide layer on the steel, put a drop of water, rubbing with copper sulfate, if not changed after rubbing, usually stainless steel; such as purple, non-magnetic high manganese steel, magnetic generally Ordinary steel or low alloy steel.
For steels with special properties, we need to adopt the following three methods for identification.
Grinding the flower discriminating differentially identifies the stainless steel on the grinder and observes the spark. Such as sparks are streamlined, and there are more dense section of the flower, that is, higher manganese containing high manganese steel or manganese nitrogen steel; if no flowers are chromium steel or chromium nickel stainless steel.
Annealing is used to identify cold-worked chromium-nickel stainless steels. If they are magnetic, they may be red-hot in the fire to allow them to cool naturally or be added to water (annealing). In general, after annealing, the magnetism is significantly reduced or completely disappeared. However, some chromium-nickel stainless steels, such as Cr18Ni11Si4AlTi steel and Cr21Ni5Ti steel, because the steel contains more ferrite elements, a considerable part of its internal structure is ferrite. Therefore, it is magnetic even in the hot working state.
Chemical Qualitative Method The Differential Chemical Qualitative Method is a method of identifying whether or not nickel in a magnetic stainless steel is a method of identification. The method is to dissolve the small piece of stainless steel in aqua regia, dilute the acid solution with clean water, add ammonia water, and then gently inject the nickel reagent. If there is a red fluffy substance floating on the liquid surface, it means that stainless steel contains nickel; if there is no red fluffy material, it proves that there is no nickel in stainless steel (but because of the low nickel content in stainless steel, it is generally only a few percent, nickel The content is not easy to reveal or determine how much, in general, the standard sample must be used after many experiments.)
The above several authentication methods show that in order to identify the stainless steel with the flu, it is necessary not only to use several methods to comprehensively test, but the test results can only determine certain types of stainless steel, and it cannot be determined which kinds of alloy elements and specific contents are contained in the steel. Therefore, the method of sensory identification is currently extremely imperfect, and some may be erroneous. There are many physical phenomena. They only know it, but they do not know why it has yet to be discussed.
The best way to correctly distinguish the stainless steel grades is to conduct in-depth investigations and studies, and the relevant testing units should make the determinations. This is the fundamental way to correctly distinguish stainless steel grades and quality. Contact electricity

Characteristics and Advantages

(1) Intelligent control design: adjustable main parameter and secondary parameter automatically according to the weight of door leaves;

(2) Low noise: Special static sound track, integration of motor, worm-gear and retarder.

(3) Anti-clamping function: automatically reverse when meeting barriers;

(4) Unique electronic motor lock: the motor will lock up when the door is forced to open.(controlled by remote or switch)

(5) Tighten force: seal door when closed, power consumption approximately 10W under standby;

(6) Advanced brushless motor(36V,100W) can automatically adopt different heavy door leaves;

(7) Bi-doors inter-locking: one of the door leaves always remains closing;

(8)Safety sensor terminal: sensor stops working when door closed;

(9)Unique coating technology: never rusty;

(10)Easy and convenient to install;

(11)Working Process: when the door leaf closes to the right place, the door leaf will slightly shift to the door frame and the ground. The rubbers on the four sides of the door leaf will completely combine with door frame and ground, which ensures air tightness. When the door is open, the rubbers will separate from door frame and ground, which avoids contraction on the ground.


                                          Technical Specification


Light Duty

Heavy Duty

Rang of the Door





Door leaf max weight


   100kg x 2      


200kg x 2

Mounting Method

Surface mounting or built-in mounting

Open Width





Power Supply

AC 220v ± 10%, 50-60 Hz

Opening Speed

300-500mm/s (adjustable)

Closing Speed

250-550mm/s (adjustable)

Creep speed

30-100mm/s (adjustable)

Hold-open time

0.5-20s (adjustable)

Airproof Force (Max.)


Manual Pushing Force


Electronic Lock Force


Power consumption


Ambient temperature

-20+50 C

Technical Details:

(1) Rubber lining sealing technology combined with V groove on the guide rail enables the door completely sealed when the door closed;

(2)Special door body location technology. Semicircular surface beam on the ground matches with the V style groove at the bottom of door leaf, which stop the door from swing and make sure it moves stable and smooth;

(3) The door body decorated with matte stainless steel or spray surface, and on the middle and both sides with sealing stripes to ensure the hermetic effect.

(4)Feet sensor switch applied to avoid contagion;


Stainless Steel Sliding Door

Stainless Steel Sliding Door,Stainless Steel Bypass Sliding Door,Stainless Steel Interior Sliding Door,Stainless Steel Folding Sliding Door

Shenzhen Hongfa Automatic Door Co., Ltd. ,