304 stainless steel rust causes

Although we often say that 304 stainless steel will not rust, but it will rust if not used properly.Next, I will tell you why 304 stainless steel rust and how to prevent 304 rust.

304 stainless steel material rust phenomenon, there may be the following reasons:
Folded chloride ion
Chloride ions are found everywhere, such as in table salt/sweat/sea water/wind/soil, etc.Stainless steel corrodes quickly in the presence of chloride ions, even more than ordinary mild steel.So there are requirements for the use of stainless steel environment, and need to often wipe, remove dust, keep clean and dry.The United States has an example: an enterprise with an oak container containing a chloride ion solution, the container has been used for more than 100 years, the 1990s plan to replace, because the oak material is not modern enough, the stainless steel replacement 16 days after the container due to corrosion leakage.
Folding solution treatment
The alloying elements did not dissolve into the matrix, resulting in low alloy content and poor corrosion resistance.
Folded intergranular corrosion
This material, which does not contain titanium or niobium, is prone to intergranular corrosion.Intergranular corrosion can be reduced by adding titanium and niobium together with stable treatment.In the air or chemical corrosion medium can resist corrosion of a high alloy steel, stainless steel is a beautiful surface and corrosion resistance, do not have to go through plating and other surface treatment, and play the inherent surface properties of stainless steel, used in a variety of steel, commonly known as stainless steel.Representative performance of 13 chromium steel, 18-8 chromium nickel steel and other high alloy steel.From the metallographic point of view, because the stainless steel contains chromium, the surface of the formation of a very thin chromium film, this film is separated from the steel and the oxygen invasion of corrosion resistance.In order to maintain the corrosion resistance inherent in stainless steel, the steel must contain at least 12% chromium.It is used when welding is required.The lower carbon content minimizes carbide precipitation in the heat affected zone near the weld, which may lead to intergranular corrosion (welding erosion) of stainless steel in some environments.
Folding surface marks
Surface mark phenomenon refers to 304 stainless steel deep processing or processing products after grinding, in the surface of the product line or point like concave mark defect.
Cause: There are foreign bodies on the surface and die surface, and scars on the surface of the holder pad.
Action: Remove foreign bodies and scars before processing. You can also remove the peel by grinding thoroughly.
Orange peel phenomenon refers to 304 stainless steel molding products in grinding or other circumstances, the surface of the same shape as orange peel phenomenon.
Reason: The grinding is not sufficient, the bigger the processing is, the more serious the orange peel is, the coarse grain of the raw material is, and the heat treatment softens.
Countermeasures: fully grind deep processing products, select suitable heat treatment conditions, control the grain size of raw materials.