Reasons for rusting of 304 stainless steel material

2019-09-11 1011

Chlorine ion

Chlorine ion is widely present, such as salt/sweat/seawater/sea breeze/soil, and so on. Stainless steel corrodes rapidly in the presence of chloride ions, even surpassing ordinary low-carbon steel. So there are requirements for the application environment of stainless steel, and frequent scrubbing is required to remove dust and maintain cleanliness and dryness. There is an example in the United States where a company uses an oak container to hold a solution containing chloride ions, which has been in use for over a hundred years. In the 1990s, the plan was to replace the container. However, due to the outdated oak materials, the container leaked due to corrosion 16 days after using stainless steel for replacement.

Solid solution treatment

The alloy elements did not dissolve into the matrix, resulting in low alloy content and poor corrosion resistance in the matrix arrangement

Intergranular correction

This type of data without titanium and niobium tens to exhibit intergranular correction Adding titanium and niobium, combined with stability treatment, can reduce intergranular corrosion A type of high alloy steel that can resist corrosion in air or chemical corrosive media Stainless steel is a type of steel that has a beautiful appearance and good corrosion resistance It does not need to go under surface treatment such as plating, but rather exercises the subsequent appearance function of stainless steel It is commonly used in various types of steel and is generally referred to as stainless steel High alloy steels such as 13 chromium steel and 18-8 chromium nickel steel representation functions From a metallic perspective, due to the presence of chromium in stainless steel, a very thin chromium film is formed on the surface, which separates it from the oxygen invading the steel and has a corrosion resistance effect In order to maintain the incoming corrosion resistance of stainless steel, it is necessary for the steel to contain more than 12% chromium Used in situations where welding is required The lower carbon content minimizes the precision of carbides in the heat affected zone near the weld seam, which may lead to intergranular corrosion (welding corrosion) of stainless steel in central environments

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Appearance mark phenomenon

Appearance mark phenomenon refers to the occurrence of line or dot shaped concave mark defects on the surface of 304 stainless steel products after deep processing or grinding.

Reason: There are foreign objects on the surface and mold surface, and there are scarrs on the surface of the edge pressing pad

Countermeasure: Remove foreign objects and scans before processing, and also remove orange peel through sufficient grinding

Orange peel phenomenon refers to the phenomenon where 304 stainless steel molded products exhibit a shape similar to orange peel during grinding or other conditions

Reason: Insufficient grinding, the larger the processing, the more severe the orange peel, the cooler the raw material grains, and the software during heat treatment

Countermeasure: Fully grind the deep processed products, select suitable heat treatment conditions, and control the grain size of the raw materials

Article source: Guangdong stainless steel faucet     http://www.kpjieyuan.com/