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There are three types of surface damage failure of stainless steel piping: wear, corrosion and surface fatigue

There are three types of surface damage failure of stainless steel piping: wear, corrosion and surface fatigue

Time:2022-03-18 Source:China Wuxi JiaNuo Special Steel Co.

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In the working process of stainless steel pipe, the surface of the steel pipe and its nearby materials may be severely damaged due to mechanical and / or chemical effects, and thus unable to work. This failure mode, which is essentially limited to the surface layer, is called surface damage failure of stainless steel tubes. Surface damage damage is a very complex phenomenon with many types, which can be broadly divided into three categories. That is, wear failure, corrosion failure and surface fatigue failure.

1. Wear failure

Stainless steel tube wear is mainly a failure mode, in this mode, under the action of mechanical forces, the relative movement of the material on the contact surface in the form of fine dust gradually blunt, so that the size of the parts or tools continue to become smaller. For example, the dulling of cutting tools and the reduction in the size of journals at the support of sliding bearings are both wear phenomena. The amount (or size) of wear per unit time (or unit stroke, per revolution) of the stainless steel tube is called the wear rate. The smaller the wear rate, the better the wear resistance of the material. On the contrary, the wear resistance of the material is worse.

Wear always occurs on the friction surface of the relative moving objects. Zhejiang stainless steel tube manufacturer only when the amount of wear exceeds a certain value, stainless steel parts or tools will fail or scrap. Therefore, if the wear resistance of stainless steel pipe is high (i.e., the wear rate is small), the service life of the parts will be long. Therefore, the accuracy and life of the part or equipment depends to a large extent on the wear resistance of the material. According to relevant statistics, 70% of the machines fail due to excessive wear.

2. Corrosion failure

Corrosion failure of stainless steel piping is the failure of parts or tools caused by chemical or electrochemical corrosion. Most corrosion occurs on the surface or from the surface, and is therefore classified as surface damage failure. Stainless steel piping surface rust is a form of corrosion. Metal corrosion is a very common phenomenon. Under the action of the atmosphere, seawater, soil and chemical materials, as well as mechanical stress, wear and tear, radiation and microorganisms, machines, factories, ships, railroad tracks, bridges and pipelines, etc. together. Metals will always be lost and lead to their destruction. Corrosion of stainless steel piping can be total corrosion of the entire surface, localized corrosion and inter-product corrosion, etc. Corrosion leads to the loss of metal materials, changes in the dimensions and properties of the parts, and eventually leads to failure.

Corrosion of stainless steel piping brings huge losses to the national economy. Wenzhou stainless steel pipe manufacturers according to relevant information, the world’s scrap steel due to corrosion is equivalent to 30% of the annual production. As a result of corrosion, a variety of equipment will add a large amount of maintenance costs. Corrosion also often leads to serious accidents, forcing the plant to close, or lead to explosions and environmental pollution. The United States in 1978, the findings show that the direct economic losses caused by corrosion accidents amounted to about $ 70 billion, accounting for 4% of the gross national economic output. 19 75 years, the United States due to floods, fires, wind, earthquakes and other natural disasters caused by economic losses of $ 12.53 billion, far less than the losses caused by corrosion. Therefore, how to prevent corrosion of stainless steel piping is a very important work.

3. Surface fatigue damage

Stainless steel pipe surface fatigue failure refers to the two mutually contacting moving surfaces (especially rolling contact) in the working process undergo alternating contact stress, resulting in the surface material due to fatigue damage and fall off, resulting in the failure of the part or tool.

According to the degree of fatigue damage to the surface of stainless steel tubes, there are two types of pitting (shallow spalling) and spalling (deep spalling).

In fact, the failure of stainless steel tubes is often not a single form. With changes in external conditions, the form of failure can change from one type to another. For example, the form of gear failure may include: broken teeth; tooth deformation; tooth surface wear and pitting, etc. The actual type of failure that occurs depends on many factors and must be analyzed on a case-by-case basis.