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Causes of Flexible Metal Conduit Welding Cracking

Sep. 23, 2019

Amored Optical Fiber Cable Supplier believes that after scientific research, the following is the actual reason for the cracking of the product.

1. Welding quality problems cause weld cracking

The Flexible Metal Conduit sections in metal corrugated hoses are mostly longitudinally welded pipes. Due to the quality problems of the longitudinal seam welding, defects such as virtual welding, over-burning, pores and dendritic looseness are generated at the weld of the bellows, so that the effective area of the bellows wall is reduced and the strength is significantly reduced, resulting in cracking and cracking of the weld.

2. Improper welding of dissimilar steel leads to cracking of the weld

The joint connection process of the product is usually welded. When the joint is welded with the net sleeve and the bellows, for example, the weld is made of a mixture of base material and filler material of two different types of pearlite and austenite. The alloy composition is diluted due to fusion into the weld, Austen The content of elements formed by the body is reduced, and the martensite structure is brittle and hard. Therefore, during the use of the product, the brittleness of the weld is increased, and cracks are generated, which causes the fatigue resistance of the weld to decrease. In the factory inspection, it is not easy to find, when it is subjected to alternating internal stress, it will accelerate its fatigue damage, often causing cracks in the weld near the joint.

Flexible Metal Conduit

Flexible Metal Conduit

3. Welding material problems lead to weld corrosion

In addition to the quality of the weld, improper selection of the weld material can also lead to weld corrosion failure. The effects of materials such as hose flanges and joints are not taken into account in the corrosive environment of the site. If carbon steel materials are used and welded with stainless steel parts such as Corrugated Conduit in China, the adverse environment for the contact between a typical small-area anode part and a large-area cathode part is formed. The conditions for the formation of galvanic corrosion exacerbate the corrosion of the weld and the surrounding area. As a result, the weld site corroded in a short time, and a gap occurred, causing Corrugated Conduit in China to leak.