Technology and Method of Stainless Steel Pipe

First, large-diameter stainless steel pipe if necessary to soften or de-nitrogen treatmentFor nitriding large diameter stainless steel pipe if the need for local softening or denitrification treatment, the following methods are generally used in the specific operation should be carried out in accordance with technical requirements.

1. the method of partial softening(1) Heat the part to be softened in a salt bath at 800 °C (50% NaC: 1 + 50% KC1) to dissolve the dispersed nitrides into the solid solution. The hardness of the large-diameter stainless steel pipe is reduced to HB350-400 or so;(2) If the softened area is small and salt bath can not be used, it can be heated by oxyacetylene flame, surrounded by asbestos rope around the softened area, and large diameter stainless steel pipe is continuously watered during heating to ensure the surrounding the hardness will not decrease.
2. N treatmentFor large-diameter stainless steel pipes that need to be softened as a whole, large-diameter stainless steel pipes should be heated in a 980C salt bath (100% Bad) so that the nitrided layer on the surface of large-diameter stainless steel pipes is completely dissolved and falls off.

Second, stainless steel pipe due to internal thermal stress caused by a hot embrittlementStainless steel welded pipe in the joints, due to the different plumbing factor, so when heated will have a lot of thermal stress, especially when the temperature changes rapidly due to thermal shock as the steel quenching will produce the same phenomenon. At the same time under normal temperature changes dozens or hundreds of repeated heating will also have thermal fatigue cracking.

The first one is a hot embrittlement caused by internal thermal stress as the temperature changes.

The second one is caused by changes in the external load in high temperature.

Stress corrosion cracking of stainless steel welded pipe after macro inspection, in a nutshell, only parts of the welded pipe subjected to stress corrosion cracking are subject to corrosion (stress corrosion cracking, pitting corrosion and crevice corrosion) without significant. Even equipment subject to severe stress corrosion damage is no exception. In some media, sometimes both severe stress corrosion (or accompanied by severe pitting), there are quite serious general corrosion.

A worker from a steel pipe company, which is located in China.