Cold processed stainless steel pipe

The production of stainless steel pipe is divided into cold processing and hot processing. No matter which processing technology is used, it will have a certain impact on stainless steel pipe.

Today we will introduce what impact the cold working process has on stainless steel pipe? In metal technology, cold working refers to the processing technology in which metal undergoes plastic deformation below the recrystallization temperature, such as cold rolling, cold drawing, cold forging, stamping, cold extrusion, etc. Stainless steel, especially austenitic stainless steel, has excellent plasticity, which makes these cold working methods easy to implement. However, these cold working methods, like welding, will inevitably bring unavoidable effects on the performance of stainless steel pipe, especially the corrosion resistance or heat resistance. Impact.

Effect of cold working on stainless steel pipe

1. Cause lattice dislocation or phase transformation of stainless steel pipe to occur on the surface, which will become the starting point of local corrosion such as pitting corrosion. This phenomenon will have direct adverse effects when the deformation reaches 20% area reduction.

2. It will lead to microscopic defects such as stainless steel pipe lattice dislocations and an increase in surface roughness, and induce martensite transformation and precipitation of carbides. For example, austenitic steel shows an increase in magnetism after cold working.

3. The degree of cold working also has a negative impact on the high-temperature durability strength of austenitic stainless steel. Generally, the higher the working temperature or the higher the fracture life requirements, the lower the degree of cold working allowed.

4. Residual stress will be left in the stainless steel pipe after cold working, and the residual stress is extremely detrimental to the stress corrosion cracking (SCC) resistance of the stainless steel pipe. Any degree of cold working will greatly increase the SCC sensitivity of stainless steel pipe.

5. For the application of stainless steel pipes subjected to alternating loads, cold working will cause adverse effects due to the decrease in elongation and residual elongation, which will increase the cracking expansion rate.

How to reduce damage to stainless steel pipe

1. The stainless steel pipe standards of most countries, especially the European unified stainless steel pipe standards, stipulate that all stainless steel seamless steel pipes must be supplied in a solution or annealed state to eliminate performance damage caused by cold working and welding.

2. Three key parameters should be paid attention to during solid solution treatment: heating temperature, rapid cooling method and high temperature residence time. Excessively high solution treatment temperature or residence time will be detrimental to the corrosion resistance of stainless steel pipe. To determine whether the solid solution is in place, hardness measurement, expansion, curling, flattening, and stretching data can all be determined, among which hardness measurement is the simplest.

3. Due to the high-temperature heating and pickling treatment of solid solution or annealing, the manufacturing cost and production cycle are significantly increased. In addition, there are waste gases and wastewater emissions such as acid mist. Some companies omit this process and use this product, which is easy to produce after use. Production and personal accidents.

For some products or application conditions that may be difficult to implement solid solution or annealing, controlling the degree of cold working (cold working deformation) and performing local low-temperature stress relief annealing are practical methods to reduce harmful effects.

Excellent stainless steel pipe supplier

Tisco is a Chinese stainless steel pipe supplier that always insists on meeting all standards for cold-processed stainless steel pipe and produces high-quality stainless steel pipe to meet customer requirements. If you want to know more about stainless steel, carbon steel, alloy and other products, please continue to follow us. We will regularly update you with industry news, company news and product news about steel to help you understand steel products.