The pickling and annealing process for 304 stainless steel consists of two steps: annealing in a controlled atmosphere softens the material and restores its ductility; pickling, using an acid bath, removes the oxide scale, resulting in a clean, smooth, and corrosion-resistant surface. This process combination produces 304 SS tubing that is ideal for applications requiring high cleanliness and formability, such as those in the food, dairy, and pharmaceutical industries, as well as fluid or gas delivery systems.
What is the annealing process for 304 stainless steel?
For type 304 stainless steel alloys, the annealing temperature used is between 1100 and 1150 degrees Celsius. During each annealing process, a scale forms, which can be removed by pickling in a mixture of nitric and hydrofluoric acids.
| Name | stainless steel 304 pickling annealing tube |
| Material | 304,316,etc |
| OD | 0.28-10mm |
| WT | 0.08-1mm |
| Technics | Seamless |
| Usage | Food industry, mediaicl industry, decoration,etc |
| Shape | Round |
Annealing
Purpose: Annealing softens work-hardened stainless steel, relieves internal stresses caused by cold working (such as drawing or rolling), and improves its formability and weldability.
Process: 304 stainless steel is heated to high temperatures between 1010°C and 1120°C (1850°F and 2050°F) to promote recrystallization of its austenitic structure.
Bright Annealing: To achieve a bright, scale-free surface, the annealing process is performed in a controlled atmosphere furnace to prevent oxidation and maintain a clean internal surface.
Pickling
Purpose: Pickling removes black scale and other contaminants formed during high-temperature processes such as hot rolling or welding.
Process: Pickling treats stainless steel with an acidic solution, such as a mixture of hydrochloric and hydrofluoric acids.
Benefits: This process improves overall surface smoothness and corrosion resistance by removing embedded particles and ensuring a clean base for the final oxide layer.
How annealing and pickling work together
Annealing restores the steel's mechanical properties and formability.
Pickling cleans the surface by removing any scale formed during the annealing process.
The result is a clean, bright, smooth, and corrosion-resistant surface, which is crucial for a variety of applications, particularly in fluid and gas transport.
Gnee Steel specializes in the production and sale of a wide range of stainless steel products, including 304, 316, 321, 904, 904L, 2205 Duplex, 2205 Duplex, and 316L stainless steel. Gnee Steel's products are widely used in the kitchen, aerospace, chemical, power, automotive, and nuclear energy sectors. We also provide custom stainless steel solutions tailored to customer needs. For stainless steel pricing or custom alloy solutions, please email ru@gneesteelgroup.com for a quote.