​Bright Annealing Conditions for 304 Stainless Steel Tube

Bright Annealing Conditions for 304 Stainless Steel Tube

The 304 stainless steel tube requires specific conditions for bright annealing. What are the exact conditions?

Bright Annealing Conditions for 304 Stainless Steel Tube:

Furnace Sealing

The bright annealing furnace must have tightly closed valves and be isolated from external air. If hydrogen is used as the protective gas, only an exhaust port is needed.

Moisture Inside the Furnace

First, check whether the furnace materials are dry. Second, ensure that the stainless steel tubes entering the furnace do not contain excessive moisture.

Maintaining Gas Pressure

To prevent micro-leakage, the protective gas inside the furnace must maintain a certain positive pressure. If hydrogen is used as the protective gas, the pressure should typically exceed 20 kBar.

Annealing Temperature (Reaching the Required Level?)

Stainless steel heat treatment usually adopts solution heat treatment, commonly referred to as annealing, with a temperature range of 1040–1120°C.

The annealing condition can also be observed through the furnace inspection port. The stainless steel tubes in the annealing zone should be in an incandescent state but must not soften or sag.

Annealing Atmosphere

The annealing atmosphere for stainless steel tubes is primarily pure hydrogen.

Therefore, the gas purity must be as close to 100% as possible. It must not contain excessive oxygen or water vapor, as the atmosphere is a critical factor in determining the quality of stainless steel tubes.