What Are the Mandatory Conditions for Bright Annealing of 304 Stainless Steel Tubes?

What Are the Mandatory Conditions for Bright Annealing of 304 Stainless Steel Tubes?

Bright annealing relies on strict process parameters for 304 stainless steel tubes. Wuxi Yinshan Stainless Steel Co., Ltd. sorts out the key technical requirements as below:

Furnace Sealing Performance

All valves of the bright annealing furnace must be fully closed to isolate the inner cavity from ambient air. If hydrogen is adopted as protective gas, only one exhaust vent needs to be reserved.

Internal Furnace Humidity Control

Two humidity control priorities:

First, ensure all furnace accessories are thoroughly dried;

Second, guarantee incoming stainless steel tubes contain no excessive residual moisture.

Sustained Positive Furnace Pressure

To prevent micro air leakage, the protective gas inside the furnace must maintain stable positive pressure. When hydrogen serves as shielding gas, the internal pressure should stay above 20 kBar.

Qualified Annealing Temperature

Stainless steel bright annealing refers to solution heat treatment with a standard temperature range of 1040℃ ~ 1120℃.

Operators can observe through the furnace inspection window: tubes in the annealing zone should present a bright incandescent state without softening or sagging deformation.

Controlled Annealing Atmosphere

Pure hydrogen is the preferred protective atmosphere for stainless steel tube annealing, with purity approaching 100%.

Excessive oxygen and water vapor inside the furnace will severely damage tube surface quality, making gas purity a core factor determining finished product performance.