Stainless Steel Strip & Tube Bright Annealing

Solution

Stainless steel strips and tubes need oxidation-free bright surfaces. Conventional annealing causes discoloration and extra polishing cost. Rexin continuous bright annealing lines adopt hydrogen shielding atmosphere, delivering mirror finish for 200, 300 and 400 series stainless steel.

Bright Annealing Working Principle & Full Production Flow

Heat stainless steel under high-purity nitrogen-hydrogen protective atmosphere to recrystallize grain, then rapidly cool under sealed atmosphere to avoid air oxidation, realizing bright oxide-free surface. Complete Line Flow:

Uncoiling

Degreasing Cleaning

Heating Zone

Soaking Zone

Water/Air Cooling

Tension Recoiling

Stainless Steel Grade Annealing Parameter Table

Steel Series	Grades	Annealing Temp	Protective Atmosphere	Main Application
200 Series	201, 202	1020–1080℃	75%H₂+25%N₂	Kitchen sinks, decorative tubes
300 Series	304, 316, 321, 310S	1040–1120℃	Pure Hydrogen H₂	Medical pipe, chemical pipeline
400 Series	410, 420, 430, 444	780–1050℃	H₂-N₂ Mixed Gas	Auto exhaust pipe, appliance housing

Core Equipment For Stainless Bright Annealing

Equipment	Specification Range	Key Feature
Continuous Strip BA Furnace	Width 50–650mm, Max 1150℃	Full fiber energy-saving lining, stable tension control
Continuous Tube BA Furnace	Tube Φ6–100mm, Max 1120℃	Radiant tube uniform heating, inner tube bright treatment
Ammonia Cracker	10–80Nm³/h Output	Dew point ≤-40℃, low cost protective gas source

High-Efficiency Energy-Saving Design

All-fiber furnace lining reduces heat loss; exhaust gas recuperator preheats combustion air or cleaning water; optimized cooling section reduces gas consumption.

Pure Hydrogen Atmosphere Annealing

Using 100% pure hydrogen as protective atmosphere achieves best surface brightness, suitable for high-end stainless steel strip production.

Intelligent Control System

PLC and industrial computer enable automatic matching of temperature, line speed, and atmosphere; automatic tension adjustment; real-time data recording; abnormal alarm and remote diagnosis.

In-Line Quality Inspection

Integrated online brightness detector, thickness gauge, and pinhole detector enable real-time monitoring and feedback of post-annealing product quality.

Critical Bright Annealing Quality Indexes

Surface Standard: Mirror silver-white, no yellow/blue oxidation discoloration, Ra ≤0.1μm
Mechanical Performance (304): Tensile strength ≥520MPa, Elongation ≥40%
Atmosphere Purity: Hydrogen ≥75%, Dew point ≤-40℃, furnace positive pressure anti-air infiltration
Cooling Requirement: Outlet water temperature ≤40℃ to avoid secondary oxidation

Stainless Processing Industry Pain Points

Unstable surface brightness due to poor furnace sealing → Fully welded airtight furnace body
High hydrogen & electricity operating cost → Waste heat recovery circulating system
Strip scratching during transmission → Soft ceramic roller tension transmission
Different material frequent parameter adjustment → PLC one-click grade switching

Advanced Stainless Annealing Technology

Pure Hydrogen High-bright Annealing: Top-grade mirror surface for medical & electronics parts
Waste Heat Recuperation: Recycle flue heat to pre-cleaning water, reduce gas consumption by 25%
Online Real-time Surface Inspection: Built-in brightness detector automatic defect alarm
Full Automatic Unmanned Line: Auto speed/temp/tension matching without manual adjustment

Conclusion

Bright annealing determines stainless steel surface appearance, corrosion resistance and deep drawing performance. High-end stainless processing factories gradually adopt full hydrogen energy-saving continuous annealing lines to cancel pickling procedures and cut production cost.

Rexin supplies integrated bright annealing solutions including furnace body, ammonia cracker, tension system and degreasing equipment. Provide your strip/tube width & thickness to get line layout and energy consumption calculation.

Our Products: Mesh Belt Furnace, Vacuum Furnace, Box Furnace, Pit Nitriding Furnace, Brazing Line, Sintering Furnace

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