Analysis Of Technical Points in Titanium Flange Processing Technology

Titanium flanges, featuring low density, high strength, and excellent corrosion resistance, are key components in high-end equipment fields such as chemical industry, marine engineering, aerospace, and nuclear power. Their processing is restricted by the material characteristics of titanium alloys, requiring the overcoming of technical difficulties including low thermal conductivity, severe work hardening, and proneness to oxidation and contamination at high temperatures.

 

 

 

1. Basis for Material Selection

Ordinary corrosion-resistant scenarios: Grade 1/Grade 2 pure titanium.

Strong acid and high chlorine scenarios:Gr7 palladium-containing titanium alloy

 

2. Standards and Inspection

Raw materials shall comply with ASTM B381 standards; physical, chemical, and mechanical property reports shall be verified upon arrival to avoid the impact of impurities on processing.

 

 

1. Core Objective

Decontamination and prevention of secondary pollution.

 

2. Process Steps

Mechanical grinding/acid pickling to remove oxide scale, oil stains, and rust → Pure water rinsing to neutrality after acid pickling → Surface passivation to form a dense oxide film and enhance corrosion resistance.

 

3. Taboos

Do not use chlorine-containing or fluorine-containing cleaning agents; use special tools; avoid contact with carbon steel to prevent iron contamination.

 

 

1. Traditional Forging Blank Process

Core control: Forging in the beta phase region at 950-1000℃ to balance plasticity and grain refinement.

Heating environment: Vacuum furnace/high-purity argon protection with a vacuum pressure to prevent oxidation and hydrogen absorption.

Process requirements: Multi-pass die forging ; timely post-forging annealing for stress relief.

 

2. Innovative Powder Metallurgy Process

Pain point solved: Addresses the low utilization rate of traditional forging.

Raw material parameters: Titanium powder with an oxygen content of 500-1000ppm.

Process flow: Cold isostatic pressing (CIP) molding

Process advantages: Material utilization rate increased without the need for piercing; applicable to flanges.

 

 

1. Cutting Tools and Cutting Parameters

Tool selection: Use carbide or diamond-coated special tools with sharp cutting edges to reduce work hardening.

Cutting parameters:

Turning: Speed 20-5m/min, feed 0.1-0.2mm/r, depth of cut 2-5mm

Milling: Layered cutting with each layer depth ≤ 3mm.

Cooling and lubrication: Use special titanium alloy cutting fluid for sufficient cooling to prevent tool adhesion and surface burning.

 

2. Machining Precision of Sealing Surfaces

Standard requirement: Comply with ASME B16.5; secondary machining is required after welding to eliminate deformation.

Raised Face :

Protrusion height: 1.6mm for 150/300lb, 6.4mm for 400lb+.

Roughness: 3.2-6.3μm; process 45-55 serrated grooves per inch.

Ring Type Joint : Sidewall roughness ≤ 1.6μm, flatness ≤ 0.01mm (ultra-precision grinding required).

Tongue and Groove/Male and Female: Roughness ≤ 3.2μm; precision positioning is required to ensure fitment.

 

 

1. Basic Heat Treatment Processes

Environmental requirement: Vacuum/inert gas protection to prevent oxidation and contamination.

Conventional annealing: below the beta transition temperature, holding for 1-3h followed by air cooling to eliminate machining stress.

Stress relief annealing: applicable to machined/welded parts to avoid subsequent deformation.

Solution aging of alpha-beta titanium alloys: Solution water quenching in the upper alpha-beta region, followed by aging to balance strength and toughness.

 

2. Quality Control of Heat Treatment

Furnace temperature uniformity: with a deviation of the effective heating zone ≤ ±5℃.

Vacuum parameters: Pressure rise rate ≤ 1.33Pa/h; vacuum degree ≥ 2×10⁻³Pa above 750℃ or high-purity argon partial pressure protection.

Inspection requirements: Hydrogen content ≤ 0.015% to prevent hydrogen embrittlement; metallographic analysis to confirm uniform structure and avoid coarse grains and excessive oxide layers.

 

 

1. Surface Treatment Processes

Core objective: Balance corrosion resistance and appearance; the treated surface shall be free of scratches, pitting, contamination, and other defects.

Basic processes:

Sandblasting: Remove burrs and oxide scales; surface roughness Ra ≤ 1.6μm to enhance coating adhesion.

Acid pickling and passivation: Optimize oxide film performance and improve corrosion resistance, suitable for chemical and marine scenarios.

Special working condition processes: Anodic oxidation or palladium plating to enhance resistance to extreme media.

 

2. Whole-Process Quality Inspection

Dimensional inspection: Verify outer diameter, inner diameter, thickness, bolt hole position, etc., in accordance with ASTM B381, with tolerance controlled at IT7 grade.

 

Mechanical properties: Sampling inspection of tensile strength, yield strength, and elongation.

Non-destructive testing: Ultrasonic testing for internal defects and penetrant testing for surface cracks; precision measurement of dimensions and roughness for RTJ grooves.Corrosion performance: Verify through salt spray or medium immersion tests to meet working condition requirements.

 

Baoji Ruihang,as a manufacturer of titanium and titanium alloy products, supply high-quality supports for customers,including titanium

flanges,rods,plates,wires and forgings. For more details about the products,please contact us via Email:Sam.Rui@bjrh-titanium.com