As key components in surgical implants (such as artificial joints, bone fixation rings, etc.) or high-end industrial fields, the production process of titanium rings must strictly follow ISO 5832-2 and other standards to ensure material purity, mechanical properties, and biocompatibility. Detailed production process flow and key control points of titanium rings (taking Ti-6Al-4V ELI as an example):
1. Material selection and pretreatment
1.1 Raw material requirements
Composition control: Ti-6AI-4V ELI alloy that complies with ISO 5832-2
Morphology selection: Usually vacuum melted (VAR) titanium ingots are used, which are forged or rolled into titanium rods or cakes as ring-blank raw materials.
1.2 Billet preparation
Cutting and blanking: Titanium rods or cakes are made into ring blanks by wire cutting or sawing, and the size allowance is controlled (about 5-10% of the outer diameter allowance).
Surface cleaning: Pickling to remove oxide scale (HF+HNO3 mixture) to avoid subsequent processing contamination.
2. Main production process flow
2.1 Hot forming process
(1) Forging/rolling ring (applicable to large-sized titanium rings)
Heating temperature: keep below the β phase transformation point (usually 900-950℃) to avoid grain coarsening.
Ring rolling process: use a radial-axial ring rolling machine to control the uniformity of wall thickness through multiple rolling passes, and the deformation amount is ≤70%.
Cooling method: air cooling or temperature-controlled slow cooling to avoid residual stress.
(2) Powder metallurgy (applicable to small-sized rings with complex shapes)
Powder preparation: prepare high-purity titanium alloy powder (particle size 15-45μm) by plasma rotating electrode (PREP) or gas atomization method.
Cold isostatic pressing: form into ring blanks under a pressure of 200-300 MPa.
Sintering: vacuum sintering (1200-1300℃/2-4h), density ≥99.5%.
2.2 Cold forming process (thin-walled precision titanium ring): Cold rolling/spinning
(1) Intermediate annealing: When the cold rolling deformation reaches 30%, annealing (700-800℃/1h) is required to eliminate work hardening.
Spinning: The titanium plate blank is gradually spun into a thin-walled ring by a CNC spinning machine, with a wall thickness tolerance of ±0.05mm.
(2) Machining
Turning/milling: Use carbide or PCD tools, low speed and high feed (to avoid tool adhesion), and the coolant must be a chlorine-free oil-based medium.
Wire cutting: Precision machining of inner holes and end faces (accuracy ±0.01mm).
3. Heat treatment process
Solution treatment: 930-950℃/1h insulation and water quenching to obtain a fine-grained β matrix.
Aging treatment: 500-600℃/2-4h air cooling to precipitate secondary α phase and improve strength (tensile strength ≥860 MPa).
Stress relief annealing: After cold working, annealing at 550-650℃/1-2h is required to eliminate residual stress.
4. Surface treatment
Electrolytic polishing: Electropolishing in an acidic electrolyte (such as H2SO4+CH3COOH), surface roughness Ra≤0.4μm.
Passivation treatment: Soak in nitric acid (20-40% concentration) to form a dense TiO2 oxide film to improve corrosion resistance.
Sandblasting (optional): Used for roughening the surface of bone implants (Ra 2-4μm) to promote bone cell attachment.
5. Common problems and solutions
5.1 Oval deformation of ring parts
Cause: Uneven stress release during rolling or heat treatment.
Measures: Use fixture shaping annealing, or add finishing rolling process.
5.2 Surface microcracks
Cause: Excessive cold working deformation or insufficient annealing.
Measures: Control the single cold deformation to ≤20%, and add pickling to relieve the stress layer before annealing.
Edgetech Industries LLC provides a variety of commercially pure Titanium and Titanium alloys in wire, sheet, bar, tube, and other forms. Titanium expanded/stamped mesh and titanium wire mesh are also available.