Required Post-Processing Steps for LENS-Printed TA15 Parts to Meet Standards

Mandatory Thermal Treatments

LENS-printed TA15 (Ti-6.5Al-1Mo-1V-2Zr) titanium alloy components require precise thermal processing to achieve standardized mechanical properties. Initial stress relief annealing at 650-750°C in vacuum or argon atmosphere is critical to mitigate residual stresses from the deposition process. This is followed by Hot Isostatic Pressing (HIP) at 890-930°C with 100-150 MPa pressure for 2-4 hours to eliminate internal defects and achieve density >99.9%. A subsequent duplex annealing treatment—consisting of solution treatment above the beta transus temperature followed by air cooling and stabilization annealing at 550-650°C—optimizes the microstructure for enhanced creep resistance and fracture toughness required for aerospace applications.

Precision Machining and Dimensional Control

The as-deposited LENS surfaces require substantial CNC machining to achieve final dimensional tolerances per aerospace standards (typically AS9100). Rough machining removes 2-4mm of surface material to eliminate the coarse columnar grain structure and heat-affected zone. Finish machining employs specialized tooling and high-pressure coolant to achieve surface roughness below Ra 1.6μm on critical interfaces. For complex internal features, deep hole drilling and EDM processes ensure precise dimensional control of cooling channels and mounting features.

Surface Enhancement and Integrity Improvement

Multiple surface treatments ensure TA15 components meet fatigue and corrosion resistance standards. Shot peening with controlled Almen intensity introduces compressive stresses of 500-800 MPa, improving high-cycle fatigue performance by 60-80%. Chemical milling removes the alpha-case layer formed during thermal processing, while laser shock peening may be applied to critical stress areas for components in defense applications. Final electropolishing creates a uniform surface finish while enhancing corrosion resistance through passivation.

Comprehensive Quality Assurance

Rigorous material testing and analysis validates compliance with industry standards. This includes ultrasonic testing per ASTM E2375 to detect internal flaws, radiographic inspection for complex internal geometries, and fluorescent penetrant inspection per AMS 2647 for surface defect detection. Mechanical testing verifies tensile strength (≥930 MPa), creep resistance at 500°C, and fracture toughness. Microstructural analysis confirms proper basketweave α+β structure with no continuous grain boundary alpha, while chemical analysis ensures composition meets TA15 specification requirements.

Certification and Documentation

Complete traceability and documentation are essential for standards compliance. This includes certification of raw material composition, documentation of all thermal process parameters with furnace charts, and detailed records of machining operations. For aerospace components, additional testing such as strain-controlled fatigue testing, stress rupture testing at elevated temperatures, and salt spray corrosion testing per ASTM B117 may be required. Final components receive material certificates with full traceability to applicable standards such as AMS, MIL, or customer-specific specifications.