Grade 21 Titanium CNC Machining Services — Ti-15Mo-3Nb-3Al-0.2Si (UNS R58210)

Engineering Challenge

Grade 21 strength is developed by aging the metastable beta matrix. Excessive heat input during machining — high cutting temperatures, slow traverse, or interrupted cuts that re-heat the same zone — can locally over-age the surface and produce inconsistent hardness, dimensional drift, and reduced fatigue life.

Our Machining Approach

We select cutting parameters and tool geometries to keep the cutting-zone temperature well below the aging range. Sharp tools, high-pressure coolant, and conservative engagement keep the bulk material cool. Material is supplied in the solution-treated condition for machining; aging is performed as a separate post-machining step per the customer specification.

Engineering Outcome

Mechanical properties consistent with the agreed specification at the machined surface and in the bulk. Final tolerance and property targets are confirmed after CAD, drawing, material condition, and inspection method review.

Engineering Challenge

The advantage of Grade 21 is its cold-formability in the solution-treated condition followed by age-hardening to 1100+ MPa UTS. Machining a part that has already been age-hardened is significantly harder and risks tool breakage; machining a part that has been cold-formed but not aged can produce springback and shape drift.

Our Machining Approach

We confirm the sequence with the customer at the RFQ stage: machine in the solution-treated condition, then age. We use a stress-relief step between heavy roughing and finishing to minimize distortion during aging. Inspection intervals are scheduled to catch any movement between machining and aging.

Engineering Outcome

Final geometry held within drawing tolerance after aging, with documented cutting parameters and the agreed heat-treatment sequence.

Engineering Challenge

Grade 21 mechanical properties are highly sensitive to solution-treatment temperature, quench rate, and aging parameters. A 10 °C shift in aging temperature or a missed quench step can move the yield strength by 100 MPa or more, and the result is not visible at the machined surface — only in subsequent mechanical testing.

Our Machining Approach

We do not perform the solution / aging treatment in-house unless explicitly contracted; we typically ship the machined part to the customer or to a qualified heat-treater with documented material condition and recommended parameters. When we do coordinate heat treatment, we use qualified vendors with calibrated furnaces and full cycle traceability.

Engineering Outcome

Heat-treatment cycle is traceable to the specific part, the agreed parameters are within the specification window, and the customer receives documented evidence of the cycle applied.