Cold Heading Wire Finishes: SAFS vs SAIP

Two conditions account for nearly all cold heading wire shipped in North America: SAFS and SAIP. Both are spheroidize-annealed, both ship with phosphate-and-lubricant (P&L) coating, both work for cold heading. The difference is in the final processing step and what it does to formability and dimensional precision.

This page explains the difference, when to choose each, and why the $2/cwt gap between them matters for some applications and not others.

What spheroidize annealing does (and why every CHQ wire needs it)

Higher-carbon and alloy steels in their as-rolled or as-drawn state have their carbon locked in a lamellar pearlite microstructure — alternating thin layers of ferrite (iron) and cementite (iron carbide). That structure is strong but rigid; under heading deformation, the lamellae break, cracks propagate along the boundaries, and parts fail.

Spheroidize annealing is a heat-treat process that converts those lamellae into discrete spheres of cementite dispersed in a soft ferrite matrix. The wire becomes:

• Significantly more ductile — the soft ferrite carries the deformation
• More uniformly deformable — no oriented weak planes for cracks to follow
• Softer overall — typically 10–20 points HRB lower

The result is wire that cold-heads cleanly instead of cracking. All CHQ wire intended for cold heading of medium-carbon or higher grades is spheroidize-annealed, just in one of two configurations.

SAFS — Spheroidized Annealed at Finish Size

In SAFS production, the wire is cold-drawn to its final diameter first, then spheroidize-annealed as the last processing step before coating. Because annealing is final, the wire arrives with:

• Maximum softness and ductility — annealing wasn’t followed by any cold work that would reintroduce strain
• Lowest internal stress — the heat treatment relieves any stress from prior drawing
• A matte coated finish — the wire surface has the natural look of annealed steel under the P&L coating

SAFS is Nevers’ default condition and what most of our customers buy. It’s the right choice when the part geometry pushes the limits of cold forming: deep extrusions, multi-blow heading, severe upsetting, or any application where cracking is the failure mode.

SAIP — Spheroidized Annealed In Process

In SAIP production, the wire is spheroidize-annealed during the processing line and then given a final light cold draw of typically 6–9% reduction before coating. That final draw:

• Sets tighter dimensional tolerances — the draw die controls the final diameter more precisely than annealing alone
• Produces a bright drawn finish — the surface looks like standard drawn wire under the P&L coating
• Slightly increases strength — the light cold work hardens the wire modestly
• Slightly reduces maximum formability — the cold draw reintroduces some internal stress

SAIP costs $2/cwt more than SAFS at Nevers. It’s the right choice when your operation cares more about diameter consistency and smooth feed behavior through automated equipment than about ultimate formability.

When to choose SAFS

Choose SAFS when any of the following apply:

• The part involves severe deformation — deep extrusion, multi-blow heading, complex geometries where cracking is a concern
• You’re heading higher-carbon or alloy grades — C1022, C1038, 10B21, or 4037 generally perform better in SAFS
• You’re working with thin-walled or deep-drawn parts — tubular rivets, self-clinching hardware, deep cups
• You have die life or reject rate problems on SAIP and need more formability

SAFS is the default for a reason — most CHQ buyers do work demanding enough that the formability matters more than the dimensional precision.

When to choose SAIP

Choose SAIP when:

• You’re running high-speed automated headers that need consistent wire diameter for reliable feed
• Your part geometry is moderate and doesn’t require maximum formability
• You’re heading lower-carbon grades — C1006, C1010, or C1018 in simple geometries — where SAIP’s slight strength advantage helps and the formability hit doesn’t matter
• Dimensional precision matters for downstream operations (thread rolling, insertion into automated assembly)
• You want a bright drawn finish for visual or post-processing reasons

The $2/cwt premium is worth it when the operation actually benefits from the tighter tolerances. It’s wasted on parts where the heading process is the limiting factor.

A practical decision framework

If you’re not sure which condition fits your operation:

1. Default to SAFS. It’s our most-stocked condition and works for the majority of cold-heading applications.

2. Try SAFS first on new parts. If you see cracking, surface tearing, or die wear at unacceptable rates, you’re likely under-annealed — switching to SAIP won’t help (it’s slightly harder, not softer).

3. Switch to SAIP when your headers demand it. High-speed automated equipment with tight feed tolerances genuinely benefits from SAIP’s dimensional precision. The premium pays back in fewer feed-related stoppages.

4. Don’t mix conditions on a part program. Once you’ve qualified a part on SAFS or SAIP, stick with that condition. Switching mid-program creates process upsets.

We’re happy to talk through your specific application — the right choice isn’t always obvious from the part drawing alone.

P&L coating — applied to every coil

Whether you order SAFS or SAIP, the wire ships with phosphate-and-lubricant (P&L) coating as a baseline. P&L isn’t optional — it’s a standard post-anneal surface treatment that provides the lubrication needed for the wire to slide through heading dies without galling.

The P&L coating is the same on both SAFS and SAIP material. The difference between the two conditions is entirely in the underlying microstructure and dimensional precision of the wire, not in the coating.

For specialty coating requirements (alternative lubricants, polymer-based coatings, etc.), let us know during quoting — most are mill-order items rather than stock.

A third condition: SAR

In addition to SAFS and SAIP, Nevers and Company offers SAR (Spheroidized Annealed Rod) on special order. SAR is a spheroidize-annealed condition that ships without phosphate-and-lubricant coating — making it appropriate for applications where the standard P&L surface is incompatible with downstream processing.

SAR is not stocked — it’s offered in variable grades and sizes on a quote-on-request basis. If your specification calls for SAR specifically, contact us with your grade, size, and quantity requirements and we’ll quote sourcing and lead time.

For most cold-heading applications, SAFS or SAIP is the right choice. SAR is specified by customers whose processing requires the bare spheroidize-annealed surface without P&L.

Stock and availability

The Nevers Stock List shows both SAFS and SAIP material across all stocked grades. Surface condition is shown next to each item: SAFS or SAIP. Both ship same-day from our Rockford, IL warehouse.

View Stock List | Request a Quote

Frequently Asked Questions

What’s the difference between SAFS and SAIP cold heading wire? SAFS (Spheroidized Annealed at Finish Size) is wire that’s cold-drawn to its final diameter first, then spheroidize-annealed as the last step — producing the softest, most ductile condition. SAIP (Spheroidized Annealed In Process) is annealed during processing, then given a light final cold draw — producing tighter dimensional tolerances and a bright finish at a slight loss of formability. SAFS costs less and is more formable; SAIP costs $2/cwt more and is more dimensionally precise.

Which should I order — SAFS or SAIP? SAFS is the right default for most cold-heading applications. It’s softer, more formable, and lower-stress, which prevents cracking in demanding upsetting and deep extrusion. Choose SAIP only if your operation needs the tighter dimensional tolerances or bright finish that the final cold draw produces — typically high-speed automated headers feeding precision parts.

Is SAFS the same as fully annealed? SAFS is fully spheroidize-annealed, which is a specific form of annealing that converts the carbide microstructure to spherical form. “Fully annealed” usually refers to a different process that produces a coarser ferrite-pearlite structure. For cold-heading wire, you want spheroidize annealing specifically — and SAFS delivers it in the most ductile form.

Why is SAIP more expensive than SAFS? The $2/cwt premium covers the additional final cold-draw step in SAIP production. After annealing, SAIP wire goes through one more pass through a draw die to set dimensions and surface finish, which adds processing cost.

Do all wires get P&L coating, or is that separate? All Nevers CHQ wire ships with P&L (phosphate-and-lubricant) coating as standard — both SAFS and SAIP material. P&L isn’t an upgrade or an option; it’s the baseline surface treatment that allows the wire to be cold-headed without galling.

Can I switch from SAIP to SAFS on an existing part program? Usually yes, but test before committing. SAFS is softer and more formable, which means heading dies may need to be re-tuned — what worked with SAIP’s slightly harder feed stock may produce flash or dimensional drift on SAFS. Run a sample lot before full conversion.

What’s “drawn-only” wire and how does it differ from SAIP? Drawn-only wire is cold-drawn to size with no annealing step — the microstructure remains lamellar pearlite. It’s used for applications that won’t be cold-headed (machining, hot forging, etc.). Don’t try to cold-head drawn-only wire in higher-carbon grades; it will crack.