THE SEIZING EFFECT OF STAINLESS STEEL FASTENERS
INTRODUCTION
When using stainless steel or aluminium fasteners, cold welding—also known as seizing or galling—can occur during assembly. The mating threads adhere until no further movement is possible, which may cause screws or bolts to fracture during tightening. This can create delays, damage and potentially hazardous situations.
If a fastener does not break during assembly, it may twist or seize before the correct preload is reached. This can lead to later failure through fatigue or external loading. Seizing may also prevent disassembly at the end of the connection’s service life. In previous investigations, concerns initially attributed to product quality were found to have been caused by seizing during installation.
WHAT CAUSES SEIZING?
When metal surfaces move against one another, microscopic surface irregularities create friction. The resulting heat and wear increase as contact pressure rises. Under severe conditions, the opposing surfaces adhere and material is transferred or torn away. This form of adhesive wear is known as galling and can progress until the components seize.
Threaded fasteners generate high contact pressure along the thread flanks. Austenitic stainless steel and aluminium are particularly susceptible because they are relatively ductile and prone to adhesive wear. When the protective oxide film is disrupted during tightening, fresh metal is exposed and can bond to the opposing thread surface.
PRODUCTS AND SITUATIONS THAT MAY INCREASE THE RISK OF SEIZING
Products that intentionally create additional thread friction, such as prevailing-torque lock nuts, substantially increase the risk of seizing. The extra friction generates concentrated heat over a very small contact area. These lock nuts do not rotate freely until they contact the clamped material, so every revolution creates friction before the joint is tightened. Unless suitable lubrication is used, consider locking methods that do not depend on continuous thread friction.
Bolted connections that require extensive thread movement because of gaps between the components also present a higher risk. The same applies to joints containing soft or resilient elements such as gaskets, spring washers, disc springs, coil springs and rubber or plastic washers. These components require more rotation to achieve the target preload, increasing sliding distance and friction within the threads.
LUBRINOX — FABORY’S ANTI-SEIZE SOLUTION
Fabory developed Lubrinox specifically to help prevent stainless steel fasteners from seizing. Unlike conventional anti-seize paste applied on-site, Lubrinox uses a pre-applied, dry lubricating coating that:
- Reduces friction to consistent and predictable levels, supporting reliable torque-tension control.
- Eliminates on-site lubrication because the fasteners arrive ready to install.
- Stays clean and does not attract dust or particles that could increase friction.
- Supports clean disassembly and helps prevent galling damage to the threads.
Lubrinox is available across a range of A2 and A4 stainless steel bolts, screws and nuts. For maximum anti-galling performance, use Lubrinox bolts and nuts together.
View the full Lubrinox range →HOW TO DIMINISH SEIZING EFFECTS
Always ensure that the fasteners are clean and free from burrs, metal particles, chips, sand and dust. Avoid damaged threads, misalignment and angled assembly, as these conditions create concentrated local friction.
Reducing the axial movement required to achieve preload also reduces risk. Stiff joints that need only limited rotation are generally less susceptible than flexible joints containing soft or spring elements.
Use a slow, smooth and even rotation speed. Avoid pulsing and impact tools whenever possible because rapid acceleration can generate intense local heating within the threads.
Combining different austenitic grades, such as A2/AISI 304 and A4/AISI 316, is sometimes recommended. However, both grades are austenitic and remain susceptible to adhesive wear. Mixing them alone does not reliably prevent seizing.
Rolled threads are generally preferred to cut threads because the rolling process normally produces a smoother and work-hardened surface. Most mass-produced stainless steel screws and bolts have rolled threads.
High-pressure lubricants and application-compatible anti-seize compounds can significantly reduce friction. Apply the lubricant evenly and account for its effect on the torque-preload relationship.
Pre-applied dry anti-friction coatings provide another option. They save assembly time and are less likely than sticky greases to collect contaminating particles.
ANTI-SEIZE METHODS COMPARED
| Method | Effectiveness | Ease of use | Best for |
|---|---|---|---|
| Lubrinox pre-applied coating | ★★★★★ | High — no preparation | Most stainless steel threaded assemblies |
| Anti-seize paste, such as MoS₂ | ★★★★ | Medium — applied on-site | High-load joints or infrequent disassembly |
| Dry anti-friction coatings | ★★★★ | High — pre-applied | Clean environments and approved food or pharmaceutical applications |
| Wax-based lubricants | ★★★ | Medium | General assembly |
| Slow, even rotation speed | ★★★ | High — technique only | All assemblies, alongside suitable lubrication |
| Mixed grades, A2 and A4 | ★ | High | Not an effective standalone method because both grades are austenitic |
| Rolled rather than cut threads | ★★★ | Not applicable — specification choice | Specification during design and procurement |
CONCLUSION
Careful fastener selection, clean and correctly aligned assembly, controlled rotation speed and suitable lubrication can prevent many stainless steel and aluminium seizing problems. These measures improve the reliability, serviceability and durability of threaded connections.
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RELATED TECHNICAL GUIDES
FREQUENTLY ASKED QUESTIONS ABOUT STAINLESS STEEL SEIZING
What is the difference between seizing, galling and cold welding?
These terms describe closely related stages of adhesive damage. Galling is the surface damage and material transfer caused by friction and adhesion between sliding metal surfaces. Seizing occurs when friction and adhesion become severe enough to prevent further movement. Cold welding describes the solid-state bonding that can form between the contacting surfaces. In fastener applications, the terms are often used interchangeably.
Why does seizing happen more often with stainless steel than with carbon steel?
Austenitic stainless steels such as A2/AISI 304 and A4/AISI 316 are ductile and susceptible to adhesive wear. Tightening can disrupt their protective chromium-rich oxide film and expose fresh metal, which may adhere to the opposing thread. Carbon steel has different mechanical and surface characteristics and is generally less susceptible under comparable conditions.
Can I prevent seizing by using an A2 bolt with an A4 nut, or vice versa?
No. A2 and A4 are both austenitic stainless steels, so mixing the grades alone does not reliably reduce seizing risk. Use suitable lubrication, a pre-applied coating such as Lubrinox, an application-compatible anti-seize paste or another verified anti-friction treatment.
What torque reduction should I apply to lubricated stainless steel fasteners?
Do not apply a universal percentage reduction. The required tightening torque depends on the lubricant’s friction coefficient, fastener geometry, material, surface finish, target preload and joint design. Follow the fastener or lubricant manufacturer’s torque data and verify critical joints through a torque-tension test.
Can seized stainless steel fasteners be salvaged?
Severely seized fasteners can rarely be salvaged. Once cold welding has substantially damaged the threads, forcing removal often fractures the bolt or strips the mating thread. Controlled cutting or replacement is normally safer. Prevention through correct assembly and lubrication is more reliable and economical.
Last updated: July 2026