A4 Stainless Steel Inch Slotted Shoulder Screws are supplied to ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80. Corrosion behaviour is superior, including marine and chloride environments, the material is largely non-magnetic, and the usable service range is approx. -200 °C to +400 °C, subject to the property class and the joint. In practice this grade is specified for marine, coastal and chemical applications.
- Grade
- ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80
- Corrosion resistance
- Superior, including marine and chloride environments
- Magnetic response
- Largely non-magnetic
- Service temperature
- approx. -200 °C to +400 °C, subject to the property class and the joint
Property values are typical for the grade. Certified mechanical test data is available on request for production orders.
Material specification page for inch slotted shoulder screws in A4 Stainless Steel. Covers the grade designation (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to Trade series (inch shoulder screws).
Why Choose A4 Stainless Steel for Inch Slotted Shoulder Screws
Specified for marine, coastal and chemical applications. For inch slotted shoulder screws, this matters when superior, including marine and chloride environments is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80 |
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| Magnetic response | Largely non-magnetic |
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| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
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| Corrosion characteristic | Superior, including marine and chloride environments |
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Corrosion Behavior in Service
A4 (316) adds 2–3% molybdenum to the A2 (304) composition, which dramatically improves resistance to chloride-pitting corrosion. For Inch Slotted Shoulder Screws in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Inch Slotted Shoulder Screws, the alternative stainless grade is A2 (304). A2 (304) suits general indoor and outdoor service; A4 (316) adds molybdenum for marine and chloride environments. Where higher strength matters more than corrosion, switch to plated alloy-steel class 8.8 or 10.9.
Using Stainless Fasteners in Aluminum
Stainless steel is more noble than aluminum, so in the presence of an electrolyte — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. The effect is driven by the area ratio: a small stainless fastener in a large aluminum section is normally acceptable, while a large stainless fastener in thin aluminum is not. Where the joint is wet, isolate the two metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.
Sizes of Inch Slotted Shoulder Screws Available in A4 Stainless Steel
| Shoulder diameter (in) | Thread options | Shoulder length (in) | Slot width (in) | Slot depth (in) | Material options | Thread class |
|---|
| 1/8 | #4-40 / #6-32 | 1/8~1-1/2 | 0.047~0.094 | 0.062~0.109 | 303 or 416 stainless / alloy steel / brass | 2A |
| 1/4 | #8-32 / #10-24 / #10-32 | 1/8~1-1/2 | 0.047~0.094 | 0.062~0.109 | 303 or 416 stainless / alloy steel / brass | 2A |
| 3/8 | 1/4-20 / 5/16-18 | 1/8~1-1/2 | 0.047~0.094 | 0.062~0.109 | 303 or 416 stainless / alloy steel / brass | 2A |
| 1/2 | 3/8-16 | 1/8~1-1/2 | 0.047~0.094 | 0.062~0.109 | 303 or 416 stainless / alloy steel / brass | 2A |
Applications & Industries
Inch Slotted Shoulder Screws are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from 1/8 to 1/2 (screw size).
Industries that specify Inch Slotted Shoulder Screws
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Light machinery
Wear-resistant pivot hardware assembled with a simple slot driver.
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Linkage mechanisms
Slotted-head shoulder screws used as pivots and bearing shoulders.
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Tooling fixtures
Replaceable guide and stop points in jigs.
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Camera and instrument mounts
Controlled shoulder length where axial position matters.
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Energy & infrastructure
Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints.
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Maintenance & MRO
Stocked replacements matched to an existing property class, thread and finish.
Typical applications
- keeping the mating part on the shoulder instead of the threaded section
- locating a rotating or sliding part on a defined cylindrical shoulder
- selecting shoulder diameter and length separately from the thread
- using the slot for low-profile manual assembly
- joints where the property class is stated on the drawing
- clamping two machined faces to a calculated preload
Service conditions to specify against
- Marine and coastal
- Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- High load
- Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- Torque and preload
- The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together.
Where to use something else
- Do not use the slot as a high-torque structural drive; it is a compact head feature for the shoulder assembly.
- Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material.
Full application guide: where Inch Slotted Shoulder Screws are used, how to specify them, and the cases they are wrong for
