Stainless Steel Round Head Slotted Screw

Choosing the Right SS Round Head Slotted Screw (Guide)
for stainless steel round head, slotted screws – mainly machine screw usage

1. What is an SS Round Head Slotted Screw?

An SS round head slotted screw is:

A screw with a domed/round head and a flat bearing face underneath

With a single straight slot for a flat-blade screwdriver

Usually supplied as a machine screw (straight shank, machine thread) to be used with a nut or tapped hole

Made from stainless steel (SS 202 / 304 / 316 etc.)

Variants exist:

Machine screw type → used with nut/tapped hole in metal/plastic

Wood / sheet-metal type → special sharp thread and point (for timber/sheet metal)

In an industrial SS fastener catalogue, “round head slotted screw” is typically understood as a machine screw unless otherwise mentioned.

2. When Should You Use an SS Round Head Slotted Screw?

Choose SS round head slotted screws when:

You need a clean, traditional-looking head that is fully round (more domed than pan)

A visible protruding head is acceptable or desired

The joint load is light to medium

Assembly and maintenance are typically done with simple hand tools (flat screwdrivers)

Typical applications:

Older-style panels, instruments, and equipment

Restoration work or retro/classic designs

Electrical and electronic terminal strips, clamps, and covers

Light sheet-metal or plastic parts, fixed with nut or tapped hole

Avoid them when:

You need flush finish → use CSK (countersunk) screws

Very high torque or vibration resistance is required → consider Phillips/Pozi/Torx or hex/socket head

Assembly is mostly with power tools at high speed → slotted heads tend to cam-out and damage easily.

3. Environment & Stainless Grade Selection
a) Choose grade based on environment

A2 (SS 304)

Standard option for general indoor & outdoor industrial use

Suitable for control panels, machines, cabinets, enclosures, brackets

Good corrosion resistance in urban/industrial atmospheres

A4 (SS 316)

Best choice for coastal, marine, poolside, and many chemical environments

Higher resistance to chlorides and pitting

Ideal for food & pharma equipment, marine hardware, chemical plants

SS 202

Lower-cost stainless for dry indoor, non-critical use

Not recommended for outdoor, marine, or wet/corrosive conditions

b) Match surrounding hardware

Match screw grade with hinges, brackets, plates, trims to avoid galvanic or visual mismatch

For harsh environments, keep all exposed hardware in A4 (316) where possible.

4. Head Shape & Slotted Drive – When is it Right?
Round head

Fully domed top – more rounded than a pan head

Flat underside bearing on the surface or washer

Very visible and decorative – often used where the screw head is part of the look

Slightly less bearing area than a large pan head, but often adequate for light clamps/plates.

Use round head when:

A classic/domestic or decorative look is desired

You are fixing plates, nameplates, clips, small fittings

Small projection above surface is acceptable and sometimes helpful (for manual access).

Slotted drive

Pros

Works with very simple hand tools (flat screwdriver)

Matches older standards and aesthetics

Good where torque is low and access is easy

Cons

High risk of cam-out (slipping) especially with power tools

Lower effective torque than Phillips/Pozi/Torx

Slot can damage quickly if screwdriver is the wrong size or misaligned

Use slotted when:

Drawings or customer spec specifically call for slotted

You’re matching existing/retro hardware

Assembly is mostly manual, low-speed, low-moderate torque.

Mechanical Properties (Guide) – SS Round Head Slotted Screws

Properties follow standard stainless fastener strength classes for machine screws.

A2-70 (SS 304) – Standard Grade

Material: A2 stainless (≈ SS 304)

Strength class: 70

Minimum tensile strength: ~700 MPa

Proof (yield) strength: ~450 MPa

Typical usage:

General mechanical assemblies

Electrical enclosures, panels, machine covers

Suitable for most indoor and outdoor (non-marine) environments.

A4-70 / A4-80 (SS 316) – High Corrosion Resistance

Material: A4 stainless (≈ SS 316)

A4-70: tensile ~700 MPa

A4-80: tensile ~800 MPa (higher strength version)

Use these when:

Environment is coastal, marine, or chemically aggressive

Hygiene or corrosion-resistance requirements are very high

You need both strength + long-term corrosion performance.

SS 202 (where used)

Material: 200-series Cr-Mn stainless

Strength generally acceptable for many light applications

Corrosion resistance lower than 304/316

Limit to dry indoor, non-critical uses where cost is more important than long life.

In most real-world uses of round head machine screws, the joint’s performance is controlled more by nut/tapped-hole strength, bearing area, and joint design than by the ultimate tensile strength of the screw.

9. Quick Selection Cheat Sheet (For Sales / Floor Use)

Environment

Normal indoor/outdoor → A2-70 (304)

Coastal / chemical / marine → A4-70 or A4-80 (316)

Dry, low-risk, cost-focused → SS 202 (if accepted)

Head Style

Want classic domed look, visible head → Round head slotted

Need low profile but not flush → Pan head

Need perfectly flush → CSK head

Drive

Slotted → when specified by drawing or aesthetic, manual assembly

For easier assembly / higher torque → consider Phillips/Pozi/Torx versions instead.

Size

Small plates → M2–M3

General light duty → M3–M4

Medium duty → M4–M6

Length

Nut joint: parts + washers + nut + 1–3 threads out

Tapped joint: 1–1.5 × diameter thread engagement.