Premium A2 (304) and A4 (316) stainless steel CSK slotted head screw. Available in metric coarse threads and select UNC/BSW on request. Mill Test Certificates (MTC), strict dimensional tolerances, and fast dispatch from ready stock.
DIN 963
Stainless Steel CSK Slotted Head Screw
TRSUTED SS CSK slotted head screw FOR DEMANDING APPLICATION
Key Specifications
Standards
-
Grades (Material)
A2 (304), A4 (316)
Strength Classes
-
Threads
Metric coarse (default). Fine/UNC/BSW available on request
Sizes
M1.6 to M 70, 3/16" to 2.1/2" (others on request)
Lengths
-
Head
-
Marking
Grade/class & manufacturer ID as applicable
Certificates
MTC 3.1 / chemical composition & mechanicals available
Compliance
RoHS/REACH; generally non-magnetic in solution-annealed state (slight magnetism possible after cold-work)
Choosing the Right Stainless Steel CSK Slotted Head Screw
Choosing the Right SS CSK Slotted Head Screw (Guide)
for stainless steel countersunk slotted head screws
1. Application & Joint Type
a) Type of joint
Light covers, name plates, panels, electrical fittings
→ SS CSK slotted machine screw is ideal (flush, neat finish).
Wood / soft sheet-metal fastening
→ Use CSK slotted wood/sheet-metal screws (tapered thread, sharp point).
Structural / high-vibration / high-load joints
→ Avoid slotted head. Prefer allen/torx/hex drive screws or bolts.
b) Flush or near-flush requirement
Need perfectly flush surface (doors, panels, hinges, machine guards)
→ CSK slotted head is suitable – head sits within countersink.
No need for flush surface
→ You can use pan/cheese/hex head instead (better drive & torque capacity).
2. Material & Corrosion Environment
Indoors / general outdoor / normal industrial atmosphere
→ A2 (SS 304) CSK slotted screw is usually sufficient.
Marine, coastal, chemical, chloride exposure, food/pharma
→ Prefer A4 (SS 316 / A4-70) for better pitting & crevice corrosion resistance.
Cost-sensitive and non-critical, mild atmosphere
→ SS 202 can be used but:
Lower corrosion resistance than 304/316
Not recommended near coastal / chemical exposure
3. Head Style & Countersink Details
Flat CSK (plain countersunk) – standard choice
Sits flush with surface when countersink is correct
Typically 90° head angle (check if mating countersink is also 90°)
Raised / oval CSK (if specified)
Slight domed top left visible
Used where a more decorative look is needed
Check before choosing:
Is the mating hole countersunk?
Is the countersink angle (90°) matching the screw head?
Is there enough material thickness to create a proper countersink without weakening the part?
Mechanical Properties (Guide)
Mechanical Properties (Guide) – SS CSK Slotted Head Screws
Most SS CSK slotted machine screws are supplied in austenitic stainless steel (A2/A4) with strength class similar to bolts but often not used at their extreme limits. Typical values:
1. A2-70 (SS 304) – Common Standard
Material: A2 (approx. SS 304)
Strength class: 70
Minimum tensile strength: ~700 MPa
Minimum proof (yield) strength: ~450 MPa
Hardness: ~210 HB max (approx., depends on size & standard)
Service temperature: up to ~300°C continuous (non-pressure critical applications)
Corrosion resistance:
Good in general atmosphere, fresh water, many industrial environments
Not ideal for strong chloride/marine conditions
2. A4-70 (SS 316) – Higher Corrosion Resistance
Material: A4 (approx. SS 316)
Strength class: 70
Minimum tensile strength: ~700 MPa
Minimum proof strength: ~450 MPa
Corrosion resistance:
Excellent in marine, coastal, chloride, mild chemical atmospheres
Better pitting/crevice resistance than A2
3. A4-80 (Where Available – For More Demanding Joints)
Material: A4 (SS 316)
Strength class: 80
Minimum tensile strength: ~800 MPa
Minimum proof strength: ~600 MPa
Used where slightly higher clamp load is required and corrosion resistance is critical.
For slotted CSK screws, this grade is less common due to drive limitations – torque may not fully utilize the higher strength.
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Frequently Asked Questions
What is an SS CSK slotted head screw?
It’s a stainless steel countersunk screw with a flat (CSK) head and a straight slot for a regular screwdriver.
The head sits flush with the surface after countersinking, giving a neat, flat finish.
Where are CSK slotted screws commonly used?
They are typically used in:
Electrical panels and control boxes
Name plates and cover plates
Door and window fittings
Light machinery covers and guards
Decorative or visible assemblies where a flush finish is required
What’s the advantage of a countersunk (CSK) head?
The head sits flush or slightly below the surface
No projection → safer, cleaner look
Good for moving parts around it (no interference)
Better aesthetics for visible fittings
What materials/grades are commonly used?
Most common:
A2 (SS 304), class A2-70 – general purpose, indoor/outdoor use
A4 (SS 316), class A4-70 – marine, coastal, chemical, food/pharma
Sometimes SS 202 for non-critical, cost-sensitive applications
What standards apply to CSK slotted screws?
Typical standards (for machine screws):
DIN 963 – Slotted countersunk flat head screws (metric)
ISO 2009 – Metric equivalent of slotted CSK screws
Your drawing may specify DIN / ISO / IS / BS – always match the standard asked by the customer.
