---
title: "A4 (316) Stainless Steel PEEK Engineering Plastic Micro Countersunk Screws"
description: "A4 (316) Stainless Steel PEEK Engineering Plastic Micro Countersunk Screws (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80): superior, including"
url: https://engineeringhardware.com/guide/material/a4-stainless-steel-peek-engineering-plastic-micro-countersunk-screws/
source: Engineering Hardware & Fasteners
---

# A4 (316) Stainless Steel PEEK Engineering Plastic Micro Countersunk Screws

Screws · Trade series (PEEK micro screws)

Mechanical properties, corrosion behaviour and the full dimensional range for this grade.

A4 Stainless Steel PEEK Engineering Plastic Micro Countersunk 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.

![A4 (316) Stainless Steel PEEK Engineering Plastic Micro Countersunk Screws reference image](https://engineeringhardware.com/wp-content/uploads/2026/09/PEEK-RENY-Plastic-Micro-Countersunk-Screws.webp)

A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) is specified for marine, coastal and chemical applications. Specified on peek engineering plastic micro countersunk screws it determines the corrosion behaviour (superior, including marine and chloride environments) and the service temperature range (approx. -200 °C to +400 °C, subject to the property class and the joint); the dimensions are ours rather than a standard's, and are listed in full below.

## Why Choose A4 Stainless Steel for PEEK Engineering Plastic Micro Countersunk Screws

Specified for marine, coastal and chemical applications. For peek engineering plastic micro countersunk 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 |
| --- | --- |
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Superior, including marine and chloride environments |

## Corrosion Behavior in Service

A4 (316) adds 2–3% molybdenum to the A2 (304) composition, which dramatically improves resistance to chloride-pitting corrosion. For PEEK Engineering Plastic Micro Countersunk Screws in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.

## Galvanic & Galling Considerations

Two important notes for stainless peek engineering plastic micro countersunk screws: (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.

## Using Stainless Fasteners in Aluminum

Expect the aluminum to corrode, not the fastener — stainless sits higher in the galvanic series, so the aluminum is the one that gives up material. A small fastener in a thick section spreads the loss over a large area and is usually fine; a large fastener in thin sheet concentrates it and is not. Keep water out of the joint, or isolate the two metals with a nylon or coated washer and a sealant.

## Sizes of PEEK Engineering Plastic Micro Countersunk Screws Available in A4 Stainless Steel

| Thread size | Example length (mm) | Head diameter (mm) | Drive | Example tensile break load (N) | Example torsional break torque (Nu00b7m) |
| --- | --- | --- | --- | --- | --- |
| M1.2 | 2.5 | 2.3 | cross recess No. 0 | 58 | 0.03 |
| M1.4 |  | 2.3 | cross recess No. 0 |  |  |
| M1.6 |  | 2.3 | cross recess No. 0 |  |  |

Dimensions are independent of the material: the table above lists the sizes supplied, and on this page every one of them is quoted in A4 Stainless Steel. The catalogue's default material column has been omitted here so it cannot be read as contradicting that.

Custom manufacturing · Made to drawing

## Need this screw in a grade that is not listed?

A4 Stainless Steel is one of the grades the catalog describes. Material and finish are usually what drives a special — a grade the standard part is not stocked in, or a coating chosen against a salt-spray figure instead of a default. Made by cold heading or warm forging.

Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

[Custom screw manufacturing](https://engineeringhardware.com/custom/screws/)[Send a drawing](https://engineeringhardware.com/custom/screws/#rfq)

## Technical Drawing

Dimensioned line drawing of M1.2 PEEK Engineering Plastic Micro Countersunk Screws to Trade series (PEEK micro screws). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.

- **Example length (mm):** 2.5
- **Head diameter (mm):** 2.3
- **Drive:** cross recess No. 0
- **Material:** PEEK engineering plastic
- **Example tensile break load (N):** 58
- **Example torsional break torque (Nu00b7m):** 0.03

## Dimensions & Specifications (Trade series (PEEK micro screws))

| Thread size | Example length (mm) | Head diameter (mm) | Drive | Material | Example tensile break load (N) | Example torsional break torque (Nu00b7m) |
| --- | --- | --- | --- | --- | --- | --- |
| M1.2 | 2.5 | 2.3 | cross recess No. 0 | PEEK engineering plastic | 58 | 0.03 |
| M1.4 |  | 2.3 | cross recess No. 0 | PEEK engineering plastic |  |  |
| M1.6 |  | 2.3 | cross recess No. 0 | PEEK engineering plastic |  |  |

Product catalog

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## Applications & Industries

PEEK Engineering Plastic Micro Countersunk Screws are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from M1.2 to M1.6.

### Industries that specify PEEK Engineering Plastic Micro Countersunk Screws

- **Prototype assemblies:** Countersunk plastic screws avoid a metal head near the component.
- **Insulated electronics:** Engineering-plastic screws provide a nonconductive threaded joint in a compact package.
- **Vacuum and analytical equipment:** Low-outgassing plastic is used around sensitive instruments.
- **Chemical equipment:** PEEK resists service environments where ordinary metal hardware may be unsuitable.
- **Automotive & transport:** Chassis, driveline and body fixings that see vibration and are assembled to a controlled preload.
- **Steel fabrication:** Bolted connections in frames, enclosures, walkways and weldments, on the bench and on site.

### Typical applications

- using the 90-degree head seat and No. 0 recess
- providing electrical insulation with a miniature countersunk screw
- checking the documented break loads instead of borrowing metal-screw torque
- matching the plastic screw to the parent thread without over-driving it
- 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 substitute metal-fastener torque for the plastic break-torque example; over-driving can fracture the screw.
- 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 PEEK Engineering Plastic Micro Countersunk Screws are used, how to specify them, and the cases they are wrong for](https://engineeringhardware.com/applications/peek-engineering-plastic-micro-countersunk-screws/)

Inside the plant

## Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

1. ![Wire rod feeding into a cold heading machine](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 01 **Cold heading** Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail. Head dimensions and under-head radius checked at set-up and per shift.
2. ![Thread rolling machine producing bolt threads](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 02 **Thread rolling** Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch. Go / no-go ring gauges to ISO 965 tolerance class 6g.
3. ![Baskets of bolts staged for heat treatment](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 03 **Heat treatment** Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it. Core hardness and tensile tested per lot to ISO 898-1.
4. ![Zinc plated bolts in a treatment basket](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 04 **Surface treatment** Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list. Coating thickness and neutral salt spray hours to ISO 9227.

## Frequently Asked Questions

### Are A4 Stainless Steel PEEK Engineering Plastic Micro Countersunk Screws magnetic?

A4 Stainless Steel PEEK Engineering Plastic Micro Countersunk Screws are largely non-magnetic.

### What corrosion resistance do A4 Stainless Steel PEEK Engineering Plastic Micro Countersunk Screws offer?

A4 Stainless Steel PEEK Engineering Plastic Micro Countersunk Screws provide superior, including marine and chloride environments with a service range of approx. -200 °C to +400 °C, subject to the property class and the joint.

### Should I choose A4 Stainless Steel or A2 (304) for PEEK Engineering Plastic Micro Countersunk Screws?

For PEEK Engineering Plastic Micro Countersunk Screws, A4 Stainless Steel suits general indoor and outdoor use; A2 (304) is preferred for marine, coastal and chemical environments. Choose by corrosion exposure first.

### Can A4 Stainless Steel PEEK Engineering Plastic Micro Countersunk Screws gall during installation?

Yes — stainless on stainless is prone to thread galling under load, especially at smaller sizes. Use an anti-galling lubricant or wax thread compound, and slow the tightening rate where possible.

### How do I request a quotation?

Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.

## Related Pages

[View the full PEEK Engineering Plastic Micro Countersunk Screws page](https://engineeringhardware.com/fastener/peek-engineering-plastic-micro-countersunk-screws/)

### More PEEK Engineering Plastic Micro Countersunk Screws Guides