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Screws · DIN 7985 / ISO 7045 and EN ISO 10644

Property Class 8.8 Steel SEMS Screws with Captive Flat Washers

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

Property Class 8.8 Steel SEMS Screws with Captive Flat Washers are supplied to ISO 898-1 property class 8.8. Corrosion behaviour is requires plating (zinc) for corrosion protection, the material is magnetic, and the usable service range is commonly limited to approx. +300 °C; confirm against the coating and the load. In practice this grade is the workhorse medium-carbon alloy class for structural joints.

Grade
ISO 898-1 property class 8.8
Corrosion resistance
Requires plating (zinc) for corrosion protection
Magnetic response
Magnetic
Service temperature
commonly limited to approx. +300 °C; confirm against the coating and the load

Property values are typical for the grade. Certified mechanical test data is available on request for production orders.

Property Class 8.8 Steel SEMS Screws with Captive Flat Washers reference image

SEMS Screws with Captive Flat Washers manufactured in Property Class 8.8 Steel (ISO 898-1 property class 8.8) are dimensioned to DIN 7985 / ISO 7045 and EN ISO 10644. The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.

Why Choose Property Class 8.8 Steel for SEMS Screws with Captive Flat Washers

The workhorse medium-carbon alloy class for structural joints. For sems screws with captive flat washers, this matters when requires plating (zinc) for corrosion protection is the primary requirement.

Mechanical & Physical Properties

Grade designationISO 898-1 property class 8.8
Magnetic responseMagnetic
Service temperaturecommonly limited to approx. +300 °C; confirm against the coating and the load
Corrosion characteristicRequires plating (zinc) for corrosion protection

Corrosion Behavior in Service

Carbon and alloy steel sems screws with captive flat washers require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.

Comparable Grades

For SEMS Screws with Captive Flat Washers, class 10.9 or 12.9 is the comparable strength step. Move up when the joint preload approaches the proof load of the current class; move down when the joint is over-specified. For corrosion-critical service, switch to stainless A2 or A4.

Sizes of SEMS Screws with Captive Flat Washers Available in Property Class 8.8 Steel

Thread sizePitch (mm)Washer outside diameter (mm)Washer thickness (mm)Property/material optionsDriveReference standard
M2.50.4560.6steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M30.570.6steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M40.790.8steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M50.8101.0steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M61.0121.6steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M81.25162.0steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Sends the selected values to the quote form below.

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Specification
Business Information

Dimensions & Specifications (DIN 7985 / ISO 7045 and EN ISO 10644)

Thread sizePitch (mm)Washer outside diameter (mm)Washer thickness (mm)Property/material optionsDriveReference standard
M2.50.4560.6steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M30.570.6steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M40.790.8steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M50.8101.0steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M61.0121.6steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M81.25162.0steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644

Applications & Industries

Where SEMS Screws with Captive Flat Washers are used, and what decides the specification in each case. Stocked from M2.5 to M8.

Industries that specify SEMS Screws with Captive Flat Washers

  • Electrical assembly Captive flat-washer screws for panels, terminals and equipment covers.
  • Appliance production High-volume screwdriving where a separate washer would slow assembly.
  • Sheet-metal enclosures Removable covers that must retain the washer on the screw.
  • Machine guarding Service hardware that stays with the cover during removal.
  • Steel fabrication Bolted connections in frames, enclosures, walkways and weldments, on the bench and on site.
  • Energy & infrastructure Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints.

Typical applications

  • combining the screw and flat washer into one captive assembly
  • spreading bearing load while preventing washer loss during service
  • using a Phillips drive for controlled production installation
  • selecting the washer outside diameter and thickness with the thread size
  • clamping two machined faces to a calculated preload
  • bolting brackets, motors and gearboxes to a frame

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 the captive washer for a hardened structural washer in a high-preload joint.
  • 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 SEMS Screws with Captive Flat Washers are used, how to specify them, and the cases they are wrong for

Video: Property Class 8.8 Steel SEMS Screws with Captive Flat Washers

Third-party video, selected automatically for this topic. It is not produced by Engineering Hardware and is not a specification source — use the tables on this page for dimensional data.

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
    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
    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
    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
    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 Property Class 8.8 Steel SEMS Screws with Captive Flat Washers magnetic?

Property Class 8.8 Steel SEMS Screws with Captive Flat Washers are magnetic.

What corrosion resistance do Property Class 8.8 Steel SEMS Screws with Captive Flat Washers offer?

Property Class 8.8 Steel SEMS Screws with Captive Flat Washers provide requires plating (zinc) for corrosion protection with a service range of commonly limited to approx. +300 °C; confirm against the coating and the load.

When should I move from ISO 898-1 property class 8.8 to class 10.9 / 12.9 for SEMS Screws with Captive Flat Washers?

Step up to class 10.9 / 12.9 when the joint preload approaches the proof load of the current class. The higher class adds preload at the same diameter, often saving size and weight.

Is Property Class 8.8 Steel prone to hydrogen embrittlement?

Class 10.9 and above can be susceptible to hydrogen embrittlement when electroplated. Specify post-plating baking, or use mechanical-zinc / zinc-flake finishes which avoid the cathodic plating step.

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.