420 (S42000) | BYBOLT

What is 420 stainless steel and its applications?

420 stainless steel (UNS S42000) is a hardenable martensitic grade used where hardness and wear resistance are important. Its mechanical properties depend strongly on carbon content and heat treatment, making an exact specification particularly important for threaded components.

Wear components: Parts requiring a defined hardened surface or section.
Precision mechanisms: Machined parts balancing hardness, finish and dimensional control.
Special tooling: Components whose wear requirements justify a martensitic stainless grade.

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Choose your 420 product

Engineering Application & Selection Guide

Carbon supports higher attainable hardness than the basic 410 grade after suitable hardening and tempering. Higher hardness alone does not establish the ductility, notch tolerance or fatigue performance required of a fastener.

420 set screws — For a point or contact feature, define the point geometry and permissible indentation as well as hardness.
420 socket head cap screws — For a special drawing, check socket and thread-root stresses before adopting a high-hardness condition.
420 custom fasteners — Where one part includes a wear face and a threaded shank, specify the acceptance requirements for each feature.

Compare 410 if the required wear performance can be met with a different strength-ductility balance. Commercial 420 descriptions may cover different carbon levels; establish the exact governing composition and condition rather than substituting on the name alone.

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420 Composition

Selected typical composition · wt.%

ElementWeight %

Cr: 13%
C: 0.20%

ASTM / ASME specifications by product form

Finished-product requirements

Specify the finished-fastener mechanical requirements, condition and inspection separately from the starting-stock specification.

420 hex bolt requirements ↗

Fasteners · dimensional references

Product	Reference
Hex bolts	ISO 4014 / ISO 4017 · ASME B18.2.1
Threaded studs	DIN 976-1 · ASME B18.31.2
Hex nuts	ISO 4032 · ASME B18.2.2
Socket head screws	ISO 4762 · ASME B18.3
Flat washers	ISO 7089 / ISO 7090 · ASME B18.21.1
Custom fasteners	Customer drawing

Raw-material specifications

Product form / scope	Reference
Product-form-specific reference · Select the applicable part and product condition.	EN 10088

Dimensions do not define material or finished-part compliance. Specify the grade, condition and applicable requirements.

How to specify round bar, plate, wire and strip ↗

420 Mechanical Properties

Reference sample and condition

Data basis: Producer typical reference
Test sample form: Rod
Condition: Annealed
Test temperature: Room temperature
Gauge length: A5

Key properties	Value
Tensile strength	650 MPa
0.2% yield strength	500 MPa
Elongation	20%

Outokumpu · Stainless Steel Handbook · Tables 2:1, 2:2, 7:5 & 7:6 · PDF pages 52–53 for tensile values; hosted by SCI ↗

Procurement and application guide

Specify the material and final condition

Specify hardness, heat treatment and section size.

Material forms in the technical reference: Rod & bar.

Define the finished-part acceptance

Include the material or bolting specification, required final condition, dimensions and quantity. State the service medium, temperature and loading where known. Agree the required tests, inspection coverage and acceptance criteria for the finished part.

Start with the information you have

Send a drawing or share the product form and dimensions. Identify any undecided requirements for review rather than copying a typical property value into the purchase order.

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