Material Selection for Custom Screws

Material selection should be reviewed together with screw geometry, forming requirements, mechanical performance, corrosion environment, operating temperature, surface finish and documentation requirements. Please provide the drawing and application conditions so that suitable material options and the corresponding manufacturing route can be evaluated.

Strength & Hardness

Corrosion Resistance

Manufacturing Process

Cost & Availability

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Common Screw Materials Overview

Material Category	Grades & Conditions	Key Properties
Austenitic Stainless Steel	SUS302HQ / SUS XM7, SUS304HC, SUS304, SUS316Cu, SUS316, SUS316L, SUS303Cu	Corrosion-resistant; suitable for cold heading or machining.
Hardenable / Martensitic Stainless Steel	SUS410, SUS420J2, SUS431, SUS440C	Magnetic; hardness, strength and wear resistance can be increased through heat treatment.
Ferritic Stainless Steel	SUS430	Magnetic and corrosion-resistant; cannot be significantly hardened through heat treatment.
Special Stainless Steel	SUS310, SUS321 / AISI 321, 17-4PH / SUS630	Heat resistance, stabilization or precipitation hardening, depending on grade.
Carbon & Alloy Steel	1006A, 1008A, 1010, 1018, 1022, 10B21, SCM435	Cost and strength options for cold heading and heat treatment.
Free-Machining Steel	1214, 1215	Good machinability for turned screws and CNC-machined features.
Medium-Carbon Steel	45# to the applicable GB specification, AISI 1045	Higher strength and hardness after appropriate heat treatment.
Copper & Copper Alloys	H59, H62, H65, H68, H70, HPb59-1, HPb59-2, Pure Copper, Phosphor Bronze, Beryllium Copper, SAE 841 / ASTM B438 Oil-Impregnated Bronze	Conductivity, formability, machinability, elasticity, wear resistance or self-lubricating performance, depending on the selected material.
Titanium	Grade 1 / GR1 / TA1, Grade 2 / GR2 / TA2, Grade 5 / GR5 / TC4	Lightweight, corrosion-resistant and high strength-to-weight ratio.
Aluminum	1100, 6061, 6061-T5, 6061-T6, 6063, 6063-T5, 6063-T6, 7075, 7075-T5, 7075-T6	Lightweight, machinable and compatible with anodizing.
High-Performance Alloys	A286 / UNS S66286 / SUH660, MP35N	High strength, corrosion resistance and elevated-temperature performance.

The materials listed are starting points for project review, not interchangeable specifications or a stock-availability guarantee. Confirm the exact grade, material certificate, wire diameter, manufacturing route, quantity and delivery schedule before ordering.

Austenitic Stainless Steel Grades for Custom Screws

Cold Heading Optimized Grades

SUS302HQ

Evaluated for cold-headed custom screws. Confirm the material designation, certificate, head deformation, wire condition and tooling requirements for the specific design.

SUS304HC

304 series wire optimized for cold heading, balancing formability and general corrosion resistance.

SUS316Cu

Copper added to improve cold heading performance, suitable for products requiring 316-level corrosion resistance and significant head deformation.

Corrosion & High-Temperature Grades

SUS304

General-purpose corrosion-resistant stainless steel, suitable for indoor, general outdoor, and equipment connections.

SUS316

Contains molybdenum, pitting and chloride resistance generally superior to 304.

SUS316L

Low-carbon 316-series material. Suitability for welding-related, chemical or corrosive conditions is evaluated from the material certificate, surface condition and service requirements.

SUS310

High chromium-nickel heat-resistant stainless steel, suitable for high-temperature environments; specific working temperature needs confirmation based on load and medium.

Machining / Turning Grades

SUS303Cu

Primarily evaluated for turning or limited forming. Material composition, certificate and the proposed manufacturing route must be confirmed; SUS303Cu is not grouped with cold-heading-optimized grades.

Food-contact projects can be evaluated with 304 or 316 based on the applicable material certificate, surface condition, cleanliness and customer or regulatory requirements.

Engineering Review: Material, Geometry and Forming Route

Review the material certificate, wire condition, head geometry, forming deformation and tooling plan together. The proposed grade and route must be validated against the drawing and inspection requirements before production. Operating temperature limits require project-specific confirmation of the standard, load and service environment.

Understanding A2 and A4 Fastener Markings

Marking	Explanation
A2-50	A2 austenitic stainless steel group, min tensile strength 500 MPa
A2-70	A2 austenitic stainless steel group, min tensile strength 700 MPa
A2-80	A2 austenitic stainless steel group, min tensile strength 800 MPa
A4-70	A4 molybdenum-containing austenitic stainless steel group, min tensile strength 700 MPa
18-8	Common term for 18% chromium, 8% nickel type stainless steel, does not represent a specific grade or strength.

Purchasing Tip: When an exact chemical grade is required, specify SUS304, SUS316, SUS316L or another applicable standard instead of relying only on A2, A4 or 18-8 markings.

Specialty Stainless Steels and Alloys

Grade	Heat Treatment & Capability	Key Applications
410	Quenchable and temperable	Self-tapping screws, wear-resistant and higher strength connections
440C	Can achieve very high hardness	High wear-resistance, high-hardness precision parts
17-4PH	Precipitation hardening stainless steel	High-strength, precision equipment, aerospace and energy components
A286	High-temperature precipitation strengthening alloy	High-temperature fasteners, engines and energy equipment

Note: The appropriate heat-treatment route and achievable mechanical properties depend on the exact grade and material condition. Confirm tensile strength, hardness, core properties and finished-part acceptance requirements before production.

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Carbon & Alloy Steel Selection

Review the target property class, screw dimensions, manufacturing route and heat-treatment requirements together. The exact steel grade is confirmed per project; a material designation alone does not guarantee the finished fastener class.

Target Requirement	Material Selection Basis	Engineering Notes
General 4.8 class connection	Carbon steel grade and wire condition subject to review	Confirm the applicable standard, screw dimensions, forming route and mechanical acceptance criteria
6.8 class requirement	Grade selected against the required finished-part properties	Confirm production route and validate mechanical properties by the agreed finished-product tests
Stable 8.8 class requirement	Suitable steel grade and heat-treatment condition evaluated by design	Review core and surface requirements, part dimensions, distortion risks and testing plan
10.9 / 12.9 class requirement	High-strength steel selection subject to engineering confirmation	Confirm the standard, grade, heat treatment, coating route and hydrogen-embrittlement risk controls
CNC Secondary Machining	Grade and preform condition matched to the required features	Evaluate forming feasibility, machining features, tolerances, material composition and strength requirements
Long screw 8.8 class	Special order wire	Requires individual assessment based on length, diameter, and heat treatment distortion risk

Trilobular Thread-Forming Screws

Heat treatment is generally recommended for trilobular thread-forming screws. Material grade, case hardness, core hardness and penetration depth should be confirmed according to the mating material and installation torque.

Hydrogen Relief Baking

For heat-treated high-strength steel fasteners, post-plating hydrogen relief baking should be evaluated after zinc, nickel or zinc-nickel electroplating to reduce the risk of hydrogen embrittlement.

Copper & Copper Alloys; Lightweight Metals: Titanium and Aluminum

Evaluate copper and copper alloys for conductivity, thermal performance and corrosion requirements. Titanium and aluminum offer lower-density options for weight-sensitive assemblies; copper is not classified as a lightweight material.

Copper & Copper Alloys

Known for excellent electrical conductivity, thermal conductivity, and corrosion resistance.

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Electrical Requirements: Provide the conductivity target, mating materials and contact conditions for material review.
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Copper: Confirm the grade, purity and material certificate against the required electrical and thermal performance.
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Copper Alloys: Specific alloy availability, forming route and mechanical properties require project confirmation.
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Finish and Assembly: Review corrosion exposure, surface treatment, dimensions and contact requirements together.

Titanium

A lower-density option for weight-sensitive assemblies. Review the selected grade against strength, corrosion exposure, operating temperature and assembly requirements.

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Grade Selection: Confirm the exact titanium grade, applicable standard and material certificate before quotation.
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Manufacturing Route: Evaluate the screw geometry, forming requirements, CNC secondary machining needs and finished-part verification plan together.

Aluminum

Lightweight and highly machinable, frequently used in electronics, instruments, and lightweight assemblies.

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Grade Selection: Confirm the exact aluminum grade against the drawing, strength and corrosion requirements.
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Material Condition: Review the specified temper, forming feasibility, CNC secondary machining and dimensional requirements.
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Surface Finish: Evaluate anodizing requirements, coating thickness, color and assembly fit for the selected grade.

Material Weight Comparison

For screws with the same geometry and dimensions, aluminum screws typically weigh approximately 34%–36% as much as carbon steel screws, while titanium screws typically weigh approximately 56%–58% as much as carbon steel screws.

Lower density can reduce overall assembly weight, but screw material selection should also consider strength, corrosion resistance, operating temperature, manufacturability, surface finish and cost. Density values are approximate and vary by grade.

Material	Typical Density
Pure Copper	Approx. 8.96 g/cm³
Brass	Approx. 8.4–8.7 g/cm³
Stainless Steel	Approx. 7.7–8.0 g/cm³
Carbon Steel	Approx. 7.85 g/cm³
Titanium	Approx. 4.43–4.51 g/cm³
Aluminum	Approx. 2.70–2.81 g/cm³

Material and Surface Finish Combinations

The performance of a screw is not determined by material alone. The following finish options require review of the exact grade, pretreatment, adhesion, coating thickness, dimensional tolerances and service environment, followed by sample validation where required.

Explore Surface Finishes

Carbon / Alloy Steel

Options for Review: Zinc-Nickel Alloy, Dacromet, Gold Plating, Bronze Plating, Electrophoresis.

* High-strength fasteners require hydrogen-embrittlement risk and process review, including applicable pretreatment, plating, baking and verification requirements.

304 / 316 Stainless Steel

Options for Review: Gold Plating, QPQ, PVD, Silver Plating, Strike Nickel, Electrophoresis, Electropolishing, Sandblasting. Confirm compatibility with the exact grade, pretreatment, adhesion and dimensional requirements.

410 Stainless Steel

Treatment Options for Review: Dacromet, Vacuum Hardening, Electrophoresis, High-Temperature Blackening. The heat-treatment and finishing sequence is confirmed for each project.