302HQ Cold Heading Wire with Copper for Low Work Hardening
302HQ cold heading wire
,copper-bearing stainless steel wire
,low work hardening heading wire
302HQ Cold Heading Wire with Copper for Lower Work Hardening
Product Introduction
Every cold heading blow hardens the metal a little more. On a part formed in four or five stations, the accumulated work hardening at the head can be the difference between a clean form and a split.
302HQ carries a deliberate copper addition that lowers the work hardening rate of the austenitic structure. The wire starts at a softness comparable to 304 but gains strength more slowly as it passes through the stations, so the last blows still act on ductile metal.
Available from 0.15 mm to 12 mm, soft annealed or spheroidize annealed, bright or soap coated.
Product Specifications
| Parameter | Specification |
|---|---|
| Grade | 302HQ, XM-7 type |
| Copper Content | 1.5–3.0%, typical |
| Carbon | ≤ 0.08% |
| Chromium | 17–19% |
| Nickel | 8–10% |
| Diameter Range | 0.15–12 mm |
| Diameter Tolerance | ±0.02 mm up to 2.0 mm; ±0.03 mm above 2.0 mm |
| Delivery Condition | Soft annealed or spheroidize annealed |
| Tensile Strength | 550–700 MPa, annealed condition |
| Hardness | ≤ 85 HRB, annealed condition |
| Surface | Bright or soap coated |
| Coil Weight | 100–500 kg |
| Reference Standard | ASTM A493, EN 10263-5 |
What Copper Does in 302HQ
Lower Work Hardening Rate
Copper in solid solution changes how dislocations multiply as the metal deforms. The practical result is a flatter strength curve through the forming sequence: the same number of blows adds less strength than it would in a standard 304.
Ductility Retained Through the Sequence
Because strength rises more slowly, the metal arriving at the last station still has elongation left. That is where head splits and fold-over cracks usually appear on long sequences, and it is the point 302HQ is chosen to protect.
Effect on Corrosion and Magnetism
Copper improves resistance to some reducing acid environments and does no harm to normal atmospheric corrosion at these levels. Like any cold worked austenitic wire, 302HQ becomes slightly magnetic after heavy deformation; copper does not remove that, it only changes how quickly strength builds.
Where 302HQ Fits Against 304
Multi-Station Headers
Parts formed in four or more blows, where each station adds strain and the last one decides the reject rate.
Parts with Severe Head Upsetting
Socket head screws, large head-to-shank ratios, and parts with a deep recess that needs metal to flow rather than tear.
When 304 Is Still the Right Choice
For two-blow parts, light forming, or applications where corrosion resistance matters more than formability, standard 304 or 304Cu may be the more economical route.
Annealing and Delivery Condition
Soft Annealed
Recrystallized and cooled to a uniform soft condition, suitable for most heading operations and easier to straighten.
Spheroidize Annealed
Carbides taken to a spheroidal form, which lowers hardness further and gives the best ductility for the most severe deformation ratios.
Applications
Socket Head and Recessed Screws
Deep recess forming where metal has to flow into a cavity without splitting at the rim.
Bolts and Large Head Fasteners
Heavy head upsetting on two- and three-blow headers, including parts with a wide bearing face.
Cold-Formed Components with Long Sequences
Parts that pass through four or more stations and need ductility at the end of the run rather than only at the beginning.
Product Advantages
- Copper addition lowers the work hardening rate, so the last forming station still meets ductile metal.
- Soft annealed and spheroidize annealed conditions available, matched to the deformation ratio of your part.
- Copper content stated as a range on the certificate, so the forming behaviour is traceable per lot.
- Diameter tolerance of ±0.02 mm up to 2.0 mm keeps die clearance and cut-off length consistent.
- Runs on the same heading equipment as 304, without changing tooling geometry.
Quality Control
Chemical composition by optical emission including copper, tensile strength and hardness, diameter and ovality, surface condition, plus an upsetting test where the part requires it. A mill test certificate 3.1 is issued with each shipment.
Selection and Ordering Notes
- State the number of forming stations and the head-to-shank ratio, so the annealing condition can be matched to the strain.
- Confirm whether soft annealed or spheroidize annealed is required for your deformation level.
- State the corrosion environment, since copper content is chosen for formability and not as a substitute for molybdenum.
- Give the diameter and tolerance class needed for your die clearance.
- For parts with a deep recess, mention the recess depth so we can advise on the annealed condition.
Send your part drawing and forming sequence, and we will match the annealing condition and copper range to the strain your header applies.
