Technical guide · 2026-08-14
Semi-Processed Electrical Steel
Semi-processed electrical steel is shipped before final magnetic properties are developed, transferring decarburizing or stress-relief annealing and part of the performance responsibility to the lamination manufacturer.
01
Definition and boundary
This is a processing-state category, not a lower grade of fully processed NOES; quoted mill data cannot replace validation after the purchaser's final anneal.
Reference information only: final acceptance is controlled by the ordered product specification, condition, dimensions and certified test results.
02
How the material system works
Cold work preserves strength for stamping before final annealing.
Customer annealing relieves stress and develops grain structure and magnetic response.
Atmosphere, carbon control and stack condition affect final loss.
03
Representative grades and systems
| Grade or system | Selection focus | Qualification |
|---|---|---|
| ASTM A683 semi-processed | Flat-rolled semi-processed electrical steel for purchaser finishing. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
| Low-carbon motor-lamination steel | Purchased with a defined decarburizing-anneal route. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
| Relay-quality semi-processed sheet | Magnetic response depends on final component treatment. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
04
Properties and trade-offs
Post-anneal core loss
Decarburization response
Dimensional and surface stability during annealing
05
Product forms and supply conditions
06
Applications and selection
Applications and selection
- Motor laminations with in-house annealing
- Relays and solenoids
- Cost-sensitive magnetic stampings
Properties and trade-offs
- Confirm furnace atmosphere and throughput before choosing semi-processed supply.
- Validate finished laminations, not only incoming strip.
- Budget oxidation, sticking and distortion controls into the route.
07
Fabrication, durability and inspection
Establish a qualified decarburizing or stress-relief cycle.
Control furnace dew point and stacking media.
Test representative stamped-and-annealed coupons.
08
Procurement checklist
- State incoming hardness and stamping condition.
- Define required post-anneal magnetic values and coupon route.
- Allocate annealing, coating, testing and nonconformance responsibility.
09
Standards, sources and review
Standards and designation context
- Applicable ASTM A06 electrical-steel product specification
- ASTM A664 grade-identification practice
- ASTM A976 insulating-coating classification