DT4 Series Magnetic Grade Comparison
The magnetic performance ranking of DT4 pure iron grades - from highest to lowest soft magnetic performance - is:
| Grade | Coercivity Hc (A/m) ≤ | Hc Aging ΔHc (A/m) ≤ | Max Permeability μ (H/m ×10⁻³) ≥ |
|---|---|---|---|
| DT4C (Super) | 48 (≤32 A/m common) | 4.0 | 0.0151 |
| DT4E (Extra) | 48 | 4.8 | 0.0113 |
| DT4A (Advanced) | 72 | 7.2 | 0.0088 |
| DT4 (Standard) | 96 | 9.6 | 0.0075 |
Note: Many DT4C material specifications now require Hc ≤ 32 A/m for precision electromagnetic applications. Our DT4C regularly achieves Hc ≤ 30 A/m.
Chemical Composition (Typical ≤)
| Element | Value (%) | Element | Value (%) |
|---|---|---|---|
| Carbon (C) | ≤0.004 | Silicon (Si) | ≤0.03 |
| Manganese (Mn) | ≤0.20 | Phosphorus (P) | ≤0.015 |
| Sulfur (S) | ≤0.010 | Aluminum (Al) | 0.15–0.50 |
| Iron (Fe) | ≥99.9 (balance) |
Full Certificate of Analysis (COA) provided with each shipment, including detailed batch test results.
Magnetic Properties (Typical)
After standard annealing (e.g., 800‑980°C in vacuum or hydrogen atmosphere), typical magnetic performance values are:
| Parameter | Value | Test Standard |
|---|---|---|
| Coercivity (Hc) | ≤30‑32 A/m | GB/T 3656 / ASTM A341 |
| Max Permeability (μmax) | ≥0.0151 H/m | GB/T 3656 |
| Saturation Induction (Bs) | ≥2.15 T | GB/T 3656 |
Mechanical Properties
| Parameter | Cold‑Finished/As‑Drawn | Annealed/Stress‑Relieved |
|---|---|---|
| Tensile Strength (σb) | ≥400 MPa | ≥270 MPa |
| Yield Strength (σs) | ≥235 MPa | - |
| Elongation (δ5) | ≥25% | ≥25% |
| Hardness (HB) | Approx. 100‑130 | Approx. 70‑110 HV |
Available Forms & Specifications
| Parameter | Options |
|---|---|
| Diameter | 2 mm – 200 mm |
| Length | 50 mm – 6,000 mm (cut to length) |
| Shape | Round Bar, Square Bar, Flat Bar, Coil (Wire Rod) |
| Surface Condition | Black (hot‑rolled), Bright Drawn (cold‑drawn), Peeled (shaved), Polished (mirror finish), Ground |
| Tolerance | ±0.1 mm to ±0.01 mm depending on process |
| Heat Treatment | As‑rolled / As‑drawn / Annealed (recommended for best magnetics) |
Quality Assurance
Melting Route: Electro‑slag remelting (ESR) for ultra‑high purity and homogeneity
Batch Testing: Each heat is tested for full chemical composition via spectrometer and gas analysis per GB/T 223 and ASTM E1019 standards
Magnetic Testing: Routine sample testing for coercivity (Hc), permeability, and B‑H curve
Traceability: Each bar is traceable to its original heat number
Certification: Full Material Test Report (MTR) / EN 10204 Type 3.1 inspection certificate available
Packaging & Delivery
Standard Packaging: Bundled with steel strapping, wood‑frame protection, covered with waterproof material
Anti‑Rust Protection: Light oil coating or VCI paper as needed
Lead Time: 7‑10 days for stock sizes; 15‑20 days for custom dimensions
Incoterms: FOB Tianjin/Shanghai, CFR/CIF, EX‑Worx, DAP
MOQ: Negotiable (trial orders of 500‑1,000 kg available for new customers)
Frequently Asked Questions
Q: Is strict annealing required after cold working?
A: Yes. Cold working processes like drawing, grinding, or turning generate lattice defects and internal stresses that raise coercivity and reduce permeability. To achieve the specified low Hc and high μ values, proper stress‑relief annealing (typically 800‑980°C in protective atmosphere or vacuum) is essential. We can supply fully annealed bars or provide raw stock for you to anneal.
Q: What is the recommended annealing process?
A: Our customers typically use 800‑980°C in hydrogen, vacuum, or nitrogen atmosphere (heating rate ≤8°C/min up to 800°C). After holding for 2‑4 hours, furnace cooling to below 200°C prevents oxidation. We provide detailed annealing specifications with each shipment.
Q: Can you supply custom lengths?
A: Yes. We offer precision cut‑to‑length bars from 10 mm to 6,000 mm. Tolerances as tight as ±0.5 mm are available for large orders.
Q: What about rust prevention?
A: Pure iron surfaces are reactive. For short‑term storage, light oil coating is sufficient. For longer periods, we offer vacuum or moisture‑proof packaging with VCI paper.
Q: What is the surface finish?
A: Hot‑rolled bars are black with mill scale; cold‑drawn bars have a smooth, bright surface (Ra ≤ 1.6 µm); ground/polished bars can be Ra ≤ 0.4 µm. Remove any decarburized layer or surface imperfections before final magnetic assembly for best performance.
Contact Us
Request factory‑direct pricing for DT4C electromagnetic pure iron bars – high permeability, low coercivity, and consistent quality for precision magnetic components.
Your trusted China manufacturer of high‑purity soft magnetic iron.
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