SHANGHAI RUICHAO INDUSTRIAL
SHANGHAI RUICHAO INDUSTRIAL
Cold rolled ultra-low carbon steel is a highly refined grade defined by an exceptionally low carbon content (typically below 0.02%), often stabilized with elements like Titanium or Niobium. This near-elimination of carbon interstitials grants it superior formability, allowing it to be deep drawn into complex shapes without aging or stretcher strains. Its excellent weldability and consistent performance make it the premium choice for demanding applications like deep-drawn automotive fuel tanks, intricate appliance components, and extra-deep drawing requirements where maximum ductility is essential.
Specification Parameters
| Parameters of Cold Rolled Ultra-Low Carbon (ULC) / Interstitial-Free (IF) Steel | ||
| Parameter Category | Key Characteristics/Values | Notes & Significance |
| Chemical Composition | C (Carbon): Very Low (< 0.005% - 0.02%) | The core defining feature. Carbon and Nitrogen are "interstitial" elements that are removed or stabilized to achieve exceptional formability. Stabilizers prevent aging for consistent properties. |
| N (Nitrogen): Very Low (< 0.004%) | ||
| Stabilizers: Ti (Titanium) and/or Nb (Niobium) added | ||
| Mechanical Properties | Yield Strength (YS): 140 - 220 MPa | Exceptionally high elongation and r-value are the key metrics, indicating superior deep drawing and stretching capability. Very low yield strength allows for easy deformation. |
| Tensile Strength (TS): 280 - 350 MPa | ||
| Elongation: 40% - 50% | ||
| r-value (Plastic Strain Ratio): 1.8 - 2.4+ | ||
| n-value (Strain Hardening Exp.): 0.22 - 0.28 | ||
| Common Grades (Examples) | ASTM A1008: DDS, EDDQ, EDDS | Grades are designated by drawing severity (e.g., Drawing Quality (DQ), Extra Deep Drawing Quality (EDDQ), Extra Extra Deep Drawing Quality (EDDS)). Higher grades have higher r-values. |
| EN 10130: DC04, DC05, DC06 | ||
| JIS G 3141: SPFE, SPFD | ||
| Microstructure | Essentially pure, clean Ferrite grain structure. | The absence of interstitial atoms (C, N) and precipitates allows dislocations to move easily, enabling the extreme ductility. |
| Key Characteristics | Non-Aging: Properties remain stable over time. | These characteristics are critical for manufacturing consistency and achieving a perfect, defect-free surface after painting in exposed applications. |
| Consistent: Highly uniform formability. | ||
| No Stretcher Strains: Eliminates Lüder's lines or fluting on surfaces. | ||
| Surface Finish | Very smooth, uniform, and pristine surface. Often certified for exposed automotive quality (O5). | The surface quality is a premium feature, making it suitable for Class-A exterior panels without imperfections. |
| Primary Application | Complex, Deep-Drawn Parts: | Used where the absolute maximum formability is required to create complex shapes without thinning or cracking. |
| Automotive exterior body panels (doors, fenders), fuel tanks, complex appliance parts, and any severely formed component. | ||
