D6AC, UNS K24728 is a medium carbon low alloy steel which improved hardenability as compared to 4340 low alloy steel, and with a carbon content of 0.42 to 0.48%. The hardenability of this alloy is better than that of AISI 4340 and D6AC can be heat treated to strengths ranging from 180 to 260 ksi, D6AC alloy is a medium-carbon low-alloy ultra high strength steel that was primarily developed for high strength structural applications requiring ultimate tensile strength values up to 280 ksi. The steel has a high yield to ultimate strength ratio, while retaining good ductility. It has good hardenability and excellent impact strength down to –210ºF (-134ºC.). This alloy has very high strength and offers excellent notch toughness. D6AC has excellent deep hardening characteristics which lend itself well to larger components. This grade is also widely used in the aerospace industry as landing gear, shafts, and axles requiring a good combination of toughness and strength.
| Grade | Chemical Composition WT % | ||||||
| C | Si | Mn | Cr | Ni | Mo | V | |
| D-6AC Vac Melt N&T | 0.46 | 0.25 | 0.75 | 1.10 | 0.60 | 1.00 | 0.10 |
| Material | Tempering Treatment | Ultimate Tensile Strength (Mpa) | 0.2 % Yield Strength (Mpa) | % Elongation | % Reduction of Area | Hardness HRC |
| LESCALLOY D6AC VAC ARC ® | 316°C (600°F) | 1931 | 1724 | 7 | 23 | 53 |
| LESCALLOY D6AC VAC ARC ® | 510°C (950°F) | 1572 | 1345 | 7 | 25 | 46 |
The alloy is weldable, even in heavy sections. Preheat and postheat treatments are applicable here for the carbon content in question.
The alloy D6AC has a machinability rating 50-55 percent of that of B1112 screw stock. Either high speed steel or carbide cutting tools are recommended.
| Grade | Shape | Dimensionmm | Qty.kg |
|---|---|---|---|
| D6AC | Tube | 185.00 x 18.00mm | 2.768 |
Steel grade
Special steel