Understanding the DIN EN Designation System
DIN EN 1.4462, 1.4410, 1.4501 and 1.4507 are duplex and super duplex stainless steel designations used across multiple DIN, EN and ISO standards. DIN standards are largely incorporated into Euronorm (EN) standards for adoption beyond Germany, which is why the same grades are specified as material numbers such as 1.4462 and as UNS numbers such as S32205 depending on the governing standard. Duplex stainless steels combine a ferritic and austenitic microstructure, giving high strength and excellent chloride corrosion resistance.
DIN EN 1.4462: The Workhorse 22% Cr Duplex
DIN EN 1.4462 equates to UNS S31803, corresponding to ASTM A182 F51, and UNS S32205, corresponding to ASTM A182 F60. S31803 was the original designation for a 22% chromium duplex stainless steel; manufacturers later optimized the composition toward the top of the limits to improve pitting corrosion resistance, and this tighter specification is designated UNS S32205. Consequently, S32205 can be dual-certified as S31803, but not vice versa. This grade accounts for about 80% of overall duplex stainless steel production and is supplied in solid bars from about 12 mm up to 450 mm diameter, plus hollow bars and plate.
DIN EN 1.4410: The 25% Cr Super Duplex
DIN EN 1.4410 equates to UNS S32750, corresponding to ASTM A182 F53. This is the 25% chromium super duplex grade most widely promoted in the industry. With increased chromium content compared with 1.4462, it offers improved pitting corrosion resistance, and its higher yield strength allows component designers to reduce section size for load-bearing applications. Solid bars are commonly stocked from about 12 mm to 16 inches diameter.
DIN EN 1.4501: Tungsten-Bearing Super Duplex
DIN EN 1.4501 equates to UNS S32760, corresponding to ASTM A182 F55. It is another super duplex stainless steel based on a 25% chromium composition, but with an addition of tungsten, which further enhances corrosion resistance in chloride-bearing environments. It is widely used in offshore oil and gas, seawater handling and chemical processing, and is available in solid bars and plate.
DIN EN 1.4507: The High-Strength Copper-Bearing Grade
DIN EN 1.4507 equates to UNS S32550, corresponding to ASTM A182 F61. Compared with F53 and F55, it delivers increased strength and corrosion performance: its minimum yield strength exceeds 85 ksi, whereas other grades are typically limited to 80 ksi. In addition, it contains up to 2.0% copper, which aids pitting corrosion resistance. It has provided more than 50 years of successful service in a wide range of demanding applications since its introduction in 1969, and is available in solid bars from about 16 mm to 14 inches diameter plus plates up to 3 inches thickness.
Other Duplex Grades and Selection Notes
A number of other duplex stainless steels exist, such as lean duplex DIN EN 1.4362, corresponding to UNS S32304, and hyper duplex DIN EN 1.4658, corresponding to UNS S32707. Lean duplex grades offer economy with moderate corrosion resistance, while hyper duplex grades extend the envelope to the most aggressive chloride environments; these products are mostly supplied as tubes and are less readily available from stock. When selecting a duplex grade, confirm the UNS number, the governing ASTM or EN standard, the required product form and the chloride and temperature conditions of the service.
FAQ
Q: What does DIN EN 1.4462 correspond to?
A: It equates to UNS S31803 (ASTM A182 F51) and UNS S32205 (ASTM A182 F60), the 22% chromium duplex grades accounting for about 80% of duplex production.
Q: What is the difference between S31803 and S32205?
A: S32205 is a tightened composition optimized toward the top of the limits for better pitting resistance; S32205 can be dual-certified as S31803, but not vice versa.
Q: What is DIN EN 1.4410?
A: It equates to UNS S32750 (ASTM A182 F53), the 25% chromium super duplex grade with improved pitting resistance and higher yield strength.
Q: What makes 1.4501 different from 1.4410?
A: DIN EN 1.4501 (UNS S32760, F55) is also a 25% chromium super duplex but adds tungsten for enhanced corrosion resistance in chloride environments.
Q: What is special about DIN EN 1.4507?
A: It equates to UNS S32550 (F61) with a minimum yield strength above 85 ksi and up to 2.0% copper, giving increased strength and pitting corrosion resistance.
Q: What are lean and hyper duplex grades?
A: Lean duplex DIN EN 1.4362 (UNS S32304) offers economy with moderate performance, while hyper duplex DIN EN 1.4658 (UNS S32707) extends performance to the most aggressive chloride environments; both are mostly supplied as tubes.
