Astm - A995 Gr4a

| Grade (UNS) | Type | PRE | Yield Strength (min) | Best For | | :--- | :--- | :--- | :--- | :--- | | | Super Duplex | >40 | 485 MPa | Seawater, high chloride, sour gas | | A995 Gr5A (J93404) | Hyper Duplex | >45 | 550 MPa | Extreme acids, ultra-high chloride | | A995 Gr1B (J92205) | Lean Duplex | ~28 | 450 MPa | General duty, lower cost than 4A | | A995 Gr2A (J93345) | Duplex (2205 equivalent) | ~35 | 450 MPa | Chemical tankers, moderate chlorides | | A351 CF8M (J92900) | Austenitic | ~24 | 205 MPa | General corrosion, not SCC resistant |

is the standard specification for cast, austenitic-ferritic (duplex) stainless steel castings intended for pressure-containing and corrosion-resistant applications. astm a995 gr4a

Due to its high strength and work-hardening rate, Gr4A is more difficult to machine than 316 stainless steel. Use: | Grade (UNS) | Type | PRE |

The high PRE number (Pitting Resistance Equivalent) of ASTM A995 Gr4A—calculated as PRE = %Cr + 3.3(%Mo) + 16(%N)—typically exceeds 40. This places it in the “Super Duplex” category. This places it in the “Super Duplex” category

ASTM A995 Grade 4A is distinguished by a dual-phase microstructure consisting of approximately equal parts of . This balanced structure provides several critical benefits: