Listado de los aceros inoxidables más comunes en la fabricación de válvulas. Tipos de aceros inoxidables, equivalencias entre inoxidables por forja y fundición, equivalencia entre normas ASTM y EN, y listado de las normas.

• Aceros inoxidables Austeníticos al Cromo-Níquel
• Aceros inoxidables Ferríticos
• Aceros inoxidables Martensíticos
• Aceros inoxidables Duplex
• Normas de aceros inoxidables en válvulas

Aceros inoxidables Austeníticos al Cromo-Níquel

Composición:
• Carbono (C): de 0.03% a 0.25% ("L" poco contenido de Carbono <0,3%)
• Cromo (Cr): de 17% a 26%
• Niquel (Ni): de 7% a 22%

Propiedades:
• Características mecánicas muy buenas.
• Elevada resiliencia a temperaturas muy bajas (-200°C).
• Apto para uso en procesos criogénicos.
• Sufijo "L" usados para soldadura.
• 70% de la producción de acero inoxidable es autenítica.

Fundición		Forja			Fittings forjados
ASTM	EN	AISI-SAE	ASTM	EN	ASTM
A351 CF8	10213-4 1.4308	304	A182 F304	10088 1.4301	A403-WP304
A351 CF3	10213-4 1.4309	304L	A182 F304L	10088 1.4307	A403-WP304L
A351 CF8M	10213-4 1.4408	316	A182 F316	10088 1.4401	A403-WP316
A351 CF3M	10213-4 1.4409	316L	A182 F316L	10088 1.4404	A403-WP316L
A351 CF10MC	10213-4 1.4581	316MB		10088 1.4580	-
-	-	321	A182-F321	10088 1.4541	A403-WP321

Aceros inoxidables Ferríticos

Composición:
• Carbono (C): < 0.1% (hasta 0.35% para contenidos de cromo de 30%)
• Cromo (Cr): de 16% a 30%

Propiedades:
• Mejores propiedades mecánicas que los austeníticos, no así en corrosión. Generalmente son más baratos
• Mejor resistencia química que los aceros inoxidables martensíticos.

Fundición		Forja
ASTM	EN	AISI	EN	ASTM
-	-	430	EN 10088 1.4016

Aceros inoxidables Martensíticos

Composición:
• Carbono (C): de 0.1% a 0.5%
• Cromo (Cr): de 12% a 17%

Propiedades:
• Tiene mejores propiedades mecánicas que austeníticos y ferríticos, pero peor resitencia a la corrosión.
• Fáciles de mecanizar.
• Poseen buena resistencia a la corrosión frente a ciertos ácidos débiles.
• Las propiedades mecánicas son modificables por medio del tratamiento térmico
• Magnético

Fundición		Forjado
ASTM	EN	AISI	EN	ASTM
A 743 CA-15	1.4008	410	10088 1.4006
-	-	420	10088 1.4021
A 743 CA-40	1.4028	420	10088 1.4034

Aceros inoxidables Duplex

Composición:
• Cromo (Cr): de 19% a 28%
• Molibdeno (Mb): hasta 5%

Propiedades:
• Son una mezcla de aceros autenístico (de 40% a 50%) y ferríticos (60% a 50%).
• Buenas propiedades mecánicas y resistencia a la corrosión.

Fundición		Forjado
ASTM	EN	SAF Alloy	ASTM	EN
A995 Gr. 1A	-		-	-
A995 Gr. 2A	-		-	-
A995 Gr. 3A	-		-	-
A995 Gr. 4A	-	SAF 2205	A-182 F51	1.4462
A995 Gr. 5A	-	SAF 2507	-	-

Normas de aceros inoxidables en válvulas

ASTM A217 / A217M - 08
Standard Specification for Steel Castings, Martensitic Stainless and Alloy, for Pressure-Containing Parts, Suitable for High-Temperature Service
This specification covers steel castings, martensitic stainless steel and alloys steel castings for valves, flanges, fittings, and other pressure-containing parts intended primarily for high-temperature and corrosive service. The grades of steels covered here are: Grade WC1, Grade WC4, Grade WC5, Grade WC6, Grade WC9, Grade WC11, Grade C5, Grade C12, Grade C12A, and Grade CA15. Heat treatment shall consist of normalizing and tempering for Grade C12A and tempering for all other grades. Heat treatments shall be performed after castings have been allowed to cool. Heat and product analyses shall be performed wherein specimens shall conform to required chemical composition of carbon, molybdenum, chromium, nickel, vanadium, manganese, phosphorus, sulfur, silicon, columbium, nitrogen, aluminum, copper, titanium, tungsten, and zirconium. The surface of the casting shall be examined visually and shall be free of adhering sand, scale, cracks and hot tears. Steels shall undergo tension test, and shall conform to the following mechanical requirements: tensile strength, yield strength, elongation, and reduction of area.

ASTM A351 / A351M - 10
Standard Specification for Castings, Austenitic, for Pressure-Containing Parts
Esta especificación cubre la fundición de acero austenítico para válvulas, bridas, accesorios, y otras partes a presión. El acero debe estar fabricado en un horno eléctrico con o sin refinación separada tales como la descarburación de argon-oxigeno. Todas las fundiciones deben recibir tratamientos calientes siguido por un rápido enfriamiento en agua u otros métodos. El acero debe cumplir tanto la composición química y propiedades mecánicas requeridas.

ASTM A182 / A182M - 09a
Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service
This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service. After hot working, forgings shall be cooled to a specific temperature prior to heat treatment, which shall be performed in accordance with certain requirements such as heat treatment type, austenitizing/solution temperature, cooling media, and quenching. The materials shall conform to the required chemical composition for carbon, manganese, phosphorus, silicon, nickel, chromium, molybdenum, columbium, titanium. The material shall conform to the requirements as to mechanical properties for the grade ordered such as tensile strength, yield strength, elongation, Brinell hardness. All H grades and grade F 63 shall be tested for average grain size.

ASTM A995 / A995M - 09
Standard Specification for Castings, Austenitic-Ferritic (Duplex) Stainless Steel, for Pressure-Containing Parts
Esta especificación cubre la fundición de acero austenitico-ferritico (duplex) para valvulas, bridas, accesorios y otras partes a presión. Los grados de acero cubiertos aquí son: Grade 1B, Grade 2A, Grade 3A, Grade 4A, Grade 5A, y Grade 6A. La función de acero debe ser tratada en caliente según la temperatura especificada y debe ser enfriada en agua u otros metodos de enfriamiento rápidos. Calentamiento y analisis del producto de forma que las muestras cumplan la composición química requerida en carbón, manganeso, silicio, fósforo, sulfuro, cromio, niquel, molibdemo, cobre, tungsteno, y nitrogeno. Todos los aceros deben pasar el test a tensión, y cumplir los siguientes requerimientos mecánicos: resistencia a tracción, módulo eslástico y elongación.

ASTM A240 / A240M - 10
Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications
Esta especificación cubre aceros inoxidables de cromo, cromo-níquel, y cromo-manganeso-níquelickel, en barras, chapas, y tiras para recipientes a presión y aplicaciones generales. El acero debe cumplir los requesitos de composión química especificados. El material debe cumplir las propiedades mecánicas especificadas.

ASTM A872 / A872M - 07a
Standard Specification for Centrifugally Cast Ferritic/Austenitic Stainless Steel Pipe for Corrosive Environments
This specification covers centrifugally cast ferritic/austenitic steel pipe intended for general corrosive service. These steels are susceptible to embrittlement if used for prolonged periods at elevated temperatures. The pipe shall be made by centrifugal casting process and furnished in the specified heat-treatment condition. The pipe shall also be machined. The grades shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, nitrogen, copper, and cobalt. Heat analysis and product analysis shall be done. Tensile requirements shall conform to the specified tensile strength, yield strength, and elongation; and hardness requirements shall conform to the specified Brinell and Rockwell C values. Tension test shall also be made.

ASTM A403 / A403M - 09
Standard Specification for Wrought Austenitic Stainless Steel Piping Fittings
This specification covers the standard for wrought austenitic stainless steel fittings for pressure piping applications. The material for fittings shall consist of forgings, bars, plates, or seamless or welded tubular products. Forging or shaping operations shall be performed by hammering, pressing, piercing, extruding, upsetting, rolling, bending, fusion welding, machining, or by a combination of two or more of these operations. All fittings shall undergo heat-treatment. Chemical and product analyses shall be performed and shall conform to the required chemical composition in carbon, manganese, phosphorus, sulfur, silicon, chromium, molybdenum, and titanium. Tension test shall be done on the fitting material to determine the tensile properties such as yield strength and tensile strength. Fittings supplied under this specification shall be examined visually for surface discontinuities, surface checks, and mechanical marks.

ASTM A743 / A743M - 06
Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application
This specification covers iron-chromium and iron-chromium-nickel alloy castings for general corrosion-resistant application. The grades of these castings represent types of alloy castings suitable for broad ranges of application which are intended for a wide variety of corrosion environments. The steel shall be made by the electric furnace process with or without separate refining such as argon-oxygen decarburization. The castings shall be subjected to heat treatment.

ASTM A744 / A744M - 06
Standard Specification for Castings, Iron-Chromium-Nickel, Corrosion Resistant, for Severe Service
This specification covers standard requirements for iron-chromium-nickel alloy, stainless steel castings intended for particularly severe corrosive applications. Alloys shall be melted by the electric furnace process with or without refining such as argon-oxygen-decarburization. Castings shall be heat treated and shall conform to the required heat treatment conditions. The materials shall conform with the prescribed chemical requirements for carbon, manganese, silicon, phosphorus, sulfur, chromium, nickel, molybdenum, columbium, copper, selenium, tungsten, vanadium, iron, and nitrogen.

ASTM A890 / A890M - 99(2007)
Standard Specification for Castings, Iron-Chromium-Nickel-Molybdenum Corrosion-Resistant, Duplex (Austenitic/Ferritic) for General Application
This specification covers castings, iron-chromium-nickel-molybdenum corrosion-resistant, duplex(austenitic/ferritic) for general application. Castings shall be heat treated in accordance with the required procedure and heat-treat temperature. Proper heat treatment of these alloys is usually necessary to enhance corrosion resistance and in some cases to meet mechanical properties. Minimum heat-treat temperatures are specified; however, it is sometimes necessary to heat-treat at higher temperatures, hold for some minimum time at temperature and then rapidly cool the castings in order to enhance the corrosion resistance and meet the required mechanical properties. The steel shall conform to the required chemical composition for carbon, manganese, silicon, phosphorus, sulfur, chromium, nickel, molybdenum, copper, tungsten, and nitrogen. Castings shall be marked for material identification with the specification designation and grade.

ASTM A276 - 08a
Standard Specification for Stainless Steel Bars and Shapes
Esta especificación no cubre barras acabadas en caliente o en frío, a excepción de barras para forja. Incluye redondos, cuadrados, y hexagonos, y laminados o formas extrusionadas, tales como ángulos, tees, y canales más usados en acero inoxidable. Las barras deben ser proporciondas en alguna de las siguientes condiciones: Condición A en la cual la barra es recocida, Condición H en la que las barras son endurecidas y templadas a una relativa temperatura, Condición T en la cual las barras son endurecidas a una temperatura relativamente alta, Condición S en la cual las barras son endurecidas a presión o trabajadas relativamente algo en frió, y Condición B en la cual las barras son relativamente trabajadas serveramente en frío. El material debe ser sujeto a un test mecánico para determinar su resistencia a tracción, límite elástico, elongación, y dureza Brinell.

ASTM A564 / A564M - 04(2009)
Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes
This specification covers bars and shapes of age-hardening stainless steels. Hot-finished or cold-finished rounds, squares, hexagons, bar shapes, angles, tees, and channels are included. These shapes may be produced by hot rolling, extruding, or forging. Type 631 and 632 stainless steels contain a large amount of ferrite in the microstructure and can have low ductility in forgings and large diameter bars. Material of types other than XM-16, XM-25, and Type 630 shall be furnished in the solution-annealed condition, or in the equalized and oven-tempered condition. Types 630, XM-16, and XM-25 may be furnished in the solution-annealed or age-hardened condition. Type UNS S46910 shall be furnished in solution annealed, cold-worked or aged-hardened condition. Shapes may be subjected to either Class A or Class C preparation for removal of visible surface imperfections. The material shall be subjected to tension, impact, and hardness tests.

EN 10213-4:2007
Technical delivery conditions for steel castings for pressure purposes.
Part 4: Austenitic and austenitic-ferritic steel grades (Q).
EN 10213:2007 aplica a aceros fundidos para componentes a presión. Esto incluye el material usado para fabricar componentes y equipos a presión.
EN 10213:2007 detalla la caractetísticas de la fundición y su composición química y propiedades mecánicas. Aplica donde las piezas fundidas se unen por soldadura por el fundidor.
EN 10213:2007 no aplica a casos en que las partes fundidas son soldadas a productos forjados (chapas, tubos, forjados), o por no fundidores.

EN 10088-3:1995
Stainless steels. Technical delivery conditions for semi-finished products, bars, rods and sections for general purposes