SAE AMS 2757A:2021 pdf download GASEOUS NITROCARBURIZING
1 . SCOPE:
1 .1 Purpose: This specification covers the engineering requirements for producing a continuous thin epsilon- iron-carbonitride compound layer on parts by means of a gaseous, low temperature process, and properties of the case.
1 .2 Application: This process has been used typically to increase wear resistance and fatigue and to improve corrosion resistance on ferrous metals, such as carbon, low-alloy, and tool steels, and cast irons, but usage is not limited to such applications. This process can be selectively applied to wear areas of the component.
2. APPLICABLE DOCUMENTS: The following publications form a part of this specification to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase order.
2.1 SAE Publications:
Available from SAE, 400 Commonwealth Drive, Warrendale, PA 1 5096-0001 .
AMS 2408 Plating, Tin
AMS 241 8 Plating, Copper
AMS 2429 Masking, Bronze Plate, Nitriding Stop-off, 9OCu – 1 OSn
ARP1 820 Chord Method of Evaluating Surface Microstructural Characteristics
SAE J423 Methods of Measuring Case Depth
SAE J864 Surface Hardness Testing With Files
2.2 ASTM Publications:
Available from ASTM, 1 00 Barr Harbor Drive, West Conshohocken, PA 1 9428-2959.
ASTM E 384 Microhardness of Materials
2.3 ASM Publications:
Available from ASM International, Metals Park, OH 44073-0002.
ASM Handbook, 9th Edition, Metallography and Microstructure
3. TECHNICAL REQUIREMENTS:
3.1 Processing Equipment:
Parts to be nitrocarburized shall be processed in an integral quench, sealed retort, fluidized bed, or atmosphere-type furnace conforming to AMS 2759. Furnace temperature uniformity requirements shall be +15 F (+8 °C).
3.1.1 Atmosphere: The nitrocarburizing atmosphere shall consist of a mixture of ammonia and a carrier gas. Acceptable carrier fases are: endothermic (AGA type 302), refined exothermic gas (AGA type 201), and high purity nitrogen; a hydrocarbon gas and/or oxygen-bearing gas aditions may be used for enrichment.
3.1.2 Furnace Controls: Shall conform to AMS 2759.
3.1.3 Thermocouples: When load thermocouples are required, they shall be sheath-protected to prevent deterioration due to furnace atmospheres.
3.2 Pretreatment:
3.2.1 Hardening: Parts, where core hardening is specified, shall be heat treated in accordance with AMS 2759 or as specified by the cognizant engineering organization to the required core hardness prior to gaseous nitrocarburizing. Tempering for the specified core hardness shall be at a temperature not less than 50 °F (28 °C) degrees above the nitrocarburizing temperature.
3.2.2 Surface Condition: Parts shall be clean and free of scale, oxide, entrapped sand, mold or core sand material, metal particles, oil, or grease prior to the nitrocarburizing process. Parts must be dry. .
3.2.3 Stress Relief: Parts, which have been machined or straightened before nitrocarburizing, may be stress relieved in accordance with AMS 2759 prior to nitrocarburizing. Stress relieving shall . be done at a temperature not less than 20 °F (11。C) degrees above the highest nitrocarburizing temperature to be used. Surfaces to be nitrocarburized shall be mechanically or chemically cleaned subsequent to stress relieving and prior to nitrocarburizing. .
SAE AMS 2757A:2021 pdf download
