SYMPOSIA PAPER Published: 01 January 1991

Promoted Ignition-Combustion Behavior of Precipitation Hardened Engineering Alloys


Promoted ignition and more recently promoted combustion are terms which have been used to describe a situation where a substance with low oxygen compatibility ignites and supports the combustion of a more combustion resistant material. Previous papers as well as a companion paper by the authors have reported on the investigation of this phenomenon as it related to carbon steels, 316L stainless steel and a number of significant engineering alloys.

Within oxygen systems there are a number of engineering alloys which receive precipitation hardening heat treatments in order to develop desired mechanical properties. Although flammability data on some of these alloys have been reported in the literature, the effect of heat treatment on flammability tendencies has not received much attention. Metallurgical processes such as solution heat treatment and precipitation hardening may affect the distribution and relative proportions of metallic and intermetallic phases; thereby influencing mechanical and in some cases physical properties. Several recent papers have suggested that metallurgical processes should receive more attention in flammability studies.

The alloys selected for investigation in this study were 17-4PH stainless steel and Inconel® 718. Both alloys may be strengthened via precipitation hardening processes. Promoted ignition-combustion tests of these alloys in both the solution annealed and precipitation hardened conditions were conducted in flowing and static (fixed volume) testers using the rod configuration used in the joint ASTM-CGA-NASA program. The flammability tests were conducted in oxygen-nitrogen gas mixtures with oxygen purities ranging from approximately 40% to 99.7% at pressures of 0.79MPa to 34.6MPa.

Author Information

McIlroy, K
Materials Engineering Laboratory, Union Carbide Industrial Gases, Inc., Tonawanda, NY
Zawierucha, R
Materials Engineering Laboratory, Union Carbide Industrial Gases, Inc., Tonawanda, NY
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Developed by Committee: G04
Pages: 288–297
DOI: 10.1520/STP17769S
ISBN-EB: 978-0-8031-5170-3
ISBN-13: 978-0-8031-1461-6