ISSN: 1945-7553
Page Count: 10

Embrittlement of an AISI 8640 Lower Bainite Steel

Rinnovatore, JV
MTA, Inc., Mt. Arlington,NJ

Lukens, KF
Metallurgist and failure analyst; mechanical engineer; and engineering technician, U.S. Army Armament Research, Development and Engineering Center, Picatinny Arsenal,NJ

Reinhold, J
Metallurgist and failure analyst; mechanical engineer; and engineering technician, U.S. Army Armament Research, Development and Engineering Center, Picatinny Arsenal,NJ

Mahon, W
Metallurgist and failure analyst; mechanical engineer; and engineering technician, U.S. Army Armament Research, Development and Engineering Center, Picatinny Arsenal,NJ

(Received 18 September 1992; accepted 8 April 1993)

Abstract

A study was performed to determine the cause of an abnormally low fracture toughness of an AISI 8640 resulfurized steel. The embrittlement effects of phosphorus and arsenic on this steel heat-treated to a lower bainitic structure were studied by employing fracture toughness tests, Charpy impact tests, X-ray fluorescent spectroscopy, and scanning electron microscopy (SEM). The results showed that the steel was embrittled by phosphorus at prior austenite gram boundaries in a manner similar to the tempered martensite embrittlement (TME) phenomenon. Arsenic is also believed to be involved in the embrittlement effect, specifically as related to producing a reduction in the upper shelf Charpy impact energy. Embrittlement was manifested by a reduced fracture toughness, an increase in the Charpy transition temperature, and intergranular fracture.

Keywords:
embrittlement, fracture toughness, Charpy impact, transition temperature, 8640 alloy steel, phosphorus, arsenic, bainite

Paper ID: JTE11775J
DOI: 10.1520/JTE11775J
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