Liquid Metal Embrittlement (LME) has been a well-known concern for many years, but the definition of when it is a risk and details on how to address this risk seem to vary throughout the refining industry. This paper first summarizes general literature on the different combinations of materials (applicable to the refining industry) which are susceptible to LME. Next, it compiles LME case histories from literature and conference minutes to help gather data on the conditions causing the risk. Some of the recent reported failures provide important tips on prevention steps and highlight how exposures to even small amounts of liquid metals can be very detrimental. Results of an informal survey of the practices to resist LME from various oil companies are included, along with a compilation of how LME is addressed in various industry standards such as API 661 on air coolers. Lastly, suggestions for future practices are given.
Liquid Metal Embrittlement (LME) phenomenon occurs when the certain molten metals wet the specific alloys, causing drastic ductility reduction that normally is associated with the formation of an intergranular crack that is sudden and brittle in nature.
High tensile stress is also known to promote cracking; however, cracks may develop merely by contacting molten metal with a susceptible alloy as there is only a small amount of low-melting-point metal required to cause LME.
It is well known that there is a risk of LME when simultaneously all three factors of susceptible microstructure, wetting by embrittlement element, and sufficient stress are presented in a situation. The absence of any of these factors will prevent the LME mechanism.
Findings confirm LME could form in various metals with different microstructures such as Face Centered Cubic (F.C.C) and Body-Centered Cubic (B.C.C) when the susceptible metal is exposed to the low melting point embrittlement agent and the applied or residual stress is above a certain threshold.
