Embrittlement of a zinc coated high manganese TWIP steel

The liquid metal embrittlement (LME) of a high manganese austenitic TWIP steel was investigated by hot tensile testing of zinc coated specimens using Gleeble® thermo-mechanical simulator. The influence of different parameters such as temperature, strain rate and pre-exposure time on the occurrence of embrittlement was studied. The results show that the steel can be embrittled by liquid zinc within a limited temperature range depending on strain rate. A critical stress for cracking has been defined for each embrittlement condition.The effect of time of contact between the steel and the liquid zinc has been investigated by performing holding at temperature before tensile testing. It has been shown that a holding of few seconds is sufficient to regain the whole original ductility.Physical mechanisms involved in LME phenomenon are discussed.

► Hot tensile tests of zinc coated specimens permit to study the LME phenomenon.
► Temperature and strain rate are key parameters in embrittlement phenomenon.
► A critical stress for cracking has been defined for each embrittlement condition.
► Holding of few seconds at high temperature permits to prevent embrittlement.