Precipitation of TiC in thermally embrittled maraging steels

It is shown that maraging steels can be embrittled by the precipitation of TiC during slow cooling and/or intermediate annealing in the austenite temperature range. An important aspect in this embrittlement is the occurrence of lamellar precipitation of TiC at the austenite grain boundaries, generating a cellular structure of large fern leaf-like carbides. Within the austenite grains a nonuniform distribution of irregularly plate-shaped TiC particles are formed with (100) austenite habit orientation. Quenching to martensite, prior to any intermediate anneals, changes the carbide distribution upon subsequent annealing treatments into a fine dispersion of TiC particles. The embrittlement resulting from the various isothermal annealing treatments in the austenite temperature region could all be directly related to the carbide distribution in the prior austenite grain boundary region.