Grain boundary structure effects on cold work embrittlement of microalloyed steels

Conventionally processed microalloyed steels contain special boundary frequencies of approximately 14% to 20%; these values being consistent with that expected from material not specifically processed to improve special boundary frequencies. Results also emphasize the importance of sample deformation history for interpreting OIM data. By analysis of crack segments, grain boundaries described by low-∑ CSL values were determined to exhibit increased resistance to cracking induced by cold work embrittlement. This is believed to arise from the structural order of low-∑ CSL boundaries, which minimize solute effects and reduce the interaction between the interfaces and glissile dislocations. The results of this study support the possible benefits of increasing the frequency of special grain boundaries in the microstructure of microalloyed steels for minimizing the detrimental effects of cold work embrittlement.