**7. Conclusions**

A literature survey has been conducted to focus on cryogenic treatments e ffects on microstructural alteration and its correlation with material mechanical properties and manufacturability. Comparative investigations have been made to evaluate the e ffects of CHT, SCT, and DCT on the microstructure and mechanical property variations. The e ffects of important parameters and their interactions such as austenitizing temperatures, ramp down, soaking time, and temperature, as well as ramp up, are discussed. The review of the literature implies that the evaluation of microstructural variations due to cryo-treatment and their interaction with mechanical properties is a complex phenomenon. Therefore, these complexities of interactions of microstructural alteration and mechanical properties depend on the adopted methods such as prior and supplementary treatments (austenitizing, quenching, and tempering), influential parameters, and demanded accuracy.

A review of the literature and the synthesis of technical contributions indicates various ways to execute cryogenic treatments. The important conclusions of this literature survey and the future directions are suggested as follows:


**Funding:** This research received no external funding. **Acknowledgments:** The authors wish to gratefully thank DEPEC group.

**Conflicts of Interest:** The authors declare no conflict of interest.
