Key factors and tools to minimize hydrogen embrittlement during Zn-Ni coating on ultra-high-strength steels

Under cryogenic conditions, steels may undergo significant changes in their mechanical behaviour, particularly in terms of strength and toughness, making proper characterization essential to ensure structural integrity and service safety.

The aim of this work is to develop knowledge on the mechanical response of different structural steels under cryogenic conditions, contributing to the design and selection of materials for low-temperature applications. For this purpose, the Small Punch Test (SPT) miniature testing technique is employed, a methodology that enables the evaluation of mechanical properties from small-sized specimens, thus optimising material consumption.

The SPT technique has been adapted and developed for application at cryogenic temperatures down to −196 °C. Using this methodology, nine industrially relevant steel grades have been analysed at different cryogenic temperatures. Force–displacement curves obtained from the tests are presented, together with the characteristic points derived from the experiments. In this way, the behaviour of the different steel grades is evaluated in terms of strength and toughness.

The results allow direct comparison between the studied materials, identifying those with the best performance under cryogenic conditions. This testing methodology provides an efficient tool for material selection and demonstrates the potential of SPT as an advanced technique for mechanical characterization in cryogenic applications.