The effect of quenching and tempering on the fracture toughness of Ni steels

The oil and gas industry is aware of the benefits of adding nickel to improve the mechanical properties of steels when exposed to low temperatures. Low-carbon steels with 3 to 9% nickel by weight are widely used in the construction of structures for transporting and storing petroleum fluids and liquefied gases. Gains in toughness can be obtained for these steels through heat treatments, such as quenching followed by tempering, among others. Knowledge of the behavior of the material at low temperatures is of fundamental importance to the industry mentioned above. In this paper, the reader can observe the results of the evaluation of the effect of quenching and tempering on the fracture toughness of 5.5Ni and 9Ni steels, with tests performed at room temperature and -100 C, since these materials can be used at low temperatures.