Abstract
The AISI 4130 steel grade is commonly used in piping systems, where optimum chemical composition and heat treatment can exhibit high yield strength, good ductility, and moderate weldability depending on composition. However, this steel grade is characterized by its low hardenability, which limits a good transformation during quenching in heavy sections. In order to improve hardenability, Ni was added and C was reduced for the same level of CE (0.7). Two chemical compositions were used; samples were quenched at critical cooling rate and tempered. With the addition up to 0.5 wt. % Ni, the alloy exhibited great improvement on strength and toughness; additionally, the alloy allowed an increase of 40°C on the tempering temperature for the same strength level. In the case of post-welding, heat treatment is required so that the alloy is less susceptible to suffering a drop in mechanical properties. Results of chemical composition, strength, and toughness are discussed.
