Journal Published Online: 30 August 2019
Volume 49, Issue 4

Effect of Specimen Cross Section and Notch Radius on the Hydrogen Embrittlement Susceptibility of Tempered and Quenched AISI 4140 Steel

CODEN: JTEVAB

Abstract

To investigate the effects of the cross section and notch radius of specimens on the susceptibility to hydrogen embrittlement of AISI 4140 steel at different hardness levels, the incremental step loading technique was used. Initially, the effect of the three factors on the fast force fracture strength values was investigated. The study was based on a full factorial design, 2 × 2 × 3, in which the cross section and notch radius factors were investigated on 2 levels and hardness on 3 levels. Tests were performed using two equipment setup configurations. In the first test, a 1-kN load cell was used for standard test specimens with nominal dimensions of 10 × 10 × 60 mm3, and in the second, a load cell of 20 kN was used for nonstandard test specimens with nominal dimensions of 30 × 30 × 200 mm3. The analysis of variance showed that the cross section factor caused statistically significant effects on the SFFS values (the stress related to PFFS), and the hardness and the interaction between the hardness and cross section had statistically significant effects on the hydrogen embrittlement of AISI 4140 steel. When analysis of variance was performed separately for each cross section, it was observed that for specimens with cross sections of 10 × 10 mm2, the notch radius and the hardness factors caused statistically significant effects on the PFFS value, whereas for specimens with 30 × 30 mm2 cross sections, none of the investigated factors had statistically significant effects because of the larger constraint effect at the notch tip. The incremental step loading technique needs fewer specimens to complete the PTH evaluation when applied using larger strain constraint (larger cross section, smaller notch root, and higher hardness).

Author Information

Júnior, Marcus Vinícius Rezende
Department of Mechanical Engineering, Federal University of Uberlândia, Uberlândia, MG, Brazil
Paes, Marcelo Torres Piza
Research and Development Center, CENPES/PETROBRÁS, Rio de Janeiro, RJ, Brazil
Filho, Waldek Wladimir Bose
Escola de Engenharia de São Carlos – USP, Parque Arnold Schimidt, São Carlos, SP, Brazil
Arencibia, Rosenda Valdés
Department of Mechanical Engineering, Federal University of Uberlândia, Uberlândia, MG, Brazil
Franco, Sinésio Domingues
Department of Mechanical Engineering, Federal University of Uberlândia, Uberlândia, MG, Brazil
Pages: 23
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Stock #: JTE20190330
ISSN: 0090-3973
DOI: 10.1520/JTE20190330