Enhancing Strain Capacity by the Introduction of Pearlite in Bainite and Polygonal Ferrite Dual-Phase Pipeline Steel

Abstract

In this study the strain capacity and work-hardening behavior of bainite (B), bainite + polygonal ferrite (B + PF), and bainite + polygonal ferrite + pearlite (B + PF + P) microstructures are compared. The work hardening exponent (n), instantaneous work hardening value (ni), and differential Crussard-Jaoul (DC-J) analysis were used to analyze the deformation behavior. The best comprehensive mechanical properties were obtained by the introduction of the pearlite phase in B + PF dualphase with the tensile strength of 586 MPa and total elongation of 31.0%. The additional pearlite phase adjusted the strain distribution, which increased the initial work hardening exponent and then maintained the entire plastic deformation at a high level, thus delayed necking. The introduction of pearlite reduced the risk of micro-void initiation combined with the high frequency of high angle grain boundaries (HAGBs) in triple-phase steel, which led to a low crack propagation rate.

Local Hydrogen Measurements in Multi-Phase Steel C60E by Means of Electrochemical Microcapillary Cell Technique

“…Depending on the specific lamellae spacing and C content, widely varying trapping energies between 11 and 80 kJ mol are reported [42][43][44], resulting in a mixed classification as both shallow and deep traps. However, it is reported that introducing pearlite into a ferritic-bainitic dual-phase steel resulted in improved resistance to HE [45].…”