A Novel Process for Hot‐Galvanized Quenching and Partitioning Steel with Excellent Yield–Ductility Synergy by Prior Treatment

Abstract

The present work is aimed at a process to obtain a hot‐galvanized quenching and partitioning (Q&P) steel with excellent yield–ductility synergy by prior treatment. For this purpose, the cold‐rolled sheets with ferrite–pearlite structure are applied to “quenching (Q),” “quenching and tempering (Q&T),” “quenching and austempering (QAT),” and “quenching and austempering followed by tempering (QAT&T)” before the continuous galvanizing line (CGL)‐compatible Q&P treatment. Compared with Q&P sample, Q + Q&P, Q&T + Q&P, QAT + Q&P, and QAT&T + Q&P samples can obtain more homogeneous filmy/lath retained austenite (RA) with an increased C concentration, which can provide the transformation‐induced plasticity (TRIP) effect and improve elongation significantly. The maximum austenite reverse transformation rates are obtained in Q&T and QAT&T samples because of the increased nucleation sites, such as grain boundaries and cementite particles. QAT&T + Q&P sample has the longest plateau region before break and obtains the attractive mechanical properties with a yield strength of 694 MPa, tensile strength of 927 MPa, total elongation of 31.3%, and product of strength and elongation above 29 GPa%.