Damage Evolution and Microstructural Fracture Mechanisms Related to Volume Fraction and Martensite Distribution on Dual‐Phase Steels

Abstract

Currently, the steel manufacturing industry faces significant challenges in meeting the necessary processing requirements to develop low-weight and high-strength materials through efficient and clean production routes. For example, in the transportation and automotive manufacturing industries, lightweight structural materials that enhance the autonomy versus fuel consumption ratio, improve passenger safety, and optimize processing costs, are increasingly a mandatory requirement in the research and development of recent manufacturing projects. [1] In this sense, the development of advanced high-strength steels (AHSS), particularly dual-phase steels (DP), has enabled the improvement of automotive engineering safety through the use of sheet metal members (safety cage components, roof rails, and rear shock reinforcements) with thin walls to improve crashworthiness. [2,3] Low-carbon dual-phase steels consist of a ferrite matrix and a second phase of distributed martensite. The two phases combined, usually produced by intercritical heat treatments (IHT) and water quenching, are responsible for the plastic flow mechanism observed in these steels. [4,5] Shear stresses are generated along grain boundaries due to the austenite to martensite transformation during the quenching process. Therefore, due to these microstructure volume changes, dislocation density increases. [6,7] As a result, a pile-up of sliding unanchored dislocations reduces yield stress and interacts to produce a high work-hardening rate. [8] Hence, the continuous plastic flow behavior evidenced by dual-phase steel results from the above-mentioned factors. [9] The deformation process of

Martensite content effect on fatigue crack growth and fracture energy in dual‐phase steels

“…Subsequently, HT2 and HT3 materials were subjected to intercritical temperatures of 813°C and 839°C for 30 min, followed by room temperature brine quenching. More details on the microstructure and heat treatment can be found in previous works 29 …”

“…For the EBSD sample preparation, the procedure consisted of grinding up to 2000 grit SiC sandpaper, followed by polishing up to 0.25 m with diamond suspension and oxide polishing suspension, finishing in Vibromet for 7 h and final surface cleaning with an ethyl alcohol jet. More details on the EBSD sample preparation can be found in previous work 29 . For the following section, crack tips refer to the singular point at which the crack propagates, and the crack path refers to the route that the crack marks, which can have many changes in direction and can even diverge and generate several routes.…”

“…More details on the EBSD sample preparation can be found in previous work. 29 For the following section, crack tips refer to the singular point at which the crack propagates, and the crack path refers to the route that the crack marks, which can have many changes in direction and can even diverge and generate several routes.…”

Effect of Intercritical Annealing Parameters on The Hardness Property: Statistical Study Using Taguchi

“…DP steel possesses excellent mechanical qualities such as high tensile strength, improved formability, continuous yielding behavior, crashworthiness, high strength-ductility, and high work hardening rates, which make it a reliable and affordable material for the manufacturing sector, including welding [5][6][7][8] . The microstructure of DP steels is significantly influenced by heat treatment, particularly during intercritical annealing, which creates a ferrite-martensite structure 9,10 . The mechanical properties of DP steels are further enhanced by factors such as annealing, quenching medium, cooling rate, grain size and pattern, and the chemical composition of the parent material [11] .…”