The Influence of In-Situ Alloying of Electro-Spark Deposited Coatings on the Multiscale Morphological and Mechanical Properties of Laser Welded Al-Si Coated 22mnb5

Recent advances in mitigating fusion zone softening during laser welding of Al-Si coated 22MnB5 press-hardened steels

“…The demand for parts with excellent toughness, impact resistance and formability has grown considerably but conventional high-strength low alloy steels have limitations in terms of strength and tend to be relatively costly [48]. Boron-alloyed steels, specifically 22MnB5, are a popular alternative due to boron's ability to act as a hardening agent while maintaining good formability [49].…”

“…The as-received condition of boron-alloyed steel consists of ferrite, pearlite, and a small amount of martensite, while the hot-stamped condition is lath martensite [13]. The addition of boron and manganese to this steel increases its hardenability and shifts the ferrite nose on the CCT diagram to the right, resulting in a fully martensitic microstructure when the steel is quenched [48]. 22MnB5 steel is considered a suitable alternative to traditional high-strength low-alloy steels and other advanced high strength steels (AHSSs), as it offers superior mechanical properties, exceptional formability, while being relatively cost-effective for producing structural parts and components with tailored properties.…”

“…Direct HS is the most commonly used method in automotive applications, and it involves heating the blank to a high temperature and then simultaneously quenching and forming it in a press equipped with a water-cooled die [51]. TWBs are made by laser welding two or more types of PHSs with varying thicknesses and properties to produce a 'blank' which is then hot-stamped to produce the final parts, which can help to reduce part weight and improve performance while potentially consolidating two or three separate parts into one component, which helps to significantly simplify the manufacturing process, saving time and reducing costs [48]. Typically, the hot-stamping process requires heating the samples in a continuous electrically-powered furnace for 5-8 min to reach an austenitization temperature of around 930 °C.…”

“…Typically, the hot-stamping process requires heating the samples in a continuous electrically-powered furnace for 5-8 min to reach an austenitization temperature of around 930 °C. Subsequently, rapid quenching and forming of the part takes place using a water-cooled die, ensuring a sufficiently high cooling rate to achieve a fully martensitic microstructure in the as-received hot-stamped base material (HSBM) [48].…”

“…The microstructure of laser-welded 22MnB5 steel is fully martensitic when laser welded without a surface coating [48], as shown in figure 1. However, due to the Al-Si coating that is commonly used in the automotive industry to protect hot-forming steels against corrosion, the coating melts into the weld pool during laser welding, which leads to the formation of a dual-phase region in the FZ composed of ferrite and martensite [13].…”