THE EFFECT OF MECHANICAL PROPERTIES AND MICROSTRUCTURAL CHARACTERISTICS ON STRETCH-EDGE FORMABILITY OF DUAL PHASE ADVANCED HIGH STRENGTH STEEL: COMPREHENSIVE REVIEW

• Main Author: FATKHUROZAK
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/57513
• Institution: Institut Teknologi Bandung

With the increasing level of demand in the automotive industry, it demands the use of steel types that have good strength and formability. The type of steel that has these properties is advanced high strength steels (AHSS). Dual phase steel is the first generation of AHSS steel which is widely used in the manufacture of vehicle components. One of its formability properties is stretch-edge-formability which has a very important role to prevent cracks at the edges during the forming process. Hole expansion test (HET) is a test commonly encountered in the industry to determine the stretch-edge-formability of dual phase steel so that the selection of the right metal material for the forming process can be carried out. In this literature study, the effect of mechanical properties and microstructure characteristics of dual phase steel on stretch-edge-formability will be analyzed. In addition, the effect of HET operating parameters on the stretch-edge-formability of dual phase steel will also be analyzed. This literature-based research was conducted by collecting and analyzing references related to the factors that affect the stretch-edge-formability of double phase steel which can be expressed by the value of the hole expansion ratio (HER). The factors that affect this HER include mechanical properties and microstructure characteristics as well as operating parameters during the hole expansion test which includes punch geometry and hole preparation. Furthermore, the correlation of these parameters to the stretch-edge-formability of dual phase steel is obtained. From the analysis of the collected data, it is found that the mechanical properties have a varied influence on the hole expansion ratio (HER) because the influence of the morphology of the microstructure is more dominant. Similar results were shown by the effect of volume fraction of martensite on HER. An increase in the difference in hardness of martensite and ferrite has been shown to decrease the HER because the localization of the strain occurs at the interface and the ferrite boundary. The difference in the hardness of this phase is influenced by the amount of carbon content in the martensite. The highest HER value is obtained with a cone-shaped punch because it provides tensile conditions compared to flat punch. Where hole preparation using punching, machining, and EDM can produce higher HER values, respectively. The largest sheared area zone (SAZ) which leaves the most defects is the cause of hole preparation by punching has the lowest HER