Papers by Keyword: Hot Rolled Steel

Abstract: The cleavage fracture behaviors are studied in notched specimens of a low alloy hot rolled steel 16MnR. The results show that two types of cleavage initiation sites are existed in notched specimens, one being related to the inclusions ahead of notch root (IC type) and the other related to inclusions located ahead of string cracks far from the notch root (SIC type). The types of initiation sites are influenced strongly on temperature, changing from IC type at -196°C to SIC type at -130°C. In both IC and SIC initiation mechanisms, the crack nucleation is induced by inclusions and the final fracture is controlled by propagation of a ferrite grain-sized crack into matrix grain. The cleavage fracture of IC initiation type in notched specimens satisfies a dual-criterion model, i.e. a critical plastic strain ep ³e_pc for initiating a crack nucleus and a critical tensile stress syy³s_f for its propagation. While for SIC initiation type, the dual-criterion model is evolved with the expression of e_p+eps³e_pc and s_yy+syys³s_f.

Abstract: Metals, despite their deterioration in a corrosive atmosphere, continue to dominate the automotive, agricultural, furniture, process and appliance industries and HRS (Hot Rolled Steel) plays a significant role in those areas. Powder coating on HRS is widely employed for protective and aesthetic purposes. Prior to powder coating, phosphating conversion coating is often used to increase effectiveness of protection. However, due to tightening environmental legislations, phosphating process is now problems for industry. Therefore, newly developed environmentally friendly conversion coats are introduced to industry. In this study a new environmentally friendly zirconium fluoro-based (H2ZrF6) generation of conversion coating has been introduced to replace the conventional phosphating conversion coatings process. It is deposited on the surface with a thin nanometre range, therefore shortening the process, which also has advantages such as being free of heavy metal and operating in low or ambient temperature. The present work closely examines Zr based nano structured conversion coatings for HRS. Extensive corrosion and adhesion studies are carried out on differently prepared HRS test panels, pre-treated with Zr based conversion coating in various conditions, such as different composition ratio, temperature and contact time.