Newly-Developed Organic Composite-Coated Steel Sheet with High Perforation Resistance 850004
A new organic composite-coated steel sheet “Zincrometal-KII” has been developed. The steel sheet consists of a specially improved thin zinc rich paint on Zn-Ni alley electroplated layer of low coating weight. Corrosion resistance, formability and weldability were investigated.
In two cyclic corrosion tests, consisting of salt spray, salt water immersion, drying and humidity, red rust initiation time of the flat part in unpainted condition of KII was about one and half times longer and its thickness reduction was reduced into less than about two third as compared to the conventional organic coated steel. Also the red rust growths of the formed part in unpainted condition and the flat part after electrodeposition were less.
The exfoliated film weights after cylindrical cup drawing and bead drawing were about one seventh of conventional one.
In weldability, the number of the continuous spot weldings was about two times larger than that of conventional one and was more than 5000 welds.