• Puttonen, Jari
• Shakil, Saani
• Abebe, Zemenu
• Lu, Wei

Abstract

This paper discusses mechanical properties after one heating and cooling cycle using experimental tests. The material tested was steel S900MC, which has the nominal yield strength of 900 N/mm2. The specimens were tested with being first heated up inside a furnace to a pre-defined temperature, then cooled down to the room temperature. I n order to study the effects of cooling rates on mechanical properties, two different cooling methods were used: cooling inside furnace, and cooling in the air.<br/><br/>The results indicated a clearly reduction of the strength when the steel was cooled from the temperature above 500 °C. The steel reduced 40% of its yield strength after cooled from 700°C, while only 20% remained when cooled from 900°C. The elastic modulus was regained to its original value after the steel was cooled from temperatures below 500°C, whereas about 80% was regained when the steel was cooled from 900°C. Cooling temperatures between 700°C and 900°C produced a large scatter among all the mechanical properties. The cooling rate did not affect the mechanical properteis when the maximum temperature remains below 700 °C before the cooling starts. However, when exposed to an elevated temperature above 700°C the effect is visible. The air-cooled specimens had higher strength and lower ductility than furnace cooled specimens. The results of this study will help to evaluate the load-bearing capacity and reusability of the steel members after fire-exposure.<br/>

Topics

• impedance spectroscopy
• strength
• steel
• yield strength
• ductility
• furnace cooled