بررسي تاثير مقدار تيتانيم بر ساختار و خواص مكانيكي فولاد فوق مستحكم Ni-Co-Mo

Effect of Ti Content on Microstructure & Mechanical Properties of Ni-Co-Mo Ultra-Strength Steel.

In this research the influence of Ti on microstructure & mechanical properties of 18Ni (300) has been investigated. For this purpose seven bars were casted under the same solidification conditions but different amounts of Ti element. All the 7 casted bars were homoginized at 1200°C for a period of 2 hours. Then, They were immediately hot rolled after homogenization, so that the out rolled temperature was in the range of 1000-1200°C. The speciments were then solution annealed at 820°C for 1 hours and finally they were aged for a period of 3 hours at 500°C. The samples were subjected to tensile, impact and hardness tests in order to relate the variation in microstructure due to different amount of Ti, to mechanical properties. The results show that by increasing the amount of Ti to about 1.05Wt%, the optimum strength and toughness of this material can be obtained. However if the amount of Ti increases more than that it requires for optimum precipitations, the amount of Ni content of matrix declines and causes a decrease in mechanical properties of material.