Question

structural steel will lose about 90% of its strength in a fire that raises the temperature to 1000 degrees fahrenheit for more than 15 minutes. if alloyed with two other metals, the steel will increase its strength by 50%. which two metals should be added? (you will need to check of two correct choices to get this question correct.)
molybdenum
chromium
titanium
magnesium
cobalt
rhenium

Explanation:

To improve the fire - resistance and strength of structural steel, Molybdenum and Chromium are commonly used alloying elements. Molybdenum can enhance the high - temperature strength and creep resistance of steel, and Chromium can improve the oxidation resistance and strength of steel. When these two metals are alloyed with steel, they can effectively increase the strength of the steel, which is in line with the requirement of a 50% increase in strength mentioned in the problem. Titanium, Magnesium, and the other un - clearly named metals (from the given options) do not have the same effect as Molybdenum and Chromium in this context.

Answer:

A. Molybdenum, B. Chromium