For the linear-elastic analysis you describe, the key pieces of material information are the elastic modulus (E) to calculate deflection and the yield stress (Fy) to check if the material remains elastic under the given loading. For steel, E is commonly around 200 GPa. The Fy can vary significantly depending on the grade of steel, so you'...
Although the deflections equation @kamran reported, are indeed what most textbooks give, the problem is that they only hold true for relatively small deflections.
I also agreewith @alephzero that there are a few errors in the calculations.
e.g. I calculate $Ix = 0.0491 cm^4$.
By my calculations, you would need a steel rod with almost 11cm diameter to support ...
I cm diameter bar at 2metres cantilever does not support its own weight within acceptable deflection limit, let alone 50kg load.
Assuming the wight of the bar is 200*8 gr=1600 gr.
$I_x= \pi d^4/64= 3.14*1/64=0.5cm^4 \quad \delta= Pl^3/3EI$
$\delta= 1.6*100^3/(3*0.5 *2039432)=$6 cm> L/180 6mm$
And this is deflection at half span, deflection at the 2 meters ...