Evolution Rage 3s mitre saw, good or bad?

I have had an Evolution Rage 3s 210mm compound mitre saw for years. It is great at giving a good cuts in metal and wood. But here's the problem, I only get about 8 good cuts out of the blade when cutting box steel and such like. What am I doing wrong, do you have the same problem? As the blades are £20 a pop its a bit expensive to cut steel at only 8 cuts per blade! What do you use, what would you suggest? Leave suggestions in the comments please. ... https://www.youtube.com/watch?v=RJq49wDsII0