On 15 Apr 2005 20:41:18 GMT, Chuck Sherwood wrote:
Why would anyone want to harden lawnmower blades? They are meant to
cut very soft material (grass) by hitting it at high speed and
splitting the stems. Hardnedd of the blade is irrelevant to grass
cutting performance.

But the blades still dull and need to be sharpened.
If the edge was harder, they would not dull as fast.
I have a relatively small yard, and I still need to
sharpen blades every 3-4 cuttings.

Are you hitting stones or dirt a lot? That seems very excessive.
Problem with hardening the blades, is that they'd then be brittle.
So, instead of rounding off, they'd fragment. Either way, not what
you want. I think it's a better approach to figure out why you only
get 3-4 cuttings out of a set of blades; mine usually go a season,
mowing about 4-5 acres with a 3-blade deck.