reading similar posts in the news group. I conclude that the wood is very hard or . . .
I'm not an expert, but I have built two rocking chairs with over 40 m&t joints each, using blue handled marples bench chisels and never had that kind of problem. One chair was walnut and the other was mesquite.
I'm curious if technique might have some bearing on all these bad chisels we keep hearing about. (Not you, but many other wood workers)
Having written the nonsense above, FWW has a video by Jim Cummings, "Small Shop. Tips and Techniques". It deals with many things, one of which is sharpening chisels and includes a very good session on removing the temper from the steel, shaping the steel as required and then setting the proper temper.
Also as I re-read my post, I'll add the following.
I keep a leather strop, charged with a sharpening compound close at hand. When an edge develops a burr, a couple of passes on the strop normally takes care of it. I don't use scary sharp techniques. I prefer diamond EZ-lap hones. I suppose I expect chisels to turn under with use. I think the burring issue is why many wood workers use micro bevels. I typically do not use them, but on one of my hand planes I do use it.
:-)