Boriding

Boriding produces an extremely hard, wear-resistant surface layer on the component. That's good for parts subject to heavy abrasion, but the layer is brittle. If you have to weld afterwards, be careful: The hard layer must be completely removed in the weld area, otherwise the structure will crack. And the heat from welding can cause the boron to attack the base material structure and make it brittle. So: grind it off before welding, and if you need the hardness again, you'll have to re-boride the part after welding.