Why Does Fracture Toughness Decrease as Material Strength Increases?

[cero]

Hi, why does fracture toughness decrease when a material increases in strength?

How do one explain this relationship? Does it have to do with stress vs. strain curve?

Thanks.

 

[Mapes]

Hi cero, welcome to PF!

We can't just give you the answer, but if you describe your reasoning, you'll likely get helpful comments. Hint: think about the plastic zone at the crack tip.