I'm not sure how that's different from many other forms of engineering. For the example I gave, bump the temperature you hold it at after quenching by 20 degrees, and it will shatter because it hit the TME (Tempered Martensitic Embrittlement) stage. Hold it above that temperature by 80 degrees, and it won't hold an edge, although it will be ductile. Increase the amount of carbon by 0.5%, and it will be remarkably brittle and weak. Decrease it by 0.5%, and it will be extremely soft and won't hold an edge. etc, etc.
A knife is fairly unimportant, but make the wrong decisions of that sort on a plane, or on a bridge, and people will die.
Even more subtle decisions can have serious consequences. See, for example, the DeHavilland Comet, which crashed because the windows were too square.
The squareness was causing them to act as stress concentrators. With the cyclic loading from pressure changes, this caused metal fatigue, and the windows would fail after hundreds of flights. This could be fixed by rounding the corners of the windows, or by using alloys that don't fatigue as easily. And this is why modern jets have rounded portholes, instead of rectangular windows.
A knife is fairly unimportant, but make the wrong decisions of that sort on a plane, or on a bridge, and people will die.
Even more subtle decisions can have serious consequences. See, for example, the DeHavilland Comet, which crashed because the windows were too square.
The squareness was causing them to act as stress concentrators. With the cyclic loading from pressure changes, this caused metal fatigue, and the windows would fail after hundreds of flights. This could be fixed by rounding the corners of the windows, or by using alloys that don't fatigue as easily. And this is why modern jets have rounded portholes, instead of rectangular windows.