> Forgings have the added advantage of variable grain direction which generally can be tailored to the stress patterns of a specific design.
This is a super underappreciated fact! It's often repeated that forging is just stronger, but just squishing steel does NOT make it stronger. Forging a part is so much more than just smashing it into a shape.
Steel cable is made of pretty ordinary steel which is stretched 100s of times its original length. That process alone makes it 2-4x stronger in that direction. You stretch steel and it gets stronger in that direction.
Do you see how complicated that optimization process becomes? The process steps are not just trying to take it to the final shape. Your piston rod needs to be strong lengthwise, so you actually want to start with a short fat ingot and stretch it out instead of one that is near-final size.
Think of making an I-beam. You could hammer out the middle, making it thinner. That would give you a bit of strength there but very little on the edges. If you instead pull the edges out, you create a long continuous stretch that will be very strong against bending. Where, how, and in what order you stretch makes all the difference. You may want to leave extra material and cut it off later, so that your grains are all oriented together instead of tapering to a point.
For any moderately complex part, this process is as complicated as modern engineering problems. With poor steel you genuinely need to understand how to foster and bring out those continuous lines or your corkscrew will unwind like playdough. Blacksmiths had a legitimately intellectual job back in the day!
This is a super underappreciated fact! It's often repeated that forging is just stronger, but just squishing steel does NOT make it stronger. Forging a part is so much more than just smashing it into a shape.
Steel cable is made of pretty ordinary steel which is stretched 100s of times its original length. That process alone makes it 2-4x stronger in that direction. You stretch steel and it gets stronger in that direction.
Do you see how complicated that optimization process becomes? The process steps are not just trying to take it to the final shape. Your piston rod needs to be strong lengthwise, so you actually want to start with a short fat ingot and stretch it out instead of one that is near-final size.
Think of making an I-beam. You could hammer out the middle, making it thinner. That would give you a bit of strength there but very little on the edges. If you instead pull the edges out, you create a long continuous stretch that will be very strong against bending. Where, how, and in what order you stretch makes all the difference. You may want to leave extra material and cut it off later, so that your grains are all oriented together instead of tapering to a point.
For any moderately complex part, this process is as complicated as modern engineering problems. With poor steel you genuinely need to understand how to foster and bring out those continuous lines or your corkscrew will unwind like playdough. Blacksmiths had a legitimately intellectual job back in the day!