I thought about the ease of welding too. Titanium 811 for example was said to have different ease of welding depending on who I talked to.
Just for the sake of price comparison, I could not find any small order suppliers of Titanium 811, or any Titanium alloy for that matter.
... Yes, other considerations ...
The price of 4130 was not the expected 25% more than carbon steel, as one source indicated. There aren't many 4130 small-order retailers, so competition is limited. That resulted in 270% price increase over the thicker carbon steel.
To me it seems that 4130...
The frame will be for automotive usage. Weight will not be a factor, due to relatively small quantity used.
The dimensions of each frame will be identical, except for the wall thickness. There is no choice, it's either 0.188 carbon steel or 0.120 4130 alloy.
I don't know if 4130 alloy can...
Both frames are made of 1.5 inch square tubes.
One is .120 inch thick 4130 steel alloy.
The other is .188 inch thick carbon steel.
Which type will create the stronger frame?