Through another part of my job, I've done lengthy testing on 4130N for tensile and Charpy tests. I can tell you it's downright scary what happens to 4130 in less than perfect conditions. Charpy values under 6 joules are common in the HAZ, and HV10 values exceeding 320. There are much better materials out there. Docol is a step in the right direction. Now, I'm not saying 4130 can't work, it just takes more careful control of welding parameters/excellent fit-up than most people think.
That, and in my experience, bending or deforming is superior to cracking/fracturing in a crash.
It's amazing sometimes how certain things are not considered critical. Take for instance grinding of the welds. All sanctioning bodies forbid it. That said, it's done all the time, then re-welded. This in my mind is usually worse, especially with 4130. (Docol will not benefit either). The extra heat you put in to the joint area by doing this is terrible from a metallurgy perspective. The whole reason for not allowing grinding, is to see what kind of welding can be done on your first crack, not your second or third. This is to try and ensure high quality welds.
I'm testing the Docol with AED to see what happens under welding conditions. I'll be testing the good and the bad alike. I agree it could be a good replacement for DOM, as that is a whole other can of worms. The tighter control on the higher quality Docol should help overall. That is the one thing I like about 4130, is the quality of the material overall. That said, nobody seems to watch the carbon content very closely, and it is a huge factor in the overall picture of fracture toughness and heat input/HAZ concerns.
