...Alaska Bart has a highly updated NSSBC.info page.
"The Rules Committee comes under pressure regularly from competitors and sponsors to outlaw expensive steels, such a Chromalloy because there is a perception that somehow these steels give an unfair advantage to chapters with money to spend. When the rules committee can find a way to outlaw such material that is enforceable we probably will. Writing an enforceable rule restricting the type of steel has proven to be difficult.
These expensive steels seem to be used primarily because they can be obtained in lighter sections. They have generally the same stiffness (i.e. same Modulus of Elasticity, E) as other steels so they don't have a real impact on stiffness. In fact going to lighter sections may have a detrimental impact on stiffness (because of reduced AE or EI). They do come in higher tensile strengths than some of the other steels however the strength levels required by most members is minimal so there's not a huge savings here either. You might also note that if member strength is based on buckling then tensile strength is a non-issue and higher strength steels have no advantage over lower strength steels in this case. In the end, we find some very competitive bridges at the national competition that do not use these steels."
4130 Alloy has no advantage whatsoever. Though most 4130 suppliers have great size selection and wall thicknesses for the competition...and for all the whiney bitch Student Chapters who say they don't have enough money...get off your ass and go seek it out, well funded Teams do every year...there isn't a silver spoon that feeds the Ags in Davis, nor the Badgers in Madison, nor the Gators in Florida, nor the Bears in Berkeley, nor the Roos in Canton, you have to work your butt off to get funding...so don't go whining about how another Team is working harder than you.
also, for the record..."Chromium Molybdenum" aka "Chrome Moly"...Chromalloy will be seen on every 20 and 22 down in South Central, South Sac, Del Paso Heights, Long Beach, Alameda, Oakland and Reno.