Elsewhere in that same Goddard book, he gives the formulation of these two together for comparison:
5160 (low chromium): 0.6% C, 0.8% Mn, 0.8% Cr
6150: 0.5% C, 0.8% Mn, 0.9% Cr, 0.18% V
L6: 0.7% C, 0.75% Cr, 1.5% Ni, 0.25% Mo
50100-B: 1.1% C, 0.45%Mn, 0.45%Cr, 0.20%V
0170-6: 0.95%C, 0.4%Mn, 0.25% Si, 0.45%Cr, 0.2% V
Cold Steel's
Carbon V: 0.95% C, 0.46%Mn, 0.16%Si, 0.48% Cr, 0.19% V
Goddard: "If a truck spring seems extra hard to work and showns a temper line when hardened it may be 6150 Chrome/Vanadium steel."
So 6150 is close to 5160 but has a touch of Vanadium, I guess to help refine the grain structure during heat treat. So 6150 should be pretty close to a touch better stuff than 5160. (I'm no maker, just a student and collector).
L6 is supposed to be a touch sumbitch, and I'd have to guess that's from the nickel content.
Well, here is from a Jim Hrisoulas book:
"Nickel increases toughness and strengthens the steel, but is ineffective in increasing hardness."
"Vanadium retards grain growth of steel even after long exposures at high temperatures. It also helps to control grain structures during heat treating. Usually present in small quantities of 0.15% to 0.20%. Tool steels that contain this element usually absorb shock better than those that don't."
More from Hrisoulas, condensed:
5160: wear resistance = high-medium
toughness = high
L6: wear resistance = medium
toughness = very high
Hope that helps some to frame this up a bit. Sounds to me like 6150 should better 5160 in all regards by a small margin... same or better edge holding, a bit better grain structure, a bit tougher maybe.
[This message has been edited by rdangerer (edited 06-06-2001).]