8670 vs 5160
These two sit at the very top of the common-steel toughness charts, close enough that testing struggles to separate them. 5160 earned its reputation in leaf springs and swords; 8670 earned its in band-saw blades that flex millions of cycles without cracking. The choice usually comes down to hardness targets and what your supplier actually stocks.
Quick Verdict
Choose 5160 for swords, giant choppers and spring-flex builds run at modest hardness — it is the proven benchmark there. Choose 8670 to get that same toughness class at a point or two more hardness, in thinner stock, usually for less money. Honest answer: both survive whatever you are planning.
Toughness
A statistical tie at the top of the charts — this pairing is the 1a/1b of budget toughness. The practical difference: 5160 is traditionally run softer (56–58 HRC) where it is nearly indestructible, while 8670's nickel lets it keep elite toughness at 59–60. Same class, different sweet spots.
Edge Retention
8670 slightly, mostly because it is comfortable a point or two harder — at equal hardness there is little between them, and both are low-wear steels that trade endurance for easy field sharpening.
Corrosion Resistance
Both rust readily; neither alloy addition helps meaningfully. Spring steel patina stories and band-saw rust stories are the same story. Oil, dry, repeat.
Heat Treat
Both are forge-friendly, deep-enough-hardening steels with wide margins. 5160's chromium wants a decent soak to do its job — rushed forge cycles leave performance on the table more often than people admit. 8670's tested 1500°F recipe with its linear no-trap temper range is about as foolproof as heat treating gets. Slight nod to 8670 for predictability.
Grinding
No meaningful difference on the belt — both grind cleanly and quickly with cheap ceramics. Stock is the real difference: 5160 runs thick (spring heritage) and suits big-blade builds; 8670 runs thin and saves grinding time on knife-sized work.
Best-Use Scenarios
5160: swords, large choppers, tomahawks, anything with spring flex in the design brief, traditional forged big blades. 8670: camp knives and choppers at knife scale, batoning blades run slightly harder, budget builds where thin stock and low price move the decision.