SUS420J2 Mod refers to modified variants of the Japanese JIS SUS420J2 stainless steel. Manufacturers typically adjust carbon content and may add small amounts of elements such as molybdenum, vanadium, or nickel to improve hardness, wear resistance, and edge stability. Unlike standard SUS420J2, which is often used in budget knives and medical instruments, SUS420J2 Mod can achieve noticeably better knife performance while preserving the excellent corrosion resistance and toughness that made the original grade popular. Because "Mod" is not a formal steel specification, the exact composition and performance vary by manufacturer.
Comparable Steels:
SUS420J2 Mod > SUS420J2 in hardness and edge retention
SUS420J2 Mod ≈ 420HC in overall performance
SUS420J2 Mod < 440A in wear resistance
SUS420J2 Mod < 12C27 in edge stability and refinement
SUS420J2 Mod < 14C28N in overall knife performance
SUS420J2 Mod > 3Cr13 in typical heat-treated performance
SUS420J2 Mod < VG-10, CPM-S30V, and MagnaCut by a significant margin
Equivalent / Similar Steels:
420HC
X46Cr13 (W-Nr 1.4034)
Modified 420 Stainless
AUS-4 (higher-performance variants)
5Cr15MoV (some compositions overlap in application class)
Typical Composition (Approximate):
Varies by manufacturer; common ranges include:
Carbon (C): 0.35–0.50%
Chromium (Cr): 12.0–14.0%
Molybdenum (Mo): 0–0.50%
Vanadium (V): 0–0.20%
Manganese (Mn): ≤1.0%
Silicon (Si): ≤1.0%
Note:
"SUS420J2 Mod" is a commercial designation rather than an official JIS steel grade. Many Japanese knife manufacturers use proprietary modified versions of SUS420J2 to improve performance while retaining the steel’s well-known corrosion resistance and ease of maintenance.