Steel selection by application — hot-work, warm-work, and the special cases

Premium hot-work steels are not "better H13." They are different chemistries inside the Cr-Mo-V family, melted to higher cleanliness, with property curves shifted relative to standard H13. The three most relevant for forge work in 2026 are Uddeholm DIEVAR, Uddeholm QRO 90 Supreme, and Bohler W360 ISOBLOC. Bohler W302 SUPERIOR is the ESR-remelted standard H13 reference and sits alongside them.

DIEVAR is a reduced-silicon Cr-Mo-V grade with ESR melting that shifts the trade surface toward toughness and thermal fatigue resistance at the same nominal hardness as H13. Uddeholm's own performance data claims 50-100% die life extension over premium H13 when the failure mode is heat checking or gross cracking. The numbers are vendor numbers and have to be read against the actual failure mode, but the chemistry and the cleanliness rationale are sound.

QRO 90 Supreme runs higher molybdenum and slightly different chromium chemistry, and is positioned for high die-surface temperature work in aluminum, copper, and brass forging and extrusion. Its hot hardness at 600°C is meaningfully above standard H13, which is why it shows up on aluminum hot-forge dies where the bulk steel sees real elevated temperature in service.

W360 ISOBLOC is a different play. It is a 5% Cr-Mo-V steel rated to run at 52-57 HRC instead of the H13 range of 44-52 HRC, and the ISOBLOC processing delivers that hardness with toughness preserved. The application is forge punches and small inserts where you want the wear resistance that comes with higher hardness but cannot give up impact tolerance. On a punch that has been failing by gross deformation at 48 HRC, W360 at 54 HRC is sometimes the move.

W302 SUPERIOR is ESR-remelted standard H13 chemistry. The premium is microcleanliness and carbide banding, not a chemistry shift. It is the right answer when the failure mode is fatigue-limited on a standard H13 die and you want the same metallurgy with the inclusions taken out.

The trap on this whole tier is the framing. The premium tier earns its place when the failure mode is in the regime these grades shift. Premium ESR earns its place on dies failing by heat checking or by inclusion-initiated cracking. It does not earn its place on dies failing by abrasive wear or by plastic deformation at the cavity face, where the wear axis is doing the work and a cleaner ingot does not change the answer.