GRADE GUIDE · H13
H13 (1.2344) is the standard hot-work tool steel: a chromium-molybdenum-vanadium chemistry that keeps its hardness around 44–52 HRC while cycling against molten aluminium or red-hot billets. Die-casting dies, extrusion dies and hot-forging tooling are built on it.
Also listed as: 1.2344 · X40CrMoV5-1 · SKD61 (JIS) · AISI H13
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Hot tooling dies by heat-checking — the craze-crack network that grows as a die surface is heated and quenched thousands of times per shift. H13 was formulated to resist exactly that: hot strength from the alloy carbides, toughness to absorb thermal shock, and temper resistance so the die doesn't soften at aluminium die-casting temperatures. The Gulf's aluminium extrusion industry runs on H13 dies almost without exception.
Against D2 it is the tougher, cooler-headed sibling — much better shock resistance, lower peak hardness, less abrasion resistance. It machines reasonably in the annealed state, nitrides beautifully for extrusion die surfaces, and premium remelted (ESR) versions serve the hardest die-casting duty. Off-cut die blocks and bar ends from tooling shops give die repairers and moldmakers certified stock in exactly the odd sizes repairs need.
Its temper resistance sits exactly in the aluminium processing window — die-casting at ~700 °C melt and extrusion containers stay below the temperatures that would soften it, while its toughness survives the thermal cycling that cracks harder steels.
Electro-slag remelted — a cleaner remelting step that removes inclusions and tightens the structure. Premium die-casting dies specify ESR H13 for longer heat-checking life; general tooling is fine on standard quality.
It can, where toughness matters more than edge retention — but at 50 HRC it wears faster than D2 in abrasive blanking. Match the failure mode: heat and shock → H13, abrasion → D2.