Blacksmith Forge 2D — Heat Curve, Forging & Quench Hardness

Forge

Forge temperature 1150°C

Quench & Temper

Temper temperature 400°C

Live Readouts

In forge — heating

0 HRC65 HRC

Temperature

20°C

Hardness

15 HRC

Hammer strikes

Forging progress

Microstructure

Ferrite/pearlite (soft)

How it works

The bar's temperature chases whatever it is exposed to by Newton's law of heating/cooling — an exponential approach that is the same equation whether the workpiece sits in the forge, on the anvil, or in a quench bath, only the target temperature and rate constant change:

dT/dt = k·(T_target − T)
forge:  T_target = forge slider,   k ≈ 0.35 /s
anvil:  T_target = 20°C (air),     k ≈ 0.05 /s
quench: T_target = 20°C (bath),    k = medium severity (water > brine > oil > air)

Steel only deforms plastically above roughly 750°C — below that the hammer just bruises cold, brittle metal instead of shaping it, exactly like the 3D forge this page pairs with. Quenching decides the resulting hardness: the bar must be above ≈780°C (fully austenitic) for any hardening to occur at all, and then how fast the chosen medium pulls heat out sets how much martensite forms versus how much softer pearlite:

severity = quench rate constant / water's rate constant
martensite fraction = clamp((severity − 0.10) / 0.90, 0, 1)
hardness = 15 + fraction × (62 − 15)   [HRC]

Water / brine — fastest quench, most martensite, hardest but most brittle result.
Oil — slower quench, partial hardening, a tougher compromise.
Air — too slow to form martensite at all; this is normalizing, not hardening.
Tempering — reheating a quenched (martensitic) bar to 150–650°C relieves internal stress and trades some hardness back for toughness; the higher the temper temperature, the more hardness is sacrificed.

Real-world relevance: this heat/forge/quench/temper sequence is exactly how a blacksmith or heat-treater controls the final hardness and toughness of a tool or blade — the same physics, whether it's a hand-forged knife or an industrial quench-and-temper line.

Cold / not forgeable Forgeable heat White / near-melting

Temperature vs. Time