1.2311 Steel

Hardness Gradient

Deep cross-sections in large mould blocks can exhibit subtle microstructural variations from the exterior to the core. In standard 1.2311 steel, chromium and molybdenum alloying elements maintain consistent tensile strength throughout the block thickness. Higher core uniformity prevents local flexing under peak packing pressures, preserving part wall thickness tolerances across multi-cavity layouts.

Inconsistent heat treatment during block forging leads to localized soft spots that deform prematurely under continuous clamping forces.

Machining Dynamics

Pre-hardened delivery states eliminate the dimensional distortion associated with quench and temper cycles performed after cut-off. High cutting speeds during CNC milling of 1.2311 steel generate predictable chip formation, though cutter wear accelerates when machining deep rib features. Tooling shops balance benching hours against cutter consumption costs when establishing feeds and speeds for complex core geometries.

Regrind blends containing abrasive fillers drastically shorten cavity finish life compared to virgin resin feeds.

Polishing Limit

Surface finishing capabilities dictate whether a cavity block can achieve high-gloss cosmetic standards on moulded components. Pre-hardened 1.2311 steel accepts polishing up to SPI A2 standards before micro-segregation of carbides creates pinholes or micro-textures on appearance surfaces. Datasheet hardness values reflect bulk block properties, whereas local polishing response varies with microscopic sulfur inclusions added during steelmaking to improve machinability.

Heavy manual polishing exposes hard carbide particles that dislodge from the softer iron matrix during extended molding runs, producing cosmetic blemishes on parts.