Stainless Steel SCS 24 Bars

Product Description

Microstructural Breakdown: Cast vs. Wrought

The primary engineering difference between a cast bar (SCS 24) and a hot-rolled/forged bar (SUS 630 / W.Nr. 1.4542) comes down to grain structure, chemical segregation, and directional uniformity.

SCS 24 (Cast Structure)

• Microstructure: Features an as-cast, coarse-grained dendritic structure. It inherently contains higher trace levels of delta ferrite stringers ($5\%\text{ to }15\%$) to prevent hot-cracking during the solidification process in the mold.

• Isotropic Properties: Cast bars exhibit uniform properties in all directions (isotropic) because the crystal growth isn't elongated by directional rolling mill forces.

• Porosity: Subject to micro-shrinkage and subsurface gas porosity, which can compromise thin-walled sections or high-vacuum sealing faces.

SUS 630 / Alloy 630 (Wrought Bar Structure)

• Microstructure: Hot working refines and breaks down the cast ingots into a fine, uniform grain matrix. Delta ferrite is minimized and broken down into isolated linear stringers.

• Anisotropic Properties: Because the material is rolled or drawn into bars, it gains distinct directionality. Longitudinal properties (along the length of the bar) feature superior fatigue life and impact toughness compared to the transverse (across the diameter) profile.

Direct Processing Comparisons

If your print allows a substitution between these two delivery formats, keep these machining and finishing dynamics in mind:

Standard Thermal Cycles

Both variations follow virtually identical heat-treatment protocols to activate the copper-rich precipitation clusters ($Cu_4Nb$ phases) that give the material its structural strength:

1. Solution Annealing (Condition A): Heat to $1040^\circ\text{C}$ ($\pm 15^\circ\text{C}$), hold to achieve a uniform solution of elements, and rapidly quench (oil or air cooling) down below $30^\circ\text{C}$ to lock in a supersaturated martensitic state.

2. Precipitation Aging (+P / H-Condition): Re-heat to an isolated temperature window between $480^\circ\text{C}$ (H900) and $620^\circ\text{C}$ (H1150) for 1 to 4 hours to control final hardness, yield limits, and impact energy thresholds.