Metallurgical Analysis
Inclusion Rating —
ASTM E45 / ISO 4967
Systematic assessment of non-metallic inclusions in steel using standard chart comparison. An essential cleanliness indicator for bearing steels, tool steels, and critical structural applications.
Request Inclusion RatingWhat is Inclusion Rating?
Non-metallic inclusions in steel originate from deoxidation products, entrapped slag, and refractory contamination during steelmaking. Their presence, type, size, and distribution significantly affect mechanical properties — particularly fatigue strength, transverse ductility, toughness, and machinability.
Inclusion rating is performed on a polished, unetched longitudinal section at 100× magnification. Each field is compared against ASTM E45 or ISO 4967 reference charts. Inclusions are classified by type (A, B, C, D) and severity (thin/heavy). Results are reported as worst-field values and average values across the examined area.
ASTM E45 Method A — Worst-field chart comparison at 100× over the full specimen area. Standard method for most specifications. Method D (automated image analysis) available for referee testing.
Applications
Bearing Steel Qualification
SAE 52100, EN 31 — inclusion cleanliness is critical for bearing fatigue life.
Tool Steel Acceptance
H13, D2, M2 — high-cleanliness requirement for die and tool life.
Spring Steel
SUP10, 65Mn — inclusion-induced fatigue failure is a primary failure mode.
Forging Quality Verification
Confirm cleanliness of forging stock per customer or standard requirement.
Failure Analysis
Determine if inclusions were the initiation site for fatigue cracking.