Especificaciones clave
- Chromium Range
- 15–28% (Cr15 to Cr28 grades)
- Hardness Range
- 55–68 HRC (after destabilisation heat treatment)
- Carbide Type
- M7C3 eutectic (hexagonal rod morphology)
- Carbide Volume Fraction
- 25–40+% (grade-dependent)
- Fracture Toughness
- 15–30 MPa*m^0.5 (K1c)
- Heat Treatment
- Destabilise 950–1,050 C, quench, temper 200–250 C
- Standards
- ASTM A532 Class II-A, II-B, III-A
- Applications
- Mill liners, pump parts, blow bars, VSI plates, grate bars
Metallurgical Characteristics of High Chrome White Iron
M7C3 Eutectic Carbide Morphology
Chromium content above 12% shifts the carbide type from M3C to M7C3. These carbides grow as hexagonal rods in cross-section and elongated blades in longitudinal section, with hardness values of 1500-1800 HV. Their discontinuous distribution avoids the crack-propagating continuous carbide networks of low-alloy white irons.
Carbide Volume Fraction Control
Carbide volume fraction ranges from approximately 25% in Cr15 hypoeutectic grades to over 40% in Cr28 hypereutectic compositions. Higher carbide volume directly increases abrasion resistance but reduces fracture toughness. The carbon-to-chromium ratio determines whether the alloy solidifies as hypoeutectic, eutectic, or hypereutectic.
Heat-Treatable Austenitic Matrix
In the as-cast condition, the matrix is predominantly austenite retained by the high alloy content. Destabilization heat treatment (900-1050 degrees C) precipitates secondary carbides from the austenite, depleting it of carbon and chromium so it transforms to martensite on quenching. This raises bulk hardness by 5-10 HRC.
Molybdenum for Thick-Section Hardenability
Sections above 75 mm thickness require molybdenum additions (1-3%) to suppress pearlite formation during cooling. Without adequate hardenability, thick castings develop soft pearlitic zones in their centres that wear preferentially and undermine component life.
Abrasion Resistance Superior to Manganese
In three-body abrasion (sliding contact with loose abrasive particles), high-chrome white irons outperform Mn14 manganese steel by 3-6 times depending on grade and conditions. This advantage is most pronounced in applications such as mill liners, slurry pump shells, and chute liners where impact energy is moderate.
Brittle Fracture Limitation
Fracture toughness (K1c) of high-chrome white irons ranges from 15 to 30 MPa per root metre, compared to 80+ MPa per root metre for austenitic manganese steel. This limits their use to applications where impact energy remains below the critical threshold for the specific grade and section thickness.
High Chrome White Iron: The Primary Abrasion-Resistant Casting Alloy
High chrome white iron is the dominant alloy family for abrasion-resistant castings in mineral processing and aggregate production, specified wherever the primary wear mechanism is sliding, gouging, or grinding abrasion rather than high-energy impact. Chromium additions from 15% to 28%, classified under ASTM A532 as Class II-A (Cr15Mo3), Class II-B (Cr20Mo), and Class III-A (Cr26/Cr26Mo), produce a microstructure of hard M7C3 eutectic carbides dispersed in a heat-treatable austenite-martensite matrix. The carbide volume fraction (25–40+%), morphology, and matrix hardness can be precisely controlled through alloy composition and destabilisation heat treatment (950–1,050 degrees C followed by quenching and tempering at 200–250 degrees C) to achieve bulk hardness values from 55 to 68 HRC. At these hardness levels, the alloy surface is significantly harder than quartz (approximately 1,100 HV) and most silicate minerals encountered in mining and quarrying operations.
The defining characteristic of high-chrome white irons is the M7C3 carbide type, which forms when chromium content exceeds approximately 12% and shifts the solidification carbide from the continuous M3C network found in unalloyed white iron to discrete hexagonal rods and elongated blades with individual carbide hardness values of 1,500–1,800 HV. This discontinuous morphology provides a meaningful improvement in fracture toughness (K1c of 15–30 MPa*m^0.5) over ordinary white iron while maintaining exceptional abrasion resistance—in standardised three-body abrasion tests (ASTM G65), high-chrome white irons outperform Mn14 manganese steel by a factor of 3–6 depending on grade and test conditions. The trade-off between abrasion resistance and impact tolerance is the central engineering challenge: high-chrome white irons deliver far greater wear life than manganese steels in sliding and gouging abrasion, but their low ductility means they cannot absorb severe impact loading (such as tramp metal strikes or large uncrushable objects) without risk of catastrophic cracking.
Applications by Component Type
High chrome white iron alloys are cast into a wide range of wear components across crushing, grinding, and pumping equipment. The specific grade is matched to the wear mechanism and impact severity of each application.
Blow Bars and Impact Crusher Parts
- Cr26 blow bars for secondary and tertiary HSI crushers processing non-metallic feed
- Cr15Mo3 impact plates for mixed abrasion-impact duties in lower chamber positions
- Cr20Mo side liners and housing protectors for horizontal shaft impactors
Mill Liners and Grinding Components
- Cr26Mo shell liners for SAG, AG, and ball mills in hard-rock mineral processing
- Cr20Mo grate plates and discharge grates for semi-autogenous grinding mills
- Cr15Mo3 trunnion liners and head liners where impact from charge is a factor
Slurry Pump Parts
- Cr26 impellers and volute liners for mineral slurry pump service
- Cr28 throat bushings and frame plate liners for ultra-abrasive tailings duty
- Cr15Mo3 suction covers and stuffing box components requiring moderate toughness
VSI Wear Plates and Rotor Components
- Cr26 anvil ring segments and cavity wear plates for rock-on-iron VSI crushers
- Cr26Mo distributor plates and rotor tips for high-throughput tertiary VSI applications
- Cr28 feed tube liners and upper/lower wear plates in extreme-abrasion vertical shaft impactors
Grate Bars and Screen Media
- Cr26Mo grate bars for hammer mills and clinker crushers in cement production
- Cr20Mo screen plates for hot clinker grizzlies and roller press circuits
- Cr15Mo3 grate bars for single-stage hammer crushers with mixed impact-abrasion loading
Need Help Selecting a High Chrome Grade?
Provide your application details, feed material, and operating conditions. ATF metallurgists will recommend the optimal alloy and heat treatment for your wear parts.
High Chrome White Iron Grade Comparison
Grade selection depends on the balance required between abrasion resistance, impact tolerance, and section thickness. Higher chromium grades increase carbide volume and abrasion life but reduce toughness. Molybdenum is added where thick sections or air-cooling conditions demand greater hardenability.
| Material | Dureza | Aplicación | Notas |
|---|---|---|---|
| Cr15Mo3 (ASTM A532 II-A) | 55-62 HRC | Pump casings, pipe elbows, cyclone liners, and moderate-abrasion components where some impact tolerance is needed | Approx. 25% carbide volume fraction. Lowest Cr grade; best toughness in the high-chrome family. Mo addition enables through-hardening in sections to 150 mm. |
| Cr20Mo (ASTM A532 II-B) | 58-64 HRC | Ball mill liners, cement mill liners, and grinding media where consistent hardness through thick sections is required | Approx. 30% carbide volume fraction. Good balance of wear life and castability. Widely used for large mill liner segments. |
| Cr26 (ASTM A532 III-A) | 60-66 HRC | VSI wear plates, slurry pump impellers, SAG mill shell liners, and high-abrasion low-impact duties | Approx. 33% carbide volume fraction. Standard high-performance grade for mineral processing wear parts. Lower toughness limits impact tolerance. |
| Cr26Mo (ASTM A532 III-A + Mo) | 62-67 HRC | Thick-section mill liners, large pump volutes, and heavy grate bars where section thickness exceeds 100 mm | Mo addition (1-1.5%) prevents pearlite in core. Critical for components that cannot be rapidly quenched due to size or geometry. |
| Cr28 Hypereutectic | 64-68 HRC | Extreme abrasion duties: chute liners in iron ore, coal pulveriser rolls, and thin-section wear tiles where impact is minimal | Approx. 40%+ carbide volume fraction. Primary M7C3 carbides form as large blades. Maximum abrasion resistance but very brittle; not suitable for impact applications. |
Cr15Mo3 (ASTM A532 II-A)
Cr20Mo (ASTM A532 II-B)
Cr26 (ASTM A532 III-A)
Cr26Mo (ASTM A532 III-A + Mo)
Cr28 Hypereutectic
Hardness values shown are after destabilization heat treatment and tempering. As-cast hardness is typically 5-10 HRC lower. Actual values depend on section thickness, cooling rate, and precise composition.
High-Chrome Preguntas frecuentes
Encuentre respuestas a preguntas comunes sobre high-chrome materiales, selección, mantenimiento y pedidos. ¿No encuentra lo que busca?
Contactar a nuestro equipoWhen should I choose high chrome white iron over manganese steel?
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What heat treatment does high chrome white iron require?
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How does section thickness affect high chrome white iron performance?
Related Materials Technology Pages
Manganese Steel Alloys
Austenitic manganese steels (Mn12-Mn22) for high-impact crusher wear parts. Work-hardening behaviour, alloy selection, and application guide.
Más informaciónMartensitic Alloys
Martensitic steels and low-alloy martensitic white irons for blow bars, hammers, and impact crusher components requiring combined toughness and hardness.
Más informaciónCeramic Insert Technology
Alumina and zirconia-toughened ceramic inserts for extreme abrasion resistance in crusher and mill wear parts.
Más informaciónTiC Insert Composites
Titanium carbide metal matrix composites for localised extreme-wear zones in blow bars, VSI rotor tips, and mill liners.
Más informaciónContenido técnico revisado por el equipo de ingeniería de ATF | Especificaciones metalúrgicas verificadas según normas ASTM/ISO
Specify the Right High Chrome Alloy for Your Wear Parts
ATF supplies high chrome white iron castings from Cr15 to Cr28 with full metallurgical certification. Send your drawings or worn parts for alloy recommendation and quotation.
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