Chromium carbide microstructure
Primary M7C3 carbides in a martensitic matrix give sustained resistance to sliding abrasion.
Crusher Wear Parts
High Chrome Blow Bars
Chromium-carbide blow bars for abrasive, low-to-medium impact crushing where wear life matters more than shock resistance.
Overview
About high chrome blow bars
High chrome blow bars are cast in hypereutectic white iron, where hard chromium carbides sit in a martensitic matrix. That structure resists sliding abrasion far better than steel, which is what makes it the default choice for limestone, dolomite, gravel and other clean, abrasive feeds.
Melco supplies high chrome blow bars in the ASTM A532 Class II and Class III families, typically 15Cr-3Mo, 20Cr-Mo and 25Cr. Each grade is heat treated in-house to 58–64 HRC and verified by spectrometer analysis and hardness testing before dispatch.
The trade-off is impact resistance: chromium carbide is hard but brittle. Where the feed carries tramp metal, rebar or large uncrushable material, a manganese or martensitic bar will outlast a high chrome one despite being softer.
Applications
- Limestone and dolomite crushing in cement plants
- Aggregate and gravel production for road construction
- Secondary and tertiary impact crushing
- Clean, abrasive feed with limited tramp metal
- Sand and gravel washing plant feed preparation
Features
What you get
Heat treated in-house
Destabilisation and tempering cycles run on our own computer-controlled furnaces, so hardness is repeatable heat to heat.
Spectrometer-verified chemistry
Every heat is analysed before pouring and the certificate travels with the casting.
Cast to your drawing or sample
Pattern shop works from OEM drawings, a sample bar or a 3D scan of a worn part.
Specifications
Manufacturing specification
Applies to high chrome blow bars produced at our works. Castings outside this range can usually be accommodated, so please ask.
| Moulding | No-bake resin sand and green sand |
|---|---|
| Melting | Induction furnace, spectrometer-controlled |
| Piece weight | 5 kg – 2,000 kg |
| Heat treatment | In-house, computer-controlled cycles |
| Dimensional control | Template and CMM check against drawing |
| Documentation | Chemical, hardness and dimensional report per heat |
Material grades
| Grade | Typical composition | Hardness | Suited to |
|---|---|---|---|
| ASTM A532 Cl. II Type B (15Cr-3Mo) | 14–18% Cr, 2.5–3.5% Mo, 2.4–3.0% C | 58–64 HRC | General high-abrasion impact crushing |
| ASTM A532 Cl. II Type D (20Cr-Mo) | 18–23% Cr, 1.5% Mo max, 2.0–3.3% C | 58–63 HRC | Abrasive limestone and secondary duty |
| ASTM A532 Cl. III Type A (25Cr) | 23–30% Cr, 1.5% Mo max, 2.0–3.3% C | 56–62 HRC | Highest abrasion, corrosive or wet feed |
Composition ranges are quoted against the published standard. Actual analysis for your heat is issued with the castings.
Gallery
From our works
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High chrome bars after fettling, before dimensional check. -
Mounting profile: the face that decides whether a bar seats square. -
Weight-matched set strapped for container loading.
Questions
High Chrome Blow Bars: common questions
When should I choose high chrome blow bars over manganese steel?
Choose high chrome when the feed is abrasive but relatively clean (limestone, dolomite, river gravel) and the crusher sees steady, moderate impact. Choose manganese steel when the feed carries rebar, tramp metal or large uncrushables, because high chrome will chip or fracture under heavy shock.
What hardness do your high chrome blow bars reach?
Typically 58–64 HRC depending on grade and section thickness. Unlike manganese steel, high chrome arrives at full hardness. It does not need to work-harden in service.
Can you match a blow bar if I only have the worn part?
Yes. Our pattern shop regularly reverse-engineers from a worn or broken sample. We recover the original profile from the unworn mounting faces and confirm the fit with you before cutting a pattern.
What is the minimum order quantity?
It depends on whether a pattern already exists. For bars we already tool, small trial sets are practical; for a new pattern we normally discuss a first production set that justifies the tooling. Send us the drawing and we will quote both routes.
More from our range
Related products
Enquiry
Enquire about high chrome blow bars
Tell us the machine, the feed and the quantity. If you have a drawing or photographs of the worn part, mention it and we will send an upload link.
Melco Castings is an independent manufacturer of replacement wear parts. Machine and OEM names are used only to identify the equipment our castings fit. We are not affiliated with, endorsed by, or a distributor for any of these manufacturers.