Hardfacing lays a wear-resistant alloy over the spot that's getting eaten, so the bucket, roll, hammer or die goes back to work instead of the scrap pile. Match the alloy to the wear and lay it down with the right process.
Ask us what you need to hard surfaceHard surfacing (hardfacing) means welding a wear-resistant alloy onto a base metal to protect it from wear. You aren’t joining two pieces — you’re adding a sacrificial skin that takes the beating so the part underneath doesn’t.
Most jobs go on in two layers. A tough build-up alloy brings the part back to size, then a hard cap takes the wear. Build work surfaces up to size with Polaris A, then hardface — never build up with a hardfacing alloy.
What you hard surface for comes down to the type of wear and what’s doing the wearing: metal rubbing on metal, or metal grinding against rock, concrete, dirt or wood. Match the alloy to that combination and the job holds up.
Every hardfacing call starts here: what type of wear is the part seeing, and what’s doing the wearing?
Metal against rock, sand, dirt, concrete or wood; hard particles scour the surface away a little at a time. Want heavy hardness and carbides.
Pounding, crushing, hammering. The alloy has to take the hit and stay in one piece. Want maximum toughness that work-hardens in service.
Sliding or rolling contact between steel parts: rails, frogs, chains, pins. Surfaces wear each other down. Want toughness over a Polaris A pad.
Most real parts, like a bucket tooth that gets hit and scoured on the same shift. Want a tough deposit that hardens where it’s loaded.
Special case — manganese steel (rail frogs, manganese buckets and wear plates): hardens on its own under impact. Needs a compatible build-up alloy (Apollo A or Apollo B) and has to stay cool while you weld it — no preheat, skip-weld, keep base metal under 500°F (260°C).
Special case — tool & die (forging dies, trim dies, punches, shear blades, knives): need a tool-steel deposit and controlled heat. Rockmount’s Midas alloys (H12, M2) come as stick and TIG rod, with Brutus as the cushion or butter layer.
Hardness buys abrasion resistance. Toughness buys impact resistance. One alloy rarely maxes out both. Where each Rockmount hardfacing alloy sits on the Rockwell C (RC) scale, 0→70:
The Apollo alloys deposit soft (11–20 RC) and work-harden under impact. Zeta C and Zeta Flux Core deposit hard (55–62 RC), built for high abrasion even with heavy impact. Olympia B and the Orion boron-carbide alloys deposit hardest (60–69 RC) — Rockmount limits them to one or two passes.
STEP TWOCommon wear parts and the Rockmount alloys their spec sheets list for them. Layering rule: build work surfaces up to size with Polaris A before hardfacing — never build up with a hardfacing alloy. On manganese steel, build up with Apollo A or Apollo B. Under Midas tool steel, use Brutus as the cushion layer.
| Part | Recommended Alloys | Process |
|---|---|---|
| Loader & excavator buckets | Apollo A, Zeta C | Stick, downhand or slight uphill |
| Bulldozer blades | Zeta Flux Core | MIG / flux core with gas |
| Dipper, bucket & shovel teeth, shovel pads | Apollo Flux Core, Apollo B, Zeta Flux Core, Zeta C, Olympia B, Orion B | Stick or MIG / flux core |
| Dredge cutters & cutter teeth | Zeta Flux Core, Zeta C | MIG / flux core or stick |
| Crusher rolls | Apollo B, Apollo Flux Core, Orion B (1 pass), Olympia B (2 passes) | Stick or MIG / flux core |
| Crushers & crusher hammers | Apollo A, Zeta C, Olympia B | Stick |
| Hammer mill hammers & impact bars | Apollo Flux Core | MIG / flux core, self-shielded |
| Manganese buckets & wear plates | Apollo A, Apollo B | Stick, keep manganese under 500°F |
| Railroad frogs, crossings & rails | Apollo A, Apollo Flux Core | Stick or MIG / flux core |
| Dragline chains & pins | Apollo A, Apollo Flux Core | Stick or MIG / flux core |
| Augers, conveyors & screws | Zeta Flux Core, Zeta C, Orion B, Orion Flux Core | MIG / flux core or stick |
| Pump housings, castings & impellers | Zeta C, Zeta Flux Core, Orion B, Orion Flux Core | Stick or MIG / flux core |
| Mining, quarry, sand & gravel equipment | Orion Flux Core, Zeta Flux Core, Olympia B | — |
| Earth-cutting & digging tools, earthmoving, ag implements | Olympia B, Zeta C | Stick |
| Worn shafts, rolls, gears & machine parts | Olympia A (1/4″ total max), Orion Flux Core | Stick |
| Cast iron parts | Olympia A (with preheat), Zeta C | Stick |
| Hot forging & header dies, punches, shear blades | Midas H12 (59 RC) | Stick or TIG |
| Pierce, blank & trim dies, broaches, knives, shears | Midas M2 (64 RC) | Stick or TIG |
Amperages are Rockmount’s recommended starting points, ±20% (±40% on Zeta C).
Superior wear resistance in high abrasion, even with heavy impact loads. High chrome and silicon carbide in a dense, tough deposit.
Parts: Dredge cutter teeth, conveyor screws, bulldozer blades, pump housings, dipper teeth, excavation equipment.
Chromium carbide for extreme abrasion even with impact. Carries 38% alloy, lays down up to 10 lb/hr — close to wire-feed speed.
Parts: Loader & excavator buckets, dragline buckets & teeth, crushing equipment, pump castings, augers, sizing screens, cast iron. Stress relief cracks are expected.
Rebuild the work surface first — never build up with a hardfacing alloy. Good pad for hard surfacing due to extraordinary ductility.
Parts: Construction equipment, boilers, tanks, piping, truck & bus frames.
Joining, build-up and wear surfacing on low alloy, manganese, medium/high carbon steels. Superior for metal-to-metal wear under stress, shock and impact.
Parts: Rails, frogs, manganese wear plates, buckets, crushers, dragline chains & pins.
High-manganese wire for tough buildup and joining manganese to manganese or low alloy steel.
Parts: Rail frogs, hammer mill hammers, impact bars, shovel pads, crusher rolls, dredge pump parts. Difficult to machine.
Hot hardness to 1000°F, machinable. Joins dissimilar steels, builds up manganese steel before a Zeta or Olympia cap.
Parts: Wedge bars to dipper teeth, crusher rolls, valve seats, alloy lips to manganese buckets.
Hardfacing of carbon, low alloy and high manganese steels and cast iron. Good impact and abrasion resistance, runs well out of position.
Parts: Worn shafts, rolls, gears, cast iron repairs.
Ultra-hard silicon carbide and chrome carbide deposit. Excellent abrasion resistance with mild impact resistance.
Parts: Earth-cutting tools, crusher hammers & rolls, sand & gravel equipment, dragline buckets & teeth. Not torch-cuttable.
Chromium-free boron carbide for extreme abrasion with light to moderate impact, full hardness in a single pass, 90% efficiency.
Parts: Crusher rolls, shovel buckets & teeth, pump housings, cutter heads, hooks, conveyors. Torch-cuttable.
Boron carbides in a martensitic matrix for extreme abrasion with light impact, 90% efficiency, exceptionally smooth.
Parts: Mining/quarry/dirt/sand work, shafts, impellers, transport screws, field work off a suitcase feeder. Torch-cuttable; hardfacing only, not for joining.
Resurfacing hot and cold work tool steels across a wide operating range. Good resistance to abrasion and shock; oil, air or water hardening.
Parts: Hot forging dies, header dies, punches, shear blades. Use Brutus as the cushion/butter layer.
Resurfacing high speed tool steels where a durable, wear-resistant cutting edge is required. Air hardens after welding, excellent friction resistance.
Parts: Pierce, blank & trim dies, broaches, knives, shears.
Two questions the hardness chart doesn’t answer: can the part be cut with an oxy-fuel torch after it’s hardfaced, and how hot will it run in service?
| Alloy | Torch-Cuttable | Published Hot-Service Rating |
|---|---|---|
| Apollo A | No | — |
| Apollo Flux Core | No | — |
| Apollo B | No | Hot hardness to 1000°F / 538°C |
| Olympia A | No | — |
| Olympia B | No | — |
| Zeta Flux Core | No | — |
| Zeta C | No | — |
| Orion B | Yes | — |
| Orion Flux Core | Yes | — |
| Midas H12 | No | Developed for hot cavities & surfaces that heat extensively during work |
| Midas M2 | No | — |
Only Orion B and Orion Flux Core can be cut with an oxy-fuel torch — every other alloy in this guide can’t. Plan on arc gouging or grinding instead. Manganese steel base metal becomes brittle above 500°F, which is why it stays cool during welding. For any other alloy on a hot-running part, talk to ZILA first.
STEP THREEThe alloy decides what the surface can take. The process decides how fast it goes on, where you can do it, and how much heat ends up in the part.
High volume — best when you’re covering square feet instead of square inches: crusher rolls, hammer mill hammers, conveyor screws, rail frogs. Zeta Flux Core runs with gas in the shop; Apollo and Orion Flux Core are self-shielded for field work. Slows down on tight spots the gun can’t reach.
The go-to and the widest alloy choice — eight of eleven hardfacing alloys come as stick rod. Works in the pit, in wind, rain or snow. Zeta C’s tubular rod lays down up to 10 lb/hr. Slower than MIG/flux core on big surfaces — rod changes and slag add up.
Precision and heat control for tool steel edges: die edges, punches, trim steels, knives, shear blades. Medium heat, no color change in the base metal. DCEN with argon; start the arc on a copper block, not the part. Deposition is slow.
How you lay the beads down changes what the surface does once it’s in service:
For coarse rock, ore or slag; the beads act as runners so material doesn’t catch.
For fine sand and soil; space beads 1/4″ to 1-1/2″ apart, across the flow.
For sand or dirt including some clay, mixed conditions; fines pack into the squares and form a protective bed.
Works like the waffle; dirt packs into the diamonds so material wears on material. Versatile for mixed conditions.
For thin or heat-sensitive base metal where distortion and warpage are a concern.
A solid overlay over the whole wear surface, each bead overlapping the last by 30–50%. Uses the most alloy and heat of any pattern.
Unknown base metal? Weird wear pattern? Tell ZILA the part, what it’s made of if you know, and what’s wearing it. We’ll tell you what goes underneath, what goes on top, and how to lay it down. ZILA is an authorized Rockmount Welding Products dealer, with stick, flux core and TIG in stock.