HTS Coatings — machining & grinding

High Carbon Steel

0.8% C, Fe-balance

  • Arc

High Carbon Steel — 0.8% carbon, a touch of manganese and silicon, iron balance — is the cost-effective workhorse build-up steel of the arc-spray world. It's the wire you reach for when a 1045 shaft comes in worn a quarter-inch under OEM, a railroad car wheel needs its tread brought back to AAR profile, or a mill roll shows enough journal wear that replacement isn't in the budget. Substrate-matching chemistry means no galvanic mismatch, no coefficient-of-expansion fight, no special tooling at the lathe after build-up.

At HTS we apply High Carbon Steel almost exclusively by twin-wire arc spray — 15-25 lb/hr deposition, thick build capacity up to 3 mm in a single process stack, and honest economics on feedstock that costs a fraction of stainless or nickel-base wires. Typical as-sprayed hardness runs 380-520 HV with tensile adhesion in the 38-58 MPa range on grit-blasted carbon steel. The deposit machines cleanly with standard carbide tooling (cuts the same as wrought 1080 bar), and the 0.8% carbon content means surfaces can be induction- or flame-hardened after machining where geometry allows.

Got a worn shaft, mill roll, tillage tool, or hydraulic rod that needs its dimensions back at a price that makes sense? Send us the drawing — this is the duty carbon-steel arc spray was invented for.

Technical data

Hardness
~380-520 HV as-sprayed (≈39-50 HRC converted); commercial arc-spray datasheets list 20-25 HRC bulk-averaged across a lamellar deposit with oxide stringers (softens the apparent bulk reading), while individual splats and any post-spray quench-hardened zones come in martensitic at 500-550+ HV; post-deposit induction or flame quench + temper on thicker build-ups can lift finished surface hardness toward 600 HV where the geometry allows heat treatment
Bond strength
Arc-spray tensile adhesion typically 5,500-8,500 psi (38-58 MPa) on properly grit-blasted carbon and low-alloy steel; Praxair/TAFA datasheet values for 80-series carbon steel wire report ~8,425 psi (58 MPa) — on the high end for an iron-base arc-spray feedstock because the deposit chemistry matches the substrate and no galvanic mismatch is in play
Max service temp
~800-900°F (425-480°C) continuous in dry oxidizing service — the limit is plain-carbon-steel oxidation, not deposit integrity
Max service temp
~425-480°C continuous; short excursions acceptable but the coating has no chromium for high-temperature scale protection and will oxidize above 500°C much the same as 1080 carbon steel bar stock
As-sprayed porosity
Arc-spray typical 4-10% depending on atomizing-gas flow, standoff, and wire feed rate; tuned parameters with increased gas flow and short standoff push deposits toward 4-5%; open-shop parameters run closer to 8-10% with visible oxide stringers on the cross-section
Typical thickness
Build-up range 20-125 mils (0.5-3.0 mm) single process; arc-spray carbon steel is specifically chosen for thick dimensional restoration — its low shrink stress tolerates heavier layers than most iron-base wires without cracking or delaminating

Where it earns its keep

  • Cheapest build-up steel on the rack — 80-point carbon-steel wire is a fraction of the cost of stainless, nickel, or carbide feedstocks and lets a shop rebuild inches of diameter on a shaft without blowing the repair budget
  • Substrate-matching chemistry — when the part is 1045 or 4140, a carbon-steel overlay shares thermal expansion and welding behavior, so downstream machining, welding, or heat treatment doesn't fight the coating
  • Low shrink stress — specifically formulated for thick build-up (0.5-3.0 mm single pass stack) without the cracking and debonding risk that plagues higher-chromium iron-base wires
  • Machinable with standard carbide tooling — turning, grinding, and milling cut the same as wrought 1080 bar; no diamond wheels, no special programs, no slow feeds
  • Respectable bond strength on grit-blasted carbon steel (5,500-8,500 psi / 38-58 MPa) because the deposit and substrate are metallurgically similar
  • Quench-responsive — the 0.8% carbon content means the deposit can be induction- or flame-hardened on the finished part to lift surface hardness into the 500-600 HV martensitic range where geometry permits
  • Readily available from every major thermal-spray wire vendor (TAFA/Praxair, Polymet, Metco, HAI) — no sole-source risk on a consumable you'll use by the kilometer

Where it doesn't

  • No corrosion resistance — this is plain carbon steel. Rusts in humid air the same as the substrate. If the service is wet, salty, or acidic, specify stainless (420SS arc wire) or a corrosion-resistant topcoat over this build-up layer
  • Moderate hardness — 380-520 HV as-sprayed is enough for sliding-shaft duty and light-to-moderate abrasion, not for hard-particle erosion, slurry service, or gouging. Pick a Ni-chrome carbide, WC-Co HVOF, or Stellite topcoat for those duties
  • Temperature-limited — no chromium means oxidation scale protection above 500°C is poor. Do not use as a standalone high-temperature coating; use Inconel, NiCrAl, or a stainless wire instead
  • Oxide stringers in the as-sprayed cross-section are higher than HVOF or plasma-equivalent deposits — acceptable for dimensional restoration, not for flight-critical or pressure-boundary wear surfaces
  • Porosity (4-10%) means this is a build-up layer, not a seal coat. If the service requires hermetic sealing against fluid, follow with an organic or inorganic sealer, or cap with a denser HVOF topcoat
  • Bond adhesion depends entirely on grit-blast profile and cleanliness — chlorides, rust bloom, or oil on the substrate will cut adhesion in half. Blast-to-spray time discipline matters

Typical applications

  • Dimensional restoration of worn carbon-steel and low-alloy-steel shafts, journals, and sleeves (pump shafts, fan shafts, gear shafts)
  • Railroad car wheel tread and rolling-stock axle build-up prior to final machining back to AAR profile
  • Agricultural tillage tool restoration — sweeps, shanks, disc bearings, planter row-unit shafts — where substrate-matching chemistry is preferred for welding and field repair
  • Hydraulic cylinder rod build-up (non-sealing diameters; sealing surfaces typically get HVOF tungsten carbide or chrome over this base)
  • Mill-roll dimensional recovery on carbon-steel work rolls and backup rolls in steel, aluminum, and paper mills
  • Induced-draft (ID) fan hub and shaft build-up — classic arc-spray carbon-steel duty per TAFA/Metco application notes
  • General industrial wear restoration on conveyors, bucket pins, press rams, crane sheaves, drum shafts
  • Pre-machining stock layer under a harder topcoat (WC-Co HVOF, Stellite, 420SS arc spray) — cheap build-up first, premium wear coat last
  • Keyway and bore repair on carbon-steel hubs, couplings, and sprocket bosses
  • Salvage of mis-machined or undersized new parts before any hardening operation

Wear modes addressed

  • Sliding and rolling wear at moderate contact stress (pump shafts, fan shafts, mill-roll service)
  • Abrasive wear in soil, coal, and mineral-handling environments (tillage, conveyors, chutes)
  • Adhesive wear in bushing/pin contact where a softer matching material is actually desirable to save the mating part
  • Fretting at press-fit interfaces where the build-up gives the assembly back its interference without welding heat
  • Dimensional loss (corrosion + wear combined) on shafts running in mild atmospheric or oily service — the coating restores OEM diameter, not corrosion rating

Industries

  • Railroads and rolling-stock maintenance (car wheels, axles, bolsters)
  • Agriculture and ag-equipment rebuilders (tillage, planters, harvest heads)
  • Pulp and paper (fan shafts, dryer rolls, winder shafts)
  • Steel, aluminum, and copper mills (work-roll build-up, fan shafts, guide rolls)
  • Mining and aggregate (conveyor shafts, crusher shafts, drum journals)
  • General manufacturing and industrial repair (pump shafts, gear shafts, press rams)
  • Power generation (ID/FD fan shafts, coal-handling equipment)
  • Hydraulic equipment rebuilders (cylinder rod build-up on heavy-equipment rams)

Substrates

  • AISI 1018 / 1020 / 1045 carbon steel — the primary substrate family
  • AISI 4140 / 4150 / 4340 low-alloy steels (shaft and mill-roll work)
  • AISI 1080 and higher-carbon tool-grade steels (wheel tread, tillage)
  • Cast iron and cast steel (rolls, housings, older industrial shafts)
  • Forged railroad wheel steels (Class B, C, D AAR wheel chemistries)
  • Weld-deposited build-up over original carbon-steel base — arc-spray caps the weld repair with a uniform machinable surface

Which process, when?

Twin-wire arc spray is the production workhorse for high-carbon-steel build-up — fast deposition rate (15-25 lb/hr on a 1/16 in wire), deep build capacity (up to 3 mm single-process stack), and honest cost per pound of deposit. Porosity runs 4-10%, adhesion 38-58 MPa on grit-blasted carbon steel. Flame-spray wire (combustion wire) is the older alternative — slower, slightly denser deposits (3-7% porosity), better suited to small shafts and field-portable repair where an arc-spray power supply isn't handy. Flame-spray powder (PMET 714 / Sprasteel 80 powder variants) hits 3-6% porosity and is the right call on thin wall repairs and OD work on smaller diameters where atomizing-gas blast from an arc gun is too aggressive. HVOF is overkill for plain carbon-steel build-up — the denser deposit is real but you're spending carbide-class money on a consumable that's supposed to be cheap. Use HVOF for the wear topcoat over this build-up layer, not for the build-up itself. Pick arc-spray for any build-up thicker than 20 mils; shift to flame-spray only when the geometry or the shop capability says so.

Sources

Data points on this page draw on the following published references. Nothing here replaces a material-specific review by our process engineers — but it's the working starting point.

Material data on this page is provided as a general reference and can vary by lot, substrate, and application. Contact HTS to confirm the right material and specification for your specific part.

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