1018, 1215, 4140, 4340, and A36 across milling, turning, and Swiss platforms — heat-treatment coordinated on the program schedule.
Carbon and alloy steels remain the structural backbone of mechanical engineering: shafts that have to transmit torque, gears that have to mesh under load, fittings that have to hold pressure, brackets that have to clamp and stay clamped. Carbon and alloy steels run routinely across the network's 5-axis trunnion mill, 12,000 RPM 3-axis VMCs, 25 HP turning centers, and Swiss-type platforms. The work splits into two camps. The first is parts machined to print in the as-supplied condition — 1018 cold-rolled bar for general fittings, 1215 free-machining bar for production turned parts, A36 structural plate for weldments and brackets. The second is heat-treated alloy steel work, where roughing and pre-finishing happen in the annealed condition, the part travels to a qualified heat-treater on the program's schedule for through-hardening, case-hardening, or tempering, and final-feature finish machining lands the critical dimensions after thermal cycling. We size every quote against that workflow so the heat-treat allowance, hardness verification, and final inspection sit in the same job traveler from kickoff.
The general-purpose low-carbon steel. Excellent weldability, good machinability, predictable cold-formed bar. Specified on shafts, pins, brackets, machine bases, and fixturing where moderate strength and good finish are enough. Carburizes well for case-hardened surface applications.
The production-turning carbon steel — sulfur and phosphorus additions break chips cleanly and lift surface speeds. The default bar grade for Swiss-type and lathe production work where the part needs steel strength but no critical heat treatment. Limited weldability is the trade-off.
Chromium-molybdenum alloy steel — the workhorse heat-treatable alloy. Pre-hardened and tempered (HT or PH) condition machines well and ships at around 28 to 32 HRC without further treatment, fine for many shaft and bracket applications. Annealed for severe machining, then through-hardened to higher Rockwell on critical wear-and-load parts.
4340 nickel-chromium-molybdenum alloy — the highest-strength common heat-treatable alloy. Specified on aerospace landing-gear class hardware, high-stress shafts, and any part where the strength margin is being tightened to the limit. A36 structural carbon steel covers plate work for brackets, baseplates, and weldments where a structural-grade is more economical than a hardenable bar.
Other carbon and alloy grades — 12L14 leaded free-machining, 1144 stress-proof, 8620 carburizing alloy, 4150, and tool steels A2 and D2 for short-run tooling components — are available against the drawing. Mill certifications and lot traceability follow every job.
Steel parts make up the load-bearing half of most mechanical bills of material. We see 4140 on rotating shafts and high-stress brackets, 4340 on aerospace and defense hardware where strength-to-weight matters, 1018 and 1215 on general production turned and milled parts, A36 on fabrication-ready plate components, and 8620 on case-hardened wear surfaces. Our customer base in air- and fluid-pump manufacturing, pressure-and-linear-transducer instrumentation, and general precision-component work runs through carbon and alloy steel constantly.
Routine machined tolerances on steel ship at ±.0002", with repeatability on precision lathe work to ±.0001". Surface finish on a finish pass runs 32 Ra or better. Surface grinding, bead blasting, vapor blasting, and tumbling within the network cover post-machining finishing. Heat treatment — through-hardening and tempering, case-hardening, carburizing, nitriding, induction hardening, and stress relief — is coordinated with qualified treaters on the program's schedule. Hardness testing and post-heat-treat dimensional verification ship as part of the inspection record. Plating, black oxide, and any coating processes are coordinated with qualified partner suppliers the same way.
303, 304, 316, 17-4 PH for corrosion-resistant work.
6061 and 7075 when weight is the design driver.
Hub page covering every alloy family we machine.
22 CNC platforms across our production network — 5-axis milling, Swiss turning, inspection.
