Carbonitriding Services — Combined Carbon & Nitrogen Diffusion Case Hardening at Reduced Temperature and Cycle Time
Shivam Forge provides carbonitriding services — a case hardening process diffusing both carbon and nitrogen into the surface of forged steel components at reduced furnace temperature compared to conventional carburizing, followed by quenching, to develop a wear-resistant case with improved hardenability. Distinct from both nitriding (no carbon, no quench) and standard carburizing. Rajkot, India. Call +91-9265772827.
Carbonitriding is genuinely its own process, not simply carburizing with an extra step or nitriding done differently, and the distinction from both neighboring processes matters for correctly specifying it. Carburizing diffuses carbon alone into a low-carbon steel surface at high furnace temperature (typically 900-950°C) over an extended soak time, followed by quenching, to build a deep, hard case. Nitriding diffuses nitrogen alone at a much lower temperature (500-550°C) with no quench at all. Carbonitriding diffuses both carbon and nitrogen simultaneously, at an intermediate furnace temperature (typically 800-870°C) — lower than carburizing's — for a shorter cycle time than carburizing requires for an equivalent case, and it does still require a quench afterward, unlike nitriding. The nitrogen addition is what makes this shorter, lower-temperature cycle work: nitrogen diffusing alongside carbon meaningfully increases the surface layer's hardenability, allowing the case to fully harden even with a milder oil quench rather than the more severe quench carburizing alone might need, which in turn helps control distortion on the quenched part. The resulting case is generally shallower than carburizing produces (carbonitriding typically develops 0.075-0.75 mm case depth versus carburizing's often deeper capability) but carbonitriding's case additionally carries improved wear and temper resistance from the retained nitrogen content, making it a genuinely distinct process suited to small-to-medium components where carburizing's deep case isn't required but nitriding's total absence of quench and shallower case aren't the right fit either.
Carbonitriding of small and medium forged steel components — gears, fasteners, pins — where a moderate case depth with good wear and temper resistance is required without the deep case and longer cycle time carburizing would demand.
Carbonitriding applied to low-carbon and low-alloy steel grades, where nitrogen's hardenability benefit allows a fully hardened case to form from a milder quench than the same steel would need under carburizing alone.
Carbonitriding of gear teeth and wear-prone component surfaces, developing a case with meaningfully better wear and temper resistance than a plain carburized case of equivalent depth, due to the retained nitrogen content.
Carbonitriding's improved hardenability supports use of a milder oil quench in place of the more severe quench some carburized components require, helping control quench distortion on components with moderate precision requirements.
Carbonitriding uses a lower furnace temperature (800-870°C vs. carburizing's 900-950°C) and shorter cycle time to produce a generally shallower case, with nitrogen co-diffusion improving hardenability and case wear resistance compared to carbon diffusion alone.
Unlike nitriding, carbonitriding requires a quench step after the diffusion cycle to harden the case, and operates at a meaningfully higher process temperature — carbonitriding is not a distortion-free process the way nitriding is, though its milder achievable quench can still reduce distortion versus conventional carburizing.
Documented case depth and hardness gradient verification through cross-sectional hardness traverse testing, confirming the carbonitrided case meets the specified depth and surface hardness for the component application.
Engineering guidance matching steel grade, furnace temperature, cycle time, and quench severity to the component's target case depth, hardness, and distortion tolerance requirements.
Carbonitriding is frequently mischaracterized as either a minor variation on carburizing or a synonym for nitriding, and both characterizations understate what's actually a genuinely distinct case hardening process occupying a deliberate middle ground between the two. Carbonitriding diffuses both carbon and nitrogen into a steel component's surface simultaneously, in a furnace atmosphere combining a carburizing gas with an ammonia addition, at a process temperature typically in the 800-870°C range — meaningfully lower than the 900-950°C conventional carburizing generally requires, and considerably higher than nitriding's 500-550°C range. This intermediate temperature, combined with a shorter overall cycle time than carburizing needs to reach comparable case depth, is carbonitriding's first defining practical characteristic.
The second defining characteristic is what the added nitrogen actually contributes beyond what carbon diffusion alone would achieve: nitrogen meaningfully increases the case layer's hardenability, meaning the treated surface can fully transform to a hard martensitic structure using a milder quench — typically oil — than the same steel might otherwise require to achieve full case hardness. This matters practically because quench severity is a primary driver of distortion risk; a component that can be adequately hardened with a gentler oil quench generally distorts less than one requiring a more aggressive water or brine quench, giving carbonitriding a genuine, if partial, distortion advantage over straight carburizing on components where quench severity was the limiting factor.
Where carbonitriding trades away some of carburizing's capability is case depth: because the process runs at lower temperature and shorter cycle time, the resulting case is generally shallower — typically in the 0.075-0.75 mm range — than carburizing's deeper case capability at extended cycle times. This makes carbonitriding the better fit for small-to-medium components where a moderate case depth with good wear and temper resistance is the actual requirement, rather than for heavily loaded, deep-case applications where carburizing's greater achievable depth is genuinely necessary. And because carbonitriding does still require a quench step — unlike nitriding, which requires none — it does not offer nitriding's near-total elimination of distortion risk, making it a distinct process choice from nitriding as well, not an alternative name for it.
For manufacturers requiring case-hardened forged steel components with moderate case depth, improved hardenability, and better wear resistance than conventional carburizing alone provides, Shivam Forge offers carbonitriding services with documented case depth and hardness verification. Contact our engineering team at +91-9265772827 or sales@shivamforge.com with your component drawing and hardness specification to discuss process parameters and quotation.
Carburizing diffuses carbon alone at high temperature (900-950°C) over an extended cycle to build a deep case, followed by quenching. Carbonitriding diffuses both carbon and nitrogen simultaneously at a lower temperature (800-870°C) over a shorter cycle, producing a generally shallower case but with nitrogen's hardenability benefit allowing a milder quench, and the retained nitrogen content improving the case's wear and temper resistance versus a plain carburized case.
Nitriding diffuses nitrogen alone at low temperature (500-550°C) and requires no quench at all, making it essentially distortion-free but slow and shallow-cased. Carbonitriding diffuses both carbon and nitrogen at a higher temperature (800-870°C) and does require a quench afterward to harden the case — it is not a no-quench process, though its improved hardenability can permit a milder quench than conventional carburizing.
Nitrogen diffusing into the surface alongside carbon meaningfully increases the case layer's hardenability, meaning the case can fully harden with a milder quench (typically oil rather than water or a more severe brine quench). This eases distortion risk on the quenched component and also improves the finished case's wear and temper resistance compared to a carbon-only carburized case of equivalent depth.
Generally no — carbonitriding typically produces a shallower case (0.075-0.75 mm) than carburizing is capable of achieving for deep-case, heavily loaded applications. Carbonitriding is better suited to small-to-medium components needing moderate case depth with good wear resistance; for deep-case requirements, conventional carburizing remains the appropriate process.
Carbonitriding does require a quench and can still introduce distortion, but generally less than conventional carburizing, since its improved hardenability from nitrogen co-diffusion often permits a milder oil quench rather than the more severe quench some carburizing applications require. For applications where any quench distortion is unacceptable, nitriding — which requires no quench at all — is the appropriate alternative.
Why Choose Shivam Forge
Shivam Forge delivers precision hot-forged components from our integrated Shapar, Rajkot facility — covering forging, CNC machining, heat treatment, and quality inspection under one roof.
