Case hardening, also known as case carburising, is a thermo-chemical heat treatment process used to produce a hard, wear-resistant surface on low carbon and low alloy steels while retaining a comparatively tougher core. This combination provides excellent resistance to surface wear, contact fatigue and rolling stress while maintaining internal toughness for load-bearing applications.
The process is widely used for components such as gears, shafts, pinions, bushes, sleeves and other power transmission parts where both surface durability and core strength are critical.
During carburising, components are heated into the austenitic region, typically between 900°C and 950°C. At this temperature, the steel transforms into austenite, which has significantly higher carbon solubility than ferrite or pearlite.
Carbon from the carburising atmosphere diffuses into the steel surface and gradually forms a controlled carbon gradient from the surface toward the core. This diffusion process develops the required effective case depth.
After carburising, the component is quenched under controlled conditions. During quenching:
Final component performance depends on proper control of:
Goswami Heat Treatment Centre operates dedicated electric carburising furnaces designed for controlled batch processing of engineering components requiring repeatable carburising cycles.
Case hardening is selected where components must resist wear and contact fatigue on the surface while maintaining core toughness for impact or transmitted loads.
Suitable steels commonly include SAE 8620, EN-353, EN-36, 16MnCr5, 20MnCr5, 17CrNiMo6 and other carburising grades depending on application requirements.
In case hardening, only the outer layer is hardened while the core remains comparatively tougher. In through hardening, hardness develops deeper through the entire section depending on material and size.
What case depth can be achieved?Typical production requirements generally range from 0.8 mm to 1.2 mm, though achievable depth depends on material, section size and cycle design.
Why is retained austenite control important?Excess retained austenite can reduce dimensional stability, hardness consistency and long-term wear performance.
Why must carbide network be controlled?Excessive carbide formation can create brittle surface conditions and negatively affect fatigue and impact performance.
Do you support regular production batch job work?Yes. We support regular batch production subject to component size, material, process requirement and delivery planning.