Through Hardening &
Tempering in India

The primary objective is to optimize the mechanical properties of a steel component across its entire cross-section. Hardening (heating to austenitising temperature and quenching) creates a hard but brittle martensitic structure. Subsequent tempering reheats the steel to a sub-critical temperature to relieve quenching stresses, transforming the brittle martensite into tempered martensite. This achieves a precise balance of high tensile strength, yield strength, and impact toughness.

Medium carbon steels (e.g., EN8, EN9) and alloy steels (e.g., EN19, EN24, 42CrMo4, 8620, EN31) are highly suitable. These grades contain sufficient carbon and alloying elements (such as chromium, nickel, and molybdenum) to achieve full hardness depth during the quenching stage.

We carefully manage the quench severity by monitoring quench oil temperature, agitation rates, and loading configurations. Symmetrical component positioning and custom fixtures prevent uneven cooling. Quench oil chemistry is continuously monitored to ensure consistent heat extraction rates, minimizing residual thermal and transformational stresses.

Through hardening increases the hardness and strength of the component uniformly from the surface to the core. It is typically applied to medium-carbon and alloy steels. Case hardening (like carburizing) only hardens the outer layer (case) of a low-carbon steel part, leaving a soft, ductile core. Through hardening is selected for parts undergoing high tensile or bending stresses throughout their volume.

Tempering temperatures range from 180°C to 650°C. Lower tempering temperatures (180°C-250°C) preserve high hardness (e.g., for wear-resistant pins or gears) but offer lower toughness. Higher tempering temperatures (500°C-650°C) reduce hardness but greatly increase ductility and impact toughness, making components resilient under shock loads.

Many hardened components are critical load-bearing parts in automotive, hydraulic, and wind energy systems. Traceability ensures that if a component experiences service failure, the entire production history (furnace charts, raw material heat numbers, quench parameters, and hardness records) can be audited to confirm adherence to specifications.

We conduct Brinell, Rockwell, or Vickers hardness testing on every batch. Each shipment is accompanied by a Quality Assurance Certificate detailing the heat treatment cycle chart, test locations, measured hardness values, and compliance with the specified drawing requirements.