Through Hardening

Achieving design properties throughout the whole part.

Through hardening is the process of using a rapid quench to increase hardness throughout a steel alloy for the purpose of increasing its strength. As opposed to case hardening, which gives steel a hard outer layer while preserving a softer, more ductile core, through hardening diffuses carbon throughout the entire section of steel.

Through hardening typically consists of three steps: the heating of an alloy to alter its physical properties, a rapid quench in a medium, such as oil, salt or caustic, and a reheating, or tempering, to eliminate excess brittleness from the treated alloy.

Through-hardened steel is commonly referred to as “tempered steel,” but this is a bit of misnomer despite the fact that tempering does, in reality, occur. Tempering is simply the process of reheating a material following initial heating and quenching to combat brittleness. It’s conducted in many heat treating processes and does not necessarily indicate that an alloy has been through hardened.

As carbon, alloy and tool undergo the heat treating process, cracks and distortion can occur – and that’s simply unacceptable. At Paulo, we understand these risks and have proven, sophisticated computer-controlled systems in place to assess and mitigate risks. This ensures consistent quality across large production orders. Our experienced metallurgical staff oversees every step, allowing for constant refinements to keep everything on time and in spec.

Through hardening applications

Through hardening is useful for applications where strength, hardness and wear-resistance are desired. It’s a process that’s used in a wide range of engineering applications, including:

  • Seat frames and seat belt buckles
  • Hand tools
  • Parts that will need to sustain heavy loads during their service life, such nuts and bolts, brackets, chains, nails and hooks
  • Springs, axles, bearings, blades, scrapers and other miscellaneous components used in industry

At Paulo, we have through hardening furnaces capable of handling cycles up to 3,500 pounds. We can handle parts measuring up to 48 inches by 36 inches by 36 inches in batch processing and continuous processing of up to 4,000 pounds per hour.

All through hardening jobs are monitored, from order placement to delivery, by our unique Production Information and Customer Service system (PICS). This system helps to guarantee technical and engineering precision for all of our through hardening orders, ensuring everything from quality control to on-time delivery.

Paulo delivers:

  • Collaborative scheduling solutions to ensure on-time delivery
  • Large variety of furnace and process options
  • Superior process control for in-range hardness
    results every time
  • Custom-designed washing equipment to clean parts before and after processing
Heat treating 101: An introduction to heat treating procedures