Hardening with salt bath quenching + tempering
Hardening is the controlled heating of steel to the austenitizing temperature followed by rapid cooling, which produces a hard martensitic structure. Our key method is hardening with salt bath quenching, which ensures uniform heat extraction over the entire surface of the part and thus significantly reduces the risk of distortion compared with conventional quenching media.
Hardening is always followed by precise tempering, which allows us to set the final properties exactly to the drawing – the right combination of hardness, toughness and dimensional stability. Depending on the part, we also use a polymer quenchant.
Benefits for your parts
Minimal distortion and excellent dimensional stability thanks to uniform cooling in the salt bath
High hardness and strength after hardening, with final properties fine-tuned by tempering
Batch-to-batch reproducibility thanks to precise control of temperatures and times
Careful handling of sensitive surfaces – suitable fixturing and attention to tolerances
Laboratory testing (hardness, metallography, reports) by agreement
Tempering – precise setting of properties
Tempering after hardening reduces the brittleness of martensite and sets the required balance between hardness and toughness according to the drawing. We provide single- and multi-stage tempering, dimensional stabilization between cycles and documentation of the hardness achieved.
Our services can also include sub-zero treatment after hardening (to reduce the proportion of retained austenite) and straightening of parts where required.
Typical applications and materials
Parts: gears, shafts, pins, cams, levers, forgings, mould and machine components.
Steels: 42CrMo4, C45E, 16MnCr5, 20MnCr5, 17CrNiMo6 and other structural and case-hardening steels.
Technical information for your quotation
To set up the process accurately and quickly, we need the following from you:
a drawing with the required hardness and the test surfaces marked
the material (steel grade) and the quantity (pieces/batches)
information on previous / subsequent operations (machining, case hardening, nitriding, etc.)
your requirements for documentation (hardness testing, metallography)
The salt bath provides uniform heat extraction and thus helps to limit distortion, especially for complex parts and gears.
Besides the choice of quenching medium, we take care of fixturing, handling and step-by-step stabilization (tempering and, where needed, straightening and sub-zero treatment). For sensitive parts we recommend a pilot batch.
The final hardness depends on the material and the drawing requirements. We verify hardness as agreed (e.g. HRC) and document it in a report.