Homepage About Longwear Surface Treatments Nitriding frequently asked questions Overview of the Nitriding technical data Longwear nitriding plant capacity Quality Contact Longwear Surface Treatments

Nitriding Technical Data

Materials and the method of enhancing component life through heat treatment should be considered at the design stage. All too frequently we have to refuse requests to nitride unsuitable materials where no thought has been given to the possible distortion resulting from an alternative surface hardening process. Other, superficially cost-effective methods of enhancing surface hardness (or case hardness), involve much higher temperatures than nitriding. Also, the distortion-inducing thermal shock caused by rapid cooling is often overlooked. The cost of remedial work following an inappropriate method of surface hardening can, in many cases, render the “cheap” solution uncompetitive.

Very basically, the process works by the load components absorbing some of the nitrogen present in the furnace atmosphere (at the process operating temperature).

Hardness testing is essential for nitriding  

Virtually all steels nitride to some extent but to provide a useful increase in surface hardness certain amounts and
types of alloying elements need to be present, generally Chromium, Molybdenum and in some cases Aluminium, Vanadium and Tungsten.

Surface hardness achieved is due to this alloy content/combination and is not greatly adjustable because of the narrow process temperature band. Case depth can be varied by extending or reducing cycle time. Longwear offers cycle times from 12 to 90 hours duration on a regular, scheduled basis. The case properties achievable with commonly nitrided materials can be seen in the chart below:





BS 970:
708 M40 or
709 M40 (EN19)

817M40 (EN24)
BS 970:
722 M24 (EN40B)
BS 970:
905 M39 (EN41)
Tool Steel P20
Tool Steel
H13 (5% Chrome)
.006"/.008" (0.15/0.2mm)
.005/.006" (.125/.15mm)
.008" (0.2mm)
c.004" (c.0.1mm)
.010/.014" (.25/.35mm)
.010/.014" (.25/.35mm)
.008/.010" (.2/.25mm)
.010/.012" (.25/.3mm)
.012" (0.3mm)
c.0.006" (c.0.15mm)
.018/.024" (.45/.6mm)
.018/.024" (.45/.6mm)
.012/.014" (.3/.35mm)
.016/.018" (.4/.45mm)
.016" (0.4mm)
c.0.010" (c.0.25mm)
.024/.028" (.6/.7mm)
.024/.028" (.6/.7mm)
.014/.016" (.35/.4mm)
.020/.022" (.5/.55mm)
.02" (0.5mm)
c.012" (c.0.3mm)
.028/.036" (.7/.9mm)
.028/.036" (.7/.9mm)
.016/.020" (.4/.5mm)
.022/.026" (.55/.65mm)
.024" (0.6mm)
c.016" (c.0.4mm)
Surface Hardness

550 - 650

52 - 58

510 - 550

50 - 52

750 - 950

62 - 68

950 - 1150

68 - 71

650 - 700

58 - 60

1000 - 1250

69 - 72


12 hour cycles -

24 hour cycles -

45 hour cycles -


90 hour cycles -


5 loads per week (including 1 over weekends)

4 loads per week (including 1 over weekends)

2 loads per week:
- on every Friday - ready Monday
- on every Tuesday - ready Friday

At least 1 load per week:
- on Thursday - ready Tuesday


We can (and frequently do) provide additional cycles to order.

Many other steels can be nitride hardened, for example:
D2, P20, D3, L6 and A2 tool steels, also alloy steels such as BS970: 817M40 (EN24)

For advice please contact us. We offer a full range of furnace cycle times on a regular, scheduled basis.

About Longwear | FAQs | Nitriding Overview | Nitriding Technical Data
Nitriding Plant Capacity | Quality | Contact Longwear | Homepage
| Terms and Conditions
Site by Emphasys