DC53 & Surface Treatments
Surface Treatments - DC53 is well suited for supporting a wide variety of surface
treatments which include Case Harden Nitride (Nitriding) which is diffused into thesubstrate tool steel or use the Physical Vapor Deposition (PVD), Chemical Vapor
Deposition (CVD) and Thermal Diffusion (TD) otherwise known as Thermal Reactive
Diffusion (TRD) which are applied on the surface.
Surface treatments are either into the surface of the substrate tool steel which is otherwise
known as case hardening or on the surface in the form of a surface coating. Thesetreatments while very hard are also very thin making them nearly impossible to detect
using a conventional hardness testing methods. When a combination of diffusion andsurface coatings are used, a Vickers Micro Hardness Tester should detect a rise in surface
hardness however, it will not reflect the hardness of the actual surface treatment alone.
Cold Process vs. Hot Process - For heat treat and application processing purposes,
surface treatment processes can be broken down into two categories, Cold Process andHot Process. Surface treatments applied below 480° C (900° F) which is lower that thesubstrate tempering temperature is considered a cold process treatment.
Nitriding and PVD coating treatments fall into the Cold Process category because thetemperatures which they are applied at are more than 28° C (50° F) below the tempering
temperature of most potential substrate tool steels and therefore, should not affect theintegrity of their initial heat treat. Tool steels such as S7, A2, and D2 typically do notmeet this requirement. DC53 however, when tempered at or above 540° C (1,000° F) isnot affected by these processes and will maintain original size and heat treat
characteristics. For intricate or large tools needing optimum size stability, third temper ofat least 400° C (750° F) can be applied. DC53 with a Case Harden Nitride and or PVD
coating are excellent for precision tooling components.
CVD and TD coatings are considered Hot Process surface treatments because they areapplied at from 925° C (1,700° F) to 1,040° C (1,900° F). The higher temperatures
typically mean better coating adhesion due to diffusion of carbon alloy elements. Thesetemperatures exceed the tempering temperatures and fall within the austenitizing range(Hardening temperature range) of most potential substrate materials and greatly affect theintegrity of the initial heat treat. Distortion and dimensional stability in the form ofgrowth by of as much as .15%, or 0,0015mm per millimeter (.0015” per inch) is to beexpected. Because this is a percentage change, larger tools will see more overall sizechange than small tools.
Nitriding - Nitriding is a process which case hardens the existing surface of the toolsteel. The most common ways to apply nitriding are: salt bath, fluidized bed and ionnitride. Although this process can be applied at nearly 535° C (995° F) potential
damaging the substrate tool steel heat treat can be avoided by choosing a process which is
at least 10° C (50° F) below the tempering temperature of the substrate material and bykeeping the case hardening depth to a minimum. The recommended case hardened depthInternational Mold Steel • 6796 Powerline Dr, Florence, KY 41042 • (800) 625-6653
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DC53 & Surface Treatmentsfor most stamping applications should not exceed 0,025mm (.001”). By keeping thecase depth shallow, it minimizes the heat exposure and prevents the formation of a whitelayer on the surface making it brittle and prone to chipping and breakage. Shallow case
Fluidized Bed or Ion nitriding applied below 500° C (930° F) work best for DC53.
PVD Coatings - Surface treatments such as Titanium Nitride (TiN), Titanium
Carbonitride (TiCN), Chrome Nitride (CrN) & Titanium Aluminum Nitride (TiAlN)
applied using the PVD process are coatings on the surface of the steel. These coatings
are very thin typically measuring less than .025mm (.0001”). Because they have very
little support of their own and require significant heat to be applied, these coatings should
only be applied to tool steels with sufficient obtainable hardness of HRC 60 after being
exposed to coating process temperatures as high as 480° C (900° F). For DC53, thestandard two tempers at or above 520° C (970° F) perform well. A third temper at 400 C(750 F) is recommended for intricate and high precision applications.
CVD Coatings – There is a correlation with a coating process temperatures and coatingadhesion. Higher coating process temperatures typically mean better coating adhesion
due to diffusion of carbon and alloy elements. There are also minimum temperature
limits as to how low of a temperature some coatings such as Titanium Carbide (TiC) canbe applied. While adhesion improves and additional coating materials become available
for this process, precision is diminished due to the high process temperatures involved.
CVD coatings are applied between 925° C (1,700° F) and 1,040° C (1,900° F) which isequivalent to the hardening temperature and well above the tempering temperature ofnearly all potential substrate tool steels. This will require some form of post coating heat
treat because the high coating process temperature has pushed the tooling up into thehardening temperature range, affecting the structure of the steel. The tool hardness will
likely be unacceptably low and un-tempered which reduces its toughness and strength.
Ideally, tooling that has been CVD coated should be annealed and re-heat treated after
these surface treatments are applied. The reason tools are heat treated prior to the coatingprocess is because its size from the annealed state to the hardened state otherwise known
as the martensitic (Hard) state differs and it is not always possible to predict how muchsize change will occur when hardening. A tip to minimize the growth of DC53 when
CVD coating, is to temper at 500° C (930° F) to 510° C (950° F) in the heat treat before
coating process.
TD Coatings – These coating are applied at between 1,010° C (1,850 F) and 1,030° C(1,886 F) and can be handled similar to CVD coating however, they can also utilize thecoating process itself as a part of the reheat treating process. By using the proper saltbath temperature in the coating process, it can be used to also hardening harden the toolsteel. For optimum hardness DC53 should be TD coated at 1,030° C (1,886° F). This
process is followed be multiple tempers at the appropriate temperatures to achieve thedesired hardness. In order to achieve optimum tool life, it is recommended to anneal andreheat treat the tool.
International Mold Steel • 6796 Powerline Dr, Florence, KY 41042 • (800) 625-6653
Web – www.imsteel.com

DC53 & Surface Treatments

Conclusion - Tools should be finished to size and polished prior to applying the surfacetreatment. A light polish after coating is also beneficial. This is particularly importantwhen applying surface treatments on form, draw, and extrusion tools.
Higher temperature surface treatments utilizing the CVD and TD process coatings should
be annealed, re-hardened, and tempered for optimum tool life.
In general, surface treatments can reduce the coefficient of friction and improve wear
resistance. Higher hardness of the substrate material offers superior strength reducing
plastic deformation resulting in optimum coating adhesion. Understanding the differencein precision capabilities based on the process temperatures and the specific properties of
the coating themselves are important. Contact your surface treatment supplier for details
on specific surface treatments.

International Mold Steel • 6796 Powerline Dr, Florence, KY 41042 • (800) 625-6653
Web – www.imsteel.com