JIS DC53 Cold Work Tool Steel Heat Treatment Analysis

What is DC53 steel?

DC53 steel is a new general purpose cold work die and mold steel whose strength and toughness approach those of high-speed steels. DC53 steel, is an improvement over alloy tool steel D2 specified in Standard (JIS) G4404. It eliminates the disadvantages of insufficient hardness and toughness, resulting from high-temperature tempering found with D2, and is intended to replace D2 in use for general purpose and precision dies. DC53 steel also has excellent machining characteristics and is well suited as a substrate for PVD surface treatments. DC53 steel can also be hot process CVD and TD (Thermal Diffusion) coated, however post heat treat is generally recommended.

Cold work DC53 tool steel overcomes the insufficient of SKD11 high temperature tempering hardness and toughness of weakness, DC53 tool steel will fully replace SKD11 tool steel in the field of general and precision mould . Its toughness is 2 times of SKD11,  DC53 toughness is more prominent in the cold work die. Made of DC53 tools steel rarely appear crack and craze, greatly improving the service life.
The DC53 tool steel has a uniform distribution of fine carbides. It has great galling and wear and fatigue resistance. It has also a High temper resistance to support PVD & nitride surface treatments. And it has Machining and grinding properties are superior to most other tool steels.

What DC53 steel used?

Stepped punch and press-punching dies

Concrete sprayer parts, rotor plates

Swaging dies and backers

Dies for cold forging

Thread-rolling circular dies

Piercing punch

Thread-rolling dies for heat-treated bolts

Forming dies

Stripper plates for lead frame blanking

Gauges

Screws for injection molding machines

Plastic Molds

DC53 steel’s Chemical Composition(%)

DC52 steel heat treatment analysis

DC53 is only as good as the heat treatment it receives. The heat treat process can be broken down into two segments, Hardening & Tempering. DC53 is typically air hardened using a vacuum furnace however it can also be processed by using a gas or electric furnace with or without a controlled atmosphere when wrapped in stainless foil or salt bath hardened by immersing the part in high temperature salts.

Hardening Vacuum Furnace:

Pre-heat to 300-400oC and then to 800-850oC allowing sufficient time to equalise. Raise to 1,020-1,040oC and allow soaking time

Quenching Vacuum Furnace:

The high hardenability of this steel enables it to be satisfactorally quenched in a vacuum furnace.

Surface Treatments:

Surface treatments such as CVD, PVD, TD and Nitriding require the use of relatively high processing temperatures. While this can be a problem with standard D2, the higher through hardness of DC53 steel at elevated temperatures will allow these surface treatments to be used

successfully.

Tempering:

Double temper according to the hardness and toughness charts below. As with D2, a third temper at 400oC should be carried out to avoid any chance of any delayed grain growth and distortion. This is the preferred heat treatment for most applications as high hardness will be the primary consideration.Where maximum toughness is required, double temper between 200 and 300oC (depending on application). Note the material tempered at the lower temperature should not be subjected to subsequent high temperature processes such as PVD.

Air hardening DC53 is best accomplished under vacuum. First, preheat and hold at 800° C (1,475° F) to 850° C (1,560° F) until the part is uniformly heated and then increase the heat to 1,030° C (1,885° F) to Austenitize, otherwise known as soaking the tool. Austenitize 25 to 30 minutes per inch at temperature (to be safe, minimum austenitize time for smaller parts under 1 inch can be up to 1 hour) up to 4 inches thick in cross section and 10 to 25 minutes per inch for thickness over 4 inches before inert gas pressure quenching (Generally in nitrogen), to rapid cool with 2 times atmosphere pressure (2 bar) or high velocity equivalent. To be safe, longer times are acceptable while shorter times are not.

For special applications, DC53 can also be forged into many shapes. The temperature for forging is between 900° C (1,650° F) and 1,100° C (2,010° F). Annealing after forging in highly recommended to minimize stress in the part and assuring optimum heat treat response.

DC53 can be annealed by uniformly heating the part to 800° C (1,475° F) to 850° C (1,550° F), and holding for 2 hours followed by a slow cooling at no more than 27° C (50° F) degrees per hour to until the it has dropped below 500° C (930° F). The part can then be removed from the furnace and allowed to continue to cool in still air to room temperature. If decarburization is a concern, annealing vacuum is recommended. In order to minimize size change, the pre-coating and post heat treat will need to be as similar as possible.

DC53 is well suited for supporting a wide variety of surface treatments which include Case Harden Nitride (Nitriding) which is diffused into the substrate 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. These treatments while very hard are also very thin making them nearly impossible to detect using a conventional hardness testing methods. When a combination of diffusion and surface 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.

DC53 is only as good as the heat treatment it receives. The heat treat process can be broken down into two segments, Hardening & Tempering. DC53 is typically air hardened using a vacuum furnace however it can also be processed by using a gas or electric furnace with or without a controlled atmosphere when wrapped in stainless foil or salt bath hardened by immersing the part in high temperature salts.

DC53 tool steel round bar and flat sections can be cut to your required sizes. Ground steel bar can also be supplied, providing a high quality tool steel precision ground tool steel bar to your required tolerances. DC53 Tool Steel is also available as Ground Flat Stock / Gauge Plate, in standard and nonstandard sizes.

These properties are obtained through its chemistry as well as its unique manufacturing processes of ladle refinement, vacuum degassing and forging methods. DC53 also has excellent machining characteristics and is well suited as a sub-straight for PVD surface treatments. DC53 can also be hot process CVD and TD (Thermal Diffusion) coated however post heat treat is generally recommended.

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