SKD61 Tool Steel

Premium JIS certified SKD61 tool steel from FCS mills offers excellent thermal fatigue resistance, superior toughness and consistent cutting performance to maximize tool life and productivity.

SKD61 is a high-carbon, high-chromium alloyed tool steel that conforms to the Japanese Industrial Standard (JIS G 4404-2015) and is classified as a hot work mould steel. Its chemical composition is centred on a balanced ratio containing carbon, chromium, molybdenum and vanadium, supplemented by silicon and manganese, while phosphorus and sulphur impurities are strictly controlled. It has excellent thermal stability.

Specific heat treatment can optimise its comprehensive performance: easy to process after annealing; hardness of 56-58 HRC after quenching (1020-1050°C air cooling); and then tempered at 550-680°C (usually 2-3 times) to form a fine grain martensite This significantly improves high-temperature strength, toughness and thermal fatigue resistance, while maintaining dimensional stability. The essence of the design is to strengthen the wear resistance with the help of vanadium and molybdenum carbides, and to enhance the corrosion resistance through chromium elements, so as to realise the long service life under high temperature and cyclic stress.

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SKD61 Tool Steel Product Introduction

SKD61 tool steel

SKD61 is a Japanese Industrial Standard (JIS) hot work die steel corresponding to ASTM/AISI grade H13, Chinese GB grade 4Cr5MoSiV1, German DIN grade X40CrMoV5-1/1.3344. The smelting process is usually EF+LF+VD+Hot rolled /Hot Forged+Annealing.
High-temperature mold applications pose a major challenge to tool engineers. Premature failure due to thermal fatigue, cracking and wear can result in costly downtime and inconsistent part quality. FCS Tool Steel's premium SKD61 tool steel addresses these challenges with an optimized chromium-molybdenum-vanadium alloy composition. With full certification and in-stock inventory, FCS Factory can help you reduce lead times and increase productivity.

SKD61 Tool Steel Types and Options

SKD61 Tool Steel Types and Options

The table below shows the size range, surface condition and tolerance details for SKD61 Mould Steel:SKD61 Tool Steel Types and Options

SKD61 Tool Steel Customized Options

SKD61 Tool Steel Types and Options

  1. Customized chemical composition: GB, DIN, ASTM, JIS and other standard grades can be produced. Chemical composition can be customized individually.
  2. Customized specifications: round steel (diameter), plate (thickness, width) can be customized production.
  3. Specialized packaging for long term storage or extreme transportation conditions: includes spraying black paint all around, wrapping plastic film, spraying anti-rust oil, and shipping in wooden crates.
  4. Customized production based on samples or technical agreements.
  5. SKD61 Tool Steel Electroslag Remelting (ESR): premium option with higher purity and isotropic properties for critical applications.

SKD61 Tool Steel Chemical Composition

SKD61 Tool Steel Chemical Composition

SKD61 Tool Steel Heat Treatment Process

1.Annealing

Purpose: to eliminate internal stresses generated during forging or rolling, reduce hardness, improve cutting performance, and prepare for subsequent processing and heat treatment.
Process parameters:
Heating temperature: 800-850 ℃, holding time 2-4 hours, with the furnace cooling to below 500 ℃, and then air-cooled.

2.Quenching

Purpose: to make the tool steel to obtain martensitic organization, improve hardness and wear resistance.
Process parameters:
Heating temperature: 1000-1050 ℃ (commonly used 1020-1040 ℃), holding time according to the size of the workpiece to determine, generally 30-60 minutes.
Cooling: oil cooling or air cooling (for small size or simple shape of the workpiece), large workpieces can be graded quenching (in the 260-300 ℃ salt bath cooling for a period of time and then air-cooled), in order to reduce the quenching stress, to prevent deformation and cracking.

3.Tempering

Purpose: to eliminate quenching stress, adjust the hardness and toughness, stable organization and size.
Process parameters:
low-temperature tempering: 150-250 ℃, insulation 2-3 hours, air-cooled, tempered hardness of 58-62HRC, for molds requiring high hardness and wear resistance.
Medium temperature tempering: 300-500 ℃, insulation 2-3 hours, air-cooled, tempered hardness of 50-58HRC, can improve the toughness, suitable for molds subject to impact load.
High-temperature tempering: 500 ℃ or more, insulation 2-3 hours, air-cooled, tempered hardness 45-50HRC, mainly for the need for higher toughness of the occasion.

4.Precautions

Heating process should control the rate of heating to avoid too rapid a rise in temperature leading to workpiece surface oxidation and decarburization. Protective atmosphere heating can be used or placed in the furnace charcoal and other anti-decarburization agent.

When quenching and cooling, choose the appropriate cooling medium and cooling method according to the shape and size of the workpiece to ensure the quenching effect while reducing the risk of deformation and cracking.

Tempering must be sufficient to ensure the elimination of internal stresses to avoid mold failure due to stress release during use. For large molds or workpieces with complex shapes, multiple tempering can be used.

SKD61 Tool Steel Quality Inspection

SKD5 Tool Steel Quality Inspection

1.Surface Condition Inspection

FCS factory has a very strict quality inspection team, we will carefully check the surface condition of each piece of tool steel to ensure that the steel surface is free from cracks, folds, knots, oxidized skin, pitting, scratches and other defects.

2.Chemical Composition Testing

To verify whether the content of alloying elements meets the standard requirements and to safeguard the basis of the mechanical properties of the material. We will let the staff use full-spectrum direct reading spectrometer to analyze multiple elements at the same time. Sampling needs to remove the surface oxidation layer, using a block specimen to stimulate the test.

3.Dimension and Tolerance Inspection

FCS factory will use professional measuring tools to inspect the dimensions and tolerances of the steel to ensure compliance with the customer's contract requirements. Corresponding gauges will be selected according to the dimensional accuracy requirements, including tape measure, high-precision vernier calipers (0.02mm), micrometers (0.001mm), and special inspection gauges. Inspection items cover: diameter, thickness, width, length, hole diameter, chamfering dimensions, etc., to ensure that the tolerances and dimensions meet the contract requirements.

4.Hardness test

Our FCS factory will use professional hardness tester to test the hardness of steel to ensure that it meets the customer's contract requirements.

5.Ultrasonic Testing

Ultrasonic Testing Standard (UT Test Standard) is: Sep 1921-84 Class3 D/d,E/e.
FCS factory uses ultrasonic testing equipment to detect macro defects inside the material (such as cracks, shrinkage holes, inclusions, white spots, etc.), and every piece of round steel and plate will be examined by a second flaw detection test before shipment to ensure that the quality is qualified before shipment.

6.Microstructure Inspection

(1) Metallographic Analysis

FCS factory will use metallographic analysis instrument to detect the microstructure state after heat treatment, including carbide distribution, martensite morphology, residual austenite content, etc.

 (2) Grain size rating

FCS factory will use the comparative method to determine the austenite grain size by comparing the microstructure of the specimen with the standard rating chart, to ensure that it meets the customer's requirements.

SKD61 Tool Steel Technical Specifications

SKD61 Tool Steel Technical Specifications

SKD61 Tool Steel Product Applications

Main application scenarios

Aluminum Die Casting Dies

SKD61 tool steel excels in aluminum die casting applications where dies are subjected to extreme thermal cycling and corrosive aluminum melts. Our steel's optimized composition provides excellent resistance to thermal cracking, thermal fatigue and die sticking. Customers report 30-40% longer mold life compared to standard hot-work steels, especially in complex, thin-walled automotive parts where thermal stresses are most severe. The steel's superior polishability also ensures a superior surface finish on cast parts.

Injection Molds

For high-temperature engineering plastics such as PEEK, PPS and glass-filled nylons, SKD61 provides an ideal balance of hardness, toughness and thermal conductivity. Molds made from our precision-ground SKD61 maintain dimensional accuracy even after thousands of high-temperature injection molding cycles. The steel's excellent response to nitriding and PVD coatings further extends mold life when processing abrasive or corrosive plastic compounds.

Hot Forging Dies

Our SKD61 exhibits excellent resistance to plastic deformation in hot forging operations where dies are subjected to extreme pressures and temperatures. High high temperature hardness retention minimizes die wear and extends the life of molding applications with complex geometries. For precision forging operations where dimensional control is critical, the consistent heat treatment response of our steels ensures predictable performance even in the most demanding applications.

Extrusion Tools

Extrusion screws, barrels and dies made from SKD61 benefit from an excellent combination of wear resistance and toughness. The steel's ability to withstand extreme torque while maintaining edge retention makes it ideal for processing abrasive compounds. Our customers in the plastics extrusion industry report significantly fewer maintenance intervals and more consistent product dimensions after upgrading to our premium SKD61 components.

Industry-specific applications

  1. Automotive: molds for transmission components, molds for structural aluminum parts.
  2. Consumer Electronics: molds for complex housings of abrasive flame-retardant plastics.
  3. Aerospace: precision forging molds for turbine components.
  4. Medical: molds for high-precision polymer components that require validation.
  5. Building Products: extrusion molds for aluminum extrusion profiles and plastic compounds.
  6. Defense: critical components that require validation of material properties.

SKD61 Tool Steel Competitive Advantage Comparison

SKD61 Tool Steel Customer Success Stories

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SKD61 Tool Steel Pricing Structure Information

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SKD61 Tool Steel Frequently Asked Questions

Q: How does SKD61 compare to H13 tool steel?

A: SKD61 and H13 are equivalent grades under different standards (JIS vs. AISI). However, our premium SKD61 is cleaner, more stable and has better heat treatment response than standard commercial H13. The chemical composition ranges are similar, but our tighter control of trace elements and advanced machining processes result in superior performance.

Q: What is the difference between your standard SKD61 and ESR variants?

A: Our SKD61-ESR undergoes additional electroslag remelting to significantly improve cleanliness and reduce non-metallic inclusions. This provides superior polishability, enhanced fatigue resistance and more consistent heat treat response - which is especially valuable for complex, highly polished molds or safety-critical components.

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