S136 is one of the most widely used stainless mold steels for plastic injection molding. Known for its excellent corrosion resistance, good polishability, and reliable wear performance, it is commonly selected for molds exposed to moisture, corrosive plastics, and demanding production environments.

After proper vacuum hardening and tempering, S136 reaches a working hardness of 48–52 HRC, providing an excellent balance of corrosion resistance, toughness, and dimensional stability. It is widely used for cosmetic packaging, household products, flame-retardant plastics, transparent components, and general industrial molds where long service life and low maintenance are required.

For applications requiring medical certification or optical-grade polishing, premium stainless grades such as STAVAX may be preferred. However, for most corrosion-resistant plastic molds, S136 offers an excellent balance between performance and cost.

Why Choose S136 Mold Steel?

S136 has become an industry standard because it combines corrosion resistance with reliable machining and polishing performance.

Its main advantages include:

• Excellent corrosion resistance
• Good mirror polishing capability
• High wear resistance after heat treatment
• Stable dimensional accuracy
• Good texture etching performance
• Suitable for humid production environments
• Long mold service life with minimal maintenance
• Cost-effective for most stainless mold applications

These characteristics make S136 a practical solution for manufacturers seeking reliable performance without the higher cost of premium remelted stainless grades.

Chemical Composition

Its high chromium content forms a protective passive layer that helps resist rust, moisture, and corrosive gases released during plastic molding.

Typical Applications

Flame-Retardant Plastic Molds

S136 performs well when molding plastics containing flame-retardant additives that generate corrosive gases during processing.

Typical products include:

• Electrical housings
• Electronic connectors
• Appliance components

PVC Plastic Molds

PVC releases corrosive by-products that can quickly damage conventional mold steels.

S136 helps reduce:

• Rust
• Pitting corrosion
• Surface deterioration
• Maintenance downtime

Typical applications include PVC fittings, pipe components, and construction products.

Cosmetic Packaging

S136 offers sufficient polishability for many cosmetic packaging applications, including:

• Cosmetic bottles
• Bottle caps
• Lotion dispensers
• Personal care packaging

Household Products

Its corrosion resistance also makes S136 suitable for plastic products manufactured in humid environments.

Common applications include:

• Kitchen accessories
• Bathroom products
• Storage containers
• Household appliances

Mold Inserts

S136 is frequently used for corrosion-resistant inserts installed in larger molds made from P20 or 718H, improving durability in areas exposed to wear or corrosive plastics.

Heat Treatment

Proper heat treatment is essential to achieve the full performance of S136.

Typical process:

Hardening

• Austenitizing: 1020–1040°C
• Vacuum hardening
• Gas quenching

Tempering

• Double tempering
• 200–250°C
• Final hardness: 48–52 HRC

Professional vacuum heat treatment helps maximize corrosion resistance while minimizing distortion.

Machining and Finishing

S136 is supplied in the annealed condition and machines well using modern carbide tooling.

For best results:

• Use coated carbide cutting tools.
• Apply adequate coolant during machining.
• Remove the EDM recast layer before polishing.
• Avoid excessive cutting heat to reduce work hardening.

S136 also provides good polishing and chemical etching performance for most commercial plastic products.

S136 vs. STAVAX

STAVAX is manufactured using a premium remelting process that provides greater cleanliness and polishing consistency. For most industrial plastic molds, however, S136 delivers excellent performance at a lower material cost.

How to Choose S136

S136 is an excellent choice for manufacturers producing:

• PVC plastic products
• Flame-retardant plastic components
• Cosmetic packaging
• Household products
• General transparent plastic parts
• Molds operating in humid environments

If your application requires optical-grade mirror finishes or medical and food-contact compliance, STAVAX may be a better option.

Frequently Asked Questions

What is S136 mold steel used for?

S136 is commonly used for corrosion-resistant plastic injection molds, especially those processing PVC, flame-retardant plastics, and transparent materials.

Does S136 require heat treatment?

Yes. Proper hardening and tempering are necessary to achieve its designed hardness and corrosion resistance.

What hardness does S136 achieve?

The recommended working hardness after heat treatment is 48–52 HRC.

Is S136 suitable for mirror polishing?

Yes. S136 provides excellent polishing performance for most commercial applications, although premium grades such as STAVAX offer greater consistency for optical components.

Is S136 better than P20?

For corrosive plastics and humid environments, S136 offers significantly better corrosion resistance than P20.

Why Choose KUTU S136 Mold Steel?

KUTU supplies high-quality S136 stainless mold steel with consistent material quality and reliable technical support.

Our services include:

• Custom cutting
• Rough machining
• Vacuum heat treatment
• Material certification
• Technical support
• Fast global delivery

Whether you are producing cosmetic packaging, PVC components, or corrosion-resistant plastic molds, KUTU provides dependable S136 mold steel to help improve mold life, reduce maintenance, and achieve consistent production quality.

S136 / S136H (Premium ESR Grade) Corrosion Resistant Stainless Plastic Mold Steel Plate – KUTU