FS139 Steel

FS139 is a high-performance hot work tool steel developed by Fushun Special Steel for molds operating under severe thermal cycling, high impact loads, and continuous high-temperature conditions.

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Product Introduction

FS139 High-performance Hot Work Tool Steel – Enhanced Toughness & Thermal Fatigue Resistance

FS139 is a high-performance hot work tool steel developed by Fushun Special Steel for molds operating under severe thermal cycling, high impact loads, and continuous high-temperature conditions.
With improved alloy refinement and optimized toughness, FS139 Steel provides excellent resistance to thermal cracking, deep hardenability, and strong mechanical stability, making it ideal for die casting, forging, and extrusion tooling.

Product Parameters (Specification)

Property	Description
Material Type	High-performance hot work tool steel
Hardness	HRC 46–52
Working Temperature	Up to 580–600°C
Microstructure	Uniform tempered martensite with refined carbides
Heat Treatment	Vacuum quenching + 2–3 tempering cycles
Applications	Die casting molds, forging tools, extrusion dies, high-temp injection molds

Product Features & Applications

High Hardness (HRC 46–52)

Provides excellent wear resistance and long tool life after vacuum quenching.

Enhanced Thermal Fatigue Resistance

Designed for molds exposed to rapid heating and cooling cycles, such as aluminum and zinc die casting.

High Toughness & Crack Resistance

FS139 Steel offers improved impact toughness, reducing chipping and cracking during heavy mechanical loads.

Stable High-temperature Strength

Maintains hardness and dimensional accuracy under prolonged hot work conditions.

Optimized for Hot Work Applications

Ideal for die casting molds, hot forging dies, extrusion tooling, hot shear blades, and thermal-stress-intensive molds.

Product Details

FS139 is produced through advanced smelting and forging processes including vacuum degassing, alloy purification, and controlled forging, resulting in high steel cleanliness and uniform carbide distribution.

After vacuum quenching and multi-stage tempering, FS139 Steel provides a reliable balance of surface hardness, core toughness, and thermal crack resistance, making it suitable for high-output industrial hot work environments requiring long tool life and stable performance.