H13 Mold Steel: Properties, Applications & Thermal Treatment Guide

H13 mold steel is an air-hardening hot work tool steel. It meets the American ASTM standard and Chinese standard 4Cr5MoSiV1. Key features include high strength, toughness, thermal fatigue resistance, and high-temperature wear resistance. It is widely used for:

• High-temperature forming dies

• Wear-resistant parts

• Cold cutting blades

• Scrap cutting blades

I. Basic Composition and Performance

1. Chemical Composition (Typical Values)

Key elements (content range):

• C: 0.32~0.45

• Cr: 4.75~5.50

• Mo: 1.10~1.75

• Si: 0.80~1.20

• V: 0.80~1.20

• Mn: ≤0.40

Each element plays a key role:

• Chromium: Improves hardenability and oxidation resistance

• Molybdenum: Boosts high-temperature strength and tempering stability

• Vanadium: Refines grain structure and enhances wear resistance

• Silicon: Improves oxidation resistance

2. Key Performance Indicators

• Hardness: Annealed ≤229HB; 48~55 HRC after quenching and tempering (adjustable for hardness-toughness balance)

• Thermal Fatigue Resistance: No easy thermal cracking under repeated heating (600~800℃) and cooling

• High-Temperature Resistance: Maintains strength and hardness below 500℃ without softening

• Machinability: Easy to machine (turn, mill, grind) when annealed; high-precision surface after quenching/tempering

II. Typical Applications

H13 is ideal for hot work molds and cutting blades due to its resistance to high temperatures, thermal shock, wear, and corrosion. Common uses:

1. Die Casting Molds

Used for aluminum, zinc, and magnesium alloy die casting (cavities, cores, sprue bushings). Resists molten metal erosion and cooling stress.

2. Forging Molds

For hot forging of steel slabs and non-ferrous metals (mold cavities, upper/lower anvils). Withstands high-temperature metal extrusion and wear.

3. Extrusion Molds

For aluminum and copper profile extrusion. Ensures profile accuracy and long mold life.

4. Hot Cutting Blades

Used in steel hot rolling lines to cut hot slabs/profiles. Prevents edge softening and chipping.

5. Cold Cutting Blades & Scrap Cutting Blades

• Cold Cutting Blades: Cuts cold metals (plates, bars, profiles) with sharp edges and durability

• Scrap Cutting Blades: Cuts metal scrap (chips, excess parts) in factories; resists wear and impact

6. Other Wear-Resistant Parts

Rolling mill guide plates, hot coining molds, glass molds, etc.

III. Thermal Treatment Process

Proper thermal treatment ensures H13’s performance. Standard steps:

1. Annealing

• Heat to 850~870℃, hold 2~4 hours

• Cool in furnace below 500℃, then air cool

• Result: Hardness ≤229HB (easy to machine)

2. Quenching

• Preheat to 600~650℃, then heat to 1020~1050℃

• Holding time: 25 mm/hour of effective thickness

• Cooling: Oil or air (reduces deformation/cracking)

• Result: Hardness 58~62HRC

3. Tempering

Temper immediately after quenching to avoid cracks. Adjust temperature for desired performance:

• High hardness (52~55 HRC): 500~520℃, 2 hours, double tempering (good for cutting blades)

• High toughness (48~52 HRC): 560~580℃, 2 hours, double tempering

• High-temperature use (die casting): 600~620℃ (balances hardness and thermal fatigue resistance)

IV. Key Quality Control

• Raw materials: Uniform composition; no shrinkage cavities, pores, or slag inclusions

• Thermal treatment: Strictly control heating, holding, and cooling rates to avoid deformation/cracking

V. Grade Equivalents

H13 has equivalent grades in different countries:

• United States (AISI/ASTM): H13

• Germany (DIN/W.Nr.): 1.2344, X40CrMoV5-1

• Japan (JIS): SKD61

• China (GB): 4Cr5MoSiV1