Die Steel Improvements for AHSS Applications
- 2018-10-23 11:51:00
- LUQIMENG Original
- 1914
HITACHI Intro
? Steel Production Methods for Die & Tooling Steels
? Typical Failure modes of Die Steels for AHSS
? Solutions to improve Tooling Performances
?Steel Types, Coatings
? Hot Stamping Die Steels
? Pre Hardened Die Steels
? Grain Oriented Die Steel Study
Ask Your Tool Steel supplier……
? Test Certifications (actuals from Mill Source )
? Method of Manufacturing
? Forged, Rolled , etc.
? Recommended Heat Treat
Surface Coating advancements have greatly improved steel performances.
Part material
? Aluminum or Steel: What type & thickness?
? Press Size (Servo or Mechanical) & Strokes per minute cycle
? Current Die Construction
? Progressive or Transfer?
? Castings? Inserts?
? Tooling steels used ?
? What coating?
? Die Clearance
? Heat Treating Recipe
? Welding (In House? Outsource? Consumable used?)
? Failure Observations: What Happened?
? What's been tried so far?
Coarse & directional carbide
? Large & anisotropic deformation after heat treatment
? Medium galling & wear resistance
? Characteristics will be affected by grain direction Small, dense & homogeneous carbide
? Small & isotropic deformation after heat treatment
? Same HT & Chem as D2
? Good galling & wear resistance
? Achieve higher hardness than
Machining of Pre-Hard Tool Steels @ 60 HRC
? 1) Machine Tool
? Rigid Construction:
? High Spindle Speed:20,000+
? 2) Cutting Tool
? Solid Carbide with ductile properties for interrupted cut
? 3) Consistent substrate of Die Steel
? Demands on Die Materials
?Wear
?Conductivity
?Watch for industry developments on 3D Additive Mfg. inserts w/ conformal cooling lines
? Use of higher alloyed Die Steel
? Upgrade to a NADCA Class C Hot Work Steel in place of AISI H13
1. Conductivity
? Class B H13 is 32.6 @ 600C Class C is 35.8 @ 600C
? Better for heat conductivity than H13 means better cycle times .
2. Toughness:
? Why? Higher Impact Values (charpy) prevent cracking on the surface of Hot Stamping Dies close to the cooling channel .
3. Wear:
? Why? NADCA Class C ( HITACHI DAC-MAGIC ) is higher strength under high temperature. Diesurfaces can reach ~ 400C & higher alloyed steels are needed to extend wear.
4. Coatablity
? Coatable and Wear resistance at room temperature, almost same as H13.
? Review Die Standards & allow for areas requiring better tooling steels in trouble-spots
? Compare results with other steels in side by side like- environments
? Insist on controlled HT path & Welding steps
? Ask for grain orientation on larger cross sections
? “If you can’t use a better tool steel, use your tool steel better”
