The Heat Treatment of Hot Die Material for Tools Used in Forging Processes
18 November 2016Hot die materials are burdened with a formidable task, which is an elaborate way of saying high temperatures and higher pressures are at work. The forging process applies compressive force and heat to the tools used in forging processes, so deformation stress is a major issue. Fortunately, heat treatment techniques extend the lifespan of the die by injecting its material profile with a much-needed hardness boost.
Hot Die Materials Endure
Two forces assail this material. Firstly, contact force takes a big chunk out of the metal’s working life. Heat extremes also cause fatigue in the die. But it’s the cyclical nature of this event that really takes its toll, for the work is conducted again and again until the die material is aged and no longer able to function. The resulting thermal wear factor, therefore, combines with mechanically-induced fatigue to cause die failure.
Solving Die Manufacturing Costs
When the forging process is cycling, the header and die configuration work the softened alloy perfectly, but the cycle does inevitably impose a cost. The workpiece conducts energy, obviously, so the die ages. Pressure extremes have a similar effect, so the forging tools are destined to fail, which is unless they’re properly heat treated and hardened. A wide range of services come to the rescue when hot die tools require heat treatment, but even the best toughening service is only as good as its source material.
Hot Die Materials: Selecting Alloys
In general, a methodical tooling approach will select an alloy that retains its hardness rating at high temperatures, and this toughness factor won’t be affected by temperature variances. This baseline requirement provides a material backbone for the heat treatment process, so existing properties are intelligently targeted and empathized while any undesirable mechanical characteristics are minimized.
Heat Treatment for Tools Used in Forging Processes
Now that the alloy has been reinforced with tungsten or vanadium, chromium or molybdenum, it’s time for the hardening and tempering stage. Elevated heat-to-strength retention factors harden the material, but that hardness rating isn’t merely skin deep. It goes deep, deep into the cross-sectional area of the tool block so that uniform mechanical resistance is assured throughout the die material’s structure.
Forging processes use dense metal alloys that are further exposed to advanced heat treatment techniques. The baseline properties of the selected metal are deeply transformed by the process, so material conductivity is also a major characteristic, one that requires proper assessment if the hardening technique is to toughen the entire cross-sectional area of the tool.
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