What is the relationship between hardness and toughness of mold materials?

   The hardness and toughness of a mold material usually exhibit a mutually governing relationship.
   Hardness is the ability of a material to resist localized deformation, especially plastic deformation, indentation or scratching. Generally speaking, higher hardness mold materials can better withstand wear and resist deformation, but often to a certain extent at the expense of toughness.

Mold Material Hardness

    Toughness, on the other hand, reflects a material's ability to absorb energy and plastic deformation before fracture. Good toughness of the material can withstand greater impact and vibration, when subjected to external forces are not easy to fracture.
   When the hardness of a mold material increases, its internal organization becomes more compact and strengthened, and the bonding between atoms is enhanced. This makes the material resistance to plastic deformation ability to improve, but at the same time also led to the reduction of its plasticity and toughness. For example, some high hardness tool steels, such as high-speed steel, are very hard but relatively brittle and may fracture when subjected to strong impacts.

Mold Material Hardness

    On the contrary, the lower hardness of the mold material, its internal structure is relatively loose, weak inter-atomic bonding, and therefore prone to plastic deformation, but has good toughness. For example, some low carbon steel, hardness is not high but good toughness.
    In practice, according to the specific working conditions of the mold needs to balance the relationship between hardness and toughness. For molds that withstand high shock and vibration, such as punches in stamping dies, need to ensure a certain degree of hardness under the premise of good toughness to prevent fracture failure. For some of the main wear and tear and require high precision molds, such as injection mold cavity, is more focused on high hardness, the toughness requirements are relatively low.
    In short, in the selection of mold materials, need to take into account the use of the mold environment, working conditions and the requirements of hardness and toughness, in order to achieve the best performance and service life.

Mold Material Hardness