Journal Published Online: 07 June 2014
Volume 3, Issue 3

Steels for Plastic Molding: Relationship between Mechanical and Microstructural Properties



In the automotive world, many components are produced by polymer injection using steel molds with very large sizes, up to 1 m × 1 m sections or even larger. These steels should have good thermal conductivity, good weldability, high machinability, and good disposition to polishing and photoengraving. Moreover, high toughness and high mechanical properties across the whole mold thickness are strongly desired and appreciated. To satisfy these demands, chemical composition and heat-treatment cycles shall be properly designed and optimized. The traditional tensile and impact tests are useful for a basic characterization of the material, whereas the fracture toughness is related to an advanced and deeper analysis. Nevertheless, traditional tests are easier to be carried out and, hence, they are often preferred instead of the more complicated fracture-toughness tests. In this paper, the authors considered different mold steels as an attempt to correlate the fundamental mechanical parameters (i.e., the yield stress, the UTS, the elongation at rupture, and the absorbed impact energy) and the microstructures to the fracture toughness. Surface and core sampling position will be considered. The analysis of the available data resulted in very good correlations among the impact energy and the mechanical properties and among the fracture toughness and the impact energy.

Author Information

Ghidini, A.
Lucchini RS S.p.A., Lovere (BG), IT
Rivolta, B.
Dipartimento di Meccanica, Politecnico di Milano, Milano, IT
Silva, G.
Dipartimento di Meccanica, Politecnico di Milano, Milano, IT
Gerosa, R.
Dipartimento di Meccanica, Politecnico di Milano, Milano, IT
Pages: 9
Price: $25.00
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Stock #: MPC20130082
ISSN: 2165-3992
DOI: 10.1520/MPC20130082