Die Material Selection Criteria for Aluminum Hot Stamping

The aim of this work is to develop a die material selection criterion for aluminum hot stamping applications. The criterion has been based on the back-to-back comparison of a set of reciprocating friction and wear tests. Three representatives belonging to different stamping die material families have been selected for the study: a cold work steel, a hot work steel, and a cast iron. These tool materials have been combined with an exemplary member from two heat treatable aluminum families: 2XXX and 6XXX. Each die-material/aluminum–alloy combination has been tested at three temperatures: 40, 200, and 450 °C. The temperatures have been selected according to different stamping scenarios: long takt time press quenching, short takt time press quenching, and very short takt time hot forming without quenching, respectively. The results show that, among the three die material options available, the cold work steel turned out to be the most favorable option for high volume production and long takt time, the hot work steel fitted best for high volume production coupled with short takt time, and cast iron turned to outstand for short runs with prototype dies and for hot stamping without die quenching.

Microstructure and Wear Behavior of Tungsten Hot-Work Steel after Boriding and Boroaluminizing

(1) Background: Boron-based diffusion layers possess great application potential in forging and die-casting due to their favorable mechanical and thermophysical properties. This research explores the enhanced wear resistance of tungsten hot-work steel through boriding and boroaluminizing. (2) Methods: Thermal-chemical treatment (TCT) of steel H21 was carried out. Pure boriding was introduced to the substrate through heating a paste of boron carbide and sodium fluoride 1050 °C for two hours. As for boroaluminizing, 16% of aluminum powder was added to the boriding paste. (3) Results: It was shown that boriding resulted in the formation of an FeB/Fe2B layer with a tooth-like structure. A completely different microstructure was revealed after boroaluminizing—namely, diffusion layer with heterogeneous structure, where hard components FeB and Mx (B,C) were displaced in the matrix of softer phases—Fe3Al and α-Fe. In addition, the layer thickness increased from 105 μm to 560 μm (compared to pure boriding). The maximum microhardness values reached 2900 HV0.1 after pure boriding, while for boroaluminizing it was about 2000 HV0.1. (4) Conclusions: It was revealed that the mass loss during wear test reduced by two times after boroaluminizing and 13 times after boriding compared to the hardened sample after five-min testing.

The Effect of Heat Treatments on the Fatigue Strength of H13 Hot Work Tool Steel

The fatigue strength of the hot work steel depends on various factors, including the mechanical, properties and behavior and bulk and the surface under layer, the microstructural features as well as heat treatments. The influence of a series of heat treatments on the fatigue strength of H13 hot work steel was investigated. Different preheating, quenching and tempering treatments were applied to four sets of specimens and fatigue tests were conducted at room temperature using a rotating bending test machine. All heat treatments resulted in a certain improvement of the fatigue strength. Highest fatigue strength obtained by applying a double tempering heat treatment (first tempering at 550 °C for two hours and second tempering at 610 °C for two hours) after initial preheating and quenching. One tempering treatment (550 °C for two hours after preheating and quenching) did not significantly improve the fatigue strength.

BÖHLER W405 ISOBLOC

Böhler (or Boehler) W405 is a hot work steel with a great combination of hardness, strength, toughness, ductility, and thermal conductivity to resist typical damage mechanisms in applications. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on forming and heat treating. Filing Code: TS-722. Producer or source: Böhler-Uddeholm North America.