Thermally-Induced Crack Evaluation in H13 Tool Steel

Abstract

This study reported the effect of thermal wear on cylindrical tool steel (AISI H13) under aluminum die-casting conditions. The AISIH13 steels were immersed in the molten aluminum alloy at 700 • C before water-quenching at room temperature. The process involved an alternating heating and cooling of each sample for a period of 24 s. The design of the immersion test apparatus stylistically simulated aluminum alloy dies casting conditions. The testing phase was performed at 1850, 3000, and 5000 cycles. The samples were subjected to visual inspection after each phase of testing, before being examined for metallographic studies, surface crack measurement, and hardness characteristics. Furthermore, the samples were segmented and examined under optical and Scanning Electron Microscopy (SEM). The areas around the crack zones were additionally examined under Energy Dispersive X-ray Spectroscopy (EDXS). The crack's maximum length and Vickers hardness profiles were obtained; and from the metallographic study, an increase in the number of cycles during the testing phase resulted in an increase in the surface crack formation; suggesting an increase in the thermal stress at higher cycle numbers. The crack length of Region I (spherically shaped) was about 47 to 127 µm, with a high oxygen content that was analyzed within 140 µm from the surface of the sample. At 700 • C, there is a formation of aluminum oxides, which was in contact with the surface of the H13 sample. These stresses propagate the thermal wear crack length into the tool material of spherically shaped Region I and cylindrically shape Region II, while hardness parameters presented a different observation. The crack length of Region I was about 32% higher than the crack length of Region II.

Wire Tool Electrode Behavior and Wear under Discharge Pulses

“…The samples with typical erosion wear traces (Figure 11c,d) correlate to non-oxide (oxygen unsaturated) structures [73,74]-secondary submicrostructures of the complex compounds (of second order) adsorbed by the eroded surface of the base material-of the first order (Figure 14b) [75][76][77], which probably contain metastable and insoluble solid solution in the form of adherent and brittle thin film and heat-affected sublayer [78][79][80][81]. The electrode's cross-section shows the intensity of the two types of wear (Figure 11g,h).…”

Fiber Laser Welding of Dissimilar 2205/304 Stainless Steel Plates

“…The influence of ferrite content in welds on the solidification and cracking at room temperature has long been documented, but it has not been accurately linked with the cracking sensitivity. A greater focus has been on the solidification behavior of stainless steel welds The basis of crack-susceptible microstructure in stainless steels is the evolution of impurity-developed and low-melting liquid films along the grain boundaries in the final phase of the solidification process [53,73]. The influence of ferrite content in welds on the solidification and cracking at room temperature has long been documented, but it has not been accurately linked with the cracking sensitivity.…”

“…This behavior has been recognized in the friction welding of different weldments, such as stainless steel to copper, steel to aluminum, and steel to titanium [26,71,72]. The basis of crack-susceptible microstructure in stainless steels is the evolution of impuritydeveloped and low-melting liquid films along the grain boundaries in the final phase of the solidification process [53,73]. The influence of ferrite content in welds on the solidification and cracking at room temperature has long been documented, but it has not been accurately linked with the cracking sensitivity.…”

Electrical Discharge Machining of Oxide Nanocomposite: Nanomodification of Surface and Subsurface Layers

“…This type of destruction is correlated to the complex wear in the presence of heat when the metastable secondary structure of the second order (formed ceramic plaques with the width of 25-30 μm for the sample machined in water and non-homogenous plaques of 8-10 μm in oil) is adherent to the heat-affected surface of the base nanocomposte. The formed surface and subsurface layers under this type of wear have the presence of partial removal of the secondary structures, which are more brittle in the case of machining in water ( Figure 14) [78,79,[84][85][86][87][88]. In the context, zinc oxide (ZnO) formed during machining in oil is an n-type semiconductor and sublimates at a temperature of 1800 °C [89,90]; copper (II) oxide (CuO) that is observed after machining in water does not react with an aqueous medium and decomposes to metallic copper in the presence of hydrogen, carbon, or carbon monoxide [91,92]:…”