The automotive industry has searched for alternatives to reduce the weight of vehicles without neglecting the user’s safety by using new materials. Advanced high-strength steels of complex phases are used in structural applications requiring good performance and reducing the weight of vehicles. However, these steels have shown edge cracking, known as fissure, during processing, which has become a challenge for steelmakers and other companies that rely on them to manufacture structural components. Such defects can be associated with the interaction between the different microstructural constituents of the steel, such as various phases and precipitates generated during its processing to achieve the required mechanical properties. The present work presents the studies evaluate the effect that processing and chemical composition exerts on edge cracking in complex phase steels of grade 800 MPa produced by different steelmaking routes.

The knowledge of the thermal boundary conditions helps to understand the heat transfer phenomena that takes place during heat treatment processes. Heat Transfer Coefficients (HTC) describe the heat exchange between the surface of an object and the surrounding medium. The Fireworks Algorithm (FWA) method was used on near-surface temperature-time cooling curve data obtained with the so-called Tensi multithermocouple 12.5 mm diameter x 45 mm Inconel 600 probe. The fitness function to be minimized by a Fireworks Algorithm (FWA) approach is defined by the deviation of the measured and calculated cooling curves. The FWA algorithm was parallelized and implemented on a Graphics Processing Unit architecture. This paper describes the FWA methodology used to compare and differentiate the potential quenching properties of a series of vegetable oils, including cottonseed, peanut, canola, coconut, palm, sunflower, corn, and soybean oil, versus a typical accelerated petroleum oil quenchant.

Metallurgical properties required in aluminum alloys are highly dependent on the cooling uniformity during the quenching process. Non-uniformity during cooling is associated with piece distortion and failure. Although the quenching process is considered the most critical step during alloy heat treating, quench tank design is still based mainly on experience. Computational fluid dynamics (CFD) offers detailed understanding of the complex behavior of fluid flow and its impact on part cooling. Detailed cooling rates can then be used to predict part metallurgical properties. Although computational fluid dynamics are being used increasingly in quench tank design, there is still considerable imprecision due to assumptions that must be made. In this work, cooling curves are obtained for a 25 mm diameter 6061 aluminum cylinder probe under different conditions. Results are also obtained numerically via computational fluid dynamics. Results show the suitability for designing quench systems based on CFD simulations.

HR-120TM alloy is a Ni-Fe-Cr alloy designed to have high strength at elevated temperature and resistance to attack in carburizing and sulfidizing environments. Applications for this alloy include components to be assembled in combustion turbines for power generation. Some of these components can be manufactured by ring-rolling procedures followed by heat treating operations. Typically, HR-120TM alloy is heat-treated in a temperature range of 1175 to 1230°C in order to promote microstructure homogenization and dissolution of heavy precipitates. An inconvenience of such heat-treating temperature range is related to excessive grain-size coarsening of wrought parts. This work presents the results of a series of heat-treatment procedures performed on seamless rings produced by ring-rolling considering industrial conditions. Lower heat-treatment temperatures are considered for evaluation of mechanical and microstructural properties. It is reported that an excellent combination of mechanical properties and microstructural characteristics is obtained when alloy is exposed to 1050°C for soaking periods above 30 minutes.