During the last years, the scientific and industrial community has focused on the astonishing properties of Fe-Mn-Al-C steels. These high advanced steels allow high-density reductions about ~15% lighter than conventional steels, high corrosion resistance, high strength (ultimate tensile strength (UTS) ~1 Gpa) and at the same time ductilities above 60%. The increase of the tensile or yield strength and the ductility at the same time is almost a special feature of this kind of new steels, which makes them so interesting for many applications such as in the automotive, armor and mining industry. The control of these properties depends on a complex relationship between the chemical composition of the steel, the test temperature, the external loads and the processing parameters of the steel. This review has been conceived to tried to elucidate these complex relations and gather the most important aspects of Fe-Mn-Al-C steels developed so far.

A General Perspective of Fe-Mn-Al-C Steels

Surface Engineering Of Light Alloys Aluminium Magnesium And Titanium Alloys

Shot peening is a dynamically developing surface treatment used to improve the surface properties modified by tool, impact, microblasting, or shot action. This paper reviews the basic information regarding shot peening methods. The peening processes and effects of the shot peening and cavitation peening treatments on the surface layer properties of metallic components are analysed. Moreover, the effects of peening on the operational performance of metallic materials are summarized. Shot peening is generally applied to reduce the surface roughness, increase the hardness, and densify the surface layer microstructure, which leads to work hardening effects. In addition, the residual compressive stresses introduced into the material have a beneficial effect on the performance of the surface layer. Therefore, peening can be beneficial for metallic structures prone to fatigue, corrosion, and wear. Recently, cavitation peening has been increasingly developed. This review paper suggests that most research on cavitation peening omits the treatment of additively manufactured metallic materials. Furthermore, no published studies combine shot peening and cavitation peening in one hybrid process, which could synthesize the benefits of both peening processes. Moreover, there is a need to investigate the effects of peening, especially cavitation peening and hybrid peening, on the anti-wear and corrosion performance of additively manufactured metallic materials. Therefore, the literature gap leading to the scope of future work is also included.

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Effects of Shot Peening and Cavitation Peening on Properties of Surface Layer of Metallic Materials—A Short Review

Digital twins are the most important parts of Cyber-Physical Systems (CPSs), and play a crucial role in the realization of the Metaverse. Therefore, two important factors: flexibility and adaptability, need to be focused on digital twinning systems. From a virtual perspective, constructing buildings, structures, and mechanisms in the Metaverse requires digital materials and components. Hence, accurate and reliable digital models can guarantee the success of implementation, particularly when it comes to completing physical twins in the real world. Accordingly, four Machine Learning (ML) methods to make digital twins of an advanced 42SiCr alloy considering all of its uncertainties and non-linearities have been employed in this paper. These ML methods accelerate the digitalization of the proposed alloy and allow users to employ them for a wide range of similar metals. Based on this technique, producers can borrow these virtual materials and build their structures in the Metaverse. This way, if the properties of the materials were satisfactory, they might buy them and start manufacturing their products. As a case study, we focus on digital twining of an 42SiCr steel with some influential factors in its mechanical properties, making the nature of the alloy complex. Processes, including heat treatment, may restore the material’s deformability; however, Quenching and Partitioning (Q&amp;P) not only eliminates the impact of cold forming but also provides advanced high-strength steel (AHSS) properties. In this research, the combined impacts of different Q&amp;P treatments were investigated on the mechanical properties of 42SiCr steel alloy. The results have shown the acceptability and accuracy of the proposed ML methods in realizing the digital twins of this complex alloy. 

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Metaverse and AI Digital Twinning of 42SiCr Steel Alloys

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Analysis of the Dual-phase Steel DP500 Stress-strain Characteristics During the Plane Shear Test

The microstructure, mechanical, tribological, and corrosion properties of Fe–Cr–Al–Y-based oxide-precipitation-hardened (OPH) alloy at room temperature are presented. Two OPH alloys with a composition of 0.72Fe–0.15Cr–0.06Al–0.03Mo–0.01Ta–0.02Y2O3 and 0.03Y2O3 (wt.%) were prepared by mechanical alloying with different milling times. After consolidation by hot rolling, the alloys presented a very fine microstructure with a grain size of approximately 180 nm. Such a structure is relatively brittle, and its mechanical properties are enhanced by heat treatment. Annealing was performed at three temperatures (1000 °C, 1100 °C, and 1200 °C), with a holding time from 1 to 20 h. Tensile testing, wear testing, and corrosion testing were performed to evaluate the effect of heat treatment on the behavior and microstructural properties. The grain size increased almost 10 times by heat treatment, which influenced the mechanical properties. The ultimate tensile strength increased up to 300% more compared to the initial state. On the other hand, heat treatment has a negative effect on corrosion and wear resistance.

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The Effect of Heat Treatment on the Tribological Properties and Room Temperature Corrosion Behavior of Fe─Cr─Al-Based OPH Alloy

The aim of this paper is to evaluate the influence of small variations in chemical composition on the corrosion resistance and mechanical properties of low-manganese and medium manganese high strength steels. Six different steels with manganese content varying from 1.5 to 4.0 wt.% and aluminium from 0.008 to 6.5 wt.% were subjected to the analysis. The other subjects for evaluation included the effect of aluminium as a replacement for silicon, niobium microalloying and the effect of heat treatment. The effect of non-metallic inclusions on localized corrosion initiation and propagation was also documented. Using potentiodynamic testing, exposure testing, tensile and impact testing, it was found that the improvement in corrosion resistance associated with increasing aluminium content is accompanied by a significant deterioration of the mechanical properties. Niobium microalloying and heat treatment was found to have no quantifiable impact on the anti-corrosion properties. The effect of aluminium content proved to be superior to the effect of nonmetallic inclusions in terms of determining the overall corrosion resistance of the experimental steels.

The Influence of Varying Aluminium and Manganese Content on the Corrosion Resistance and Mechanical Properties of High Strength Steels

This paper investigates the evolution of microstructure and its related mechanical properties of Q-P processed medium-carbon AHSS steel. The investigated informations were compared to the structures and mechanical properties of quenched and tempered, austempered specimens made of the same steel grade. According to the correlations between observed microstructures after Q-P, quenching and tempering, austempering the presence of bainite in Q-P processed specimens was found. The hypothesis of bainite growth durinq Q-P processing was devoleped. The experimental results show that during Q-P heat treatment the bainite transformation can occur even when the partitioning temperatures are below the temperature Ms of experimental steel. Ms. Because of the nature of bainitic trasnformation, Q-P procesing leads to the migration of carbon in to the surroundings of bainitic ferrite. The partition of carbon between banitic ferrite and retained austenite can be the dominant mechanism of stabilization of retained austenite in the microstructure after the heat treatment process.This effect is very likely to greatly contribute to enhanced ductility of Q&P-processed specimens.

Evolution of Mechanical Properties and Microstructure in Q&P Processed Unconventional Medium-Carbon Silicon Steel and Comparison between Q&P Processing, Quenching and Tempering, and Austemperingfor

This work aimed to characterise microstructure and mechanical properties of polymer composite samples. The main task was to adapt the well-known techniques of metallography (i.e. sample preparation and microscopic examination) to documentation of multi-component polymer materials and to optimize the methods of light and electron microscopy for this particular purpose. There were several issues (e.g. low melting point, absence of electrical conductivity), which made the process different from metal samples preparation and observation and which needed to be addressed. Various mounting resins were tested for the samples to find the suitable one, then the process of grinding and polishing was optimized and finally the microstructure was documented using light and scanning electron microscopy (SEM). Samples in the undeformed state were examined as well as the samples subjected to tensile test at different temperatures. Prior to the microscopic observations the material was analysed using methods of thermal analysis (TG A, DSC) and infrared spectroscopy (FT-IR). The tensile tests were employed not only to determine the mechanical properties but also to obtain deformed samples for further microscopic observation.

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Microstructure and properties of polymer composites

In this paper, the properties of three low carbon steels containing different percentage of manganese (1.5 or 3 wt%) and aluminium (1.5 or 2 wt %) were tested using dilatometric analysis and metallog-raphy. The steels had chemical compositions typical for TRIP (Transformation induced plasticity) steels and the two steels with an increased manganese content already belonged to the third genera-tion of AHS (advanced high strength) steels. The dilatometric measurement was employed not only to determine the characteristic transformation temperatures but also to simulate the heat treatment procedure commonly used for TRIP steels. Resulting microstructures obtained through this simula-tion were evaluated and compared. The two main alloying elements were proved to have a significant effect on the transition temperatures and thus on the processability and overall resulting properties of the material.

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Jan Hajšman

Papers

The Effect of Heat Treatment on the Tribological Properties and Room Temperature Corrosion Behavior of Fe─Cr─Al-Based OPH Alloy

The Influence of Varying Aluminium and Manganese Content on the Corrosion Resistance and Mechanical Properties of High Strength Steels

Evolution of Mechanical Properties and Microstructure in Q&P Processed Unconventional Medium-Carbon Silicon Steel and Comparison between Q&P Processing, Quenching and Tempering, and Austemperingfor

Microstructure and properties of polymer composites

Comparison of high strength steels with different aluminium and manganese contents using dilatometry