Ultrahigh Strength Steel: Development of Mechanical Properties Through Controlled Cooling

Maity, Samir; Kawalla, Rudolf

doi:10.5772/26514

Cited by 4 publications

(3 citation statements)

References 29 publications

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“…Ultra-high strength steels can be defined as a type of advanced high strength steels (AHSS) with a multiphase microstructure, which obtain a good combination of strength and ductility by grain refinement and thermomechanical processing. In addition, UHSSs and HSSs are considered as members of high strength low alloy (HSLA) steels due to their strength levels and low alloy contents [3,4]. Microstructures of HSSs and UHSSs usually consist of a combination of irregular ferrite, bainite, martensite, and retained austenite [5].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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Weldability of cold-formed high strength and ultra-high strength steels

Afkhami

Björk

Larkiola

2019

Journal of Constructional Steel Research

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Hollow sections and cold-formed steels have a key role in modern structures and machinery. In addition, to benefit from full potentials of cold-formed steels, it is usually required to weld them to other steel parts of structures. However, data provided by relevant standards, such as Eurocode 3, do not cover newly developed high strength and ultra-high strength grades of this material. Thus, further study is critical to complete available data in literature and standards. Regarding this matter, having a good weldability for cold-formed high and ultra-high strength steels is vital for development of contemporary steel structures. Thus, newly developed steels S700MC and S1100 were selected to be investigated in this study. To do so, bended base metals with different degrees of coldforming were welded to their straight (virgin) counterparts. Next, welded joints were investigated via microstructural analysis, hardness measurement, tensile test, and Charpy impact test to assess the weldabilities of the cold-formed base metals. Results show that the final joints had acceptable characteristics, and the cold-formed base metals showed good weldability. However, bending and pre-straining criteria recommended by the manufacturer must be satisfied to have an acceptable joint after welding. Beyond that criteria, fracture elongation and notch toughness of the welded joints decreased, and some welded samples failed from their cold-formed base metals.

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Section: Accepted Manuscriptmentioning

confidence: 99%

“…This lack of definition might be due to the constant development of these steels. Currently, the upper limit of yield strength for commercial grades of UHSSs has reached 1400 MPa, and it is getting higher progressively [4]. In this study, according to difinitions provided by [6],…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Weldability of cold-formed high strength and ultra-high strength steels

Afkhami

Björk

Larkiola

2019

Journal of Constructional Steel Research

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“…The dataset used to train, test, and validate the ANN modeling was collected from various experimental test results of related transmission gear materials that were publicized by researchers. [20][21][22][23]. The amount of the experimental data collected should be adequate enough to give an essential amount of input data, and, at the same time, control the amount to avoid overuse of costly experimental resources.…”

Section: Materials Datamentioning

confidence: 99%

Prediction of Mechanical and Toughness Properties of Ni-Modified Cr-Mo Alloy Steels for Transmission Gear

Hailu

Redda

2021

JERA

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The purpose of the study was to predict the mechanical and toughness properties of Ni-modified alloy steels by adding 1.55%, 1.75%, and 1.95% of Ni-content to the existing Cr-Mo alloy steel of transmission gear material. Typically transmission gears have been working under severe working situations of loads and rotations. Due to these situations, the properties and qualities of gear materials are highly affected consequently, fatigue failure is instigated. So, improving the mechanical and toughness properties of the existing gear material is very vital and compulsory since these properties have a direct impact on gear fatigue failure. Investigations have been done on determining the mechanical and toughness properties of the Ni-modified Cr-Mo alloy steels, through ANN modeling prediction by associating the complex relation of input (chemical composition, tempering temperature) and output parameters (mechanical and toughness properties), and verified by experimental test approaches. Explored these materials property with ANN modeling and experimental test show that the more Ni-content added to the Cr-Mo alloy steel, the higher the ultimate and yield strength can achieve at every instant of tempering temperature. Likewise, fracture toughness, impact toughness, and percent of retained austenite of these materials were also investigated thoroughly as tempering temperature varies. Thus, a 1.55 % Ni-modified Cr-Mo alloy steel has a higher value of both impact toughness and fracture toughness compared with other Ni-modified alloy steels. Similarly, surface hardness was slightly decreased as the amount of Ni-content added increased at each instant of tempering temperature. Lastly, based on both predicted and experimental results, 1.55 % of Ni-modified Cr-Mo alloy steel showed a better combination of mechanical and toughness properties. Keywords: ANN modeling; Yield strength; Ni-modified; Tempering temperature; Fracture toughness; Surface hardness

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