Scientific and technological bases for creation of cold-resistant steel with a guaranteed yield strength of 315–750 MPa for the Arctic. Part 2. Technology of production, structure and properties of sheet hire performance

2019 ◽  
pp. 14-41
Author(s):  
O. V. Sych
Keyword(s):  
Yield Strength ◽  
Thermomechanical Processing ◽  
The Arctic ◽  
Accelerated Cooling ◽  
Low Alloy Steels ◽  
Hot Plastic Deformation ◽  
Metal Thickness ◽  
Alloy Steels ◽  
Technology Of Production ◽  
Technological Methods

On the basis of the conducted research, a complex of scientific and technological methods has been developed for various technological processes (thermomechanical processing with accelerated cooling, quenching from rolling and separate furnace heating with high-temperature tempering). The developed method provides the formation of the structure of acceptable heterogeneity and anisotropy according to different morphological and crystallographic parameters throughout the thickness of rolled products up to 100 mm from low alloy steels with a yield strength of at least 315–460 MPa and up to 60 mm from economically alloyed steels with a yield strength of at least 500–750 MPa. The paper presents results of the industrial implementation of hot plastic deformation and heat treatment schemes for the production of cold rolled steel sheet with yield strength of at least 315–750 MPa for the Arctic. The structure of sheet metal thickness is given, providing guaranteed characteristics of strength, ductility, cold resistance, weldability and crack resistance.

Scientific and technological bases for creation of cold-resistant steel with a guaranteed yield strength of 315–750 MPa for the Arctic. Part 1: Principles of alloying and requirements for sheet metal structure

2019 ◽  
pp. 22-47 ◽  
Author(s):  
O. V. Sych
Keyword(s):  
Yield Strength ◽  
Sheet Metal ◽  
Structural Parameters ◽  
Metal Structure ◽  
The Arctic ◽  
Accelerated Cooling ◽  
Critical Temperatures ◽  
Critical Opening ◽  
Metal Thickness ◽  
And Performance

The results of the choice of rational alloying and microalloying of cold-resistant steels with a guaranteed yield strength of 315–750 MPa are presented on the basis of the established interrelationship of phase transformations, structure, mechanical properties and performance characteristics when varying the content of basic alloying elements. Quantitative requirements for various structural parameters and their maximum permissible difference in sheet metal thickness up to 100 mm have been developed, depending on the strength category, manufacturing technology (thermomechanical treatment with accelerated cooling, hardening from separate furnace or rolling heating with high temperature tempering), which provide guaranteed characteristics of strength, cold resistance (impact work KV at test temperature –60 ... –80°С, critical temperatures of viscousbrittle transition Ткand zero ductility NDT) and crack resistance under the criterion of the critical opening in the top CTOD fracture.

Empirical Correlation between Parameters from Small Punch and Tensile Curves of Mn-Mo-Ni Low Alloy Steels by Using Test and FE Analysis

2007 ◽  
Vol 353-358 ◽  
pp. 420-423
Author(s):  
Min Chul Kim ◽  
Jae Bong Lee ◽  
Maan Won Kim ◽  
Bong Sang Lee
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Empirical Relationship ◽  
Close Correlation ◽  
Tensile Tests ◽  
Displacement Curve ◽  
Low Alloy Steels ◽  
Element Analysis ◽  
Small Punch ◽  
Alloy Steels

A load-displacement curve from a small punch test includes several useful information that is related to standard test properties such as the tensile property, fracture toughness and ductilebrittle transition temperature. In this study, the empirical relationship between the material property factors in SP curves and the tensile curves has been investigated by comparing test results and finite element analysis results. SP and tensile tests and finite element analyses were performed for several Mn-Mo-Ni low alloy steels with different manufacturing processes. It was found that the yield loads (Py) in the SP curves, if they were adequately defined, were linearly related to the yield strength (σ0). The yield loads defined from the intersection point of two lines tangent to the elastic bending region and plastic bending region showed a better relation with the yield strength than those from the offset line. The slope of the SP curves from the simulation results had a close correlation with the hardening coefficient and strength constant as well.

scholarly journals Energy power parameter effect of hot rolling on the formation of the structure and properties of low-alloy steels

2021 ◽  
Vol 6 (12 (114)) ◽  
Author(s):  
Sergey Sheyko ◽  
Anton Matiukhin ◽  
Volodymyr Tsyganov ◽  
Andrey Andreev ◽  
Anna Ben ◽  
...  
Keyword(s):  
Hot Deformation ◽  
Relative Elongation ◽  
Motor Vehicles ◽  
Accelerated Cooling ◽  
Low Alloy Steels ◽  
Two Phase ◽  
Plastic Properties ◽  
Alloy Steels ◽  
Increased Strength ◽  
Effect Of Hot Rolling

The temperature and degree of hot deformation for steel 10HFTBch have been determined. This made it possible to ensure an increase in the mechanical properties of this steel, namely, the ultimate strength up to 540–560 MPa, as well as the relative elongation up to 25–29 %. As a result, it became possible to increase the service life of wheels with increased carrying capacity. This, in turn, will make it possible to increase the load of the transported cargo by motor vehicles several times. The mechanism of the influence of the energy-power parameters of rolling on the formation of the macro- and microstructure of a two-phase steel in the process of hot deformation is disclosed. The applied scheme provided an increase in the homogeneity of the structure of the developed steel, which saved the central part of the rolled section from overheating. It has been established that a decrease in the temperature of the end of deformation leads to a decrease in the size of the recrystallized austenite grain, and, consequently, to a refinement of the ferrite grain. Also an important factor in preventing the growth of ferrite grains in the upper part of the ferritic region is the abolition of cooling of the steel in coils. The recommended mode for multicomponent alloy steel 10HFTBch is as follows: the temperature of the end of rolling is 850 °C, the beginning of accelerated cooling is 750 °C, and the temperature of strip coiling into a coil is 600 °C. The basis for ensuring the increased strength of two-phase steels is the ratio and distribution of structural fractions – ferrite (initial and precipitated from austenite), as well as martensite. When hardened by such traditional "martensite formations" as manganese, the ability to control properties is limited. This is reflected in a narrow range of variation in the strength and ductility of the developed steel. The optimal combination of strength characteristics of plastic properties reduces the metal consumption of the product by 15–25 %.

scholarly journals Fractographic Analysis of Mechanical Properties of Microalloyed Steel

2021 ◽  
Vol 2070 (1) ◽  
pp. 012174
Author(s):  
N B Garg ◽  
A Garg
Keyword(s):  
Mechanical Properties ◽  
Impact Energy ◽  
Thermomechanical Processing ◽  
Microalloyed Steel ◽  
High Strength ◽  
Low Alloy Steels ◽  
The Past ◽  
Alloy Steels ◽  
Quenching And Tempering ◽  
Subsequent Quenching

Abstract Extensive efforts made over the past few decades have enhanced the rising performance of High-Strength Low-Alloy steels. Use of thermomechanical processing was considered for this research. However, the desired mechanical properties are obtained by formulating alloys. Further, to enhance mechanical properties, impact energy, the subsequent quenching and tempering are used. The metallurgical transformation caused by deformation followed by cooling and/or heat treatment has added influences on steels’ mechanical properties. The rational decrease in impact energy value is complex.

Hydrogen stress cracking resistance and hydrogen transport properties of ASTM A508 grade 4N

CORROSION ◽  
10.5006/3949 ◽  
2021 ◽  
Author(s):  
Esteban Rodoni ◽  
Andreas Viereckl ◽  
Zakaria Quadir ◽  
Aaron Dodd ◽  
Kim Verbeken ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Yield Strength ◽  
Alloy Steel ◽  
Hydrogen Diffusion ◽  
Low Alloy Steels ◽  
Low Alloy Steel ◽  
Cracking Resistance ◽  
Stress Cracking ◽  
High Nickel ◽  
Alloy Steels

Low alloy steels combine relatively low cost with exceptional mechanical properties, making them commonplace in oil and gas equipment. However, their strength and hardness are restricted for sour environments to prevent different forms of hydrogen embrittlement. Materials used in sour services are regulated by the ISO 15156-2 standard, which imposes a maximum hardness of 250 HV (22 HRC) and allows up to 1.0 wt% Ni additions due to hydrogen embrittlement concerns. Low alloy steels that exceed the ISO 15156-2 limit have to be qualified for service, lowering their commercial appeal. As a result, high-performing, usually high-nickel, low alloy steels used successfully in other industries are rarely considered for sour service. In this work, the hydrogen stress cracking resistance of the high-nickel (3.41 wt%), quenched and tempered, nuclear-grade ASTM A508 Gr.4N low alloy steel was investigated using slow strain rate testing as a function of applied cathodic potential. Results showed that the yield strength and ultimate tensile strength were unaffected by hydrogen, even at a high negative potential of -2.00 V<sub>Ag/AgCl</sub>. Hydrogen embrittlement effects were observed once the material started necking, manifested by a loss in ductility with increasing applied cathodic potentials. Indeed, A508 Gr.4N was less affected by hydrogen at high cathodic potentials than a low-strength (yield strength = 340 MPa) ferritic-pearlitic low alloy steel of similar nickel content. Additionally, hydrogen diffusivity was measured using the hydrogen permeation test. The calculated hydrogen diffusion coefficient of the ASTM A508 Gr.4N was two orders of magnitude smaller when compared to that of ferritic-pearlitic steels. Hydrogen embrittlement and diffusion results were linked to the microstructure features. The microstructure consisted in a bainitic/martensitic matrix with the presence of Cr<sub>23</sub>C<sub>6</sub> carbides as well as Mo and V-rich precipitates, which might have played a role in retarding hydrogen diffusion, kept responsible for the improved HE resistance.

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