Effect Study of Thermal Cutting Methods on the Edge’s Microstructure of High-Strength Steel Grade S700MC

2019 ◽  
Vol 946 ◽  
pp. 928-933
Author(s):  
Ivan A. Ilin ◽  
Anna A. Krasnoperova ◽  
Evgenii A. Sirotkin
Keyword(s):  
High Strength Steel ◽  
Laser Cutting ◽  
Low Carbon Steel ◽  
High Strength ◽  
Effect Study ◽  
Plasma Cutting ◽  
Low Carbon ◽  
Cutting Method ◽  
Thermal Cutting ◽  
Steel Grades

The paper presents the results of metallographic studies of laser and plasma cutting methods of high-strength steel for the purpose of its application for the preparation of sample edges without subsequent machining. It is shown that as a result of the thermal and physical-chemical processes in heat affected one (HAZ), there is a change in the phase and chemical composition of the metal. The depth of the HAZ is changed from 261 μm to 337 μm. The maximum hardness at the cutting edge is 410 HV10. On the surface after the laser cutting there is an oxidized layer of metal, saturated with oxygen, nitrogen and other gases as a result of contact with the oxygen jet and the surrounding air; its thickness is hundredths or even thousandths of a millimeter. A feature of the plasma cutting method is the formation of a deeper oxide layer on the surface with a thickness of 9...14 μm, in contrast to the laser cutting method. The analysis of existing research to improve the technology of repair welding of low-carbon steel is performed. The obtained results can be used in the development of high-strength steel grades welding technology in terms of preparation of edges for welding using thermal cutting methods, which are currently quite conservative.

Fatigue Crack Retardation of Low Carbon Steel in Saltwater

1984 ◽  
Vol 106 (1) ◽  
pp. 38-42 ◽  
Author(s):  
K. Tokaji ◽  
Z. Ando ◽  
T. Kojima
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
High Strength Steel ◽  
Low Carbon Steel ◽  
High Strength ◽  
Low Carbon ◽  
Zone Size ◽  
Propagation Behavior ◽  
Crack Propagation Behavior ◽  
Tensile Overload

The crack propagation behavior following the application of a single tensile overload in 3 percent saltwater was examined using a low carbon steel, which has a considerably lower static strength than high strength steel used in previous report. Experiments were carried out under sinusoidally varying loads at a load ratio of 0 and a frequency of 10 Hz, and the effects of saltwater were evaluated by comparing with the result in air and result on high strength steel. A single tensile overload was found to cause delayed retardation, just as it did in air. The overload affected zone size was not affected by saltwater and showed the same value in both environments. This observed trend differed from the result on high strength steel in which the overload affected zone size was larger in 3 percent saltwater than in air, and thus it was found that the effect of saltwater on retardation behavior was different even in the similar steels. Retardation cycles were smaller in 3 percent saltwater than in air. Since the overload affected zone size was not affected by saltwater, the decrease in retardation cycles was attributed to the higher rates of fatigue crack propagation in 3 percent saltwater. Thinner specimen showed stronger retardation than thicker one. The behavior at midthickness of thicker specimen showed delayed retardation as well as the result in air. Moreover, the crack propagation behavior following the application of a single tensile overload in 3 percent saltwater was well explained by the crack closure concept.

Mechanical Joining of Various Materials by Clinching Method

2015 ◽  
Vol 662 ◽  
pp. 205-208 ◽  
Author(s):  
Ľuboš Kaščák ◽  
Emil Spišák ◽  
Jacek Mucha
Keyword(s):  
High Strength Steel ◽  
Steel Sheet ◽  
Low Carbon Steel ◽  
Surface Preparation ◽  
High Strength ◽  
Low Carbon ◽  
Steel Sheets ◽  
Joint Properties ◽  
Wide Range ◽  
Grade Steel

Clinching is a simple, cheap and efficient method of joining that enables to join two or more sheets without any additional elements such as rivets, bolts or nuts. In addition, clinching does not require a surface preparation e.g. drilling (riveting), cleaning and roughening of the surface (adhesive boding) and other types of surface preparations (arc welding). Clinching is utilized in a wide range of applications and can be applied to different materials such as low carbon steel sheets, high-strength steel sheets, aluminium alloys, magnesium alloys. The paper presents the results of evaluation of clinched joint properties. The advanced high-strength steel sheet DP600 in combination with the drawing grade steel sheets DC06, DX51D+Z and high-strength low alloy steel sheet H220PD were used for experiments. The influence of position of the sheets relative to the punch and die of the tool on the carrying capacities of the clinched joints was observed as well. The tension test and microhardness test were used for the evaluation of clinched joint properties.

Effect of Thermal Cutting Methods on the Fatigue Life of High Strength Structural Steel S690Q

2015 ◽  
Author(s):  
Tiberio Garcia ◽  
Sergio Cicero ◽  
Jose A. Álvarez ◽  
Isidro Carrascal ◽  
Antonio Martin-Meizoso
Keyword(s):  
Fatigue Life ◽  
Structural Steel ◽  
High Strength Steel ◽  
Stress Ratio ◽  
High Strength ◽  
Specimen Geometry ◽  
Middle Section ◽  
Cutting Method ◽  
Thermal Cutting

This paper analyzes the effect of different cutting methods on the fatigue life of high strength steel S690Q. The research covers three cutting methods (oxy-fuel, plasma and laser) and two specimen geometries: plain specimens with rectangular sections and cut edges, and specimens with machined edges and a cut hole in the middle section. All the specimens were conducted to failure by applying fatigue cycles, the stress ratio (R) being 0.1, and the corresponding S-N curves were obtained for each combination of cutting method and specimen geometry. Measurements of roughness and hardness have been performed in order to explain the influence of the cutting method on the fatigue life of this particular steel. Fatigue results have been compared with the predictions provided by current fatigue standards, analyzing the possibility of extrapolating their S-N curves, focused on oxy-fuel cuts, to plasma and laser cuts.

scholarly journals Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1988
Author(s):  
Tibor Kvackaj ◽  
Jana Bidulská ◽  
Róbert Bidulský
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
High Strength Steel ◽  
Single Phase ◽  
Hsla Steel ◽  
High Strength ◽  
Strength Properties ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Steel Grades

This review paper concerns the development of the chemical compositions and controlled processes of rolling and cooling steels to increase their mechanical properties and reduce weight and production costs. The paper analyzes the basic differences among high-strength steel (HSS), advanced high-strength steel (AHSS) and ultra-high-strength steel (UHSS) depending on differences in their final microstructural components, chemical composition, alloying elements and strengthening contributions to determine strength and mechanical properties. HSS is characterized by a final single-phase structure with reduced perlite content, while AHSS has a final structure of two-phase to multiphase. UHSS is characterized by a single-phase or multiphase structure. The yield strength of the steels have the following value intervals: HSS, 180–550 MPa; AHSS, 260–900 MPa; UHSS, 600–960 MPa. In addition to strength properties, the ductility of these steel grades is also an important parameter. AHSS steel has the best ductility, followed by HSS and UHSS. Within the HSS steel group, high-strength low-alloy (HSLA) steel represents a special subgroup characterized by the use of microalloying elements for special strength and plastic properties. An important parameter determining the strength properties of these steels is the grain-size diameter of the final structure, which depends on the processing conditions of the previous austenitic structure. The influence of reheating temperatures (TReh) and the holding time at the reheating temperature (tReh) of C–Mn–Nb–V HSLA steel was investigated in detail. Mathematical equations describing changes in the diameter of austenite grain size (dγ), depending on reheating temperature and holding time, were derived by the authors. The coordinates of the point where normal grain growth turned abnormal was determined. These coordinates for testing steel are the reheating conditions TReh = 1060 °C, tReh = 1800 s at the diameter of austenite grain size dγ = 100 μm.

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