Effect of [Al]s, [Mg], [Ca] in Molten Steel on Inclusion Content for High Speed Wheel Steel during LF-VD Process

2014 ◽  
Vol 898 ◽  
pp. 60-63
Author(s):  
Yu Tang
Keyword(s):  
Fatigue Life ◽  
Molten Steel ◽  
High Speed ◽  
Refining Process ◽  
Fatigue Performance ◽  
Wheel Steel ◽  
Inclusion Content ◽  
High Basicity ◽  
Secondary Refining ◽  
Improve Fatigue

In order to improve fatigue life of wheel steel, LF-VD secondary-refining process is done with Al-deoxidation and slag of high basicity, high Al2O3 content and low oxidizing property. Inclusion content would be influenced by [Al]s, [Mg], [Ca] in molten steel. It is found that Al2O3 inclusions, which are the products of Al-deoxidation, would react with [Mg], [Ca] in molten steel to transform into CaO-MgO-Al2O3 complex inclusions, which is the key for the enhancement of fatigue performance for wheel steel.

Effect of Slag Composition on [Mg], [Ca] Content in Molten Steel for High Speed Wheel Steel

2013 ◽  
Vol 746 ◽  
pp. 501-504
Author(s):  
Tang Yu
Keyword(s):  
Molten Steel ◽  
Slag Composition ◽  
High Speed ◽  
Refining Process ◽  
Wheel Steel ◽  
Complex Inclusion ◽  
High Basicity ◽  
Secondary Refining ◽  
Positive Factor ◽  
Improve Fatigue

In order to improve fatigue life of wheel steel, secondary-refining process is done with Al-deoxidation and slag of high basicity, high Al2O3 content and low oxidizing property. [M, [C content in molten steel would be influenced by slag composition. It is found that high basicity, high Al2O3 content and low oxidizing property is positive factor for proper [M, [C content in molten steel which is the key of inclusion transformation from Al2O3 to CaO-MgO-Al2O3 complex inclusion, contributing to the enhancement of fatigue performance for wheel steel.

Effect of Slag Composition on Total Oxygen of High Speed Wheel Steel

2013 ◽  
Vol 690-693 ◽  
pp. 114-117
Author(s):  
Yu Tang
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Wheel Steel ◽  
Al2o3 Content ◽  
Inclusion Interaction ◽  
Secondary Refining ◽  
Positive Factor ◽  
Improve Fatigue

In order to improve fatigue life of wheel steel, secondary-refining process is done with Al-deoxidation and slag of high basicity, high Al2O3 content and low oxidizing property. By slag-steel-inclusion interaction, harmful inclusions could be controlled well to be eliminated by floation, lowering T[O] content to 0.0007% in round billets, enhancing fatigue life of wheel steel. It is found that (Al2O3) in slag is positive factor for decrease of T[O], while (CaO)/(Al2O3), (SiO2) in slag and [Al]s in molten steel is negative factor for it. As a result, by INSTRON fatigue testing machine, tested steel samples achieve ultra-high cycle of 108 above, realizing experimental purpose of improving fatigue life of wheel steel.

Effect of Slag Composition on Fatigue Life of High Speed Wheel Steel

2013 ◽  
Vol 675 ◽  
pp. 264-269
Author(s):  
Yu Tang
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Oxide Inclusion ◽  
Wheel Steel ◽  
Al2o3 Content ◽  
Confocal Laser ◽  
Composition Analysis ◽  
In Situ Observation

In order to improve fatigue life of wheel steel, secondary-refining process was done with Al-deoxidation and slag of high basicity, high Al2O3 content and low oxidizing property. By morphology observation and composition analysis with FESEM, it is found that during LF-VD process, by slag-steel-inclusion interaction, Al2O3 inclusions could transform to MgO-Al2O3 spinel, and later on to CaO-MgO-Al2O3 inclusions, which are inclined to be eliminated by floatation, lowering T[O] content to 0.0007%, enhancing fatigue life of wheel steel. By In-Situ observation with CONFOCAL laser scanning microscope, it is found that MnS precipitates during solidification process, which would core oxide inclusion to form MnS-oxide complex inclusion, contributing to fatigue life improvement of wheel steel. By INSTRON fatigue testing machine, it is found that by successful inclusion control, tested samples achieve ultra-high cycle of 108 above, realizing experimental purpose of improving fatigue life of wheel steel, boosting domestic production process of CRH high speed wheel steel.

scholarly journals Understanding the Relations between Surface Stress State and Microstructure Feature for Enhancing the Fatigue Performance of TC6 Titanium Alloy

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1261
Author(s):  
Song Shu ◽  
Xin Huang ◽  
Zonghui Cheng ◽  
Yizhou Shen ◽  
Zhaoru He ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fatigue Life ◽  
Stress State ◽  
Surface Stress ◽  
Strengthening Mechanism ◽  
Fatigue Performance ◽  
Shock Peening ◽  
The Relationship ◽  
Change Of Microstructure ◽  
Improve Fatigue

Fatigue performance has always been an important factor affecting the application of titanium alloy. The service life of TC6 titanium alloy is easily reduced under a continuously alternating load. Therefore, there is an urgent need for a new method to improve fatigue performance. Laser shock peening (LSP) is a widely proposed method to enhance the fatigue performance. Here, through experiments and finite element simulations, it was found that LSP can prolong the fatigue life of TC6 by improving the surface stress state. In strengthening processes, the generation of residual stress was mainly attributed to the change of microstructure, which could be reflected by the statistical results of grain sizes. The content of grains with a size under 0.8 μm reached 78%, and the microhardness value of treated TC6 was 18.7% higher than that of an untreated sample. In addition, the surface residual compressive stress was increased to −600 MPa at the depth of 1500 μm from the surface. On this basis, the fatigue life was prolonged to 135%, and the ultimate fracture macroscopic was also changed. With the treatment of LSP, the fatigue performance of TC6 is highly promoted. The strengthening mechanism of LSP was established with the aim of revealing the relationship between microstructure and stress state for enhancing the fatigue performance in whatever shapes.

Mechanical Behavior and Fatigue Performance of Carburized Steel Specimens

2016 ◽  
Vol 853 ◽  
pp. 72-76
Author(s):  
Ke Ji Pang ◽  
Huang Yuan
Keyword(s):  
Mechanical Property ◽  
Fatigue Life ◽  
Fracture Strain ◽  
Base Material ◽  
Fatigue Performance ◽  
Mechanical Parts ◽  
Carburized Steel ◽  
Carburized Layer ◽  
Compressive Residual Stresses ◽  
Improve Fatigue

Carburization is popular in design and fabrication of mechanical parts, such as gears, to improve fatigue performance. However, it is still open how to characterize the mechanical property of carburized steel and to quantify effects of the carburization to fatigue life of carburized parts. In the present paper four types of specimens differently treated and carburized are experimentally investigated. The experiments confirm significant increments in hardness and yield stress due to carburization. The fracture strain of the carburized steel is significantly smaller than that of the base material. Although the fatigue performance of the carburized steel is slightly worse than the base material, the solid carburized specimen shows significantly longer fatigue life. The fatigue limit increases from ca. 300 MPa for the base material to 550 MPa for the tensile carburized specimens. Detailed measurements display that the carburized layer in a carburized specimen possesses high compressive residual stresses, which arises the fatigue performance of the carburized steel.

The Melting Temperature of CaO-(2CaO•SiO2)-B2O3-SiO2-(Al2O3) Slag System

2012 ◽  
Vol 217-219 ◽  
pp. 35-38 ◽  
Author(s):  
Hong Ming Wang ◽  
Pei Si Li ◽  
Gui Rong Li ◽  
Mian Zhang ◽  
Zhao Zhao ◽  
...  
Keyword(s):  
Melting Temperature ◽  
Slag System ◽  
Refining Process ◽  
Alumina Content ◽  
Melting Temperatures ◽  
High Basicity ◽  
Secondary Refining ◽  
Mass Ratios ◽  
Fluxing Agent

The melting temperatures of CaO-(2CaO•SiO2)-B2O3-SiO2-(Al2O3) slag system were investigated. The results indicate that B2O3 has significant fluxing effect on this slag system. When the content of B2O3 is about 10% in these slag system, the mass ratios of w(CaO)/w(SiO2) and (CaO)/w(Al2O3) can be controlled in the scope of 1.5-8.0, the melting temperature of slag is still lower than 1340°C, which is suitable for steelmaking and secondary refining process. As a conclusion, when 10% B2O3 is employed as fluxing agent, a kind of CaO-based slag system with ultra-high basicity, ultra-low alumina content as well as low melting temperature can be obtained.

Effect of Slag-Metal Reaction on Transformation of Al2O3 inclusions in Pipeline Steel

2011 ◽  
Vol 284-286 ◽  
pp. 1143-1147
Author(s):  
Qiang Li ◽  
Xin Hua Wang ◽  
Hai Bo Li
Keyword(s):  
Molten Steel ◽  
Pipeline Steel ◽  
Refining Process ◽  
High Grade ◽  
Secondary Refining ◽  
Calcium Aluminates ◽  
Hydrogen Induced Cracking ◽  
Liquid Calcium ◽  
Calcium And Magnesium ◽  
Refining Time

For high grade pipeline steel, elimination of Al2O3 inclusions can improve the susceptibility of hydrogen-induced cracking (HIC) and stress corrosion cracking (SCC). In the present work, the transformation of Al2O3 inclusions with slag-metal reaction was studied by controlling ladle slag and relative technologies in LF-RH refining process. It is found that Al2O3 inclusions decrease with increasing refining time, and no pure Al2O3 inclusions exist in molten steel at the end of secondary refining; the remained inclusions in molten steel are liquid calcium aluminates and semi-liquid CaO-MgO-Al2O3 complex inclusions. The analysis of thermodynamic equilibrium proves that CaO and MgO in slag can be reduced by aluminum in molten steel, which is the source of calcium and magnesium in molten steel.

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