scholarly journals Selective Oxidation during the Austenitic Annealing of a CMnSi Steel

2006 ◽  
Vol 15-17 ◽  
pp. 129-134 ◽  
Author(s):  
Tom van de Putte ◽  
Zinedine Zermout ◽  
Didier Loison ◽  
Serge Claessens ◽  
Jan Penning
Keyword(s):  
Phase Composition ◽  
Water Vapour ◽  
Selective Oxidation ◽  
Steel Surface ◽  
High Strength ◽  
Surface Region ◽  
Protective Atmosphere ◽  
Major Influence ◽  
Residual Water ◽  
Passenger Cars

High strength multiphase CMnSi steel is increasingly used in passenger cars. Si and Mn alloying levels are typically in the range of 1-2% in mass. While Si improves the mechanical properties, it considerably deteriorates the galvanisability of steel. Residual water vapour in the reducing gas atmosphere during the intercritical or austenitic annealing results in the selective oxidation of Si and Mn at the steel surface. Besides Mn and Si, C is oxidized as well at the steel surface, leading to the formation of CO gas and decarburisation of the steel surface. This decarburisation has a major influence on the phase composition in the steel surface region: it shifts the ferrite to austenite transformation to higher annealing temperatures, leading to differences in surface and bulk microstructure. The phase composition influences the solubility and diffusivity of all alloying elements near the surface. The evolution with temperature of the selective oxidation at the steel surface has been studied by interrupted annealing in a protective atmosphere containing residual water vapour. The influence of the annealing temperature on the selective oxidation of Mn and Si is characterized by XPS (X-ray Photo-electron Spectroscopy) analysis.

Challenges in hot-dip galvanizing of high strength dual phase steel: Surface selective oxidation and mechanical property degradation

2012 ◽  
Vol 206 (16) ◽  
pp. 3428-3436 ◽  
Author(s):  
Huachu Liu ◽  
Fang Li ◽  
Wen Shi ◽  
Srinivasan Swaminathan ◽  
Yanlin He ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Selective Oxidation ◽  
Steel Surface ◽  
Dual Phase Steel ◽  
High Strength ◽  
Dual Phase

Processing strategy for high strength Ni-based hybrid composite clad on SS 316L steel through microwave heating

2021 ◽  
pp. 095440542110213
Author(s):  
Sarbjeet Kaushal ◽  
Satnam Singh ◽  
Dheeraj Gupta
Keyword(s):  
Sliding Wear ◽  
Steel Surface ◽  
Steel Substrate ◽  
Microstructural Analysis ◽  
High Strength ◽  
Phase Changes ◽  
Microwave Exposure ◽  
Pull Out ◽  
316L Steel ◽  
Microwave Applicator

Processing of nickel-based high strength composites and alloys is a difficult and thought-provoking task. In this work, a strategy of heating through microwaves radiation is utilized to process the high strength hybrid Ni-based composite clad on SS 316L steel surface containing 15% (WC-8Co) and 5% Mo. The premixed composite powder was placed on the steel surface and irradiated with domestic microwave applicator having 2.45 GHz fixed frequency and 900 W power. The hybrid clad was successfully developed within 12–15 min of microwave exposure. The processed clad was subjected to various metallurgical and mechanical characterizations to understand the microstructures and phase changes. Microstructural analysis study revealed that the clad of ∼0.85 mm thickness was obtained and presence of dispersed reinforced particles of WC-8Co and Mo in nickel matrix were observed. Some inter-metallic phases of W2C, Ni2Mo4C, Ni4W and NiSi2 were observed in the clad. The average microhardness of the composite clad was712 ± 58 HV. The microwave processed clad exhibited a flexural strength of 852 ± 6 MPa with deformation index of 35 × 10−5 mm/N. Further, the sliding wear study revealed that the sliding velocity of 1.0 m/s favoured the formation of oxide tribo layers. The various mechanisms of wear revealed by the analysis of worn-out surfaces were abrasion, adhesion, surface pull-out and deformation of surfaces. The microwave processed clad revealed significant improvement in wear resistance in comparison to the steel substrate.

scholarly journals Influence of Fe Oxidation on Selective Oxidation Behavior of Si and Mn Added in High Strength Sheet Steel

2013 ◽  
Vol 99 (3) ◽  
pp. 221-227 ◽  
Author(s):  
Yusuke Fushiwaki ◽  
Yasunobu Nagataki ◽  
Hideki Nagano ◽  
Wataru Tanimoto ◽  
Yoshiharu Sugimoto
Keyword(s):  
Selective Oxidation ◽  
Oxidation Behavior ◽  
Sheet Steel ◽  
High Strength ◽  
Fe Oxidation

Mechanical Property of Phosphoaluminate Cement

2010 ◽  
Vol 150-151 ◽  
pp. 1754-1757 ◽  
Author(s):  
Peng Liu ◽  
Zhi Wu Yu ◽  
Ling Kun Chen ◽  
Zhu Ding
Keyword(s):  
Mechanical Property ◽  
Compressive Strength ◽  
Phase Composition ◽  
Electrical Properties ◽  
Pore Size Distribution ◽  
Pore Size ◽  
High Strength ◽  
Curing Time ◽  
Hydration Products ◽  
Resistance Value

The influence of curing time on the mechanical property of the phosphoaluminate cement (PAC) was investigated, and the mechanism was discussed as well. The phase composition and morphology of hydration products, electrical properties, porosity and pore size distribution of PAC cured different age were analyzed with XRD, EIS and MIP. The results showed PAC has the property of early-high strength, and the compressive strength of PAC cured for 1 day was about 70% of 28 days’. The main hydration products of PAC are micro-crystal phase and gel of phosphate and phosphoaluminate which formed compacter microstructure. In addition, there are no calcium hydroxide (CH) and ettringite (AFt) produced during the process of hydration. The compressive strength of PAC increased with age, which was due to more products continuously produced. The ac resistance analysis manifested as the change of the nyquist pattern and resistance value.

The structure, phase composition, and residual stresses of diffusion boride layers formed by thermal-chemical treatment on the die steel surface

2021 ◽  
Vol 23 (2) ◽  
pp. 147-162
Author(s):  
Undrakh Mishigdorzhiyn ◽  
◽  
Nikolay Ulakhanov ◽  
Aleksandr Tikhonov ◽  
Pavel Gulyashinov ◽  
...  
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Low Temperature ◽  
Residual Stresses ◽  
Diffusion Layer ◽  
Chemical Treatment ◽  
Steel Surface ◽  
Boron Content ◽  
Die Steel ◽  
Temperature Mode

Introduction. Control and management of technological residual stresses (TRS) are among the most critical mechanical engineering technology tasks. Boriding can provide high physical and mechanical properties of machine parts and tools with minimal impact on the stress state in the surface layers. The purpose of this work is to determine the temperature modes of diffusion boriding, contributing to a favorable distribution of TRS in the surface layer of die steel 3Kh2V8F. The paper considers the results of studies on the TRS determination by the experimental method on the UDION-2 installation in diffusion layers on the studied steel surface. Boriding was carried out in containers with a powder mixture of boron carbide and sodium fluoride as an activator at a temperature of 950 °C and 1050 °C for 2 hours. The obtained samples of steels with a diffusion layer were examined using an optical microscope and a scanning electron microscope (SEM); determined the layers' microhardness, elemental, and phase composition. The experiments resulted in the following findings: as the boriding temperature rose from 950 °C to 1050 °C, the diffusion layer's thickness increased from 20 to 105 μm. The low-temperature mode of thermal-chemical treatment (TCT) led to the formation of iron boride Fe2B with a maximum boron content of 6 % and a microhardness up to 1250 HV. A high-temperature mode resulted in FeB formation with a top boron content of 11 % and a microhardness up to 1880 HV. Results and Discussions. It is found that boriding at 950 °C led to a more favorable distribution of compression TRS in the diffusion layer. However, significant TRS fluctuations in the diffusion layer and the adjacent (transitional) zone could affect the operational properties after TCT at a given temperature. An increase in the TCT temperature led to tensile TRS's appearance in the layer's upper zone at a depth of up to 50 μm from the surface. Despite tensile stresses on the diffusion layer surface after high-temperature TCT, the distribution of TCT is smoother than low-temperature boriding.

Oxidising Role of Water Vapour in the 250 Kev D+ Induced Radiolysis of Polyimide Kapton-H

1988 ◽  
Vol 100 ◽  
Author(s):  
U. K. Chaturvedi ◽  
A. Patnaik ◽  
Ramji Pathak ◽  
R. N. Chakraborty ◽  
A. K. Nigam
Keyword(s):  
Partial Pressure ◽  
Water Vapour ◽  
Ion Beam ◽  
Adsorbed Water ◽  
Vacuum System ◽  
Residual Water ◽  
Implantation Time ◽  
Polymeric Surface ◽  
Imide Ring

Residual water vapour present in the vacuum system has been observed to play a dominant oxidising role in the 250 keV D+ induced radiolysis of polyimide (Kapton-H). The partial pressure (pp) of water in the vacuum system decreases sharply as the D+ beam impinges the polymeric surface, but soon after, it recovers to its initial value as the accumulated dose increases. Emission of CO2 is observed which has its maximum at a time when the H2O partial pressure is at a minimum. The CO2 level also returns to its original level with time. This complementary variation of CO2 and H2O confirms that absorbed and adsorbed water molecules are radiolysed by the ion beam and initiate oxidation of the radiolytically evolved CO to yield CO2 on and within the ion implanted surface of the polyimide. Further, the small enhancement in the 28 amu peak (N2 + CO), which exhibits no maximum/minimum over the entire implantation time, can be understood in terms of the evolution of N2 from the imide ring as a result of radiolysis of this nitrogen containing polymers.

Elimination of Rusting Layer from High-Strength Steel Surface Using Different Laser Cleaning Methods

2019 ◽  
Vol 46 (7) ◽  
pp. 0702003
Author(s):  
雷正龙 Zhenglong Lei ◽  
孙浩然 Haoran Sun ◽  
陈彦宾 Yanbin Chen ◽  
田泽 Ze Tian
Keyword(s):  
High Strength Steel ◽  
Steel Surface ◽  
High Strength ◽  
Laser Cleaning ◽  
Cleaning Methods

The Preparation of High-Strength and Micropore Lightweight Bauxite Aggregate by In Situ Polymerization and Decomposition

2011 ◽  
Vol 194-196 ◽  
pp. 2135-2139
Author(s):  
Yi Neng Fang ◽  
Hua Zhi Gu ◽  
Yun Sheng Fen ◽  
Lin Jun Wang ◽  
Yan Jing Li
Keyword(s):  
Phase Composition ◽  
Pore Size ◽  
Aluminium Hydroxide ◽  
Average Pore Size ◽  
High Strength ◽  
Organic Polymer ◽  
Low Grade ◽  
Pore Former ◽  
Average Pore

High-strength and micropore lightweight bauxite aggregate was fabricated by low grade raw bauxite powder, aluminium hydroxide powder and organic polymer (OP). OP was used as consolidator, binder and pore former and aluminium hydroxide was used as pore former. The influence of OP and aluminium hydroxide content on the property of the samples was studied. The phase composition and the microstructure of the sintered samples were characterized by XRD, SEM and the pore size distribution was measured by mercury porosimety. The results demonstrate that the bulk density of the samples decreases linearly and the apparent porosity of the samples increases gradually with the addition of OP. The lowest density reached 1.13g/cm3when adding 35% OP and 10% Al(OH)3. The average pore size is around 5μm, and increases with the addition of OP increased. The XRD showed the main phase of the sample is mullite and some little amount of corundum.

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