Structure of a Carbon Steel–Stainless Steel Bimetal

Bimetallic samples may be produced by casting St3 structural steel between sheets of Kh18N9T stainless steel in a mold, with subsequent hot rolling of the three-layer sheet. Such samples have a structure in which Kh18N9T stainless steel appears at the outer edge on both sides, while the core consists of St3 structural steel. Analysis of the boundary between the steels confirms the absence of defects: it is continuous and of high quality. The microstructure of the junction is investigated by optical, scanning-probe, and electron microscopy. Three structural components are observed from the pearlitic to the austenitic steel: a weakened section of the ferritic layer; a strengthened section of the ferritic layer; and a dark-etching layer at the austenitic steel. The following results are obtained by scanning-probe microscopy—in particular, the constantforce contact method—and optical metallography: on approaching the boundary from the St3 steel, a carbon- free layer with purely ferritic structure is observed, rather than the usual structure for low-carbon steel, which consists of a ferrite matrix with pearlite colonies. On approaching the boundary from the Kh18N9T steel, a carburized layer is observed. In addition, the boundary includes an intermediate carbide layer (depth up to 50 μm). The change in microhardness in the region where the St3 structural steel meets the external layer of Kh18N9T stainless steel indicates considerable increase in strength of the materials. Elemental microanalysis of the St3 steel–Kh18N9T steel boundary reveals the change in concentration of the alloying elements on approaching the boundary. The presence of chromium in St3 steel and the increase in carbon concentration in Kh18N9T stainless steel confirm that two opposing diffusional fluxes are formed: the diffusion of carbon from the St3 steel; and the diffusion of alloying elements from Kh18N9T steel. The resulting carbides explain the increased hardness of both steels close to the boundary.     

Effect of Cerium on Structure and Properties of Granular Bainitic Steel

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Structure Evolution and Solidification Behavior of Austenitic Stainless Steel in Pulsed Magnetic Field

 To understand the solidification behavior of austenitic stainless steel in pulsed magnetic field, the solidification process is investigated by means of the self made high voltage pulse power source and the solidification tester. The results show that the solidification structure of austenitic stainless steel can be remarkably refined in pulsed magnetic field, yet the grains become coarse again when the magnetic intensity is exceedingly large, indicating that an optimal intensity range existed for structure refinement. The solidification temperature can be enhanced with an increase in the magnetic intensity. The solidification time is shortened obviously, but the shortening degree is reduced with the increase of the magnetic intensity.     

Antibacterial Properties of Cerium-Bearing Stainless Steel Bearing Cerium

Antibacterial Properties of Cerium-Bearing Stainless Steel Bearing Cerium     

Morphology and Forming Mechanism of Rare Earth Inclusions During Solidification of Steel

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Effects of Cerium on Microalloying in Low Sulfur Nb-Ti-Bearing Steel

The CCT curves of supercooled austenite were investigated by using THERMECMASTOR-Z simulation machine, test samples refined from 50 kg vacuum induction furnace and two-stage controlled roiling in laboratorial condition. Test results show that influence of cerium （Ce） addition in low sulfur Nb-Ti-Bearing steel is as follows： Ce can increase the transformation point tara and tAr1, enlarge the interval of transformation （tAr3-tAr1） . Ce moves CCT and rightwards , and reduces hardenability. Ce increases bainitic transformation temperature and enlarges curves upwards interval of bainite formation. With higher cooling rates, Ce changes the martensite from coarse strip to fine strip. It decreases Ms, enhances the trend of lath martensitic structure and limits the formation of lamellar crystal.     

Effects of Cerium on Microalloying in Low Sulfur Nb-Ti-Bearing Steel

The overcooling austenite CCT curves were investigated by using THERMECMASTOR-Z simula-tion machine, the test samples refining from 50kg vacuum induction furnace and two-stage controlled rolling in laboratorial condition. Test results show that addition cerium (Ce) in low sulfur Nb-Ti-bearing steel affects as follows: Ce can. increase the transformation point t Ar3 and t Ar1, enlarge the intervals of temperature (tAr1-tAr3).Ce can make the CCT curves to move upper and right, reduce the hardenability. Ce can increase the transformation temperature of bainite and enlarge intervals of bainite. The martensites become from coarse strip to fine strip by Ce in higher cooling rates. Ce can decrease MS and enhance the trend of lath martensitic structure and limit the formation of lamellar crystal.     

Studies on Welding and Sensitization of Chrome–Manganese Austenitic Stainless Steel

The standard composition of austenitic stainless steel (ASS) includes Cr and Ni. However, due to rising cost of Ni, search for suitable alternative is always on. Manganese, on account of being an austenite stabilizer, can be considered as a replacement of Ni. Chrome–manganese steel (part of 200 series of ASS) contains chromium (≤15%) and low nickel. However, there is not enough confidence about their service life. Present work is an attempt to study the effect of welding and sensitization characteristics of this steel. The heat affected zone (HAZ) is identified microstructurally as per ASTM standard A262 Practice A test. Time temperature sensitization (TTS) diagram is established and critical cooling rate (CCR) is estimated. double loop electrochemical potentiokinetic reactivation (DLEPR) technique is used to quantify degree of sensitization (DOS) for heat treated and welded samples. The DOS for thermally aged sample at 750°C for 180 min is found to be 32.56% whereas for welded sample it is 31.30%. The results are discussed and mechanism of micro-structural changes due to welding of such steel is suggested.     

Effects of Rare Earth on Structure and Mechanical Properties of Clean BNbRE Steel

The effects of REinsteel include cleaning,mod-ifyinginclusions and alloying[1 ~4]. With the develop-ment of steel-making and continuous casting process-ing,the fluctuation range of the composition of steelwas mini mized ,the cleanliness of steel was i mpr…     

Effects of Si and Mn Contents on Low-Temperature Toughnes of 10CrSiNiCu Steel

Ｉｎｓｕｆｉｃｉｅｎｔｌｏｗ－ｔｅｍｐｅｒａｔｕｒｅｔｏｕｇｈｎｅｓｏｒｈｉｇｈｔｒａｎｓｉｔｉｏｎｔｅｍｐｅｒａｔｕｒｅｉｓｔｈｅｍａｉｎｒｅａｓｏｎｆｏｒｈｏｔｒｏｌｅｄ１０ＣｒＳｉＮｉＣｕｓｔｅｅｌｐｌａｔｅｓｆａｉｌｕｒｅｔｏｍｅｅｔｔｈｅ...     

Production Conditions and Properties of Layered Materials Type of Composite Based on a Stainless Steel ― Steel

Fabrication conditions and some properties of wear-resistant and corrosion-resistant layered materials type of composite based on a stainless steel steel were investigated. The materials were produced by joint pressing and sintering of the layers. The working layer was based on stainless steel Kh18N15 with additions of Cr₃C₂ and MoS₂, and the substrates were unalloyed iron, low-alloy chromium steel, and stainless steel. The quality of layer bonding was evaluated by metallographic investigation and electron-probe microanalysis of the interface between layers, and also determination of the strength properties. It was established that the most favorable conditions for structure and property formation in the layered composites are obtained by using a stainless steel substrate and a working layer with an intermediate sublayer.     

Effects of Si and Mn Contents on Low-Temperature Toughness of 10CrSiNiCu Steel

Effects of Si and Mn contents on low-temperature toughness of 10Cr SiNiCu steel were studied in this paper. The results indicated that by properly lowering Si content and increasing Mn content, the strength is increased slightl y, and the low-temperature toughness is improved markedly. When Si content decr eased from 0.96 % to 0.72 % or 0.42 mass%, the 50 % FATT dropped by 50 ℃ and the crack pr opagation energy in the process of impact increased obviously. The main reason for the improvement of toughness lies in the refining of grain size and the decre asing of the deteriorative effect of Si.     

The Effect of Cold Rolling on Microstructure and Mechanical Properties of a New Cr–Mn Austenitic Stainless Steel in Comparison with AISI 316 Stainless Steel

In the present study the effect of room temperature rolling on microstructure and mechanical properties of a new Cr–Mn austenitic stainless steel (containing 12 %Cr, 23 %Mn and 0.13 %C) and AISI 316 steel was investigated. The specimens of these steels were cold rolled at various thickness reductions of 0, 12, 25, 37 and 50 %. Microstructural investigations were carried out using optical microscopy, magnetic field test and X-ray diffraction technique. Hardness and tensile test methods were also done to evaluate the mechanical properties. Results showed that some of austenite phase transformed to martensite during cold rolling in the 316 steel, while there was no strain induced transformation in the Cr–Mn steel. It was also found that the newly developed steel had higher strength and higher specific strength than those of the 316 steel, while its ductility was the same as that of the 316.     

Effects of Hydrogen Ion Implantation on TiCC Coating of Stainless Steel

Titanium carbide coatings are widely used as various wearresistant material. The hydrogen erosion resistance of TiCC films and the effect of hydrogen participation on TiCC films were studied. Seventyfive percent TiCC films are prepared on stainless steel surface by using ion mixing, where TiCC films are deposited by rf magnetron sputtering followed by argon ion bombardment. The samples are then submitted to hydrogen ion implantation at 12×10-3 Pa. Characterization for the 75% TiCC films was done with SIMS, XRD, AES, and XPS. Secondary ion mass spectroscopy (SIMS) was used to analyze hydrogen concentration variation with depth, XRay diffraction (XRD) was used to identify the phases, and Auger electron spectra (AES) as well as Xray photoelectron spectra (XPS) were used to check the effects of hydrogen on shifts of chemical bonding states of C and Ti in the TiCC films. It is found that TiCC films on stainless steel surface can prevent hydrogen from entering stainless steel.     

Effects of RE and Vanadium on Microalloyed Steel

The effects of RE were studied by TEM, SEM, ICP and thermal simulation methods in vanadium microalloyed steel. The content.of RE in the solid solution can reach the order of 10^-5 --10^-4 in steel. The solid solution of RE was found to reduce the stability of precipitated V (C, N ), impede the precipitation of V (C, N ) in austenite, and accelerate and refine the precipitation of V (C, N) in ferrite. The combined effect of RE and V is to delay the dynamic recrystaUization, refine the grains and second phase particles, and to promote the precipitation of V (C, N) obviously. Thus the microalloying with RE and V leads to raising the strength and toughness of steel.     

Directional Solidification,Structure, and Mechanical Properties of a Eutectic Nb–Si Alloy with a Natural Composite Structure for GTE Blades

Directional solidification in a liquid-metal coolant and the formation of a natural composite structure in a eutectic niobium–silicon alloy are studied to produce GTE blades in ceramic molds. The microstructure and the phase composition of the alloy are analyzed in parts of variable sections. The shortand long-term strengths of the niobium–silicon composite material are measured at a temperature of 1200°C.     

Physical Properties and Solidification Structure of Al－SiEutectic Alloy Melt with Cerium Modification

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Effect of Cr–Mo Addition on the Microstructure and Mechanical Properties of Medium-Carbon Steel

Herein, the effects of Chromium–Molybdenum (Cr–Mo) addition on the microstructural evolution and mechanical properties of medium-carbon steel after spheroidization annealing are systematically studied through scanning electron microscopy, electron backscatter diffraction, and tensile testing. Cr–Mo addition hinders the proeutectoid ferrite + pearlite transformation, thereby promoting the bainite transformation. Moreover, it refines the pearlite lamellar spacing as well as decreases the average carbide diameter, increases the number of carbides per unit area, and hinders ferrite recrystallization. Compared with those in the B1 steel annealed for 8 h, the size of carbides and their number per unit area in the CM1 steel are 30% lower and 2.2-fold higher, respectively. Due to finer ferrite grains, smaller carbides, and a higher amount of carbides, the strength of steel improves, and the plasticity slightly reduces after Cr–Mo addition. After 2 h of annealing, the yield strengths of Cr–Mo steels are 77.5–109.5 MPa higher than those of base steels; the elongations are above 20%. The contributions of the strengthening mechanism of steel to the yield strength are as follows (from high to low): grain boundary, precipitation, solid solution, and dislocation strengthening.     

In Situ Observation of Phase Transformation and Structure Evolution of a 12?pct Cr Ferritic Stainless Steel

This work focuses on an in situ observation of phase transformation of a 12?pct Cr ferritic stainless steel using high-temperature laser scanning confocal microscopy. ?????????? phase transformation temperatures are determined to be approximately 1073?K and 1423?K (800?°C and 1150?°C), respectively. The onset of phase transformation is found to occur at grain boundaries. When the temperature is beyond 1518?K (1245?°C), the grain growth rate suddenly becomes very high, and the grain growth is related to the self-organizing of adjacent grains. ?????? phase transformation has been mostly restrained when cooling rates are in the range of 22.4?K/s to 13.3?K/s (22.4?°C/s to 13.3?°C/s) except for at grain boundaries. Martensitic phase transformation, rather than ?????? phase transformation, occurs when the cooling rates are in the range of 8.5?K/s to 2.2?K/s (8.5?°C/s to 2.2?°C/s). The starting temperature of martensitic phase transformation is approximately 697?K to 728?K (424?°C to 455?°C) for specimens heated to 1373?K (1100?°C) (i.e., ?? phase field), which is 50?K to 100?K (50?°C to 100?°C) higher than that of specimens heated to 1723?K (1450?°C) (i.e., ?? phase field). Many bulges remain on the surfaces of the specimen heated to 1723?K (1450?°C), and their formation mechanism is analyzed.