0Cr18Ni9 Stainless Steel Research Articles

Research on accelerated corrosion of 0Cr18Ni9 stainless steel in marine atmospheric environment of the South China Sea

Research on accelerated corrosion of 0Cr18Ni9 stainless steel in marine atmospheric environment of the South China Sea

Microstructure, mechanical properties and tribocorrosion characteristics of (Mo1-xCrx)5Si3 alloys

(Mo1-xCrx)5Si3 alloys were prepared by vacuum arc melting technique. The microstructure and mechanical properties of (Mo1-xCrx)5Si3 alloys were characterized using a scanning electron microscope (SEM), X-ray diffraction (XRD) and nano-indentation tests. The tribocorrosion characteristics of the alloys were investigated using a tribocorrosion tester in 3.5 wt% NaCl solution. The results revealed that the thermal expansion anisotropy ((CTE(c)/CTE(a))) of the (Mo1-xCrx)5Si3 alloys decreased from 2.25 to 1.45 with increasing Cr content. The Cr-alloyed (Mo1-xCrx)5Si3 alloys exhibited a high hardness, and their fracture toughness, ratios of H3/E2 and H/E were improved. (Mo1-xCrx)5Si3 alloys showed a strong wear-corrosion combined effect, and an opposite trend between friction coefficient and OCP values was observed during the tribocorrosion tests. The tribocorrosion resistances of (Mo1-xCrx)5Si3 alloys were better than that of 0Cr18Ni9 stainless steel due to the formation of Cr2O3-MoO3-SiOx protective films. The (Mo0.8Cr0.2)5Si3 alloy exhibited the best tribocorrosion characteristics with a low friction coefficient and wear rate. For the 0Cr18Ni9 and Mo5Si3 alloy, pure wear (Vw) was dominant, nevertheless, corrosion-induced wear (Vcw) was the main tribocorrosion mechanism of (Mo0.8Cr0.2)5Si3 alloy.

Evolution of interfacial structure of the joints between a tungsten-copper composite and austenitic stainless steel

Joining of CuW70 composite and 0Cr18Ni9 stainless steel was successfully achieved at temperatures 1150 °C with durations from 15 to 90 min after adding a pure copper intermediate layer. Microstructure, phase composition and elemental distribution at the interfacial region were studied. The optimum joining interface with a dense microstructure was obtained at a joining temperature of 1150 °C with a duration of 60 min. Interdiffusion of atoms occurred at the interface between the tungsten-copper composite and stainless steel, resulting in formation of various compounds such as W0.6Cu0.4, Cu3.8Ni and Fe0.946Ni0.054. An iron chromium-rich layer was formed at the interface near the tungsten-copper composite side, and an island structure containing Cr, Cu, and Ni was formed near the stainless steel side.

Bi-sulfide existence in 0Cr18Ni9 steel: correlation with machinability and mechanical properties

This work investigates the effect of Bi addition on the formation of sulfide inclusions, and also aims to improve the machinability and mechanical properties of type 0Cr18Ni9 stainless steel. Smelting experiments as well as machining and tensile tests were carried out in various low and high Bi content steels. Results show that the forms of Bi-MnS inclusions were: isolated particle, cavity-bridge link, semi- and complete encapsulation. The forms of MnS inclusions were found as: mushroom or rod-like, long strip, spherical, and spindle shape. The normalized frequency of 0.065, corresponding to the inclusion area above 50 μm2, was the greatest at 2300 ppm Bi, reflecting an increase in the number of larger-sized inclusions. The averge hardness of steel matrix and the inclusions at 0 ppm Bi was 179 and 166 kgf/mm2, while that after Bi addition was 154∼168 and 155∼166 kgf/mm2, respectively. The Bi addition to steel improved the surface finish of the steels after machining and increased the ductility of steel, but had little effect on the yield strength of steel.

Facile preparation and tribological property of alloyed Fe3Si coatings on stainless steels surface by molten-salt infiltration method

Alloyed Fe3Si infiltration coatings on the surface of 2Cr13 and 0Cr18Ni9 stainless steels were easily prepared via non-electrolysis infiltration in a molten salt. The infiltrated coatings on a 20 carbon-steel surface were used for comparative study. The microstructure of each infiltration coating was examined via XRD and SEM. The hardness and toughness of Fe3Si coatings were investigated by using a microscopic hardness tester, nano-indentation and static-indentation tests. Furthermore, the wear resistance of the coatings was evaluated using a ball-on-disk wear tester. The results indicated that alloying elements in the stainless-steel substrates participate in the mutual thermal diffusion of Fe-Si and alloyed Fe3Si coatings containing elemental Cr and Cr, Ni can be easily obtained. Cr and Ni alloying elements can increase the growth rate of the infiltration coatings, help to reduce the defect density, and improve the compactness of these coatings. In addition, the surface wear resistance capacity of alloyed Fe3Si coatings was 2.3 times and 3.7 times that of the corresponding 2Cr13 and 0Cr18Ni9 stainless-steel substrates, respectively. The reason lie in that Cr- or (Ni, Cr)- alloying has endowed Fe3Si coating higher hardness and surface toughness simultaneously.

Analysis of Numerical Simulation of 0Cr18Ni9 Stainless Steel Pipe Welded Joint

0Cr18Ni9 stainless steel pipe is a commonly used welding material, which has great demand in shipbuilding, boiler pressure vessel and construction engineering. In this paper, for a given welding process condition, select reasonable parameters, carry out numerical simulation process on welded joints, analyze the temperature field distribution law and stress field value of welded joints, and judge whether it is consistent with the actual.

Microstructure and Mechanical Properties of Selective Laser Melting 0Cr18Ni9 Stainless Steel

The 0Cr18Ni9 samples were prepared by laser selective melting technique, and the effects of different power and scanning speed on the microstructure evolution were observed. Through the observation of the microstructure and the analysis of the densification test results, the optimum process parameter was 280W, 960mm/s. The tensile strength (678MPa) and yield strength (554MPa) of the transverse tensile specimens formed under this condition are higher than that of the longitudinal specimens. However, the longitudinal specimen is more plastic than the transverse specimen.

Effect of additional axial tension on formability of equal curvature-diameter bending without mandrel for 0Cr18Ni9 stainless steel tube

The equal curvature-diameter (ECD; R0/D0 = 1.0; where R0 is the bending radius, and D0 is the outer diameter of tube) bending process without mandrel was regarded as the tube’s minimal bending condition. Compared with pure bending, this represented a very complex physical process with multifactor effects. The quality and forming limit of tube bending are affected by additional axial tension (AAT); therefore, in this study, the ECD bending process without mandrel for tubes was performed by combining the finite element (FE) method and experimental research. The effects of AAT on the bending formability, such as wall thickness variation, cross-section distortion, and springback, were investigated. The results showed that: (1) under a certain friction coefficient between the tube and pressure die, AAT was constant, the maximum wall thickness variation rate, the maximum cross-section minor axis variation rate, and the springback angle all increased with the increase of the bending angle; (2) under a certain bending angle, maximum wall thinning rate, maximum cross-section short axis variation rate, and springback angle were positively associated with the friction coefficient, while the wall thickening rate was negatively associated with it. These data implied that the maximum wall thinning rate, the maximum cross-section short axis variation rate, and the springback angle all increased, while the maximum wall thickening rate decreased with the increase of AAT; (3) when the friction coefficient was too small, AAT was too small. Although the degree of the wall thinning, cross-section distortion, and springback were relatively small, the degree of wall thickening was large and even wrinkled. On the contrary, when the friction coefficient was too large, AAT was too large. Although the degree of maximum wall thickening was relatively small, the degree of maximum wall thinning, maximum cross-section short axis variation rate, and the springback angle were large, and the tube’s surface was extensively scratched. When the friction coefficient was too large, it would have a negative impact on the comprehensive bending formability of tube. In conclusion, our study indicates that in order to ensure a tube’s comprehensive bending formability, AAT should be properly controlled by reducing the friction coefficient between the tube and pressure die.

Effect of addition of stainless steels on the microstructure and properties of SiCp/LY12 resistance spot welding joint

SiCp/LY12 composite plates were successfully joined by resistance spot welding (abbreviated as: RSW). 1Cr18Ni9 stainless steel thin slice with 0.12 mm thickness was placed between the spot electrode and weld specimen in the process of welding. The effect of stainless steel thin slices on the microstructure and comprehensive properties of joints was investigated comparatively by means of OM, SEM and joint tensile shear test. The results show that, when the specimens are welded directly without adding stainless steel, SiC particles in the joints are not evenly distributed, there have different zones across the weld, including SiC particles sparing zone, SiC particles concentration zone and SiC particles transition zone. By comparison, with the addition of stainless steels, the SiC particles are uniformity throughout the weld. The analysis of tensile shear fracture reveals that when the specimens are welded directly under the best welding parameters, the diameter of weld nugget is 4.3 mm, the button shape after tearing is irregular elliptical-type, and the tensile shear force of joint is 1242 N. While, when welded by adding stainless steels, the diameter of weld nugget is 5.3 mm, the buttons shape is regular circle with a tensile shear force of 1693 N. It can be attributed to produce more heat and well mobility in the course of spot welding. Moreover, joining of stainless steels can cause equalization of spot electrode pressure. The research has led to the discovery of apparent improvement of microstructure and properties in RSW joint of 15%SiCp/LY12 composites due to the addition of stainless steels.

Study on brush of moving electrode type electrostatic precipitator (MEEP)

MEEP was an efficient particle removal technology for coal plant and sintering machine. As the stability of brush in MEEP was relatively poor, the experiments was designed for the brush which was made by 0Cr18Ni9 stainless steel wire to find the failure mode and cause. Combining the results of the experiments, the failure models of brushes were different under different conditions and the brushes were suitable for being used in the condition of small diameter particles. And the life span of brushes can be more than 6 years.

Different crystal growth and microsegregation mechanisms based on interface evolution in 0Cr18Ni9 stainless steel ingot

Through the microstructure characterization, the different microsegregation and crystal growth phenomena were revealed in a 0Cr18Ni9 stainless steel ingot. Because the solute redistribution is slight in the step growth of δ ferrite-austenite transition, the different distribution of residual δ ferrite, which are depended on the solute segregation, should be traced back to the microsegregation in solidification. And the residual δ ferrite traced back to microsegregation in solidification further implies the complicate crystal growth behaviors. Under different solidification conditions, the shape and forward direction of crystal interface are different. Especially, the discrete crystal growth can happen in a scale smaller than dendrite grains and dendrite stems. The underlying mechanism for discrete crystal growth is explained based on interface evolution. Finally, the effect of different crystal growth behaviors on microsegregation is analyzed.

Fabrication of 3D Microelectrodes by Combining Wire Electrochemical Micromachining and Micro-electric Resistance Slip Welding

Micromachining, using microelectrodes, is a key technology for manufacturing three-dimensional (3D) microstructures. However, 3D microelectrodes are difficult to fabricate, 3D microstructures are fabricated mainly using simple-shaped tools microelectrode with a layer by layer scanning strategy. Based on micro double-staged laminated object manufacture (micro-DLOM), 3D microelectrodes can be obtained by combining closed loop middle-speed wire (Ø100∼180μm) electrical discharge machining (WEDM) and thermal diffusion welding. But it is difficult to obtain 3D microelectrodes with an edge length of end face less than 100μm, though by low speed wire electrical discharge machining (LS-WEDM) or femtosecond laser cutting, the dimension of 3D microelectrodes can be further miniaturized, they are both very expensive. To solve the problem above, this paper proposed a low-cost method combining wire (Ø8μm) electrochemical micromachining (WECMM) and micro-electric resistance slip welding to fabricate 3D microelectrodes. Firstly, with WECMM combining low frequency micro-vibration and travelling of wire electrode, 30-μm-thick 0Cr18Ni9 stainless steel foils were cut to obtain multi-layer two-dimensional (2D) microstructures. Secondly, through micro-electric resistance slip welding, the multi-layer 2D microstructures were laminated and bonded to fit 3D microelectrodes. Moreover, this paper investigated the influences of applied voltage, feed speed, wire electrode travelling and micro-vibration on machining surface quality and dimensional accuracy. Based on the studies above, two typical 3D microelectrodes with a dimension less than 100μm were successfully fabricated. Finally, applying the fabricated 3D microelectrodes to micro-electrochemical machining (micro-ECM), 3D micro-cavities were obtained.

Impulse Pressuring Diffusion Bonding of Titanium to Stainless Steel Using a Copper Interlayer

Impulse pressuring diffusion bonding of commercially pure titanium to 1Cr18Ni9 stainless steel was carried out using a copper interlayer in an attempt to reduce the bonding time and alleviate the detrimental effect of interfacial reaction products on bonding strength. Successful bonding has been achieved at 850 °C under a pulsed pressure of 8∼20 MPa within a duration of only 120∼180 s, which is notably shortened in comparison with conventional diffusion bonding. Microstructure characterization revealed that a sequence of Ti-Cu intermetallic compounds were formed at the Ti/Cu interface and the Cu/stainless steel interface was characterized by the presence of solid solution of Cu in γ Fe without any interfacial reaction products. Maximum bonding strength of 346 MPa was obtained when the joint was bonded for 120 s. Upon tensile loading, the joints fractured along the Ti/Cu interfacial reaction layer in a brittle cleavage manner, indicating that the impulse pressuring diffusion bonding can alleviate the harmful influence of interfacial intermetallic compounds on joint performances to a certain extent, but it is infeasible in completely eliminating the negative effect of the brittle intermetallic compounds.

Wrinkling behavior in tube hydroforming coupled with internal and external pressure

Control and use of wrinkles is a challenge in tube hydroforming because wrinkle was always considered as one of the defects of tubes from the traditional view. In this paper, a dedicated experimental setup was designed and manufactured, using which the investigation of wrinkling behavior coupled with internal and external pressure can be realized. The effect of internal or external pressure on 5A02 aluminum alloy tubes and 0Cr18Ni9 stainless steel tubes were all investigated using this setup. It was found that the number and shape of wrinkles are strongly dependent on the internal or external pressure. More important is that the geometrical configuration of wrinkles can be perfectly characterized using the Gauss function rather than the sine function adopted in the published literature. In addition, the fitted Gauss functions for every wrinkle were integrated in order to compare their area with the corresponding area of die cavity, so as to obtain the appropriate process parameters for the useful wrinkle, which can be formed in advance and then flatted in the calibration stage.

Corrosion and Protection of 0Cr18Ni9 Stainless Steel Cooling Water Pipe in Power Plant

This paper analyzed the morphology and reasons of pitting corrosion perforation of 0Cr18Ni9 stainless steel cooling water pipes in a power plant and pointed out the measures to prevent the pitting corrosion under this condition. The results showed that: the reason of pitting corrosion of 0Cr18Ni9 stainless steel cooling water pipes was the existence of multiple Cl-and easily fouling Ca2+ and Mg2+ in water, with the corrosion products mainly the oxides of Fe and Cr; the economic measures to prevent pitting corrosion were to increase the pH of water and decrease the content of Ca2+ and Mg2+.

Influence factors of precision of femtosecond laser ablating 0Cr18Ni9 stainless steel

The 0Cr18Ni9 stainless steel sheet was cut and drilled by a femtosecond laser, and the influence factors of machining accuracy of femtosecond laser ablation were studied. The morphology of stainless steel ablation zone and metallographic structure of cutting seam were examined by means of Nikon SMZ800 optical microscope and 4XC optical metallographic microscope. Based on the laser speckle on the surface of stainless steel observed by a coaxial CCD in the process of stainless steel ablation, the laser beam divergent propagation behavior was simulated using COMSOL Multiphysic numerical simulation software, and the beam divergence angle was calculated. Experimental and simulation results demonstrate that when the laser repetition rate is 5 kHz, the edge of cutting seam and hole are obviously blackened; metallographic phase shows that grain size significantly gets larger at cutting seam and heat affected zone cant be avoided in the femtosecond laser ablation process; metal-air hybrid plasma induced by ultra-high power density femtosecond laser makes the laser beam scatter along the direction of propagation in the process of machining, the divergence angle is between 6 to 10. The existence of heat affected zone and the behavior of the metal-air hybrid plasma are the main factors influencing the precision of femtosecond laser ablation.

Microstructural Investigation of W-Cu Composite and 1Cr18Ni9 Stainless Steel Brazed Joint with Ag-Cu Filler Metal

AbstractAbstract: Tungsten-copper (W-Cu) composite and 1Cr18Ni9 stainless steel were brazed with Ag-28wt%Cu brazing filler metal in a vacuum furnace, via controlling brazing temperature 855–865 °C and holding time 30 min. Microstructure, microhardness, four-point bend strength, element distribution and phase constituents near interface of the brazed joint, were investigated by a series of standard technique. Results indicated that Ag-Cu eutectic phase near W-Cu composite side and the bulk phase near 1Cr18Ni9 steel side were formed in the brazing seam region. Microhardness of the eutectic phase was low, while that of the bulk copper-rich phase was high. Four-point bend strength was as high as 576 MPa, and the fracture occurred at interface near 1Cr18Ni9 steel side. On the brazed interface, Cu and a little W element were transited from W-Cu composite into the brazing seam region, as same as Fe from 1Cr18Ni9 steel. Ag contained in the brazing filler metal was diffused into the W-Cu composite. Element concentration of Ag was high at interface of both two base metals, which was helpful to promote the metallurgical reaction. Phase constituents of the brazed joint were Cu(Ag, Fe), Ag(Cu) and a little of Ag0.7Fe0.3 and FeCu4, formed in the metallurgy of Fe from 1Cr18Ni9 steel and the Ag-Cu brazing filler metal.

Analysis on the pitting corrosion of 0Cr18Ni9 stainless steel and research of the electrochemical behavior under different pH

not Available.

Effect of Wall Thickness of the Billet on 1Cr18Ni9 Stainless Steel Tube Stagger Spinning Process

The stagger spinning process of 1Cr18Ni9 tube was investigated by using finite element method. The metal flow rule around the roller during the tube stagger spinning was analyzed. The influences of wall thickness of the billet on effective stress and spinning force were studied using software Deform. The simulated results indicate that the proper wall thickness of the billet should be 8~15 mm, for the billet with length of 100mm and inner diameter of 200mm.

飞秒激光烧蚀0Cr18Ni9不锈钢精度的影响因素

飞秒激光烧蚀0Cr18Ni9不锈钢精度的影响因素