Microstructure Of Stainless Steel Research Articles

Influence of Multiple Repair Welding on Microstructure and Properties of 06Cr19Ni10 Stainless Steel

AbstractRepair welding technology is widely used in the manufacturing and maintenance of rail transit equipment to repair welding defects. However, repair welding induces modifications in joint performance, and it is necessary to study the microstructure evolution behavior to reveal the reasons. In this study, the effects of multiple repair welding on the microstructure, mechanical, and fatigue properties of 06Cr19Ni10 stainless steel samples were studied. The surface texture and fracture morphology analyses of the samples were conducted by optical microscopy (OM), scanning electron microscopy (SEM), and its equipped backscattered electron diffraction (EBSD) technique. The mechanical and fatigue properties of the samples with different repair welding times were further obtained by hardness, tensile, and fatigue tests. The results show an increase in the grain size and the substructure content in the heat-affected zone (HAZ), and the austenite orientation is changed, attributable to multiple repair welding. Multiple heat inputs result in a significant increase in hardness from 165 HV to 185 HV, a noticeable decrease in tensile strength and elongation, and an upward trend in yield strength. Under the constant stress level, the heat input of multiple repair welding causes a decrease in the fatigue life and significantly reduces toughness in the instantaneous fracture zone of the secondary repair sample.

Performance prediction of 304 L stainless steel based on machine learning

With the development of testing technology and data mining methodologies, machine learning (ML) has been widely applied for predicting the performance of materials in various systems including stainless steel with improved performance. To address the limitations of traditional experimental and statistical methods in predicting the thermal deformation of materials, a predictive machine learning model was developed based on the data obtained from thermal simulation compression tests. Specifically, the Arrhenius and the Modified Johnson-Cook (J-C) Constitutive Model were developed utilizing experimental data to initially predict the rheological behavior of 1.52% Cu-304L stainless steel. Then, a physical metallurgy (PM)-guided Back Propagation (BP) model was developed, and Genetic Algorithm (GA), Whale Optimization Algorithm (WOA), and Mind Evolutionary Algorithm (MEA) were incorporated into the model for optimization purposes, respectively. Finally, the results indicate that the PM-MEA-BP model exhibits superior predictive performance, accurately forecasting the texture evolution of 304L stainless steel with random crystal orientation under rolling deformation conditions. Additionally, the present work also clearly demonstrated that the model not only satisfies precision requirement but also has certain guiding significance for optimizing process parameters and forecasting the microstructure and properties of stainless steel.

Effect of Subsequent Continued Heating After Hot Rolling on the Microstructures and Mechanical Properties of Hot-Rolled Super Ferritic Stainless Steels

Effect of Subsequent Continued Heating After Hot Rolling on the Microstructures and Mechanical Properties of Hot-Rolled Super Ferritic Stainless Steels

Influence of Heat Treatment Temperature on Microstructure, Hardness and Sensitization of UNS S32205 Duplex Stainless Steel

Influence of Heat Treatment Temperature on Microstructure, Hardness and Sensitization of UNS S32205 Duplex Stainless Steel

Deep Learning-Driven Prediction of Mechanical Properties of 316L Stainless Steel Metallographic by Laser Powder Bed Fusion.

This study developed a new metallography-property relationship neural network (MPR-Net) to predict the relationship between the microstructure and mechanical properties of 316L stainless steel built by laser powder bed fusion (LPBF). The accuracy R2 of MPR-Net was 0.96 and 0.91 for tensile strength and Vickers hardness predictions, respectively, based on optical metallurgy images. Feature visualisation methods, such as gradient-weighted class activation mapping (Grad-CAM) and clustering, were employed to interpret the abstract features within the MPR-Net, providing insights into the molten pool morphology and grain formation mechanisms during the LPBF process. Experimental results showed that the optimal process parameters-190 W laser power and 700 mm/s scanning speed-yielded a maximum tensile strength of 762.83 MPa and a Vickers hardness of 253.07 HV0.2 with nearly full densification (99.97%). The study marks the first application of a convolutional neural network (MPR-Net) to predict the mechanical properties of 316L stainless steel samples manufactured through laser powder bed fusion (LPBF) based on metallography. It innovatively employs techniques such as gradient-weighted class activation mapping (Grad-CAM), spatial coherence testing, and clustering to provide deeper insights into the workings of the machine learning model, enhancing the interpretability of complex neural network decisions in material science.

Effect of activating fluxes on the geometry, hardness, and microstructure of 316L stainless steel in GMAW

Effect of activating fluxes on the geometry, hardness, and microstructure of 316L stainless steel in GMAW

Effect of nitrogen content on microstructure and mechanical properties of duplex stainless steels via wire arc additive manufacturing

Effect of nitrogen content on microstructure and mechanical properties of duplex stainless steels via wire arc additive manufacturing

A comprehensive study on the microstructure evolution and mechanical property characterization of selective laser melted 18Ni300 stainless steel during heat treatment processes

The influence of different heat treatment processes on the microstructure and mechanical properties of 18Ni300 stainless steel manufactured by selective laser melting has been investigated in the present study. The microstructures, nanoprecipitates, and mechanical properties of the differently heat-treated samples were analyzed using various precision instruments. Compared with a non-treated 18Ni300 stainless steel sample, the results showed that the microstructure was mainly composed of fine lath-like martensite, with a large number of nano-precipitates dispersed both within the martensite and in the boundaries. In addition, there was a preserved amount of austenite between the lath-like martensite and the spherical nanoprecipitate in the SAT sample. The interactions between the martensite matrix and the nanoprecipitates and dislocations were assumed to be the main reason for the high strength of 18Ni300 stainless steel. These precipitates included rod-shaped or needle-shaped, Ni3Ti, Ni3Mo, and Ni3(Ti, Mo) nano-precipitates, as well as spherical Ti–Al nano-oxidized precipitates and massive Ni-rich precipitates. The shear and by-pass mechanisms between the strengthened nano-precipitate and the dislocations were found to depend on the size of the nanoprecipitate. The influence of the nanoprecipitation on the indentation hardness became more evident after heat treatment, but the effect on the indentation modulus was not that obvious. The AT- and SAT-treatments significantly improve the strength, hardness, and modulus of samples but were found to reduce the toughness and plasticity. After the AT- and SAT-treatments, the protrusions became smaller, and the small isometric protrusion of a shear lip became significantly smaller than for the as-built material.

Effect of Solution Treatment Temperature on Microstructure, Mechanical Properties and Corrosion Resistance of Ultra-High Nitrogen Stainless Steel

Effect of Solution Treatment Temperature on Microstructure, Mechanical Properties and Corrosion Resistance of Ultra-High Nitrogen Stainless Steel

Evaluation of 3D printed 316L stainless steel microstructure and mechanical property by laser ultrasonics

ABSTRACT In this paper, the laser ultrasonic non-destructive testing technology was used to detect the microstructure and mechanical properties of selective laser melting (SLM) 316 L stainless steel after post-treatment. The microstructure and mechanical properties of additively manufactured 316 L stainless steel were measured by Scanning electron microscopy (SEM), Electron backscatter diffraction (EBSD), tensile testing, etc. The laser ultrasonic longitudinal wave signal characteristic values were coupled with the microstructure and mechanical properties of SLM 316 L stainless steel. The results show that: The yield strength has a good correlation with wave speed and attenuation. With the increase of holding temperature and holding time, the grain size increases, the low angle grain boundary decreases, the yield strength gradually decreases from 409 MPa to 359 MPa, the wave velocity increases from 5579 m/s to 5700 m/s, and the frequency domain attenuation coefficient increases from 0.13 dB/mm to 0.16 dB/mm, the central frequency domain is about 10 MHz. The ultimate tensile strength is related to the frequency domain attenuation. The ultimate tensile strength decreases with the increase of the frequency domain attenuation coefficient. It can provide a reference for the evaluation of mechanical properties by laser ultrasonic testing.

The effect of microstructure of an advanced duplex stainless steel on the pitting corrosion and chloride-induced stress corrosion cracking resistance

The effect of microstructure of an advanced duplex stainless steel on the pitting corrosion and chloride-induced stress corrosion cracking resistance

Experimental investigations on influence of processing parameters on the microstructure and properties of AM-printed stainless steel

ABSTRACT The current study has investigated the mechanical properties and microstructure of the DMLS processed 316L experimentally by varying process parameters and solution annealing as a post-processing technique. The feedstock material characteristics, laser power input, layer thickness, scanning velocity, hatch spacing, and building direction are important factors to consider. The modified microstructure not only affects mechanical performance and corrosion resistance but also alters the specimen's properties. An analysis of the powder feedstock and density measurement has been conducted. The samples were subjected to tensile testing, hardness testing, and microstructural analysis. According to the Taguchi analysis findings, the most significant parameter affecting product quality was layer thickness. The observation of grain boundary precipitation in a few samples could be reversed through solution annealing. The results of this study will assist in determining the optimal process parameters for achieving the desired mechanical properties.

Augmenting microstructure and tribological performance of wire arc additive manufactured PH13-8Mo stainless steel via TiC/TiB2 nano-particles incorporation

This study aimed to investigate the effect of TiC and TiB2 nano-inoculants addition on the microstructure and tribological behavior of PH13-8Mo stainless steel processed through wire arc additive manufacturing (WAAM). The incorporation of TiC/TiB2 inoculants demonstrated notable efficiency in mitigating the anisotropic wear and scratch response and enhancing wear resistance observed in the as-printed state. This improvement was ascribed to the refinement of the grain structure, disruption of the columnar structure, and increased content of the retained austenite. Notably, TiB2 inoculation exhibited superior grain refinement and achieved the highest hardness. However, the TiC-inoculated condition demonstrated the best wear resistance, attributed to its excellent combination of hardness and fracture resistance, and a higher contribution of strain-induced martensite transformation during wear testing. Additionally, the implementation of post-printing solutionizing and aging treatment was found to improve the scratch and wear resistance of the alloy, attributed to the formation of nano-sized β-NiAl precipitates. The main wear mechanism observed involved oxidation wear, adhesive wear, and three-body abrasive wear. The findings of this study highlight the significant potential of incorporating ceramic-based nano-particles for improving the wear resistance of WAAM PH13-8Mo components, particularly in demanding applications like injection molding dies where superior abrasion resistance is paramount.

Effect of heat treatment processes on the microstructure and mechanical properties of 00Cr13Ni5Mo super martensitic stainless steel (SMSS)

The effects of quenching and tempering temperatures on the microstructure and mechanical properties of super martensitic stainless steel (SMSS) 00Cr13Ni5Mo were studied. The SMSS after heat treatment is composed of martensite (α phase) and a small amount of austenite. When the quenching temperature is 930 °C, with the increase of tempering temperature, the enrichment of Ni in martensite leads to the formation of reverse austenite, the content of martensite phase decreases from 84.9 % to 80.0 %, and the average grain size increases from 23.23 μm to 27.07 μm. When tempering at 580 °C, the content of martensite phase decreases from 80.0 % to 83.7 % with the increase of quenching temperature. The average grain size increased from 25.23 μm to 35.01 μm. When the quenching temperature is 930 °C, the hardness and yield strength of SMSS decrease, and the hardness and yield strength are the highest at 530 °C, which are 275 HV and 873 MPa. The plasticity increases first and then decreases, and the plasticity is the best at 580 °C. The elongation and reduction of area were 22.87% and 71.41%. These changes in mechanical properties are mainly related to the content of martensite and reversed austenite in the microstructure. The tensile strength and elongation of SMSS under different process conditions were compared. The results show that when the quenching temperature is 930 °C and the tempering temperature is 580 °C, the comprehensive performance of SMSS is the best, reaching 18700 MPa•%. This value is 31% higher than that of forgings. Finally, the formation mechanism of reversed austenite was discussed, and the strengthening model of SMSS 00Cr13Ni5Mo was established.

Evaluation of near immersion active cooling on the microstructure and mechanical properties of AISI 316L stainless steel obtained with additive manufacturing by DED-Arc

Evaluation of near immersion active cooling on the microstructure and mechanical properties of AISI 316L stainless steel obtained with additive manufacturing by DED-Arc

A Comparative Study on the Performance and Microstructure of 304NG Stainless Steel in Underwater and Air Laser Welding.

In order to facilitate the application of underwater laser welding technology in in situ repairs of nuclear power plants, this study conducted comparative experiments between local dry underwater laser welding and laser welding in air on 304NG nitrogen-controlled stainless steel. The aim was to explore its microstructural evolution and mechanical properties in underwater environments. It was found that, near the fusion line of laser welding in air, columnar dendrites gradually evolved into cellular dendrites toward the weld center, eventually disappearing, resulting in a skeletal ferrite and serrated austenite structure. The underwater laser welding joints exhibited similar characteristics yet with more pronounced alternation between columnar and cellular dendrites. Additionally, the size of cellular dendrites decreased significantly, and needle-like ferrite was observed at the weld center. The hardness of underwater laser welded joints was slightly higher than that of in-air laser welded joints. Compared to laser welding in air, the strength of underwater laser welding joints increased from 443 MPa to 471 MPa, and the displacement increased from 2.95 mm to 3.45 mm, both types of welded joints exhibited a mixed mode fracture characterized by plasticity and brittleness.

Microstructure and mechanical properties of 316L stainless steel manufactured by multi-laser selective laser melting (SLM)

The microstructure and mechanical properties of 316L stainless steel samples manufactured by dual-laser selective laser melting technology, were investigated in compare with that of the single-laser scanning samples. It was found that the porosity of the dual-laser overlap samples was lower than that of single laser forming samples due to the different laser energy density absorbed by the powders. Furthermore, it was found that the crystal structure and crystal orientation of both zones were similar. From the TEM observation, it was noted that the number density of nano-oxides in the overlap zone was higher than that in the single laser forming zone. This reason was suggested as the difference of the oxygen content inside the melt pool during the forming process. The strength and microhardness of the single-laser samples was lower than that of the dual-laser overlap samples, but the elongation was higher. By analyzing the strengthening mechanism, it was revealed that Orowan strengthening was the main reason for the difference. These results could guide the large-size component manufactured using the muti-laser selective laser melting technology.

Effect of nitrogen pressure on the microstructure, conductivity, and corrosion resistance of ZrN-coated stainless steel as bipolar plate for proton exchange membrane fuel cell

Zirconium nitride (ZrN) coatings were deposited on the stainless steel using multi-arc ion plating under varying nitrogen partial pressures (PN) ranging from 0.5 to 3.5 Pa. The effect of phase composition, microstructure, and surface morphology on the corrosion resistance and conductivity of the ZrN-coated stainless steel in a simulated proton exchange membrane fuel cell (PEMFC) cathode environment was systematically explored. XRD and TEM revealed that the columnar-structured ZrN coating mainly comprised the fcc-ZrN phase. The Zr3N4 phase was discovered near the substrate during coatings prepared at low nitrogen partial pressures. Surface defects were reduced at nitrogen partial pressures exceeding 2.5 Pa. The ZrN coating exhibited enhanced corrosion resistance and conductivity (ZrN-3.5, Ecorr = 0.307 V, Icorr = 2.085 × 10−7 A/cm2, Rct = 1.125 × 105 Ω·cm2) compared to bare stainless steel in the simulated PEMFC cathode environment. The presence of surface defects influenced the corrosion resistance, while differences in conductivity were related to the phase composition and microstructure of the coating. Thus, the findings indicate that ZrN coatings prepared under optimal deposition conditions can have potential applications in PEMFC bipolar plates.

Micro-macro relationship between microstructure and mechanical behavior of 316L stainless steel fabricated using L-PBF additive manufacturing

Micro-macro relationship between microstructure and mechanical behavior of 316L stainless steel fabricated using L-PBF additive manufacturing

The effect of tempering temperature on microstructure and corrosion resistance of M390 powder metallurgical martensitic stainless steel

The corrosion resistance of M390 powder metallurgical martensitic stainless steel with different tempering temperatures was investigated by potentiodynamic polarization measurements, salt spray tests, and microstructural analyses utilizing scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The tempering temperature had no significant effect on the size and volume fraction of carbides. The corrosion resistance of M390 steel gradually deteriorated with increasing tempering temperature, and a loss passivation (LOP) effect was observed when tempered at 450 °C, 500 °C, and 550 °C. Transmission electron microscopy (TEM) analysis showed that the width of the Cr-depleted zones around the undissolved M7C3 carbides increased with increasing tempering temperature, while the Cr content in these zones decreased, which was the main reason for the deterioration of corrosion resistance. This study offers valuable insights into optimizing the tempering process to improve the corrosion resistance of M390 steel for practical applications.