scholarly journals Superior Strength and Ductility of 304 Austenitic Stainless Steel with Gradient Dislocations

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2613
Author(s):  
Qingsong Pan ◽  
Song Guo ◽  
Fang Cui ◽  
Lijun Jing ◽  
Lei Lu
Keyword(s):  
Stainless Steel ◽  
Mechanical Performance ◽  
Uniform Elongation ◽  
Deformation Mechanisms ◽  
Coarse Grained ◽  
304 Stainless Steel ◽  
Deformation Twins ◽  
304 Austenitic Stainless Steel ◽  
Multiple Deformation ◽  
Strength And Ductility

Materials with designed gradient nanograins exhibit unprecedented mechanical properties, such as superior strength and ductility. In this study, a heterostructured 304 stainless steel with solely gradient dislocation structure (GDS) in micron-sized grains produced by cyclic-torsion processing was demonstrated to exhibit a substantially improved yield strength with slightly reduced uniform elongation, compared with its coarse grained counterparts. Microstructural observations reveal that multiple deformation mechanisms, associated with the formation of dense dislocation patterns, deformation twins and martensitic phase, are activated upon straining and contribute to the delocalized plastic deformation and the superior mechanical performance of the GDS 304 stainless steel.

Rolling tuning microstructure and tensile properties of nano/microcrystalline 304 stainless steel

2019 ◽  
Vol 33 (28) ◽  
pp. 1950344 ◽  
Author(s):  
Yu Shi ◽  
Peiqing La ◽  
Yijun Han ◽  
Fuan Wei ◽  
Jie Sheng ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Tensile Properties ◽  
Uniform Elongation ◽  
Thickness Reduction ◽  
Coarse Grained ◽  
304 Stainless Steel ◽  
Microcrystalline Structure ◽  
Aluminothermic Reaction ◽  
Austenite Grains ◽  
Strength And Ductility

The effect of rolling parameters on microstructure and tensile properties of nanocrystalline/microcrystalline 304 stainless steel (SS) casted by the aluminothermic reaction was investigated in this work. It was found that majority of the nanocrystalline austenite of the 304 SS rolled at 700[Formula: see text]C and 900[Formula: see text]C grew up and transformed to sub-microcrystalline. While the nanocrystalline/microcrystalline structure still retained rolled at 900[Formula: see text]C with 40% deformation followed 600[Formula: see text]C with 70% thickness reduction, and microcrystalline austenite grains distributed evenly. The strength and ductility of the various rolled 304 SS were improved compared with the as-casted 304 SS steel. The steel rolled at 900[Formula: see text]C with 80% deformation exhibited a uniform elongation as large as 31.3%, which is almost the same ductility level of counterpart coarse-grained steel. The rolled steel at 700[Formula: see text]C with 80% deformation achieved the maximum tensile strength but the smallest elongation. The sample, two-step rolled at 900[Formula: see text]C with 40% thickness reduction and then 600[Formula: see text]C with 70% thickness reduction, yielded the satisfactory combination of strength and ductility. The yield strength and elongation were appropriate 767 MPa and 22.8%, respectively, which resulted from the optimized nanocrystalline/microcrystalline structure and distribution.

Effective hydrogen diffusivities of AISI 304 stainless steel with Ni or Au coating

2020 ◽  
Vol 62 (6) ◽  
pp. 593-596
Author(s):  
Krittayot Wannapoklang ◽  
Sirichai Leelachao ◽  
Anchaleeporn W. Lothongkum ◽  
Gobboon Lothongkum
Keyword(s):  
Stainless Steel ◽  
Hydrogen Diffusion ◽  
304 Stainless Steel ◽  
Phase Identification ◽  
Aisi 304 Stainless Steel ◽  
Aisi 304 ◽  
304 Austenitic Stainless Steel ◽  
Hydrogen Assisted Cracking ◽  
Stainless Steel Coupon ◽  
Effective Hydrogen

AbstractMetallic coatings which provide a hydrogen diffusion barrier are thought to reduce hydrogen assisted cracking on stainless steel. The influence of a metallic layer on the hydrogen migration of AISI 304 stainless steel was investigated using a commercial electroplating layer of Ni and Au on a thin stainless steel coupon. Phase identification was performed using an X-ray diffractometer to determine the average thicknesses, measured from back-scattered scanning electron images. Regarding the ASTM G148-97 practice, the effective hydrogen diffusivities of AISI 304 austenitic stainless steel, nickel and gold were measured as 7.07 × 10-13, 2.72 × 10-14 and 9.64 × 10-16 m2 × s-1, respectively. In this work, a gold layer was found to be most effective for the prevention of hydrogen diffusion when compared with untreated and Ni-plated 304 stainless steel.

Effect of Ultrasonic Impact Treatment on the Stress Corrosion Cracking of 304 Stainless Steel Welded Joints

2008 ◽  
Author(s):  
Gang Ma ◽  
Xiang Ling
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Welded Joints ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
304 Stainless Steel ◽  
Ultrasonic Impact Treatment

High tensile weld residual stress is an important factor contributing to stress corrosion cracking (SCC). Ultrasonic impact treatment (UIT) can produce compressive stresses on the surface of welded joints that negate the tensile stresses to enhance the SCC resistance of welded joints. In the present work, X-ray diffraction method was used to obtain the distribution of residual stress induced by UIT. The results showed that UIT could cause a large compressive residual stress up to 325.9MPa on the surface of the material. A 3D finite element model was established to simulate the UIT process by using a finite element software ABAQUS. The residual stress distribution of the AISI 304 stainless steel induced by UIT was predicted by finite element analysis. In order to demonstrate the improvement of the SCC resistance of the welded joints, the specimens were immersed in boiling 42% magnesium chloride solution during SCC testing, and untreated specimen cracked after immersion for 23 hours. In contrast, treated specimens with different coverage were tested for 1000 hours without visible stress corrosion cracks. The microstructure observation results revealed that a hardened layer was formed on the surface and the initial coarse-grained structure in the surface was refined into ultrafine grains. The above results indicate that UIT is an effective approach for protecting weldments against SCC.

Effect of Ultrasonic Impact Treatment on the Stress Corrosion Cracking of 304 Stainless Steel Welded Joints

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Xiang Ling ◽  
Gang Ma
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Welded Joints ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
304 Stainless Steel ◽  
Ultrasonic Impact Treatment

High tensile weld residual stress is an important factor contributing to stress corrosion cracking (SCC). Ultrasonic impact treatment (UIT) can produce compressive stresses on the surface of welded joints that negate the tensile stresses to enhance the SCC resistance of welded joints. In the present work, X-ray diffraction method was used to obtain the distribution of residual stress induced by UIT. The results showed that UIT could cause a large compressive residual stress in access of 300 MPa on the surface of the material. A 3D finite element model was established to simulate the UIT process by using the finite element software ABAQUS. The residual stress distribution of the AISI 304 stainless steel induced by UIT was predicted by finite element analysis. In order to demonstrate the improvement of the SCC resistance of the welded joints, the specimens were immersed in boiling 42% magnesium chloride solution during SCC testing, and untreated specimen cracked after immersion for 23 h. In contrast, treated specimens with different impact duration were tested for 1000 h without visible stress corrosion cracks. The microstructure observation results revealed that a hardened layer was formed on the surface and the initial coarse-grained structure in the surface was refined into ultrafine grains. The above results indicate that UIT is an effective approach for protecting weldments against SCC.

Influence of Different Deformation on Microstructure and Properties of 304 Austenitic Stainless Steel

2012 ◽  
Vol 500 ◽  
pp. 690-695 ◽  
Author(s):  
Fei Han ◽  
Gao Yong Lin ◽  
Qian Li ◽  
Rui Fen Long ◽  
Da Shu Peng ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Work Hardening ◽  
Room Temperature ◽  
Austenitic Stainless Steels ◽  
Fcc Metals ◽  
Steel Sheets ◽  
Deformation Twins ◽  
304 Austenitic Stainless Steel ◽  
Ε Martensite

In this paper, a kind of 304 austenitic stainless steel sheets has been investigated, and systemic tests were conducted to study the law and mechanics of work hardening of 304 austenitic stainless steel. The results of microstructure analyzing of 304 austenitic stainless steels showed that when it was deformed by means of tensile testing at room temperature, obvious work hardening was caused by the changes of structure during the deformation. The strain-induced α-martensite, ε-martensite and deformation twins enhanced flow stress obviously, which is the main reason for the strong work hardening in FCC metals and alloys with low stacking fault energy as 304 austenitic stainless steel.

Numerical Simulation and Experimental Analysis of Laser Surface Remelting of AISI 304 Stainless Steel Samples

2010 ◽  
Vol 636-637 ◽  
pp. 1119-1124
Author(s):  
Noé Cheung ◽  
M.A. Larosa ◽  
Wislei R.R. Osório ◽  
M.S.F Lima ◽  
Maria Clara F. Lerardi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Stainless Steel ◽  
Laser Surface ◽  
Temperature Fields ◽  
304 Stainless Steel ◽  
Operating Parameters ◽  
Aisi 304 ◽  
Laser Surface Remelting ◽  
304 Austenitic Stainless Steel

The aim of this work is to develop a heat transfer mathematical model based on the finite difference method in order to simulate temperature fields in the laser surface remelting process. Convective heat transfer in the remelted pool is taken into account by using the effective thermal conductivity approach. Experiments of laser surface remelting of AISI 304 austenitic stainless steel samples were carried out in the present investigation, and numerical simulations were applied for the CO2 laser machine operating parameters. The work also encompasses the analysis of microstructural and microhardness variations throughout the resulting treated and unmolten zones. This study permits to conclude that numerical simulation is a useful tool in setting the laser operating parameters, enabling pre-programming of the extent of the treated area.

Investigations on the Microstructure and the Fracture Surface of Pulsed Nd: YAG Laser Welding of AISI 304 Stainless Steel

2012 ◽  
Vol 445 ◽  
pp. 418-423
Author(s):  
Seyed Ali Asghar Akbari Mousavi ◽  
A. Garehdaghi
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Cooling Rate ◽  
304 Stainless Steel ◽  
Chemical Compositions ◽  
Operational Parameters ◽  
Δ Ferrite ◽  
Higher Power ◽  
304 Austenitic Stainless Steel ◽  
Pulsed Nd:Yag Laser Welding

The paper presents pulsed Nd:YAG laser welding of the 304 stainless steels. The welding tests were carried out with various operational parameters. The effects of laser welding variables on the geometry, microstructure and solidification of the weld are considered. The austenitic or ferritic solidification is produced in the 304 austenitic stainless steel depended upon the cooling rate and its chemical compositions. The possiblity of austenitic solidification compared with the ferritic solidification decreases with the chromium to nickel equivalent ratio and that increases with cooling rates. Moreover, more δ ferrite is obtained if the cooling rate is increased or the higher power laser is used. The surface of fracture samples was considered and the reason for failure was investigated. The study shows that the fracture is in ductile type.

Formation of Ultrafine Grained Structure in SUS 304 Stainless Steel Produced by High Pressure Torsion (HPT)

2007 ◽  
Vol 561-565 ◽  
pp. 847-852 ◽  
Author(s):  
Jin Guo Li ◽  
Minoru Umemoto ◽  
Yoshikazu Todaka ◽  
Koichi Tsuchiya
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
High Strain ◽  
Rotation Speed ◽  
High Pressure Torsion ◽  
304 Stainless Steel ◽  
Ultrafine Grained Structure ◽  
Ultrafine Grained ◽  
304 Austenitic Stainless Steel ◽  
High Rotation Speed

SUS 304 austenitic stainless steel was processed by HPT at room temperature with different rotation speed. It was found that the microstructure evolution and composed phases along the progress of HPT were sensitive to the strain rate (rotation speed). During deforming with the low strain rate, the deformation-induced dynamic phase transformation (DPT) from austenite (γ) to martensite (α’) occurred and the microstructure is characterized by elongated submicron α’ grains after 10 revolutions. While the euqiaxed nanocrystalline α’ grains were produced after HPT at the continuously alternative low and high strain rate. XRD analyses showed that multiple DPT of γ→α’→γ→α’ took place during HPT at the continuously alternative low and high rotation speed. Based on the experimental results, it was proposed that the euqiaxed ultrafine grained structure were produced by multiple DPT under the high strain and strain gradient.

scholarly journals Improving the Mechanical Properties of 304 Stainless Steel Using Waterjet Peening

2019 ◽  
Vol 26 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Yun ZOU ◽  
Zhenkuan SANG ◽  
Qilong WANG ◽  
Tingchao LI ◽  
Dalei LI ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Compressive Stress ◽  
Residual Compressive Stress ◽  
304 Stainless Steel ◽  
Surface Morphologies ◽  
Strength And Ductility ◽  
Effect Phase ◽  
Refinement Effect

Abstract: In this study, waterjet peening (WJP) treatments under different water pressures were utilized to improve the mechanical properties of 304 stainless steel. The surface morphologies, microstructures, phases, and mechanical properties under different pressures in the WJP process were systematically investigated. The results show that WJP treatments successfully introduced a hardening layer and residual compressive stress. The optimal hardening layer, hardness, residual compressive stress, tensile strength, and ductility were all recorded at the pressure of 200 MPa. The improved hardness, tensile strength, and ductility of 304 stainless steel treated with WJP treatments at the pressure of 200 MPa can be attributed to the hardening layer with much apparent grain refinement effect, phase transformation, smaller surface roughness, and a specific residual compressive stress, as compared with the WJP treatments under other water pressures.

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