Effect of recrystallization on degree of sensitization in nickel free austenitic stainless steel

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sourabh Shukla ◽  
Awanikumar P. Patil ◽  
Ashlesha Kawale ◽  
Anand Babu Kotta ◽  
Inayat Ullah
Keyword(s):  
Stainless Steel ◽  
Thermal Aging ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
Austenitic Stainless Steels ◽  
Content Type ◽  
High Deformation ◽  
Strain Induced Martensite ◽  
Degree Of Sensitization ◽  
Cold Worked

Purpose Effect of grain size on degree of sensitization (DOS) was been evaluated in Nickel free steel. Manganese and nitrogen contained alloy is a Ni-free austenitic stainless steels (ASS) having type 202 grade. The main purpose of this investigation is to find the effect of recrystallization on the DOS of stainless steel after the thermo-mechanical processing (cold work and thermal aging). Design/methodology/approach In the present investigation, the deformation of 202 grade analyzed using X-ray diffraction (XRD) and microstructural testing. Optical microstructure of Ni-free ASS has been done for cold worked samples with thermally aged at 900°C_6 h. Double loop electrochemical potentiodynamic reactivation test used for findings of degree of sensitization. Findings Ni-free ASS appears to be deformed more rapidly due to its higher stacking fault energy which gave results in rapid transformation from strain induced martensite to austenite in form of recrystallized grains, i.e. it concluded that as cold work percentage increases more rapidly recrystallization occurs. XRD results also indicate that more fraction of martensite formed as percentage of CW increases but as thermal aging reverted those all martensite to austenite. So investigation gives the conclusion which suggests that with high deformation at higher temperature and duration gives very less DOS. Originality/value Various literatures available for 300 series steel related to the effect of cold work on mechanical properties and sensitization mechanism. However, no one has investigated the effect of recrystallization through thermomechanical processing on the sensitization of nickel-free steel.

Effect of thermal aging on IGC of cold worked Cr-Mn austenitic stainless steel

2019 ◽  
Vol 66 (6) ◽  
pp. 757-767
Author(s):  
Sourabh Shukla ◽  
Awanikumar P. Patil ◽  
Ankur Bansod
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cold Work ◽  
Optical Microscope ◽  
Thermal Ageing ◽  
X Ray Diffraction ◽  
Content Type ◽  
Degree Of Sensitization ◽  
Cold Worked ◽  
Test Result

Purpose The purpose of this study is to investigate the effect of prior cold work after annealing and thermal ageing on intergranular corrosion or sensitization of Cr-Mn austenitic stainless steel (ASS) is necessary. Such a study is particularly important because ASS are mostly used and welded in mill-annealed condition, which is equivalent to fully annealed material with some cold worked (CW). Design/methodology/approach The effect of 15% CW of 202 ASS were investigated using microstructural (optical microscope), mechanical (grain size and hardness) and electrochemical methods (double loop electrochemical reactivation [DLEPR]) followed by thermal ageing (800°C, 900°C and 1000°C). Findings X-ray diffraction analysis shows the presence of martensite in CW samples. The increase in martensite formation (800°C and 900°C) can be observed with the variation of thermal ageing (TA) duration (1, 2 and 3 h). However, there was decreased in the formation of martensite at the temperature of 1000°C because of martensitic reversal. The DLEPR test result shows higher degree of sensitization (DOS) for 800°C and 900°C but for 1000°C, there was re-homogenization of samples which leads to lower DOS (thermal ageing for 1, 2 and 3 h). Originality/value For 300 series steel, there are various literature available for the effect of cold work on mechanical properties and DOS. However, no one has investigated the effect of cold work and thermal ageing on the sensitization of 202 Cr-Mn ASS.

The effect of reversion of Strain Induced Martensite (SIM) and grain refinement on the Intergranular Corrosion of High Mn steel

CORROSION ◽  
10.5006/3778 ◽  
2021 ◽  
Author(s):  
sourabh shukla ◽  
Awanikumar Patil ◽  
Ankur Bansod
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Grain Refinement ◽  
Thermal Aging ◽  
Intergranular Corrosion ◽  
Cold Work ◽  
Manganese Steel ◽  
Stainless Steel Sample ◽  
High Manganese ◽  
Strain Induced Martensite

The surface phase constituent of high-manganese austenitic stainless steel after cold work (15%, 30%, and 50%) and thermal aging at 900°C for 30 min. and 6 hrs, was characterized using X-Ray diffraction spectrum. The microstructural analysis was conducted using an optical microscope, a scanning electron microscope, and the electron back scattered diffraction technique. The double-loop electrochemical potentiokinetic reactivation test was used to measure the Intergranular corrosion resistance (degrees of sensitization). The results showed that fine-recovered grains of austenite and strain-induced martensite together formed the surface of high-manganese steel after cold work. Because of the formation of strain-induced martensite in the cold work samples, their Intergranular corrosion were much higher than that of the as-received sample. Besides, the degree of sensitization of 15% cold work was higher (i.e., more intergranular corrosion) compared to the degrees of sensitization of 30% and 50% cold work. On the contrary, the intergranular corrosion of high-manganese austenitic stainless steel sample subjected to cold work was eliminated during thermal aging at 900°C for six hours because of the reversion of strain-induced martensite and fine-reverted austenite grains. Owing to this grain refinement of austenite, faster diffusion rate of Cr at higher temperature and cold work helped healing of Cr-depletion zone in a shorter time. In other words, because the results showed that on 50% cold work and thermal aging at 900°C for six hours, the high-manganese austenitic stainless steel does not become susceptible to intergranular corrosion. Hence, it could be beneficial to investigate the intergranular corrosion of high-manganese austenitic stainless steel.

Enhancement of corrosion protection of low nickel austenitic stainless steel by electroactive polyimide-CuO composites coating in chloride environment

2019 ◽  
Vol 66 (6) ◽  
pp. 774-781 ◽  
Author(s):  
Jeetendra Kumar Malav ◽  
Ramesh C. Rathod ◽  
Vipin Tandon ◽  
Awanikumar P. Patil
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Copper Oxide ◽  
Corrosion Protection ◽  
Electrochemical Techniques ◽  
Ultra Violet ◽  
Austenitic Stainless Steels ◽  
Inorganic Filler ◽  
Content Type ◽  
Anticorrosion Performance

Purpose The purpose of this study is to improve the anticorrosion performance of low nickel stainless steel (AISI 201) in 3.5% NaCl by electroactive polyimide/copper oxide (EPI/CuO) composites coating. Design/methodology/approach Electroactive polyimide/copper oxide (EPI/CuO) composites were prepared by oxidative coupling polymerization followed by thermal imidization method. Findings The functional and structural properties of composites were characterized by X-ray diffraction, Fourier transmission infra-red and ultra violet-visible spectroscopy and the surface topography was characterized by field emission scanning electron microscope analysis and anticorrosion performance in 3.5 Wt.% NaCl was evaluated by electrochemical techniques. The obtained results of electrochemical techniques measurement indicated that the composites coated samples give better corrosion protection against attacking electrolyte. Originality/value The ever-increasing price of nickel (Ni) is driving the industries to use low-Ni austenitic stainless steels (ASSs). However, it exhibits relatively poor corrosion resistance as compared with conventional Cr-Ni ASSs. Nonetheless, its corrosion resistance can be enhanced by polymeric (electroactive polyimide [EPI]) coating. CuO particles exhibit the hydrophobic properties and can be used as inorganic filler to incorporate in EPI to further enhance the corrosion protection. The present research paper is beneficial for industries to use low-cost AISI 201, enhance its corrosion resistance and replace the use of costly conventional Cr-Ni ASSs.

Effect of Cold Rolling on Sensitization of 304 Stainless Steel Weldments

2013 ◽  
Vol 856 ◽  
pp. 60-63
Author(s):  
M. Milad ◽  
N. Zreiba
Keyword(s):  
Stainless Steel ◽  
Heat Input ◽  
Cold Work ◽  
304 Stainless Steel ◽  
Optimum Level ◽  
Microstructural Investigation ◽  
Welding Heat Input ◽  
Degree Of Sensitization ◽  
Electrochemical Potentiokinetic Reactivation ◽  
Cold Rolled

The sensitization of stainless steel type AISI304 (304SS) is evaluated as a function of pre-welding cold work and welding heat input. 304SS is cold rolled to various percentages of thickness reduction of up to 50% at ambient temperature before being TIG welded. The susceptibility of 304SS to sensitization (weld decay) is evaluated using ASTM A262, practice A and electrochemical potentiokinetic reactivation tests. The results indicate that the influence of pre-welding cold work on the degree of sensitization (DOS) is distinct and appreciable within the range of 10% to 35% CR. In addition, within this range the optimum level of cold work after which the DOS starts to decrease is found to be inversely related to the amount of welding heat input. At higher levels of cold work of ≥ 35% CR, it is found that neither the cold work nor the heat input significantly influences the amount of DOS. Microstructural investigation showed that the predominant intergranular corrosion (IGC) occurs at austenite grain boundaries and less likely at ferrite / austenite interfaces of the weld metal. Meanwhile, transgranular attack at austenite bulk matrix along the defects is rarely observed.

Microstructure and Post-Irradiation Annealing Behavior of 20% Cold-Worked 316 Stainless Steel

2000 ◽  
Vol 650 ◽  
Author(s):  
J. I. Cole ◽  
T. R. Allen ◽  
H. Kusanagi ◽  
K. Dohi ◽  
J. Ohta
Keyword(s):  
Stainless Steel ◽  
Cold Work ◽  
Microstructural Development ◽  
Dislocation Loops ◽  
Annealing Behavior ◽  
Post Irradiation ◽  
316 Stainless Steel ◽  
Dose Rates ◽  
Cold Worked

ABSTRACTMicrostructural examination and in situ post-irradiation annealing studies were carried out on 20% cold-worked 316 stainless steel (SS) hexagonal duct material following irradiation in the reflector region of the EBR-II reactor. Stainless steel hexagonal ducts were used to house reactor subassemblies and provide a valuable source of information on irradiation behavior of reactor structural materials at lower dose-rates (on the order of 10-8 dpa/sec) than previously examined. The microstructural development of samples irradiated to doses of 1, 20 and 30 dpa is examined, while the post-irradiation annealing behavior of a sample irradiated to 20 dpa is described. Annealing studies were performed at 370 and 500°C to examine the kinetics of radiation damage recovery as a function of annealing temperature. The initial (pre-annealed) microstructures consists of a substantial density of irradiation induced chromium-rich M23C6 and M6C carbides which form both on the grain boundaries and within the grain interiors. Recovery of the cold- work is evident in the 1 dpa sample while samples irradiated to 20 and 30 dpa possess dense populations of voids and dislocation structures consisting of networks of line dislocations and faulted dislocation loops. Results indicate that post-irradiation annealing of the samples at 370°C for 1 hour has little effect on the microstructure, while further annealing at 500°C for 1 hour results in void shrinkage, the formation of small cavities, and a reduction in the dislocation loop and network density.

Effect of number of welding passes on the microstructure, mechanical and intergranular corrosion properties of 409M ferritic stainless steel

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sachin Ambade ◽  
Chetan Tembhurkar ◽  
Awanikumar Patil ◽  
Diwesh Babruwan Meshram
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Ferritic Stainless Steel ◽  
Transverse Direction ◽  
Corrosion Properties ◽  
Content Type ◽  
Degree Of Sensitization ◽  
Number Of Passes

Purpose This paper aims to study the effect of number of welding passes on microstructure, mechanical and corrosion properties of 409 M ferritic stainless steel. Shielded metal arc welding (SMAW) process is used to weld two metal sheets of 409 M having 3 mm thickness as bead-on-plate with single, double and triple passes. Microstructures were observed at transverse section with the help of optical microscope and with increasing number of passes grain growth, and the width of heat-affected zone (HAZ) increases. The results of tensile tests revealed that as number of passes increases, there is reduction in tensile strength and ductility. Double loop electrochemical potentiokinetic reactivation (DL-EPR) test revealed that as number of passes increases, the degree of sensitization increases. This is due to the deposition of chromium carbides at the grain boundaries and the associated depletion of chromium. Design/methodology/approach Three welded plates of single, double and triple pass were welded by SMAW process. From three welded plates (single, double and triple passes), samples for microstructural examination were cut in transverse direction (perpendicular to welding direction) with the help of wire-cut electrical discharge machine (EDM). The welded plates were sliced using wire-cut EDM along transverse direction for preparing optical microscopy, tensile testing, microhardness and DL-EPR testing specimens. Findings From the microstructure, it was observed that the large grain growth, which is dendritic, and the structure become finer to increase in number of welding passes. As number of passes increases, the width of HAZ increases because of the higher temperature at the welded zone. The tensile strength decreases to increase the number of welding passes because of grain coarsening and chromium carbide precipitation in sensitized zone and wider HAZ. The maximum microhardness value was observed for single-pass weld as compared to double- and triple-pass welds because of the fast cooling rate. The degree of sensitization increases to increase the number of passes because of chromium carbide deposition at the grain boundaries. Originality/value The authors declare that the manuscript is original and not published elsewhere, and there is no conflict of interest to publish this manuscript.

scholarly journals Investigation of Thermally Induced Deterioration Processes in Cold Worked SAF 2507 Type Duplex Stainless Steel by DTA

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 937
Author(s):  
Tibor Berecz ◽  
Éva Fazakas ◽  
Enikő Réka Fábián ◽  
Péter Jenei ◽  
János Endre Maróti
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
X Ray Diffraction ◽  
Thermally Induced ◽  
Σ Phase ◽  
Hardness Tests ◽  
Strain Induced Martensite ◽  
Kissinger Plot ◽  
Cold Worked ◽  
High Degree

Thermally induced deterioration processes were studied in cold worked (up to 60% deformation) SAF 2507 type super-duplex stainless steel (SDSS) by differential thermal analysis (DTA). DTA results revealed two transformations. Parent and inherited phases of these transformations were examined by other methods too, such as micro-hardness tests, optical metallography and X-ray diffraction (XRD). Finally, these transformations were identified as the formation of α’- and σ-phases. Formation of strain-induced martensite (SIM) and recrystallization were not experienced until 1000 °C, despite high degree of cold working. Activation energies of the σ-phase precipitation and α’-phase formation were determined from the Kissinger plot, through DTA measurements—they are 275 and 220 kJ/mol, respectively—in good agreement with the values found in the literature.

Influence of Alloying Elements on the Stress Corrosion Behavior of Austenitic Stainless Steel

CORROSION ◽  
1969 ◽  
Vol 25 (1) ◽  
pp. 15-22 ◽  
Author(s):  
A. W. LOGINOW ◽  
J. F. BATES
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Corrosion Cracking ◽  
Magnesium Chloride Solution ◽  
Stress Corrosion Resistance ◽  
Cold Worked

Abstract In certain applications, stress corrosion cracking of austenitic stainless steels has occurred when these steels are subjected to tension stresses (residual and applied) and are exposed to hot chloride solutions. Although stress corrosion cracking can be prevented by treatments to relieve residual stresses and by control of the environment, such procedures are expensive and not always reliable. An extensive study was therefore undertaken to develop a steel that would-be inherently resistant to stress corrosion cracking. The results of the study, conducted on stressed specimens of experimental steels immersed in a boiling 42% magnesium chloride solution, showed that carbon and nickel improved the stress corrosion resistance of annealed steels, and? nickel and silicon increased the resistance of cold-worked steels. It was also found that nitrogen decreased the resistance of annealed steels whereas phosphorus and molybdenum decreased the resistance of cold-worked steels. Manganese, copper, chromium, sulfur, and aluminum had little or no effect on stress corrosion resistance. This study resulted in the formulation of a steel composition containing 18% chromium, 18% nickel, 2% silicon, and 0.06% carbon, with low phosphorus and molybdenum contents. This steel was melted in an electric furnace; and1 its, stress corrosion, corrosion, and mechanical properties were determined. Test results show that the new steel (called USS 18-18-2 stainless steel) is much more resistant to stress; corrosion cracking than currently available austenitic stainless steels. Furthermore, the resistance of this steel is better than that of a 20% chromium, 34% nickel alloy that is being marketed; for its resistance to stress corrosion cracking.

The Effect of Phase Transformation on the Tensile Fracture of Austenitic Stainless Steel

2016 ◽  
Vol 869 ◽  
pp. 508-513
Author(s):  
Verônica Scarpini Cândido ◽  
Sergio Neves Monteiro
Keyword(s):  
Stainless Steel ◽  
Martensitic Transformation ◽  
Work Hardening ◽  
Austenitic Stainless Steels ◽  
Tensile Fracture ◽  
Aisi Type ◽  
310 Stainless Steel ◽  
Strain Induced Martensite ◽  
Work Hardening Rate ◽  
Micro Dimples

The tensile fracture of two austenitic stainless steels with different degrees of stability for low temperature strain induced martensitic transformation was investigated. A stable AISI type 310 stainless steel displayed typical tensile stress-strain curves with decreasing work hardening rate at temperatures in the interval of 25 to-196°C, in which no martensitic transformation occurred. By contrast, a metastable type 302 stainless steel with martensitic transformation from 25 to-196°C showed a range of plastic deformation with increasing work hardening rate. The fracture of the stable 310 steel presented the characteristic cup and cone ductile aspect with micro dimples and sparse evidence of intergranular cracks. On the contrary, the martensitic transformation in the metastable 302 steel causes a neckless fracture with generally brittle appearance, despite the relatively high strain attained at fracture. At-80 and-196°C, associated with higher amount of transformed martensite, the fracture surface was covered with micro-craters formed around inclusions enveloped by thin strain induced martensite lamellae.

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