Influences of Energy Input and Metal Powder Addition on Carbide Precipitation in AISI 430 Ferritic Stainless Steel Welds

2017 ◽  
Vol 4 (2) ◽  
pp. 234-243 ◽  
Author(s):  
M.O.H. Amuda ◽  
E.T. Akinlabi ◽  
S. Mridha c
Keyword(s):  
Stainless Steel ◽  
Metal Powder ◽  
Ferritic Stainless Steel ◽  
Energy Input ◽  
Carbide Precipitation ◽  
Powder Addition ◽  
Steel Welds ◽  
Metal Powder Addition ◽  
Aisi 430

Influences of Grain Refining Conditions on Sensitization in 16 wt% Chromium Ferritic Stainless Steel Welds

2012 ◽  
Vol 576 ◽  
pp. 496-499
Author(s):  
M.O.H. Amuda ◽  
S. Mridha
Keyword(s):  
Stainless Steel ◽  
Oxalic Acid ◽  
Ferritic Stainless Steel ◽  
Cryogenic Cooling ◽  
Inert Gas ◽  
Grain Refining ◽  
Powder Addition ◽  
Titanium Powders ◽  
Steel Welds ◽  
Metal Powder Addition

The paper discusses sensitization characteristics in medium chromium Ferritic Stainless Steel (FSS) welds processed at two different grain refining conditions namely metal powder addition and cryogenic cooling. Tungsten Inert Gas (TIG) torch welded samples were exposed to 10% oxalic acid electrolytic etch for evaluation of sensitization. Empirical analysis indicated that, though both the grain refining conditions reduced the sensitization width relative to the conventional weld, the width was virtually nil with cryogenic cooling suggesting the elimination or reduction of sensitization. Similarly, the microstructure of cryogenically cooled welds showed no ditched grain boundary but aluminum powder treated welds revealed extensive ditching and none in titanium treated welds while knifeline attack was observed in welds treated with the mixture of aluminum and titanium powders.

Grain Refinement in Medium Chromium Ferritic Stainless Steel Welds via Aluminum Powder Addition

2012 ◽  
Vol 445 ◽  
pp. 717-722 ◽  
Author(s):  
M.O.H. Amuda ◽  
S. Mridha
Keyword(s):  
Stainless Steel ◽  
Grain Refinement ◽  
Ferritic Stainless Steel ◽  
Aluminum Powder ◽  
Travel Speed ◽  
Energy Conditions ◽  
Melt Pool ◽  
Powder Addition ◽  
Process Factors ◽  
Steel Welds

Grain refinement in medium chromium ferritic stainless steel weld was attempted via elemental (aluminum) powder pre-placement technique prior to melting under a TIG torch. A Box-Behnken experimental design was adopted with current, travel speed and the amount of aluminum powder added as the process factors for producing weld pool. The resolidified weld tracks were characterized using microscopy, microhardness and mechanical testing. The degree of grain refinement achieved was evaluated using a scaling index known as Grain Refinement Index (GRI). The findings showed that the GRI is influenced by the concentration of the aluminum powder introduced into the melt pool. Furthermore, high GRI does not necessarily translate to better mechanical properties relative to the conventional weld. This suggests that the grain size effect might not be the only factor influencing the property of weld metal. However, weld track treated with 0.08mg/mm2 of aluminum powder exhibited about 20% improvement in properties relative to the conventional weld made under the same energy conditions.

scholarly journals Exploratory Study of Sensitization in Cryogenically Cooled Ferritic Stainless Steel Welds

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. O. H. Amuda ◽  
S. Mridha
Keyword(s):  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Heat Affected Zone ◽  
Cryogenic Liquid ◽  
Cryogenic Cooling ◽  
Martensite Content ◽  
Steel Grades ◽  
Single Grain ◽  
Steel Welds ◽  
Aisi 430

Enhanced cooling via forced convection using cryogenic liquid is an option for controlling grain growth in the heat affected zone (HAZ) of ferritic stainless steel welds which improves joint strength. However, this technique seems to alter the martensite distribution in the high-temperature heat affected zone (HTHAZ) which is a critical constituent in rating the susceptibility to sensitization in ferritic stainless steel grades; any such information is not available in the literature. Thus, it is imperative to establish the influence of cryogenic cooling on sensitization dynamics in the HTHAZ. This paper discusses the influence of cryogenic cooling on sensitization in an AISI 430 ferritic stainless steel weld. It is established that cryogenic cooling increases the cooling rate in the HTHAZ and reduces the martensite volume percent by an average of 20%. This reduction in martensite content in the HTHAZ increases the level of ditched structure in cryogenically cooled welds and yields more ferrite-martensite ditched grain boundaries than in conventional welds. Although the cryotreated welds exhibit greater ditched boundary, the structure is still classified as nonsensitized, since no single grain boundary is completely surrounded by ditches.

Microstructure and Mechanical Behavior of AISI 430 FSS Welds Produced with Different Elemental Metal Powder Addition

2019 ◽  
Vol 297 ◽  
pp. 195-203 ◽  
Author(s):  
Nabil Bensaid ◽  
Mohamed Hadji ◽  
Riad Badji ◽  
Mohamed Farid Benlamnouar ◽  
Taher Saadi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Arc Welding ◽  
Tensile Tests ◽  
Gas Tungsten Arc ◽  
Powder Addition ◽  
Steel Welds ◽  
Equiaxed Grains ◽  
Metal Powder Addition ◽  
Aisi 430 ◽  
Scanning Electron

In this study the effect of the Titanium and aluminum powder addition on microstructure and mechanical properties of AISI 430 ferritic stainless steel welds produced by gas tungsten arc welding was investigated. It’s observed that the addition of aluminium (Al) or titanium (Ti) reducing the grains size, increase the equiaxed grains fraction and improve the mechanical properties with varying degrees. While the addition of mixture (Al+Ti) leads to better improving in mechanical properties and reducing of grains size up to 85 %. The details of tensile tests, optical microscopic observations, microhardness, tensile test and Scanning electron microscopy (SEM) fractography, are discussed.

Effect of Energy Input on Microstructure and Hardness of TIG Welded AISI 430-Ferritic Stainless Steel

2011 ◽  
Vol 264-265 ◽  
pp. 390-396 ◽  
Author(s):  
M.O.H. Amuda ◽  
S. Mridha
Keyword(s):  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Heat Input ◽  
Energy Input ◽  
Microstructural Characterization ◽  
Input Rate ◽  
Thin Sections ◽  
Steel Grades ◽  
Aisi 430

Studies on the weldability of ferritic stainless steel grades suggests that low heat input rate and better heat transfer dynamics are appropriate for the control of grain size and microstructural feature in thin sections. However, the optimal welding conditions to achieve combination of such characteristics are yet to be established. In the present investigation, AISI 430 ferritic stainless steel is TIG welded using energy input between 0.205 and 2.05kj/mm and characterized in terms of microstructure and hardness. The microstructural characterization of the welds with varying heat input rates suggests the presence of interdendritic martensite in the fusion zone and grain boundary martensite in the HAZ in conjunction with some intermetallics in varying proportion. The hardness values across the welds indicate that grain growth and the presence of intermetallics are minimized when welded with increased heat input rates that permits transformation within the dual phase regions. The study provided a new insight into the contribution of heat input rate in the production of unwanted weld microstructural features and assisted in the design of methods and techniques for tailoring weld microstructures with optimum properties.

Microstructure and Mechanical Properties of Silicon Carbide-Treated Ferritic Stainless Steel Welds

2021 ◽  
pp. 395-411
Author(s):  
Muhammed O. H. Amuda ◽  
Taiwo Folorunsho Lawal ◽  
Shahjahan Mridha
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Grain Morphology ◽  
Grain Structure ◽  
Weld Geometry ◽  
Powder Addition ◽  
Steel Welds ◽  
Equiaxed Grain

To further previous works on grain refinement in ferritic stainless steel (FSS) welds via elemental powder addition, microstructure evolution and mechanical properties in non-metallic carbide treated FSS weld is discussed. Silicon carbide (SiC) powder preplaced on medium chromium FSS bevelled joint was fusion melted using tungsten inert gas (TIG) torch at different combination of process parameters. The incorporation of the powder in the weld pool constricted the weld geometry in addition to grain modification from columnar to equiaxed grain structure. Whilst significant improvement was obtained in hardness characteristics in powder treated welds, those of ductility and tensile strength were marginal. The study also established that welds mechanical properties are controlled by a combination of phenomena such as phase fraction and grain morphology.

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