K.T. Ng

Bio: K.T. Ng is an academic researcher. The author has contributed to research in topics: Carbon steel & Alloy. The author has an hindex of 1, co-authored 1 publications receiving 148 citations.

Stability and design of stainless steel structures – Review and outlook

Abstract: This paper provides a review of recent developments in research and design practice surrounding the structural use of stainless steel, with an emphasis on structural stability. The nonlinear stress-strain characteristics of stainless steel, which are discussed first, give rise to a structural response that differs somewhat from that of structural carbon steel. Depending on the type and proportions of the structural element or system, the nonlinear material response can lead to either a reduced or enhanced capacity relative to an equivalent component featuring an elastic, perfectly plastic material response. In general, in strength governed scenarios, such as the in-plane bending of stocky beams, the substantial strain hardening of stainless steel gives rise to capacity benefits, while in stability governed scenarios, the early onset of stiffness degradation results in reduced capacity. This behaviour is observed at all levels of structural response including at cross-sectional level, member level and frame level, as described in the paper. Current and emerging design approaches that capture this response are also reviewed and evaluated. Lastly, with a view to the future, the application of advanced analysis to the design of stainless steel structures and the use of 3D printing for the construction of stainless steel structures are explored.

About metastable cellular structure in additively manufactured austenitic stainless steels

Abstract: The quick-emerging paradigm of additive manufacturing technology has revealed salient advantages in enabling the tailored-design of structural components with more exceptional performances over ordinary subtractive processing routines. As a peculiar feature, sub-micro cellular structures widely exist in additively manufactured (AM) metallic materials. This phenomenon primarily appears with high-density dislocations and segregated elements or precipitates at the cellular boundaries. The discovery of novel metastable substructures in various alloys through numerous investigations has proven their substantial effects on the engineering properties of AM components. This paper reviews the most recent research momentum regarding the formation mechanisms (elemental segregation, dislocation cell and oxide inclusion), the kinetics of the size and morphology, the growth orientation and the thermodynamic stability of these cellular structures by taking AM austenitic stainless steel as an exemplary material. Another topic of concern here is the inherent correlation between the unique cellular microstructure and the corresponding mechanical properties (strength, ductility, fatigue, etc.) and corrosion responses (passivity, irradiation damage, hydrogen embrittlement, etc.) for this category of AM materials. The design, control, and optimization of cellular structures for additive manufacturing techniques are expected to inspire new strategies for advancing high-performance structural alloy development.

Analyzing melting process of paraffin through the heat storage with honeycomb configuration utilizing nanoparticles

Abstract: To intensify the charging rate of thermal storage, new honeycomb configuration has been utilized in this work. The various material were utilized for solid structure namely: Stainless steel (SS); Aluminum-6061-T4 (Al-6061) and pure aluminum (Al). The holes were filled with mixture of paraffin (RT82) and Al 2 O 3 nanoparticles. To create various configurations of holes with honeycomb shape, the geometric factor (b 2 ) has three levels and another geometric factor was calculated to reach the equal volume of paraffin in all geometries. Characteristics of NEPCM were measured based on homogeneous model. The two dimensional laminar melting process was simulated based on finite volume approach. The size of mesh and value of time step have been optimized to decrease the computing price and precision of code was tested with matching the data with exist published article. With decrease of b 2 , the thickness of honeycomb reduces and number of holes increases. When b 2 = 1 mm, the required time decreases around 90.87% and 24.28% with changing the material from SS to Al and Al-6061. With utilize of Al, the melting time decreases around 27.96% with reduce of b 2 . The lowest period is about 6.548 min which belongs to case with pure aluminum and b 2 = 1 mm. • To improve the charging rate, new honeycomb configuration was applied. • The holes were filled with mixture of paraffin (RT82) and Al 2 O 3 nanoparticles. • The minimum required time is about 6.548 min. • Required time decreases around 90.87% with material alters from SS to Al.