A Comparative Analysis among Quenched, Tempered, and Stepped Cooled TIG Welded SS-304 Plates Based on Tensile Strength, Hardness, and Microstructural Appearance

The present experimental work critically analyses the changes in microstructural orientation and mechanical properties of TIG (tungsten inert gas) welded AISI-304 (SS) plates which have undergone through various heat treatments. The characteristics of heat-treated samples have been compared with those of untreated samples which is denoted by the original sample in this study. Five SS-304 plates were welded by the TIG method. Out of five, four plates were heat treated and one plate was put in the original condition. Four heat treatment includes quenching, stepped heat treating (sand + water), tempering-1 (quick quench then sand cooling), and tempering-2 (quick quench then air cooling). In all the five plates, the tensile test and microhardness test have been performed. In addition, microscopic observation of cross-sectional surfaces has also been carried out. The base metal (BM) zone of all five plates mainly consists of equiaxed γ-grains, although twin can be observed only in the original sample. The heat-affected zone (HAZ) imparts both lathy and dendritic type δ-ferrite at the transition of the BM and welded zone (WZ). At the welded zone, the γ-matrix has become coarse with numerous spots and dendrites of δ-ferrite could be seen. Sample 3, tempered by means by water sprinkling for a very short time and then cooling in sand, has shown satisfactory results among all. The sample has achieved the 23% higher extension value and 10% higher hardness at WZ than these of the original sample, although a negligible loss (0.2%) of ultimate tensile strength (UTS) is also reported in sample 3

Investigation on mechanical, gas barrier, and biodegradation properties of graphene oxide reinforced bovine trimmings derived collagen biocomposite

Now-a-days, let out a huge number of bovine trimmings based solid waste from tanneries has caused significant environmental concerns. To overcome this problem, this study emphasizes on bovine trimmings derived collagen based high-performance composite with graphene oxide (Col-GO) by using solvent evaporation method. The Col-GO composite film formation was governed by plasticization with glycerol, crosslinking reaction of collagen chain; and H-bonding interaction between GO and collagen functional groups. The Col-GO composite films were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and contact angle measurements. FTIR and TGA results indicate that interfacial H-bonding interaction between GO with collagen, and thermal stability of Col-GO composites film. Contact angle results indicate that hydrophobicity of Col-GO films was significantly enhanced compared to pure collagen film. The SEM analysis results indicate the homogeneous integration of GO in the Col-GO composite film. The composite film exhibits improvement in tensile strength and Young's modulus (YM) by 45% and 33% respectively. The water and gas barrier properties of the composite film improved by 47.4%, 66.57%, and 87.34%, respectively compared to pure collagen film. The Col-GO composite film showed excellent biodegradation in the soil burial test, degrading 79.47% in 42 days. The potential of the biodegraded Col-GO composite sample as a biofertilizer has been investigated by cultivating Spinacia oleracea seeds. The Col-GO composite film might be a very promising bio-compostable flexible and sustainable packaging film alternative to plastic packaging made from oil. © 2023 John Wiley & Sons Ltd