V. Venkateswara Rao

Bio: V. Venkateswara Rao is an academic researcher. The author has contributed to research in topics: Maraging steel & Welding. The author has an hindex of 3, co-authored 3 publications receiving 37 citations.

Influence of post-weld heat treatments on microstructure and mechanical properties of gas tungsten arc maraging steel weldments

Abstract: The response to post-weld heat treatment of an 18%Ni (250 grade) gas tungsten arc weld metal has been investigated. The post-weld heat treatments are (a) direct aging at 480°C/3 h/air cooling, (b) solutionising at 815°C/1 h/air cooling+aging at 480°C/3 h/air cooling and (c) homogenisation at 1150°C/1 h/air cooling+solutionising at 815°C/1 h/air cooling+aging at 480°C/3 h/air cooling. Metallographic characterisation of fusion zone revealed pronounced segregation of titanium and molybdenum along the interdendritic and intercellular boundaries. This led, during subsequent aging, to austenite reversion at temperatures much lower than in wrought (unwelded) material. Solutionised treatment at 815°C does not remove the segregation. Homogenisation treatment (1150°C/1 h/air cooling) succeeded in making the composition become homogenised. Mechanical properties including tensile, hardness and impact toughness were evaluated. Tensile test results showed that directly aged weldments exhibited lower strength bu...

Microstructure, hardness and residual stress distribution of dissimilar metal electron beam welds: maraging steel and high strength low alloy steel

Abstract: The present investigation reports on a study that has been taken up to develop an understanding of the electron beam welding characteristics of similar and dissimilar combination of maraging steel and high strength low alloy steel, which are in the hardened condition, i.e. maraging steel, in a solution that was in treated and aged condition, whereas high strength low alloy steel in a quenched and tempered condition before welding. The joint characterisation studies include microstructural examination, microhardness survey across the weldment and measurement of residual stresses. Maraging steel weld metal is under compressive stress rather than tensile stress as observed in low alloy steel welds because the martensite transformation occurs at a relatively low temperature. It has been observed that, in dissimilar metal welds, tensile stress is observed at the fusion boundary of low alloy steel and weld metal, whereas compressive stress is obtained at the location between weld and maraging steel fusi...

The effect of post-weld heat treatments on the microstructure and mechanical properties of maraging steel laser weldments:

Abstract: The role of post-weld heat treatments on the microstructure and mechanical properties of maraging steel laser welds has been investigated. The post-weld heat treatments are (a) direct ageing at 480...

Advances in additive manufacturing of metal-based functionally graded materials

Abstract: Over the 2010s technological improvements allowed metal additive manufacturing to graduate from a prototyping tool to a widespread, full-scale manufacturing process. Among the capabilities still un...

Single Pass Laser-Arc Hybrid Welding of Maraging Steel Thick Sections

Abstract: Maraging steel 250 grade plates of 10 mm thickness were welded in single pass using a laser-arc hybrid welding (LHW) setup comprising 3.5 kW CO2 laser and synergic pulse metal inert gas (MIG) welding power source at a welding speed of 1 m/min. The influence of single-pass welding on the bead characteristics, microstructure, and mechanical properties was investigated. The size and volume fraction of reverted austenite was effectively reduced in the fusion zone. Moreover, the width of the heat-affected zones (HAZ) was reduced and the microhardness results did not show significant softening in the HAZ after post weld aging. Tensile testing of the welds in transverse direction showed 97.3% weld efficiency. The fusion zone exhibited KIc fracture toughness of 77.4 MPa√m which was affected by the distribution pattern of reverted austenite. The study vividly brings out the process advantages of LHW for accomplishing thick section welds of maraging steel in single pass with narrow groove and lesser filler wire con...

Investigating the effect of electrode preheating in novel water-cooled advanced submerged arc welding process:

Abstract: In this paper, a novel developed water-cooled advanced submerged arc welding (WASAW) process has been designed and established. The developed WASAW process can be utilized for higher preheating cur...

Laser surface melting: A suitable technique to repair damaged surfaces made in 14 Ni (200 grade) maraging steel

Abstract: A high power solid Nd-YAG laser, operating in continuous mode, was used to re-melt the surface of a maraging steel, 14 Ni (200 grade), in different heat treatment conditions. Processing parameters were optimized for the employment of this technique as a repairing procedure of damaged surfaces to increase the useful life of tools made in maraging steels. Different zones can be found in laser-heated material. In addition, the absence of austenite reversion, consistent with the low nickel content of this steel, was found with the exception of a few very small pools of austenite found in a narrow layer in the heat-affected zone of samples corresponding to one of the studied heat treatment conditions of steel. Laser surface melting (LSM) combined with aging heat treatment causes a significant rise in the hardness (from 325 to more than 520 HV0.1) and in the wear resistance of the surface layer (with a decrease in the volume of lost material from 0.52 mm3 in the steel in the laser surface melted condition to 0.28 mm3 in the steel in laser surface melted and finally peak age hardening condition).