The Liquid Propulsion Systems Centre (LPSC) is a research and development centre functioning under Indian Space Research Organisation. It has two units located at Valiamala, in Thiruvananthapuram of Kerala, and Bengaluru of Karnataka. LPSC is augmented by ISRO Propulsion Complex at Mahendragiri of Tamil Nadu.LPSC is engaged in development of liquid and cryogenic propulsion stages for launch vehicles and auxiliary propulsion systems for both launch vehicles and satellites. Activities related to liquid propulsion stages, cryogenic propulsion stages and control systems for launch vehicles and spacecraft is done at Thiruvananthapuram. Precision fabrication facilities, development of transducers and integration of satellite propulsion systems are carried out at Bangalore. The developmental and flight tests along with assembly and integration are done at ISRO Propulsion Complex, Mahendragiri in Tamil Nadu.The development of liquid propellant stages for PSLV, control systems for SLV-3, ASLV, PSLV and GSLV, satellite propulsion systems including those for INSAT and IRS and production of pressure transducers are done by the LPSC for India. The LPSC has developed indigenous cryogenic upper stage for Geosynchronous Satellite Launch Vehicle (GSLV) which was successfully test fired by ISRO on 4 August 2007.LPSC's current director is Dr. V Narayanan. He succeeded Mr. S Somnath in January, 2018 after which Shri S Somnath was appointed as Director of VSSC.
The study of hot deformation behavior of as-cast AA2219 aluminum alloy is essential for optimizing thermomechanical processing and controlling microstructural evolution, ensuring high-performance aerospace components. Uniaxial hot compression tests were conducted on direct chill cast and homogenized AA2219 alloy to study the flow behavior and consecutive microstructure evolution, in the deformation temperature range of 325–500 °C and strain rate of 0.001–10 s−1. The flow stress deviation caused by the frictional effect and the adiabatic temperature rise was corrected. The peak stress reduced with increasing temperature and decreasing strain rate. Based on the experimental results, the constitutive equation representing hot deformation behavior was developed using the Arrhenius-type model. The activation energy was estimated to be 159.6 kJ/mol, indicating the prime softening mechanism as dynamic recovery. Optimum hot working conditions (375–425 °C/0.001 s−1) are suggested based on contour maps of strain rate sensitivity parameter and efficiency of power dissipation.
In this paper, the repeatability of laser powder bed fusion (LPBF) process during the additive manufacturing (AM) of Inconel Alloy 718 (IN718) is thoroughly investigated. The main objective is to study batch to batch consistency with respect to repeatably and reproducibility of the AM process and its effect on mechanical and microstructural characteristics. This study further compares properties of LPBF IN718 alloy with its wrought counterpart. The results indicate high repeatability in microstructural characteristics, such as grain size and phase distribution, across multiple printing batches of Inconel Alloy 718. Microscopic analysis showed presence of long columnar grains parallel to build direction and fine equiaxed grains perpendicular to it. Additionally, evaluations of mechanical properties including yield strength (YS), ultimate tensile strength (UTS), and elongation at fracture (ef) generally show little variation across various batches, demonstrating excellent repeatability and reproducibility. YS and UTS were observed to be 1200 and 1400 MPa, respectively, for all samples with near isotropy. On the other hand, elongation to failure exhibited anisotropy with orientation parallel to build direction having higher elongation (> 20
Purpose This study aims to investigate the densification behavior and defect evolution of CuCrZr alloy fabricated by laser powder bed fusion (LPBF), with emphasis on the effects of laser power (LP), scanning speed (SS), hatch distance (HD) and powder bed layer thickness (PBLT) on density, microstructure, defects and mechanical performance. The suitability of volumetric energy density (VED) for predicting densification and defect formation is also evaluated. Design/methodology/approach A statistically validated experimental framework based on a modified Taguchi method was used to optimize the LPBF process parameters. Eighty-one CuCrZr specimens were fabricated under different processing conditions. Density measurements, optical and scanning electron microscopy, defect characterization and mechanical testing were performed to establish process-structure-property relationships and evaluate the effects of post-heat treatment. Findings The optimized parameters of LP = 370 W, SS = 610 mm/s, HD = 0.10 mm and PBLT = 30 µm produced relative density above 99.6% with minimal defects. Lack-of-fusion defects, gas porosity and interlayer cracking were strongly influenced by melting pool behavior and process parameter interactions. Microstructural analysis revealed a transition from fine equiaxed grains to elongated columnar grains along the build direction. Direct aging produced the highest strength, with a yield strength of 435 MPa and ultimate tensile strength of 437 MPa, while solution treatment followed by aging increased elongation up to 13%. Originality/value The results demonstrate that VED alone is insufficient for predicting densification because different parameter combinations with similar VED values produced distinct density levels and defect morphologies. The modified Taguchi framework provides a systematic approach for optimizing LPBF parameters and establishing relationships between processing conditions, defects, microstructure and mechanical performance of CuCrZr alloy.
This paper investigates the combined effect of heat treatment and cold working on 12Cr21 duplex stainless steel. Five different temperatures were selected for solution treatment in the range of 900–1080 °C with a cold reduction of 15 and 30
Thrust chamber of liquid rocket engine consists of two shells to form the cooling passage for regenerative cooling. Inner shell consists of several channels and ribs for the coolant to flow. The inner and outer shells of Thrust Chamber are joined together by brazing. Conventionally, brazing filler material (BFM) is tack welded on the outer shell, which melts at the brazing temperature to facilitate the joining. The parts have to be rotated during brazing in Rotary Vacuum Brazing Furnace (RVBF) to avoid accumulation of BFM due to gravity. In the current study an alternate brazing technique is attempted in which coatings are provided on inner and outer shells in place of BFM, which react at a specific temperature to form in-situ braze alloy. This type of process is widely referred as Transient Liquid Phase bonding (TLP), Diffusion brazing (DB), Contact reactive brazing, etc. Fluidity of the in-situ formed braze alloy is minimal and there is a real scope of carrying out static brazing of components using coatings instead of complex RVBF. To demonstrate the static brazing technology, brazing trial was carried out on a simulator hardware. Hardware was brazed at 1000 °C using a Vacuum compression furnace and aged at 510 °C. Post brazing the hardware was subjected to burst test and hardware failed at a pressure of 878 bar.
