Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

2 Archives of Civil and Mechanical Engineering

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Residual stresses evolution and process route optimization of TC4 profiled rolled rings incorporating thermal bulging

100%

Lv N. , Liu D. , Wang J. , Rao H. , Nan J.

Archives of Civil and Mechanical Engineering

2023

tom Vol. 23, no. 3

art. no. e200, 2023

The thermal processing of rolled rings inevitably generates and accumulates massive residual stresses, as quenching residual stresses produced by water cooling treatment. Non-uniformly distributed residual stresses would seriously affect the structural strength, dimensional stability and service life of the component. In the traditional rolling process of titanium alloy rings, the quenching residual compressive stresses introduced by solution treatment could reach – 400–600 MPa, for which effective control of the stresses is an urgent issue to be solved. In this research, the stress control efficiency of rolling rings under different process routes was explored according to the thermal bulge stress relief technique. The FEM model of the stress evolution in the whole process of the rolled ring was established. The residual stresses on the ring surface are characterized by the hole-drilling method, while the microstructures are characterized by electron backscatter diffraction. The results indicated that the optimized process incorporating the thermal bulging stress relief technique reduced the levels of stress values to within about ± 50 MP and the stress homogenization index by approximately 60–90%.

Numerical and experimental investigations on Mannesmann effect of nickel‑based superalloy

86%

Zhang Z. , Liu D. , Man T. , Li N. , Yang Y. , Pang Y. , Wang J.

Archives of Civil and Mechanical Engineering

2022

tom Vol. 22, no. 3

art. no. e133

The preparation of nickel-based superalloy tubes by rotary tube piercing (RTP) process is still difficult due to the Mannesmann effect (central cracking phenomenon) has not been clarified. The combinations of numerical analysis and experiment verifications method were adopted in the study. The critical parameters for central cracking were determined by experiments. It was found that the evolution process of central cracking for nickel-based superalloy includes voids nucleation, growth and aggregation. Based on the obtained critical parameters, the evolutions of stress, strain, strain rate, temperature and damage were discussed by numerical simulation. By comparing the experiment results and simulation results, the Normalized Cockcroft and Latham (NCL) model was determined as the most suitable model. Considering the influences of temperature and strain rate on the damage threshold, the NCL model of Inconel 718 alloy was established by high-temperature tensile test. Based on the above results, it is found that the maximum shear stress promotes the plastic deformation, which provides necessary conditions for the generation of defects, and the maximum principal stress induces the generation of voids and expansion of micro-cracks, which directly leads to the central cracking. The essence of central cracking is ductile fracture under tensile stress.