Validated prediction of weld residual stresses in austenitic steel pipe girth welds before and after thermal ageing, Part 2: modelling and validation

An extensive finite element simulation campaign was undertaken to examine the complete manufacturing history and high temperature thermal ageing of thick-walled girth-welded austenitic steel pipes fabricated from Esshete 1250 austenitic steel. The simulations examined the impacts of prior quenching of pipe material, fabrication of closely adjacent welds, and axial restraint during welding. The simulations considered both simple isotropic and kinematic hardening behaviour, and a large matrix of Lemaitre-Chaboche mixed isotropic-kinematic hardening material constitutive models, with a focus on examining the most accurate evolutionary hardening behaviour for weld metal. High temperature (650°C) service exposure was modelled using an RCC-MR type creep model, and the sensitivity of the predicted relaxation to variability in the model parameters was assessed. The predicted residual stresses were validated using measurements made with the deep hole and incremental deep hole drilling techniques and the contour method

Load partitioning and evidence of deformation twinning in dual-phase fine-grained zr-2.5%Nb alloy.

In situ neutron diffraction loading experiments were carried out on a cold-rolled dual-phase (a-phase, '"' 10% b-phase) Zr–2.5%Nb alloy at room temperature. The specimens were cut at different angles from the rolling direction (RD) towards the transverse direction (TD), thus the loading axis changes gradually from the rolling to transverse direction. Due to the strong texture of the studied alloy, and unidirectional nature of deformation twinning, the changing loading direction with respect to initial texture has a significant impact on the collaborative slip-twinning deformation mode in the hexagonal close-packed (hcp) a-phase. The present neutron diffraction results provide direct evidence of {1 - 1.2}/1 - 1. - 1S ‘‘tensile’’ twins in the a-phase of dual-phase Zr–2.5%Nb alloy at room temperature. Additionally, TEM analysis was employed to confirm the presence of ‘‘tensile’’ twins, and determine if other type of twins were present. It is further clear from the neutron diffraction results that applied load is gradually transferred from the plastically softer a-phase to the plastically harder b-phase which acts as a reinforcing phase having a yield strength in the range 750–900 MPa depending on the loading direction

Examining Stress Relaxation in a Dissimilar Metal Weld Subjected to Postweld Heat Treatment

Dissimilar metal welds are often required in nuclear power plants to join components made from austenitic steels to those from ferritic steels, particularly in fast breeder reactor plants, in order to join the intermediate heat exchanger to the steam generator. The process of welding alters the microstructure of the base materials and causes residual stresses to form, both because of the change in the microstructure and the differing thermal histories in various regions. Postweld heat treatment (PWHT) is required to relieve the residual stresses and achieve preferable microstructural gradients across the weld joint. Therefore, in order to arrive at the optimal PWHT process, it is necessary to investigate the effects of heat treatment on the joint integrity, microstructure, and residual stress relaxation in the welds. To investigate the effect of PWHT on the residual stress relaxation and corresponding alteration of microstructure across a welded joint, a dissimilar weld between modified 9Cr-1Mo steel and austenitic stainless steel AISI 316LN was made using autogenous electron beam welding. To achieve this, the welding process was first modeled numerically using finite element analysis, and the residual stress predictions were validated by experimental investigation using neutron diffraction. The validated model was then used to study the residual stress relaxation through the simulation of PWHT. The predicted stress relaxation was compared with contour method measurement of residual stresses in the actual welded plate subjected to PWHT. The results indicate that, although some relaxation of residual stresses occurred during PWHT, there is still a significant portion of highly localized residual stresses left in the specimen

Worker\u27s Compensation and the Employee\u27s Right to Maintain a Tort Action Against the ParentCorporation. Gulfstream Land and DevelopmentCorporation v. Wilkerson.

The plaintiff in Gulfstream Land & Development Corp. v. Wilkerson1 sustained injuries when he fell into a hole located on the premises of Gulfstream Land & Development Corporation. His employer was Gulfstream Utilities Corporation, the wholly owned subsidiary of Gulfstream Land & Development Corporation

Residual stress characterization of single and triple-pass autogenously welded stainless steel pipes

Using neutron diffraction the components of the residual stress field have been determined in the region near a mid-length groove in two identical austenitic stainless pipes in which weld beads had been laid down. One pipe sample had a single pass, and the second a triple pass, autogenous weld deposited around the groove circumference. The results show the effect on the stress field of the additional weld deposited and are compared to the results of Finite Element Modelling. The hoop stress component is found to be generally tensile, and greater in the triple pass weldment than in the single pass weldment. The hoop stresses reach peak values of around 400 MPa in tension. X-ray measurements of the residual stress components on the near inner surface of the pipe weldments are also presented, and show tensile stresses in both pipes, with a higher magnitude in the three-pass weldment

Gender through the Generations: Changes in the Representation of Women in Spanish Advertising

This project examines the portrayal of women in Spanish television commercials. The objective of the investigation is to determine if there are significant increases in the representation of women in commercials from three separate years (1990, 2000, and 2010) in order to observe the level of responsiveness of advertising to a more gender-equalized Spanish society. Throughout Spain’s history, women’s roles in the country’s society have changed, with a stronger female presence in the work force as well as in the media. Upon completing this study, it will be determined whether television advertisements in Spain follow these societal trends by increasing the number of women portrayed as central figures in commercials. The study consists of content analysis of a sampling of randomly generated Spanish commercials from each observed year, with an equal number of commercials falling into seven categories of products every year. The chosen years allow for focus on the advertising industry’s responsiveness to changes in society over two ten-year periods (1990 to 2000 and 2000 to 2010) and the entire twenty-year period (1990 to 2010). The categorization of variables is based on the 1975 pioneering work of McArthur and Resko

Validated prediction of weld residual stresses in austenitic steel pipe girth welds before and after thermal ageing, part 1: Mock-up manufacture, residual stress measurements, and materials characterisation

A series of engineering-scale multi-pass pipe girth weld mock-ups were manufactured using conventional manual metal arc techniques from Esshete 1250 austenitic steel. They were characterised in detail, in order to provide validation benchmarks for finite element prediction of weld residual stresses. The fabrication sequence comprised initial solution heat treatment and quenching, manufacture of five closely spaced girth welds in a single assembly, and then separation into five individual weldments. Detailed welding records were kept, to allow subsequent calibration of weld heat source models. Residual stresses were measured using diverse methods (incremental deep hole drilling and the contour method), in both the as-welded condition and after thermal ageing at 650 °C. The measurements showed good agreement, providing reliable validation targets for predicted residual stresses in both states. Detailed mechanical property characterisation was performed on both parent material and weld metal, comprising monotonic and isothermal cyclic testing over a range of temperatures from ambient up to 1000 °C. The test data were used to derive a range of Lemaitre-Chaboche mixed isotropic-kinematic model parameter sets for use in finite element simulation. These welds and their supporting characterisation comprise a reliable benchmark for weld residual stress simulation in an engineering-scale weldment