Papers by Keyword: Type 316LN Stainless Steel

Abstract: An isochronous stress-strain curve (ISSC) needs to be generated for a creep design application for high-temperature materials. To generate the ISSC for type 316LN stainless steel (SS), a series of creep data, which was obtained from creep tests with different stress levels at 600oC, was used. Creep curves were modeled by means of a nonlinear least square fitting (NLSF) of the Garofalo model. In the fitting of the creep curve, a secondary creep region was separated into first and second phases, and its fitting range was suitable to use for the first phase. The Garofalo model revealed a good agreement with the experimental creep data, and its parameters, P1, P2 and P3 revealed a good linear relationship as a function of a stress. The ISSCs for type 316LN SS at 600oC were successfully generated up to 300,000 hours.

Abstract: The creep properties of type 316LN SS welded by the SAW process have been evaluated. The creep tests for both the base and weld metals were conducted with different stress levels at 550oC and 600oC. The creep-rupture time of the weld metal did not show a large difference when compared to that of the base one, though it exhibited a little lower value at 600oC. The creep rate of the weld metal was lower than that of the base one at the same stress and rupture-time conditions. Especially, the creep-rupture ductility of the weld metal is found to be decreased by about 60%, compared to the base one. This is due to the decreasing of tensile elongation and the increasing of the yield stress in the weld metals.

Abstract: This paper presents the results of the Minimum Commitment Method (MCM) applied to predict the creep rupture life of type 316LN SS. Constant A, and the function of P(T) and G(σ) being used in the MCM equation were determined. To determine a proper value of the constant A, a focal point method and a trial and error one were adopted, respectively. It was found to be A=-0.02~-0.05 for type 316LN SS. Each prediction curve with the A values were presented up to 106 hours and compared to the experimental data at each temperature. Using the short-term creep rupture data for under 2,000 hours, a long-time rupture reaching up to 106 hours was predicted by the MCM.

Abstract: To predict the creep-rupture life of type 316LN stainless steels which are major structural components of liquid metal reactors, a number of creep-rupture data were collected through literature survey and experimental data of KAERI. Using the data, the creep-rupture life was analyzed by means of the Larson-Miller, the Orr-Sherby-Dorn and the Manson-Haferd parametric methods. Polynomial equations for predicting the creep life were obtained. In order to analyze the acceptance and use of the parametric methods, standard error values were accurately investigated by statistical process of the creep data. As for the results, the three parametric methods are found to be favorable in predicting the creep life of type 316LN stainless steel. Each method did not generate a large error in the standard error of the estimate with variations of the temperatures, but the Orr-Sherby-Dorn and the Manson-Haferd methods showed a better agreement than the Larson-Miller one. Especially, at higher the 700oC, the Manson-Haferd method conformed well to the experimental data. The reason is because the Manson-Haferd method includes two constants of ta and Ta.