This report describes the work done at NISTBoulder for the Microstructural Engineering in HotStrip Mills project, and is separated into two sections: Subtask C2.5 begins with page 1, and Subtask C2.6 begins with page 110. The objective of Subtask C2.5 is to develop constitutive models to predict stress-strain behavior of steels under hot-rolling conditions and the objective of Subtask C2.6 is to develop models for predicting mechanical properties of hot-rolled steels as functions of chemical composition, microstructural features, and processing variables.For Subtask C2.5, we have developed four models that are suitable for predicting the stress-strain behaviors of the following eight steels: A36, DQSK, HSLA-V, HSLA-NB, HSLA-SO/Ti-Nb, HSLA-SO/Ti-Nb, and two interstitial-fie (IF) grades. The development of these models has been based on experiments conducted at MSTBoulder. To support the modeling effort, one servohydraulic machine was designed and built to generate data at high strain rates (up to 50 s"), which was not previously possible at NIST. The model predictions compared favorably with data fiom CANMET, which have strain rates up to 150 s-*. The model forHSLA-80M'i-Nb was used in the Sims equation to calculate the rolling forces for rolling an HSLA-80 slab. The calculated results agree well with the mill measurements. All the models are currently used in the Hot-Strip Mill Model (HSMM developed at the University of British Columbia-Canada.In subtask C2.6, equations have been developed and validated for plain C and HSLA steels produced on the hot-strip mill. The lower yield strength, ultimate strength, and % total elongation are the main outputs fiom the equations. For thicker, platetype products, the ductileto-brittle transition temperature can also be predicted. The HSMM allows for considerable flexibility and detail in the setup for the hot-strip mill and still provides accurate predictions for yield and ultimate strength, about +A35 MPa. The two sets of equations developed for the structure-property relationships are applicable to a wider range in chemistry than just the eight grades in the program. Base strength equations are considered applicable to grades where the microstructure is predominantly polygonal ferrite; prediction of precipitation strengthening is applicable to steels with Nb contents from 0.02 to 0.09%, 0.08 % V, and excess Ti levels up to 0.025%. Foreword.This project is a cooperative effort involving the National Institute of Standards and Technology (MST), the University of British Columbia (UBC-Canada), and U. S. Steel. Subtasks C2.5 and C2.6 of the project were performed at MSTBouIder, and the remaining of the project were done at UBC-Canada. At the start of the project, U.S. Steel provided all the samples for experiments. Later, Dofasco, LTV Steel, Rouge Steel, and Stelco also contributed samples of some steel grades. In addition to these steel companies, the authors also wish to acknowledge the following companies for their support and active participation during the condu...

This paper describes the probabilistic fracture mechanics (PFM) analyzes of the conditional probability of failure (CPF) due to brittle fracture of circumferential welds (CW) from a cold overpressurize event in boiling water reactors (BWR) operated for 72 EFPY. This analysis used the Fracture Analysis for Vessels, Oak Ridge (FAVOR) computer code, developed at the Oak Ridge National Laboratory (ORNL), under United States Nuclear Regulatory Commission (NRC) funding. Two typical vessel configurations and the associated material properties for the beltline materials, CW, axial welds (AW), and plates (PL) were used. The analyses consider the potential effects of different fabrication options, shop vs field. Shop-fabrication is mainly by submerged arc weld (SAW) process, while field fabrication used the shielded metal arc weld (SMAW) process. In either case, repairs would have required the SMAW process. The calculations show that field-fabricated vessels would have a slight increase in the CPF compared to shop-fabricated vessels, but the assumed fraction of repair welds was more significant than the fabrication option. The details demonstrate the relative importance of surface-breaking flaws vs. embedded flaws for the assumed transient. The results confirm the conclusions from the original analysis from BWRVIP-05 and BWRVIP-74, the CPF for CW is orders of magnitude less than that of PL and AW regions of the vessel; therefore, the ASME Code-required volumetric examinations of the CW every 10 years as part of the in-service inspection (ISI) program does not change the overall CPF for the vessel. In all the cases analyzed, the total CPF values of the BWRs for 72 EFPY are below the goal for safe operation.

This report describes the work done at NISTEIoulder for the Microstructural Engineering in Hot-Strip Mills project and is separated into two sections: One section begins with page 1, and the other begins with page 6 1. The first section deals with the development of constitutive models to predict stress-strain behavior of steels under hot-rolling conditions and the second section deals with the development of models for predicting mechanical properties of hot-rolled steels as functions of chemical composition, microstructural features, and processing variables. The two sets of equations developed for the 0.02 5 'Yo.