Application of a Composite Model in the Analysis of Creep Deformation at Low and Intermediate Temperatures
The creep behaviors of TA2 and R60702 at low and intermediate temperature were presented and discussed in this paper. Experimental results indicated that an apparent threshold stress exhibited in the creep deformation of R60702. Meanwhile, the primary creep phase was found as the main pattern in the room temperature creep behavior of TA2. Compared with exponential law, the power law has been proved to be a proper constitutive model in the description of primary creep phase. It also showed that θ projection method had its significant advantage in the evaluation of accelerated creep stage. Thus, a composite model which combined power law with θ projection method was applied in the creep curves evaluation at low and intermediate temperature. Based on the multiaxial creep deformation results, the model was modified and discussed. A linear relationship existed between composite model parameters and applied load. Finally, the creep life could be accurately predicted and the composite model method is suitable for application in low and intermediate temperature creep life analysis.
Creep behaviour of post-weld heat-treated 2.25Cr-1Mo ferritic steel base, weld metal and weldments
Abstract The evaluation of the creep rupture behaviour of 2.25Cr-1Mo ferritic steel at 773 and 823 K over a stress range of 130–300 MPa has been carried out. The material conditions examined include base material, weld metal and weldments (comprising base, weld and heat-affected zones). Specimens for creep testing were taken from single-V-weld pads, fabricated by manual metal arc welding using basic coated 2.25Cr-1Mo electrodes, and were given a post-weld heat treatment (973 K for 1 h). Microstructure and hardness in the as-welded, post-weld heat-treated and creep-tested conditions were evaluated. The heat-affected zone consisted of coarse-grain bainite, fine-grain bainite and intercritical structure regions. Generally, the weld metal exhibited significantly higher creep rupture strength than the base material, while the composites showed inferior creep strength. Ductility was found to decrease with increasing rupture time for all the material conditions. The rupture elongation exhibited by the base material was significantly higher than that shown by weld metal and composite specimens. Composite specimens crept at a faster rate while weld metal deformed at a slower rate than base metal. The applied stress (σ) dependence of the secondary creep rate (es was found to follow a power-law relationship of the form e = Aσ n . At all test conditions, transgranular fracture was observed. Failure in the composite specimens occurred in the intercritical structure of the heat-affected zone. Interrupted creep tests at 823 K on composite specimens have revealed progressive localization of creep deformation in the intercritical structure prior to fracture. An attempt has been made to establish equations that can predict the weld joint creep properties on the basis of the base and weld metal properties.
Alicyclic Analogue of Mescaline
WE wish to describe the preliminary pharmacology of a mescaline analogue, 2-(3,4,5-trimethoxyphenyl)-cyclopropylamine (TMT, II). This compound was selected for synthesis as a potential long-acting psychotomimetic which would be useful for studying the mode of action of mescaline-like compounds.