Deformation-induced martensitic transformation behavior in cold-rolled and cold-drawn type 316 stainless steels

We investigate deformation-induced martensitic transformation behavior in cold-rolled and cold-drawn specimens of type 316 stainless steel. Deformation-induced martensite preferentially nucleates at the twin boundary between the austenite matrix and a deformation twin. In the cold-rolled specimen, martensite formed at the twin boundary has a Kurdjumov–Sachs (K–S) relationship with both the austenite matrix and the deformation twin (“double K–S relationship”). In the cold-drawn specimen, two kinds of deformation twins with different twin planes are typically formed, and therefore deformation-induced martensites are formed where the deformation twin boundaries intersect: martensite thus has an imperfect “triple K–S relationship” with the austenite matrix and the two deformation twins. The complicated crystallographic orientation relationship between austenite and martensite grains strongly restricts the formation of some variants of deformation-induced martensites. Because of the difference in number of nucleation sites in the cold-drawn and cold-rolled specimens, martensitic transformation is more enhanced in the former than in the latter.     

Microstructure development of steel during severe plastic deformation

The microstructure development during plastic deformation was reviewed for iron and steel which were subjected to cold rolling or mechanical milling (MM) treatment, and the change in strengthening mechanism caused by the severe plastic deformation (SPD) was also discussed in terms of ultra grain refinement behavior. The microstructure of cold-rolled iron is characterized by a typical dislocation cell structure, where the strength can be explained by dislocation strengthening. It was confirmed that the increase in dislocation density by cold working is limited at 10¹⁶m⁻², which means the maximum hardness obtained by dislocation strengthening is HV3.7 GPa. However, the iron is abnormally work-hardened over the maximum dislocation strengthening by SPD of MM because of the ultra grain refinement caused by the SPD. In addition, impurity of carbon plays an important role in such grain refinement: the carbon addition leads to the formation of nano-crystallized structure in iron.     

KOSI — An integrated system for discovering functional relations from databases

This paper describes an integrated system called KOSI (Knowledge Oriented Statistic Inference) for discovering functional relations from databases. The key feature of KOSI is that AI techniques and statistical methods are cooperatively used in the discovery process based on incipient hypothesis generation and evaluation, in which multi-search is performed in meta control. Two types of search, which use respectively different type of heuristics, are used inattribute calculation which is a kind of operation in which new attribute is generated as a function of the existing attributes. Third type of search, which is based on regression analysis, is mainly used for evaluating/selecting the best functional relation from the results of attribute calculation. Furthermore, a model-base and meta/domain knowledge are used for controlling the multi-search, and the methods of forming scopes/clusters can be used as a step of pre-processing before the search. KOSI is organized into multi-level structure for knowledge discovery and management efficiently. We try to provide a systematic manner of discovering functional relations, to support qualitative/quantitative discovery, and develop a more robust, general-purpose discovery system.     

Production of horse radish peroxidase by plant cell culture

Calluses were induced from the stem and the root tissues of horse radish plantlets. Cell aggregate selections were carried out on them to obtain a cell line with higher peroxidase activity, and the isozyme patterns of the peroxidases from the cultured cells and their utility values as a clinical diagnostic reagent were investigated. The repetition of the cell aggregate selection resulted in increases in peroxidase activities in each generation of selection; about eleven fold in the 13th generation of selection from the stem tissues and about nine fold in the 13th generation from the root tissues. One of the cell lines (N5K6-S), originally derived from the stem tissues, after selectin showed a tenfold increase in peroxidase activity within two weeks of culture in a liquid medium. The value as a clinical diagnostic reagent of peroxidases extracted from the N5K6-S cells was estimated to be equivalent to those already commercially available for the same purpose. There were significant differences in the isoenzyme patterns of the peroxidases from root tissues and those from cultured cells. From these results, the possibility of commercial production of peroxidase utilizing plant tissue and cell culture techniques was discussed.     

Knowledge-based man-machine systems

A new method of increase user gain in man-machine interaction is discussed. In particular, attention is directed to describing a model in the computer. An intelligent system provided with the knowledge base and the inference mechanism is proposed for the purpose, whereby illustration is given of the system describing both structure and attributes of the real object in the same framework.