In a hot-rolled H-beam, covering the upper surface of web by insulator (web-insulating) and cooling the outside surface of flange by water (flange-cooling by water) after rolling are considered effective measures for reducing the residual stress. To confirm this, the relation between the residual stress and the time of their treatment under various finishing temperature conditions was investigated using the analytical method for thermal stress. This method is characterized by taking phase transformation into consideration.
The outline of results obtained is as follows;
(1) The longer the time to insulate web or to cool flange after rolling is and the smaller the difference in finishing temperature between flange and web is, the lower the tensile residual stress in flange and the compressive residual stress in web are. Namely the residual stress is reduced in the whole cross section in this case.
(2) In the case of large size H-beam (H : 900×300×16×28 mm), the time to cool flange (heat transfer coefficient : 250 kcal/m²·h·°C) after rolling for reducing the residual stress in web is about a quarter of the time to insulate web.
(3) It is possible to reduce the residual stress below the required value by combining the control of the difference in finishing temperature with the control of the difference in cooling rate between flange and web after rolling.
(4) The choice of either web-insulating or flange-cooling by water after rolling should be made by considering the influence on the metallurgical quality and the ease of control as well as the effect of reducing residual stress.

抄録全体を表示

A method of numerical simulation for hot caliber rolling is proposed, in which deformation of a material is analyzed in an ordinary manner by three-dimensional rigid-plastic FEM, while temperature distribution in the material is calculated using a new combined method of three-dimensional FEM, two-dimensional FEM and one-dimensional FDM. Moreover, residual stress of the material is analyzed by conventional two-dimensional elastic-plastic FEM. First, the calculated residual stress distributions due to the thermal stress distributions are found to agree well with experimental ones. Next, the method is applied to a simulation of the deformation and temperature in an actual H-shape rolling process, in which a H-shape is produced from a beam blank after 20 passes and strain and temperature distributions in cross sections are obtained. The calculated shape and temperature of the material are found to agree well with measured ones.

抄録全体を表示

The influence of carbon and vanadium contents on mechanical properties of ferrite-pearlite microalloyed steels was investigated by instrumented Charpy impact tests, tensile tests, rotating bending tests and microstructure observation. The following was obtained.
(1) The crack initiation energy in impact test is not affected by carbon and vanadium contents.
(2) The change in Charpy impact value is related to the crack propagation energy.
(3) The optimum balance of carbon and vanadium contents for the crack propagation energy varies corresponding to the aimed hardness.
(4) The fatigue limit of ferrite-pearlite steels is effectively improved by vanadium addition in comparison with carbon.

抄録全体を表示

To analyze residual stress in rolled H-beams, a numerical method for the prediction of temperature and thermal stress has been developed by taking phase transformation into account. Temperature during cooling and residual stress calculated by the present method agree well with the measured ones.
The infulence of finishing temperature and sectional size on residual stress is investigated by using the method. The results obtained are as follows;
(1) The larger the thickness ratio of flange to web (tf/tw) is, the higher the stress is.
(2) The larger the difference in finishing temperature between web and flange (Tfo-Two) is, the higher the stress is.
(3) The larger the ratio of sectional area of flange to web (Sf/Sw) is, the lower the tensile stress in flange is and the larger the compressive in web is.
(4) The smaller the amount of non-transformed phase (austenitc amount) in web is and the larger the amount in flange is at finishing rolling, the higher the stress is.
(5) The larger the compressive stress in web is and the larger the ratio of inner width to thickness in web (Bw/tw) is, the more frequently the web buckling occurs.

抄録全体を表示

A mathematical simulator during accelerated cooling after rolling in steel plates has been developed. The simulator can predict simultaneously the temperature, the thermal stress and the shape defect during cooling with taking the phase transformation into account.
The transverse temperature distributions at the entry of cooling device and at the exit of hot leveller were measured in an actual plate plant, and also the thermal stresses after cooling (the residual stresses) and the cambers after longitudinal cutting were measured. It was confirmed that their values can be predicted by the simulator.
The residual stresses predicted by the above mentioned simulator was compared with those by a simplified elastic method which requires only the transverse temperature distribution at the exit of hot leveller in calculation. When the transformation is finished in all cross section at the exit of hot leveller, both values are completely coincident. But there is a big difference between the two when the transformation is not occurred in all cross section or is occurred partly at the exit of hot leveller.

抄録全体を表示

ヨーロッパ各国語で氷河を意味するglacier, Gletscherなどの語に対応する日本での最初の訳語は, 1846年にあらわれた「宿氷」「氷野」である。その後, 「氷山」も氷河の訳語として辞書に現れる.明治時代には「氷田」もひろく用いられた.「氷河」を使用し始めたのは地質学者神保小虎で, 1891年のことである.谷を下流に流動するという谷氷河の実態が理解されるようになったため, 川との類似性から氷の川として「氷河」の語が生まれたと推定される.

抄録全体を表示

The effects of aging and stress-aging (called hot stretching) at the temperatures from 120°C to 700°C on the mechanical properties, relaxation values, Charpy impact values and SCC behavior of hard drawn SUS 304, SUS 316 stainless steel wires have been studied.
The main results obtained are as follows:
(1) Yield and tensile strength of the wires increased by aging at 230°C and 530°C as well as by hot stretching. The strengthening after 230°C treatment may be due to the strain aging by C and the increase of strength after 530°C treatment results from precipitation of Cr₂₃C₆ on dislocations.
(2) Stress relaxation values up to 250°C are low due to precipitation of Cr₂₃C₆. Almost no difference can be observed between aging and hot stretching.
(3) Impact value at -96°C of SUS 304 stainless steel wire which was measured with 1 mm V-notched specimen was found to be about the same as that of 9% Ni steel.
(4) It is considered that in comparison with high carbon PC wire SUS 304 stainless steel showing high tensile strength is insensitive to SCC in NH₄SCN and NH₄NO₃ solutions.
(5) In practice, tension member of the austenitic stainless steel wire and strand which were produced by aging at 500°C may be useful in special industrial field, for example, (a) SUS 304, in cryogenic field use (b) SUS 316, in intensive magnetic field use as a nonmagnetic material.

抄録全体を表示

市立大町山岳博物館が収蔵する美術資料の山岳風景画（山岳画）10点について、山座同定を中心に描画風景と山岳風景との同定を行い、作画モチーフとなった山岳風景および描いた地点を推定するに至ったので、その内容について詳述した。これは、2015（平成27）年度に当館で開催した企画展「山岳風景画の世界 ―“山博”収蔵コレクション―」にともなって実施した山岳画に関する現地調査等をもとにしたものである。 描かれた個々の山岳風景を詳細に確認することで、作画モチーフとしたと推定される実際の山岳風景が各作品の画面の中に忠実に再現されていたことが示された。このような収蔵美術資料に関する情報はこれまで不足するものであったが、今回の同定によって各資料情報を蓄積することができた。それにより、当館の収蔵資料のうち、山岳画という分野でのコレクション化が一層図れ、ひとつの資料群として資料価値を高めることにつながった。

抄録全体を表示

Studies on the cooling of a carbon-steel disk were made to discuss the heat transfer accompanied with phase transformation.
Hypereutectoid steel, eutectoid steel and hypoeutectoid steel were used as the disk. Its diameter and height are both 30 mm. The disk was cooled from the bottom by a jet of water or nitrogen gas, after it was heated inductively up to about 1 200 K. Heat-transfer coefficients which are necessary for the analysis of heat transfer in the system, were obtained by analysing the cooling curve of a copper disk, under the assumption of one dimensional heat conduction in the disk. These values of heat-transfer coefficients could be successfully used for the prediction of cooling curves of stainless steel disk.
In the case of carbon steels, the heat generation by phase transformation was accounted in the one-dimensional heat conduction equation. The fractions of various phases such as austenite, martensite, bainite, ferrite and pearlite were estimated by the use of the continuous cooling transformation diagram (CCT diagram). Calculated cooling curves in carbon steels by the present model were in good agreement with the observed ones.

抄録全体を表示

景観研究は, 明治以降西欧の科学的思想が導入され, 学問が進歩するのと並行して発展してきた。また, 景観は国民生活と深い係わりがあり, 国土開発が急速に進んだ昭和30年代以後は, 研究内容が広がり, 分化し, 多彩さが加わったように思われる。本論はこの昭和30年代を一つの節目と考え, それ以前を胎頭期と位置づけて研究の発展を史的に概観した。昭和30年代に至る社会の変遷と研究内容の特徴から, 6つの時代区分を設けて考察した。

抄録全体を表示

The influence of carbon, manganese, chromium and vanadium on toughness of ferritepearlite microalloyed steel was investigated by instrumented Charpy impact test which was able to measure both crack initiation energy and crack propagation energy. Further. the effect of carbon and vanadium on fatigue limit was investigated by rotating bending fatigue test. As a result. high-strength and high toughness microalloyed steels that contained 1.1% manganese. 0.5% chromium and optimum balance of carbon and vanadium for each aimed strength and toughness were developed.

抄録全体を表示

「氷河」の語は，自然地理学の教科書 “Physiography” の “glacier” から翻訳され1884年に出現した．訳者は，スコットランドに留学し，氷河の流動を理解していたと思われる西邨 貞である．「氷河」は氷河流動の認識から生まれた．「氷河」が出現する以前に，谷氷河の様相は流動も含めて1877年にすでに紹介されていたが，glacierは「氷帯」と訳された．「氷帯」の翻訳者は，氷河の実態を知らなかったことと，氷河の語は古くから冬の凍結した河を意味したため，「氷河」を使わなかったと思われる．「氷河」が現れたあとも，「氷田」が明治時代中頃（1884-1895）にはしばしば使われた．「氷河」が一般的になったのは，1900年ごろ以後である．

抄録全体を表示

「国造り」の一貫であった古代の土木。それを古典記述と照合して辿り、前回迄の社会資本調査1), 2), 3) に繋いで継続性のある思索を展開させることを目的とする。それに近年、神話が史実や遺跡の根拠となった例も多くあり、土木史分野も神話を全くの蔑ろにすることなく、確認して研究の展開を図る方法もあると考える。
一方、今日の社会資本整備はその必要性と効果、そして環境影響評価などが益々社会に厳しく問われている。「土木の自然破壊」という言葉が社会に蔓延することを憂い、人と自然の関係が根本的に変わる筈もなく、人命を尊び安全な生活に導く土木本来の使命が決して終わった訳ではないと危惧する。一面的捉え方の自然観は危険で、この限りに於いては社会資本が社会資本の意味を失うことが多い。咀嚼された究極の論理を、対象に応じた表現を施し、多くが納得できる教育と広報の場が必要だと痛感している。
何れにしても社会資本の真価をもっと広義に永く鑑み、新たな土木分野の開発を試みる努力を怠らないことである。脈動する歴史に一度目を向けてものの道理を解り、それを基本理念としてその上に構築される術を英知としなければならないと考えて以下の調査に及んだ。

抄録全体を表示

Low carbon high manganese cast steels with various Mn contents were processed by Q, QT and QLT treatments to examine the toughness in V-notched Charpy impact and dynamic fracture toughness tests. For 5%Mn steel, the toughness was improved greatly by the microstructural refinement and the introduction of stable and fine retained austenite during the QLT treatment. The retained austenite is considered to give transformation induced plasticity. For 10%Mn and 15%Mn steels, the QLT treatment did not improve the low temperature toughness because of a large amount of epsilon martensite contained.
The dynamic fracture toughness did not always correspond to the Charpy impact toughness owing to notch tip effect.

抄録全体を表示

For the purpose of lowering the thermal expansion coefficient of high manganese austenitic steel, the effects of carbon and manganese content on the thermal expansion coefficient from O to 100°C were investigated. The permeability after cold working and electrical resistivity were measured in these steels. These physical properties were also investigated after addition of various alloying element such as Si, Cu, Ni, Cr, Mo, Co, and Al in 0.25%C-25%Mn (or 21%Mn) based steel. The decrease of carbon content and the increase of manganese content markedly reduced the thermal expansion coefficient. The addition of ferrite forming elements did not result in increase of permeability, but electrical resistivity was markedly increased with addition of Si or Mo in 0.25%C-25%Mn steel. Particularly, the mechanism controlling the thermal expansion coefficient of high manganese austenitic steel is discussed by making reference to existing theories.
Hot ductility and strengthening due to controlled rolling in high manganese austenitic steel were studied to establish the optimum processing condition.

抄録全体を表示

A consideration into a view of safety on natural disaster reduction in Japan as we see proverbs such as traditions, historica l events in China, folklores and folk beliefs Fumio YOSHIMOTO and Satoshi MINAMI Proverbs such as traditions, historical events in China, folklores and folk beliefs on“Rain”“The Wind”“A Thunderbolt”and“An Earthquake”are classified into“regions”“The Four Seasons”“Plants and Animals”and“Each of Era”for basic safety education and promotion on mitigating against natural disasters in Japan stretches to the winds. These types of proverbs are precious in that they represent the longstanding deep bound between the Japanese people and their tradition of agriculture and fisheries etc. Special observations about the great Kanto earthquake of Sept.1,1923and the great Hanshin-Awaji Earthquake of Jan.17,1995are thrown into this consideration.
This original articles suggest important basic actions to take in a natural disaster and also include basic information about preparing for and mitigating against natural disasters with keeping“Regions”“The Four Seasons”“Plants and Animals”and“Each of era”under observations. Especially proverbs including“Mammals”“Birds”“Reptiles”“Amphibians”“Fishes”“Insects”and“Crops”etc are useful for us to take responsibility for making. our wise communities safer.

抄録全体を表示