This part is the conclusion of previous 12 parts, especially describing the effects of the Pb % on the machinability and the wear resistivity are fully discussed. There are two sides of the effects of Pb on the properties of brass ; one is the static effect and the other is dynamic one. The static one is not so large, but the dynamic one is very severe. So the shock value of the brass containing nearly 2% of Pb is about half of that of ordinary brass without Pb.
The cutting phenomenon is entirely affected by the dynamic property of the brass to be cut, so the cutting force is rapidly decreased by adding Pb. The wear phenomenon, however, is affected by the dynamic property as well as the static one. Both effects on wear are not so large, that, for example, the brass with more than 2% Pb shows the low resistivity against wear at the annealed state, but if we strengthen its static property by cold working, we have the Pb-brass with nearly as high wear-resistivity as the ordinary brass.

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一般的に、/ステンレス鋼の接合は難しくないと言われていた。しかし、RoHS指令などの影響で鉛フリーのを用いた場合、接合が困難になる事が報告されている。 本研究では、/ステンレス鋼の接合について、とステンレス鋼のろう材のぬれについて調査を行う事を目的とした。また、評価法として、とステンレス鋼間のフィレット部を評価することによって、ろう材のぬれ広がりの調査を行った。

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First, it has been made clear by the electron diffraction analysis that the causes of the wear of brass are the oxidation of sliding surfaces and the adhesion of rubbing metals. The thickness of the adhered layer of brass to steel surface is about 1μ, and grows to the maximum on such a condition of adhesive wear as to produce more oxidized powder.
Dropping powder at the adhesive wear consists of the small sized oxidizing powder and large metallic powder. And the metallic powder becomes larger on the sliding conditions of high speed and high pressure and in case of the metal of high Pb content and high rolling reduction.
The mechanism of adhesive wear is influenced by the combined effects of the adhesive force, the oxidation of ruptured surface by wear, and the downward tendency of brittleness of materials by the rising of temperature.

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One of the most unfavorable defects of a spring sheet of brass is that the spring properties change with time at room temperature after working or low-temperature annealing. The authors have researched the phenomenon and could find the possibility to suppress the secular change after low-temperature annealing. The secular change after final low-temperature annealing was considered to be related with the change after cold-rolling. The secular change after cold-rolling had a tendency to stabilize the spring properties and, if the brass plate as rolled was low-temperature annealed after being left at room temperature long enough to stabilize its properties of cold-rolled condition, the change after low-temperature annealing could be decreased. The secular change of two-phase brass, namely, of 60/40 brass, could be considered as the combined effect of α- and β-brass, though β-brass showed more complicate change than α-brass. All the experiments were carried out atroom temperature and the constat temperatures of 25° or 40°.

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6/4とS15CK炭素鋼の摩擦圧接継手の引張強さに及ぼす圧接条件の影響を調べた．その結果，摩擦時間の増加とともに継手の引張強さが増加し，摩擦圧力30MPaでは3.8s以降，90MPaでは1.5s以降の摩擦時間で母材から破断する継手を得ることができた．

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近年，環境負荷低減の目的により鉛レス快削の開発が進められている．しかしながら鉛レス快削と比較して被削性が劣ることや，生産性低下が問題となっており，鉛レス快削の被削性向上が求められている．このことから本研究では各種鉛レス快削の二次元切削，および材料の摩擦試験を実施し中の添加元素が変化した際の被削性について検討した．

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In this paper, genesis of some lattice textures of ore minerals is discussed., The studies have been made by many authorities on the lattice intergrowth formed by unmixing of a solid solution, which has been primarily deposited from the fluidal solutions., However, no considoration has been made on the exsolution from the secondary solid solution, which has been produced by mutual diffusion between solid minerals., The writer has experimentaly confirmed the unmixing phenomena of the secondary solid solution as follows; 1) Some solute minerals, such as massive chalcopyrite, vein-like chalcocite or covellite, drop-like klaprothite and massive tetrahedrite, diffuse in host minerals, such as bornite, at high temrperatures from 400°C to 500°C and form the various solid solution 2) The solid solutions, thus obtained, can unmix upon annealing at low temperatures of about 200°C and give some exsolution textures, such as lattice, cell and emulsion ete., The phenomena, as described above, may be expected to occur in such geological cases when some earlier minerals suffer higher temperature at later stage of mineralization or the ore bodies receive the thermal effect by igneous action., From this point of view, more attention must be given on the ore textures formed by thermal metamorphism., Explanation of Plate 1) Lattice intergrowth of chalcopyrite (light gray line) in bornite (Bo) from the Ginmu mine, Hiroshima Prefrcture., Ch, massive chalcopyrite., ×95., 2) Chalcopyrite (light gray line) lamellae unmixed from the secondary solid solution, formed by Solid diffusion between bornite (Bo) and massive chalcopyrite (Ch) at 500°C for one hour, by keeping at 200°C during 17 hours., ×95., 3) Lamellea, semi-cells, worm-like and dot-like bodies of Chalcopyrite (light gray line and spot), obtained under the same conditions as in 2)., Bo, bornite; Ch, massive chalcopyrite., ×95., 4) Chalcopyrite (ch) in lamellae, semi-cells and worm-like crystals, produced by annealing the secondary solid solution, same as before, at 200°C for 16 hours., Bo, primary bornite; bo, secondary bornite formed by thermal decomposition of massive chalcopyrite (Ch)., ×95., 5) Secondary covellite (Co) replaced the bornite (Bo) from the obari mine., Ch and Kl, chalcopyrite and klaprothite lamellae unmixed from the primary solid solution respectively., ×95., Etched with KCN., 6) Crystallographic itatergrowth of bornite (light gray) and chalcocite (dark gray) obtained by slowly cooling the secondary solid solution, formed by solid reaction of bornite and secondary covellite, as showed in 5), under heating condition of 440°C for one hour., Annealing condition, from 300°C to 200°C for 7 hours., Py, pyrite produced by thermal decomposition of bornite., ×300., Etched with KCN., 7) Pyrite (Py) produced by thermal decomposition of bornite at 440°C for one hour., Be, fine lattice intergrowth of bornite and chalcocite, obtained by unmixing of the solid solution under the same condition as in 6)., ×95., Etched with KCN., 8) Myrmekitic texture formed by solid diffusion between bornite (dark gray) and wittichenite (light gray) at 400°C during 20 hours., ×300.,

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Machined surface of the brass containing Pb of over 1.0% is very good in quality, because the growth of built-up edge is prevented by the particle of Pb. But the surface machined at slow cutting speed is scarcely affected by Pb, and the increase of hardness and ref.nem.ent of grain by plastic working or heat treatment give good effects on the quality of surface which is cut by the tool of small top rake angle.
Pb percentage of up to 1.0 give large improvement by decreasing work loss and time necessary for drilling more than it does on the cutting force. It means that the discharge of drilled chip grows easy by adding Pb. The brass heat-treated at 720°C has good machinability for drilling.

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The wear loss of 70:30 brass sliding on steel shaft(hardened to H_RC 6062)has been measured. Pure α-brass does not scarcely wear at up to the speed of 150 cm/s, and while the hardened steel shaft wears by lapping with the powder of Fe (Fe₂ O₃) which has been slightly seized from the steel surface in the first step. The wear properties of α-brasses containing Pb are varied by Pb content. The most brittle material among these Pb-brasses wears in such a manner as 60:40 brass does, and the wear loss suddenly increases more than that of brass at a certain rubbing speed. The fact that the wear of β-phase alloy decreases with the rising of rubbing speed, coincides with that the β-strUcture becomes tough under the high temperature.

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The wear rate at the initial state of β mono-crystal is more or less larger than that of polycrystalline brass, and to which the coefficient of friction has similar relation, too. But, as to the wear at the the constant state, the difference between the wear rates for monocrystal and for polycrystal is scarcely appreciable.
The presence of slightly traceable β in α-brass has considerably bad effect on its wearresistivity.
The special Pb-brass in which the grains of Pb are found mostly at the grain boundary wears more than common Pb-brass.

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近年，環境負荷低減の目的より，従来の鉛快削

の開発が進められている．しかし，これらの鉛レスと比較して切削抵抗が高いなどの問題を抱えている．先行研究より，PCD工具を用いて鉛レスを切削すると超硬工具と比較して切削力とすくい面の溶着が低減した．この原因を調査するため，本研究では工具-被削材の界面反応について第一原理計算による検討を実施した．

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First, the influences of hardness of steel shaft on the wear of brass have been studied, and then wear phenomena in rubbing against a shaft made of same kind of brass have been observed.
The wear manner of 60 : 40 brass and 70 : 30 brass containing pb is little influenced by the hardness of mate-steel. But, the wear of the 70 : 30 brass free from Pb, rubbed against annealed steel, is perfectly adhesive and the wear of that aginst hardened steel is oxidizing.
In rubbing the blanks of same kind of brass each other, the wear grows easily adhesive, and its relationship to rubbing speed is similar to that of the adhesive wear between brass and steel.

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チャンネルフロー電極法を用いて，，耐脱亜鉛腐食，青銅の分極曲線を測定し，耐脱亜鉛腐食の電気化学挙動を調べた．チャンネルフロー電極法では，銅合金から溶解するCu(I)イオンとCu(II)イオンを分極曲線の測定と同時に定量できる．重炭酸イオンと塩化物イオンを含む溶液中におけるのアノード分極曲線は，約0 V vs. SSEより卑な電位での亜鉛の選択溶解域(領域 I)と，約0 V vs. SSEより貴な電位での亜鉛と銅の同時溶解域(領域 II)に分けられる．JBMA T303テストで第1種にランキングされる脱亜鉛腐食感受性の小さい耐脱亜鉛腐食では，領域 Iの電流値が小さく，領域 IIにおける亜鉛溶解の比率が小さいことがわかった．一方，12か月に及ぶ，耐脱亜鉛腐食，青銅の淡水通水試験の結果，は脱亜鉛腐食を起こす場合にも，第1種の耐脱亜鉛腐食は脱亜鉛腐食を起こさず，全面腐食となる傾向が大きい．また，耐脱亜鉛腐食の浸漬電位はSUS316のものに近いので，通水しながらの短絡試験においてもガルバニック腐食は見られなかった．

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