The fatigue strength of lead free copper alloy castings such as bismuth, bismuth-selenium, and silicon-zinc copper alloy castings was investigated by conducting fatigue tests at a constant stress amplitude under tension-tension cyclic loading. No fatigue limit was observed in the S-N curves obtained for the copper alloy castings, therefore, the endurance ratio, defined as the ratio of the stress amplitude at 10⁷ cycles to the tensile strength of the material, was evaluated from the S-N curve. Results of the fatigue tests showed relatively small values of endurance ratio ranging from 0.1 to 0.2 for the lead free copper alloy castings. Effects of notch on the fatigue strength were also examined. For the bismuth and bismuth-selenium copper alloy castings, the fatigue strength of notched samples was higher than the tensile strength of the castings. The triaxial stress state in tension was thought to be created at the cross section of the notch root due to plastic constraint. Meanwhile, in the case of silicon-zinc copper alloy castings which have higher tensile strength, the notched sample showed lower fatigue strength than the tensile strength. Basic mechanical properties including notch effects on the tensile strength of the copper alloy castings tested are also described in the present report.

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  This study is concerned with the effects of Se addition on macro segregation of Bi of CAC911 copper alloy, and the effects of P and Ni addition on solidification structures and mechanical properties of CAC912 copper alloy with improved high temperature tensile strength over CAC911 copper alloy. In case of CAC911 copper alloy, step bar casting and an interrupted solidification process were carried out to examine the effects of Se addition on solidification structures. As a result, it was found that addition of Se reduced the inverse segregation of Bi, and improved distribution of fine porosities. In case of CAC912 copper alloy, a 180℃ tension test and unidirectional solidification were carried out to examine the effects of P and Ni additions on solidification structures and mechanical properties. As a result, it was found that P addition improved the strength of grain boundary at higher temperatures, and improved the 180℃ tensile strength. Single addition of Ni did not improve 180℃ tensile strength, but addition of Ni with P did.

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  Elimination of lead has been accelerated worldwide, as is the case for copper alloys where various kinds of lead free free-cutting materials have been developed.
  Among those, lead free alloys used in faucet applications, which satisfy water quality standard, are now subject to verification under real environment conditions after having been in service for several years.
  Particularly, CAC804 alloy developed by Mitsubishi Shindoh Co., Ltd., which has been used for a water meter since 2000 in substitution for conventional materials, shows no indication of corrosion problem as was once of concern.
  Introduced in this report are various properties of CAC804 with real-life examples, which are summarized as follows :
  1) CAC804 generates segmentalized chips when machined under dry condition with no problem in manageability of chips.
  2) CAC804 shows excellent corrosion resistance as a water meter in the use for eight years.
  3) CAC804 is suitable for permanent mold casting as well and makes it possible to predict casting defects through solidification simulation.
  4) The grain refinement technology for casting structure mentioned herein improves not only strength and elongation of a casting at the same time, but also casting quality and other properties such as reduced casting defects.

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  When copper sulfide is directly crystallized from copper alloy melt, sulfide floats and separates because of the low density. The purpose of this study was therefore to reduce the activity of sulfur (S) by solidification of the semistable system (monotectic system) in the double equilibrium diagram of the Cu-Cu₂S system and disperse the spheroidal sulfide. The properties of sulfide dispersed lead-free bronze castings in the cooling and heating processes were examined. The results of investigations on the mass effect of lead-free bronze castings were as follows. (A) When Ni was added (Ni≤1mass%) and solidified in the monotectic system in the double equilibrium diagram of the Cu-Cu₂S system to reduce the activity of S, it was possible to crystallize fine spheroidal sulfide in the Cu (α) dendrite clearance and prevent flotation and separation. (B) Spheroidal sulfide in the heating process did not float and separate because it was fused together with Cu (α) from the beginning. (C) Sulfide dispersed lead-free bronze castings had the same mass effect as many copper alloys.

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  Parts such as joints, valves, and water meter cases are typically made of lead bronze castings. Because of its harmful effects on the human body and the environment, use of lead is restricted for waterworks parts. The following are the results of research on the characteristics of thermal analysis curves, casting and solidification characteristics, and optimum cutting conditions of sulfide dispersed lead-free bronze castings newly developed by the authors.
  (1) The spheroidal ratio sulfides of the alloy system used for the developed castings are related to the cooling speed of monotectic and eutectic reactions, which increases as the falling gradient of the cooling speed increases.
  (2) Regarding the shrinkage cavities of Tatur's mold castings made of the same alloy system as that used for the castings developed this time CAC902 alloy, there are more internal shrinkage cavities but less external shrinkage cavities compared with the CAC902 alloy. This is due to the skin formation type solidification of the alloy system.
  (3) Cutting tests were performed using an AC3000 ceramic tool on a lathe at 1,000rpm. Favorable results were observed in the range of effective rake angles from 5 to 8 degrees.

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  Sulfide dispersed lead-free bronze does not contain rare metals such as bismuth (Bi) or selenium (Se). There alloys produce smaller amount of porosities and have excellent castability characteristics. The sulfide has solid lubrication properties and functions as a chip breaker. This report summarizes how the alloy structure affects the cast structure, mechanical properties and machinability, and discusses the pressure resistance properties of the alloys. Furthermore, the alloy composition for JIS application was also determined based on the present results. It was concluded that (1) when the amount of Zn exceeds 4mass%, the sulfide profile collapses, the amount of ZnS increases and elongation lowers, (2) when the amount of S becomes 0.7mass% or higher, a hyper-monotectic structure is produced and, the liquid phase L₂ is separated from the liquid phase L₁, causing large sulfides to appear, after which the mechanical properties deteriorate, (3) the composition ranges for JIS applications of sulfide dispersed lead free bronze are determined to be 3.0mass% to 5.0mass% for Sn, 1.0mass% to 3.0mass% for Zn, 0.1mass% to 1.0mass% for Ni, and 0.2mass% to 0.6mass% for S, and (4) the investigation verified that the cutting coefficient, fluidity and pressure resistance capacity, the JIS application alloys are equivalent to those of the JIS CAC406 alloy.

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