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SynopsisWith a view mainly to safety considerations of LPG storage tanks, Vnotch Charpy, three point bending COD and wide plate tension tests were undertaken on four plate materials and thirteen weld metals welded by shielded metal arc, submerged arc and automatic TIG welding processes. In respect of fracture toughness of the weld metals, some correlation was seen between V-notch Charpy absorbed energy and three point bending COD value, both these values being found to be particularly high for Ni free 1.4Mn-Ti-B type weld metal. For the base metal, Ti-added Al-killed steel showed good toughness in the heat-affected zone by both V-notch Charpy and through-thickness notched three point bending COD tests. This latter test applied to specimens with surface notch, however, yielded a low COD value within 400 pm of fusion line for all the metals tested and for all values of heat input. Nonetheless, tensile tests using wide plate welded specimens with artificial defects located in the region of lowest toughness proved that, from considerations of fracture mechanics, all the joints possessed ample strength against brittle fracture initiation. It should thus appear that evaluation of welded joints may not always be valid when based on local three-point bending COD test, and that it should be more practical to assess the safety of such welded joints by wide-plate tests.

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higher than that of Sn-37Pb eutectic, so the temperature on the soldering process becomes higher. With regards to Environmental and health concerns with Pb have led protecting heat weak electronic components from heat, to development of lead-free solders to replace the soldering process in low temperature is desirable. commercial Sn-Pb solders in electronic packaging Therefore, Sn-Zn system solders are expected as the applications. Sn-3Ag-0.5Cu solder is one of the solders candidate solders able to produce PWBs in lower applied to both the reflow solderingprocess and the wave temperature soldering process. Sn-8Zn-3Bi solder is soldering process. However, its melting temperature is practically used for the reflow soldering process. about 30 K higher than that of Sn-Pb eutectic, so the However, the wave soldering process using Sn-Zn solders temperature on the soldering process becomes higher.has scarcely been investigated [2], [3]. So, weWith regards to protecting electronic components from investigated the study of the influences of Cu addition on heat, the soldering process in low temperature is wave soldering [1] before. Then, it was found that the desirable. Therefore, Sn-Zn system solders are expected wave soldering process using Sn-Zn solder was possible.as the candidate solders able to produce PWBs in lowerAnd it was found that wettability was relatively good.temperature soldering process. Sn-8Zn-3Bi solder is However, it was found that nitrogen gas atmosphere practically used for the reflow soldering process.under the content of 1 OOppm 02 was necessary to conduct However, the wave soldering process using Sn-Zn solders the wave soldering process for Sn-Zn solder.has scarcely been investigated. So, we investigated the In this study, the influence of several kinds of impurity study of the influences of Cu addition on wave soldering on the properties of wave soldering for Sn-Zn system [1] before. solder is discussed by using small sized wave soldering In this study, the influence ofseveral kinds ofimpurity equipment. on the properties of wave soldering for Sn-Zn system solder is discussed by using small sized wave soldering 2. Experimentation equipment. As a result, it was found that the solderabilities of Sn-Zn solder became worse by the The evaluations of solderabilities are conducted by addition of Cu, especially in solder bridging. It is several kinds of solders. Evaluated solders are produced thought that this is because ofthe rise of liquidus line on by the addition of impurity (Bi, Cu, Pb) as a standard to Sn-9Zn alloy to the addition of Cu. Therefore, the Sn-9Zn solder. Basic tests and practical tests were impurity level of Cu on Sn-9Zn solder should control conducted as the evaluation of wave soldering properties. under the content of 0.1%.On the basic tests, wetting balance test, spread test and bridge test were conducted under the nitrogen atmosphere.On the practical tests, the evaluations of wave soldering soldering, impurities, wettability.properties using mini-sized wave soldering equipment were...

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