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Study on Growing Mechanism of Defects on Tin Alloy Layer During its Quenching

锡合金层淬火过程中缺陷长大机制的研究

基本信息

批准号：
02650695
负责人：
MIYATAKE Osamu
金额：
$ 1.28万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02650695/
关键词：
Tinplate Surface Defect Quench Boiling

项目摘要

1. Relation between surface defects and crystal size(1) Tinplate is quenched into cooling water of 90ﾟ C and its surface is observed. All of the surface defects are located at the center of each crystal grain. This fact shows that the surface defects are growing due to the local cooling on the surface.(2) With the decrease of cooling water temperature, the size of -the crystal grains decreases while the number of the crystal grains without the surface defects increases. The configurations of the crystal grains without the surface defects are similar to those which are cooled in the air. It is also found that the duration time of boiling becomes shorter with the decrease of cooling water temperature. These facts show that the surface area being cooled without the local cooling increase when the boiling is not last for a long time, and thereby that the surface defects do not appear on such an area.II. Cause of local coolingBased on the experiments, a hypothesis is deduced that the local cooling are caused due to the contact between solid surface and water during the transition boiling. The hypothesis can explain the results that the number of the surface defects has a maximum value at the water temperature of 70ﾟC.III. Thermal stress on tinplate surfaceTensile stress is developed when the melted tin layer is solidified on the surface due to the local cooling. The tensile stress is actually the cause of growing the surface defects.

1.表面缺陷与晶粒尺寸的关系（1）将镀锡板置于90 ℃的冷却水中淬火，观察其表面形貌。所有的表面缺陷都位于每个晶粒的中心。这一事实表明，由于表面上的局部冷却，表面缺陷正在增长。(2)随着冷却水温度的降低，晶粒尺寸减小，无表面缺陷的晶粒数量增加。没有表面缺陷的晶粒的形状与在空气中冷却的晶粒的形状相似。随着冷却水温度的降低，沸腾持续时间变短。这些事实表明，当沸腾持续时间不长时，没有局部冷却的被冷却的表面积增加，从而在这样的面积上不会出现表面缺陷。局部冷却的原因在实验的基础上，提出了过渡沸腾过程中固体表面与水接触导致局部冷却的假设。这一假设可以解释在70 ℃时表面缺陷数量最大的结果。镀锡板表面的热应力由于局部冷却，熔化的锡层在表面凝固时产生拉应力。拉应力实际上是表面缺陷生长的原因。