A Construction of Judging System of Welding under Pulsating Loads

脉动载荷焊接判定系统的构建

基本信息

批准号：
05650950
负责人：
KIM You-chul
金额：
$ 1.47万
依托单位：
Osaka 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：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05650950/
关键词：
Welding in service Repair work Reinforcement work Critical strain for hot crack Prevention of hot crack Prevention of solidification crack 高温割れ凝固割れ割れ防止荷重作用下の溶接割れ発生限界ひずみ割れ判定法変動荷重溶接割れ高温割れ発生条件限界ひずみ

项目摘要

The structures in service conditions such as offshore structures, towers, bridges and so on are always suffered the pulsating loads by waves, current, wind or moving vehicles, etc. So, repair, reinforcement or reconstruction works by welding on these structures are done under the pulsating loads.The weld cracking test under the pulsating loads is carried out. As the results of the experiments, the accumulation strain, epsilon_t, by which the weld metal was repeatedly applied at a short time from the liquidus to the solidus was proposed as a measure for deciding hot crack initiation under the pulsating loads. epsilon_t was expressed with the relative root gap opening displacement, DELTAdelta, which can be easily measured before welding. The practical deciding equation for hot crack initiation under the pulsating loads using DELTAdelta was derived. Applying the practical deciding equation to the results of the hot cracking test for the case that the uniform pulsating loads are applied, its validity was shown.It is found that the hot cracks under the pulsating loads can be classified into crack of solid-liquid state and crack of solid state by conducting the high temperature tensile test on the weld metal. The former is called a solidification crack and the latter is HS (Hot Crack in Solid state) - type crack. Concerning the solidification crack initiation, the main factor was the product of DELTAdelta by the external loads and repeated number. The main factor for HS-type crack initiation was the maximum strain rate (the maximum root gap opening rate) by the external loads in a cycle.Welding is applied to the actual work for a bridge in service and its validity demonstrated.

服务条件下的结构，例如海上结构，塔，桥梁等，总是通过波浪，电流，风或移动的车辆等造成脉动负载。因此，在脉动载荷下进行了焊接裂纹测试，通过焊接这些结构来进行焊接来进行修复，修复，加固或重建工作。作为实验的结果，提出了从液体到固体的短时间反复应用焊接金属的积累应变，以确定脉冲负载下的热裂纹启动的措施。 EPSILON_T用相对的根间隙开口位移Deltadelta表示，在焊接之前可以轻松测量。得出了使用Deltadelta在脉动载荷下进行热裂纹启动的实际决定方程。将实用的决定方程式应用于施加均匀脉动载荷的情况下的热开裂测试结果，显示其有效性。发现脉冲载荷下的热裂纹可以分类为固态裂纹和固态的裂纹，并通过对焊接金属进行高温张力测试来分类。前者称为固化裂纹，后者为HS（固态的热裂纹） - 型裂纹。关于固化裂纹的启动，主要因素是外部载荷和重复数字的乘积。 HS型裂纹引发的主要因素是周期中外部载荷的最大应变速率（最大根间开放率）。将焊接应用于服务桥梁的实际工作及其有效性。