Development of Nondestructive Assessment Methodology for Residual Life of Martensitic Heat Resistant Steel

马氏体耐热钢剩余寿命无损评估方法的发展

基本信息

批准号：
10555225
负责人：
MARUYAMA Kouichi
金额：
$ 8万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10555225/
关键词：
Structure Materials for High Temperature Use High Cr Heat Resistant Steel High Temperature Creep Martensitic Lath Structure Recovery of Lath Structure Nondestructive Residual Life Evaluation Hardness

项目摘要

High Cr ferritic heat resistant steel is widely applied to the thick section components of power plants to be used in creep regime. In this research, nondestructive residual life assessment of such high Cr steel with tempered martensitic lath structure was examined, and the results are summarized as follows :1.There are four factors that may control creep deformation and fracture of the high Cr ferritic heat resistant steels. They are dislocation(lath)structure, precipitates on grain- and sub-boundaries, fine particles within subgrains, and solute atoms such as W and Mo.Among these factors, the lath structure in the most important obstacle that determines yield stress of the steel. Its recovery is closely related to the progress of creep deformation and the subsequent failure. Therefore, this recovery of lath structure should be taken as the measure of life assessment.2.As a result of the recovery of martensitic lath structure, lath width increases with increasing creep strain. The relative increase in lath width Δλ/Δλ^* is linearly related to creep strain. Δλ is the change in lath width from the original value, and Δλ^* is the value of Δλ at rupture. The coefficient of linear relation does not change with creep condition or alloy composition.3.Based on the linear relation between lath width and creep strain, we can evaluate creep strain of a component of engineering plants. Creep curve under any creep condition can readily predict with the aid of creep database. Residual life can be assessed from the estimated creep strain and the creep curve predicated.4.The residual life assessment based on the measurement of lath width is applicable to rotor steel tempered at low temperature. However, in boiler steel(such as HCM12A)tempered at higher temperature, brittle fracture takes place by the coalescence of grain boundary cavities. Life assessment based on cavity growth should be employed in this case.

高Cr铁素能耐热钢被广泛应用于用于蠕变状态的发电厂的厚截面组件。在这项研究中，检查了具有钢化板条板条结构的这种高CR钢的无损残留生命评估，结果总结如下：1。有四个因素可以控制蠕变发育和高Cr抗铁质耐热钢的裂缝。它们是脱位（板条）结构，在晶粒和子边界，亚晶粒内的细颗粒以及诸如W和mo等固体原子（这些因素），这些因素的固体原子，最重要的障碍物的板条结构决定了钢的压力。它的恢复与蠕变发展的进展和随后的失败密切相关。因此，应将板条结构的恢复作为衡量生命评估的测量。2。由于马氏体板条结构的恢复，随着蠕变应变的增加，板条宽度增加。板条宽度δλ/δλ^*的相对增加与蠕变应变线性相关。 δλ是与原始值的板条宽度的变化，而δλ^*是破裂时δλ的值。线性关系的核心不会随蠕变条件或合金组成而变化。3。基于板条宽度和蠕变应变之间的线性关系，我们可以评估工程植物组成部分的蠕变应变。在任何蠕变条件下，蠕变曲线都可以借助蠕变数据库轻松预测。可以从估计的蠕变应变和预测的蠕变曲线中评估残留寿命。4。基于板条宽度的测量的残留寿命评估适用于低温下的转子钢温度。但是，在锅炉钢（例如HCM12A）中，在较高的温度下恢复了脆性裂缝，这是通过晶界腔的合并发生的。在这种情况下，应基于空腔生长的生命评估。