摘要
基于纳米压痕技术,对转子钢焊接接头不同区域(母材、焊缝和热影响区)开展了压入位移控制的单向压痕实验和压入载荷控制的循环压痕实验研究.首先,通过压入位移控制的单向压痕实验,采用多次测试取平均值的方式获得了焊接接头各个区域的弹性模量和硬度分布特征,同时对各区域弹性模量中值点的载荷-压入深度曲线进行了分析;其次,对各个区域进行压入载荷控制的循环压痕实验,比较其压入深度随循环周次的演化特征.结果表明,焊接接头不同区域力学性能差异较大,热影响区的弹性模量、硬度、抗拉强度和抗循环变形能力最高,焊缝次之,母材最弱;三个区域在循环压痕载荷下的接触载荷-压入深度滞回环曲线均表现出类似棘轮变形的演化特征,且母材演化速度高于焊缝,高于热影响区.研究结果对汽轮机焊接转子的焊接工艺的优化、寿命预测和可靠性设计具有重要的借鉴意义.
Base on the nano-indentation technology,the local mechanical and plastic behavior in different regions (e.g.weld metal, base metal and heat affected zone)of the rotor steel welded joint were investigated by the displacement-controlled simple and force-controlled cyclic indentation tests.Firstly,the distributions of elastic modulus and hardness across the welded joint were obtained from the displacement vs.controlled simple indentation tests at a number of locations,with the corresponding load-indentation depth curves analyzed.Then,the force-controlled cyclic indentation tests for the three regions were carried out to get the evolution of their indentation depth vs.cyclic numbers.It shows that,the welded joint exhibits obviously different mechanical behavior at different regions.The elastic modulus,hardness,tensile strength and the cyclic deformation resistance are the highest in the heat affected zone,and were smaller in the weld metal zone and smallest in the base metal zone.All the three regions exhibit similar ratcheting evolution behaviors in their cyclic contact load vs.indentation depth hysteresis loops.The evolution speed in the heat affected zone is much slower than that in the weld metal zone and the base metal zone.The research results provide important guidance for the optimization of welding process,life prediction and reliability design of turbine welding rotor.
作者
郭素娟
崔元元
黄毓晖
轩福贞
GUO Sujuan;CUI Yuanyuan;HUANG Yuhui;XUAN Fuzhen(School of Mechanical and Power Engineering,East China University of Science and Technology,Shanghai 200237,China)
出处
《力学季刊》
CSCD
北大核心
2018年第4期742-749,共8页
Chinese Quarterly of Mechanics
基金
上海市自然科学基金(18ZR1408900)
关键词
焊接接头
力学行为
局部塑性
纳米压痕
循环周次
welded joint
mechanical behavior
local plasticity
nano-indentation
cyclic cycle
