25Cr2Ni2MoV钢焊接接头低周疲劳性能研究

Low Cycle Fatigue Performance of 25Cr2Ni2MoV Welded Joints

对新型汽轮机焊接转子材料25Cr2Ni2MoV焊接接头及其母材进行应变控制的低周疲劳试验,并进行了相应的断裂位置统计和循环变形特征分析。试验结果表明,焊接削弱了焊接接头的疲劳强度,受到结构非均匀性和各部分力学性能的相对不匹配等因素的影响,焊接接头的断裂位置体现出明显的应变水平依赖性;焊接接头和母材在循环变形过程中均表现出循环软化特性,且存在明显的拉压不对称性,拉压不对称程度随应变水平的增加而增加;与母材相比,焊接接头表现出更加明显的平均应力松弛现象,且平均应力绝对值随着循环周次不断减小最后趋于常值。

The strain controlled low cycle fatigue tests for the 25 Cr2 Ni2 MoV turbine rotor steel welded joint and the 25Cr2Ni2MoV base metal are proceeded .Base on the experiment results ,some statistic and analysis have been carried out on the fracture position and the cycle deformation behavior of the welded joint .It is shown that the welding weakened the fatigue strength of welded joints ,and the fracture position of the welding joints exhibits obviously strain level dependence , due to its structural inhomogeneity and mechanical property mismatching;the welded joints and base metal exhibited cyclic softening and tension-compression asymmetry behavior during the cyclic deformation ,which become more obvious with the in-creasing of strain level;the welded joints shows much more obvious mean stress relaxation phenomenon than the base material ,while the absolute value of the mean stress decreases and trends to a constant val-ue cycle by cycle .