外加磁场作用方向对焊接残余应力的影响

INFLUENCE OF MAGNETIC FIELD ORIENTATION ON WELDING RESIDUAL STRESS

针对新近发展起来的降低钢铁工件中残余应力的脉冲磁处理方法作用规律较为复杂的现状,研究了磁处理降残余应力效果的外磁场方向这一关键因素。通过盲孔法在16Mn焊接应力试样上进行残余应力的研究,研究脉冲磁处理前后试样中的残余应力分布,并对不同外磁场方向导致的磁处理效果进行对比。试验结果表明,在其他处理参数相同的情形下,不同的外磁场方向可导致不同的磁处理效果：磁场沿最大主应力方向进行处理,残余应力变化不明显；而磁场与最大主应力方向垂直进行处理,可获得较为明显的残余应力降低效果。采用电阻应变片研究不同外磁场方向引起试样中的磁致伸缩,获得不同外磁场方向作用下试样中磁致伸缩的不同特征,分析认为,这与脉冲磁处理效果的方向敏感性密切相关。

Since the rule of pulse magnetic treatment, which is a novel method to reduce residual stress in steel structures, has not been clear yet, the magnetic field orientation, which is a key factor influencing the variation of residual stress in the process of magnetic treatment, is studied. Firstly, samples with required stress are manufactured by bead on plate welding. Secondly, residual stress distribution is surveyed by hole-drilling method. Then different samples are processed in the magnetic field with different orientations and the residual stresses are measured again. By comparing the residual stress before and after treatment, it is shown that under the same conditions different magnetic field orientations will lead to different residual stress variations. When the field is parallel to the maximal stress, residual stress is changed imperceptibly, while residual stress can be changed obviously if the applied field is perpendicular to the maximum stress. In order to explain the orientation phenomena, the magnetostriction under different field orientations is investigated. And the experimental results show that magnetostriction performs dramatic differently with different magnetic field orientations, which may be the main reason to explain the relationship between field orientations and residual stress variations.