低合金钢焊接接头扩散氢的局部聚集规律

采用显微镜下录象测氢法，研究了４种不同预处理状态下的低合金钢焊接接头扩散氢局部聚集的规律，发现在熔合区和粗晶区与细晶区交界处，呈扩散氢随时间变化的负指数、对数正态和正态三种曲线形态。研究结果表明，焊接接头不均匀的组织分布，引起氢扩散系数的变化是造成扩散氢聚集规律变化的主要原因，这对于焊接工程中防止冷裂纹产生，以及进一步探讨氢致裂纹的形成机理，提供了实验与理论依据。

STUDY ON LOCAL ACCUMULATING LAW OF DIFFUSIBLE HYDROGEN IN WELDED JOINT OF LOW ALLOY STEEL

The local accumulating law of diffusible hydrogen at welded joints of four kinds of low alloy steel under different pretreatments were studied using the method for measuring hydrogen bubbles under a microscope by a video vecorder (MHB). It has been found that the lognormal law, normal law and negative index law for the local accumulation of the diffusible hydrogen occured in the fusion zone, and the juncture of coarse grained and fine grained zones. The result shows that difference of hydrogen diffusible coefficients which was induced by the non uniform distribution of microstructure was the major cause of the difference of diffusible hydrogen local accumulating law. With the laws metioned above, the testing and theoretical basis has been provided for prevention of the cold cracks in welding engineering and further investigation of the cause of cold cracks.