Abstract：Tensile tests were carried out on single-side thinning and full-section specimens.By analyzing the metallography，the machining surface with tensile failure andfracture，the effect of single-side thinning on the elongation after breaking of Q420B thick plate was discussed. The results showed that the elongation after fracture of the single-side thinning sample of Q420B thick plate was lower. There were microcracks in the center of tested sample. The fracture was a mixture of toughness and brittleness，but compared with the full-section sample，the brittle zone of the single-side thinning tensil especimen accounted for a large proportion of the fracture section and the fracture was V-shaped. It was proposed，when the thick plate tensile test was carried out，the processing and test methods were optimized under the condition of meeting the requirements of the standard，such as adjusting the width of the sample or properly thinning or strengthening the capacity of the testing machine.
2019, Vol. 37 
