以Q235和20g为研究对象,采用平板无缺陷拉伸试样。通过测量试样轴线上各点应变,将屈服问题深入到单点屈服的层面上,深入研究点屈服的力学行为及扩展规律。结果表明:低碳钢点屈服的力学行为基本相同,点应变曲线经历应变线性增加、剧增和基本稳定3个阶段,点屈服过程对应于应变剧增阶段;点屈服扩展则对应于应变稳定区;点屈服的力学行为具有3个典型特征:屈服应变大,一般在2×104μm以上;屈服过程持续时间短,一般从十几秒到几十秒不等;点屈服处的应变具有不均匀性。 Taking Q235 and 20g as the research objects, flat-plate non-defect tensile specimens were used. By measuring the strain at each point of the sample axis, the problem of yielding is developed to the level of single point yield, and the mechanics behavior and propagation law of point yielding are further studied. The results show that the mechanical behavior of the low-carbon steel is basically the same as that of the yield strain. The strain curve of the low-carbon steel experiences three stages of linear increase, sharp increase and basic stability. The point yield process corresponds to the stage of rapid increase of strain. The mechanical behavior of point yielding has three typical characteristics: large yield strain, generally above 2 × 104μm; short duration of yielding process, generally ranging from tens of seconds to tens of seconds; strain at yield point has inhomogeneity .