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无磁钻杆摩擦焊焊缝塑性环演变规律

Evolution law of corona bond of non-magnetic drill rod weld by friction welding

  • 摘要: 文中通过试验与数值模拟相结合的方式,研究了无磁钢连续驱动摩擦焊界面塑性环演变规律与焊缝处出现条带状组织的原因. 塑形环形核位置随着转速增加逐渐地从靠近边缘位置移向焊缝中心,塑形环宽度也逐渐增加. 在无磁钢塑性环演变的过程中,塑性环经快速形核、迅速扩展,随着塑化金属的挤出,塑性环集中在界面中心. 界面温度场演变过程与塑性环形核及扩展演变规律基本一致. 随着转速的增加,等效应变的最大值逐渐减小,而等效应力的最大值略有增加. 当塑性环位置位于距焊缝中心距离为0.12r1 ~ r1且塑性环宽度小于 r1时,塑性环发生扩展. 当塑性环位置接近距焊缝中心距离为0 ~ 0.12r1,塑化金属被挤出时,塑性环将不再发生扩展. 另外,由于塑性环没有扩展的动力,且界面中心的温度低于外缘温度,造成塑性环在界面中心无法再发生扩展. 这种不扩展现象导致焊缝呈现“纺锤形”热流模式,导致焊缝形成了条带状组织,进而造成强度下降.

     

    Abstract: In this paper, experiments and numerical simulations were conducted to study the evolution law of the corona bond at the interface of non-magnetic steel by continuous drive friction welding and the reasons for the appearance of banded structures at the weld. The nucleation position of the corona bond gradually moved from a position close to the edge to the center of the weld as the rotational speed increased, and the width of the corona bond gradually increased. During the evolution of the corona bond in non-magnetic steel, the corona bond underwent rapid nucleation and rapid expansion. As the plasticized metal was extruded, the corona bond concentrated at the interface center. The evolution process of the interface temperature field was basically consistent with the nucleation of the corona bond and its extended evolution law. With the increase in rotational speed, the maximum value of equivalent strain gradually decreased, while the maximum value of equivalent stress slightly increased. When the corona bond was 0.12 r1 ~ r1 away from the center of the weld, and the width of the corona bond was less than r1, the corona bond expanded. When the position of the corona-bond is close to the distance from the weld center is 0 ~ 0.12r1 away from the weld center, and the plasticized metal was extruded, the corona bond no longer expanded. In addition, since the corona bond had no driving force for expansion, and the temperature at the interface center was lower than that at the outer edge, the corona bond could no longer expand at the interface center. This non-expansion phenomenon caused the weld to present a spindle-shaped heat flow pattern, resulting in the formation of a banded structure in the weld and further leading to a decrease in strength.

     

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