Effect of Dynamic Loads on the Limit Stresses and Second Critical Brittle Temperatures of Butt Weld Joints

Experimental results for cracked butt weld joints of 09G2 and 12GN2MFAYu steels are evaluated at different ratios of static and dynamic stresses over a wide range of climatic temperatures. The tests were performed on a unit built upon the impact-testing machine. The opening of crack edges was measured with a displacement gauge. The crack propagation was followed with a TV camera and microscope. In low-temperature tests of specimens over the range of 20–(−100)°C, cooling and automatic temperature control systems were used. Experimental studies resulted in the diagrams of limit stresses, their assessment demonstrated that static and breaking dynamic loads were linearly related. At a preset temperature, the dynamic component of limit stress is shown to decrease with the static one. The weld joint of 09G2 steel was established to exhibit higher sensitivity to dynamic loads over the whole temperature range. It was demonstrated that limit stresses and second critical brittle temperatures should be evaluated with due regard to both static and dynamic components. The limit stress and second critical brittle temperature under combined loading of weld joints are dependent on the ratio of static and dynamic stresses. Without regard for dynamic stresses, underestimation of limit stresses and overestimation of second critical brittle temperatures are taking place. With an increase in dynamic overloading coefficients and dynamic ratios, the limit stress decreases, while the second critical brittle temperature increases. Second critical brittle temperatures of weld joints in steels with higher mechanical properties are found to be much lower.

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Correspondence to V. A. Degtyarev.

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Translated from Problemy Prochnosti, No. 6, pp. 89 – 98, November – December, 2018.

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Degtyarev, V.A. Effect of Dynamic Loads on the Limit Stresses and Second Critical Brittle Temperatures of Butt Weld Joints. Strength Mater 50, 901–908 (2018). https://doi.org/10.1007/s11223-019-00038-z

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  • weld joint
  • critical brittle temperature
  • diagram of limit stresses
  • yield stress