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本文首先对焊接接头焊前预热产生附加热应力的机理进行了分析,得到两端刚性固定对接接头模型预热时附加热应力的计算公式,即:附加热应力Δσ_r的大小与拘束度 R、加热宽度 L_Q、预热温度与室温之差(T-T_R)成正比,与焊缝的厚度 hw 成反比。接着分析了在不同预热条件下实际结构产生附加热应力的趋势,提出了在不同情况下附加热应力的估算方法。通过实验室的平板刚性拘束裂纹试验(PRRC)和在实际焊接结构上的验证,说明有关分析和公式是正确的。最后,提出了减小或消除实际焊接结构上的附加热应力的具体措施。
In this paper, the mechanism of additional thermal stress on preheating of welded joint is analyzed firstly, and the formula of additional thermal stress at preheating of rigid fixed butted joint at both ends is obtained, that is, the size of additional thermal stress Δσ_r and restraint R, Heating width L_Q, preheat temperature and room temperature is proportional to the difference (T-T_R) is inversely proportional to the thickness of the weld hw. Then the tendency of additional thermal stress in actual structure under different preheating conditions is analyzed, and the method of estimating the additional thermal stress under different conditions is proposed. Through the laboratory rigid restrained crack plate test (PRRC) and the actual structure of the weld test, indicating that the analysis and the formula is correct. Finally, the specific measures to reduce or eliminate the additional thermal stress on the actual welding structure are proposed.