一次元的温度分布を有する矩形板の熱弾塑性応力問題に関する研究 (第3報)

溶接接手の低温応力緩和法について

抄録

It is well established that contraction on welding results in plastic strain and residual stresses of yield point magnitude in and around any welded joint. Although the magnitude of these residual stresses may be reduced by the low-temperature stress relieving treatment and the principles and applications of the method have been described in a number of papers, but still there is a divergence of opinion on its effectiveness.
Many factors influence the effectiveness of the application of the method. Therefore, one analytical approach to this problem is presented in order to clarify certain optimum conditions that : will give a desirable stress distribution in reducing the residual stresses in the weld to about zero value without imposing any undesirable stresses elsewhere. The theory used herein is described in the previous reports. For simplicity and clarity, longitudinal residual stress pattern. developed by butt welding of two plates is assumed stepwise. Then, the stress changes during thermal stress relieving cycle are analyzed using dimensionless parameters. From the final results, , the optimum conditions to give the desirable stress distribution can be determined very easily.
It is shown that the heated band width is most important factor and if a strip of width somewhat greater than half of effective width of a plate is heated symmetrically to a uniform temperature which is determined by use of formula (9) or (29) and then water cooled rapidly, almost : complete stress relief is realized. However, the effectiveness of such treatment is diminished by the notable hardening of the material in and adjacent to the welded joint.
Some experimental verifications are good in accord with the results of the present theory.