焊缝横向冷裂纹试验方法──G－Bop试验探索

A TESTING METHOD OF HYDROGEN INDUCED TRANSVERSE CRACKING IN WELD METAL──G-Bop TEST

本文通过对ｇ－Ｂｏｐ（ｇａｐｐｅｄｂｅａｄ－ｏｎ－ｐｌａｔｅ）试验的系统研究和进一步探索，对利用这种简便、经济、实用的小型试验方法研究焊缝横向冷裂纹敏感性及指导生产中的成功应用将起重要作用。试样采用虎钳夹紧的方式可以有效地解决试样角变形的防止问题，以保证可靠拘束；采用预堆焊过渡层的方法，可以保证试验焊缝不被稀释且成分均匀，并可以模拟多层焊焊缝状态。Ｇ－Ｂｏｐ试验中，焊缝横向冷裂纹开裂程度可以用面积裂纹率上，或长宽裂纹率（Ｌ＋Ｂ）ｃｒ来表示，且后者更为方便实用；裂纹主要从焊缝底部及指状熔深两侧拐角起裂并往上扩展，小裂纹优先起裂于焊缝底部，多裂纹源起裂的不同裂纹面相交形成明显的撕裂台阶。Ｇ－Ｂｏｐ试验的重要特点之一是对缺口间隙不敏感，这对简化试验过程及提高试验结果的可靠性十分有利；其另一重要特点是试验拘束条件比厚板窗形拘束试验更为严格，试验结果可以直接用于指导焊接生产。

On the basis of overall studies and further exploration of G-Bop(gapped bead-on-plate) test, it will play an important role in applying this sim-ple,economic and practical small test successfully to study the Hydrogen-Induced-Transverse-Cracking in weld metal and direct the welding production. The clamp-ing pattern employed could prevent the sample from angle-distorting and keep reli-able restraint. Buttering in advance could keep weld metal from being diluted and im-itate the state of multi-pass weld metal. Cracking susceptibility in G-Bop testcould be represented by area cracking ratio S_(cr) or(length + breadth) cracking ratio(L+B)_(cr),the latter is more convenient and practical. Cracks may initiate from thebottom and turning of the finger-shaped weld, then propagate upward. And smallcracks may occour preferentially at the bottom of the weld. One of the important features of G-Bop test is insensitive to gap width,whichis very benificiaI to simplify the testing process and gain much reliable results. An-other is that the restraint in G-BOP test is more severe than that in Window-Type-Restraint-Weld-Cracking test. And the result could be applied to directly guidethe welding production.