Prevention of the liquid metal embrittlement in Weldment.

钢的硬度和晶粒尺寸及其对熔融锌中液体金属包裹破裂的应力和敏感性的影响（LMEC）已被调查。该实验是使用商用可焊接结构钢和可持续负载测试（XSLT）在430 ° C-470 ° C加热范围内进行熔化锌，并在热滴加压中对热影响区（HAZ）的钢进行了研究。该实验使用JIS G3444 STK 55和370 ° C-470 ° C加热范围内的合成HAZ进行可持续载荷测试。在热激活过程中，LMEC的钢和焊接行为是非粒度（IG）类型对应的，在热滴液凝胶中有效的LMEC。对熔化锌中钢材和钢材的断裂压力的估计是通过衡量Vicker的硬度和粒度获得的，这些估计值与测试结果是正确的。LMEC的敏感性受到钢和钢材的硬度的影响; LMEC行为受到热激活过程的影响，LMEC的敏感性受到HAZ的硬度的影响。HAZ的沿海谷物地区展示了最高的LMEC敏感性。钢的相对困难被锌的存在所减少。钢的LMEC反应速率过程是由锌的谷物边界扩散控制的。LMEC在钢中的核扩散和LMEC的传播可能有一个密切的关系，以减少锌的间能，使锌的颗粒边界扩散。

The effect of hardness and grain size of steels and their welds on fracture stress and sensitivity of Liquid Metal Embrittlement Cracking in molten Zinc (L MEC) was investigated. The experiment was conducted using commercial weldable structual steels and Sustained Load Test (SLT) was conducted in molten Zinc with heating range of 430゜C-470゜C.The liquid metal embrittlement cracking of heat affected zone (HAZ) of steel in hot dip galvanizing was investigated. The experiment was conducted using synthetic HAZ of JIS G 3444 STK55 and Sustained Load Test at 370゜C-470゜C heating range in liquid (molten) and solid Zinc.The LMEC behavior of steels and welds in molten Zinc is of thermal activated process, and fractures are intergranular (IG) type witch corresponds to actual LMEC in hot dip galvanising. Estimation of fracture stress of steels and welds in molten Zinc is obtained by measuring Vicker's hardness and grain size, and these estimation values are correspond with test results. The sensitivity of LMEC is affected by hardness of steels and welds.LMEC behavior is of thermal activated process and LMEC sensitivity is affected by hardness of HAZ. The coarse grain region in HAZ showned the highest LMEC sensitivity. The interfacial enegy of steel is redused by the exsistence of Zinc. The reaction rate process of LMEC of steel is controlled by grain boundery diffusion of Zinc. The nucleation and the propagation of LMEC in steel are likely to have a close relation to the reduction of interfacial energy due to the grain boundery diffusion of Zinc.