对金属材料内部裂纹愈合的机理、行为和规律进行深入研究，是改善金属材料性能、提高品质和延长使用寿命的重要基础性工作，对丰富材料学理论具有十分重要的意义。本文利用高温显微镜，原位、动态观察了平板撞击铜试样剖分面上孔洞的愈合过程，并对出现明显愈合现象的愈合孔洞进行了扫描电镜下的精细组织观察。观察结果显示，几十μm级孔洞在温度为750℃时开始愈合，在900℃时明显愈合；愈合孔洞的精细结构由μm级团状颗粒与nm级颗粒组成。基于上述实验观察到的现象，提出了孔洞愈合过程的唯象模型，该模型认为，开放式孔洞的愈合过程为孔洞棱边的钝化及形状的规则化，及由孔洞内界面的弓出而导致的孔洞愈合。

The research purpose on the healing of inner crack in metallic materials is to provide an effective approach for improving their properties and prolonging their lifetime. The crack healing process of 20MnMo steel with inner pre-crack was analyzed. It was found that all inner cracks could be healed in different degree. There were very fine ferrite grains in healing region. The micro-crack healing process in single crystal of BBC-Fe was simulated by the molecule dynamics method, which showed that the critical temperature of crack healing in BBC-Fe is 673K There were micro-voids, dislocations and twins left after crack healing.

With the development of technology, metalforming has become a very complex huge engineering system. We divided the problems involved in advanced metalforming processes into four levels, e.g., mechanism analysis, system base, subsystem and system. As it is impossible to do all the requisite tests, it is reasonable to make use of modeling and simulation to investigate the advanced metalforming system. By simulation, we can leam the overall relations of system variables, analyze the full process of system models, and optimize models and system. Now, modeling and simulation have been, widely used in Chinese metalforming engineering. The main reason is that it can decrease development cost, improve working reliability, and increase training safety of engineering system. In the past decade, Chinese scientists and engineers engaged in metalforming engineering have performed creative and fruitful research works, and gain a good profit. In this paper, authors will make a brief review about modeling and simulation done by their research group and other Chinese colleagues.

In order to investigate the flowing behavior of metal in rolling turbine blade steel with asymmetric pass,a FORTRAN program for calculating three-dimensional deformation was prepared.The program based on the principle of rigid-plastic FEM used 20-nodal isoparametric elements. The assumptions about initial velocity field and friction force were put forward, Through calculations,the flow of material and the distribution of velocity,strain and unit draught pressure were obtained.The experiment was performed with plasticine,lead and steel. The result of experiment and calculation are the same in egularity,and can be used in practical rolling process.