多孔壁面沟槽的犁切-热处理成形机理

多孔壁面沟槽具有良好的强化传热能力,但该结构制造困难,为此,文中提出了犁切-热处理技术.该技术首先利用犁切工艺,在铜管内表面加工出沟槽;然后在氢还原氛围下进行热处理,使沟槽表面产生多孔层.文中还采用扫描电子显微镜观察了该结构的表面形貌;结合塑性成形理论和热处理空位跃迁理论,分析了该结构的成形机理.结果表明:采用犁切-热处理技术可成功地制造出多孔壁面沟槽;在热处理温度的推动和氢病的综合作用下,犁切时沟槽壁面表层金属产生的微裂纹和晶格缺陷是产生多孔层的主要原因.文中通过金相分析证实了以上结论.

Formation Mechanism of Porous Grooves on Tube Walls by Ploughing-Heat Treatment

In order to overcome the difficulty in manufacturing pipe-wall porous grooves that possess excellent capability of heat transfer enhancement,first,a ploughing-heat treatment method was proposed,by which grooves were manufactured on the inner surface of a copper tube by ploughing and a porous layer was formed on the groove surface via the heat treatment in hydrogen environment.Next,the surface morphology of the porous grooves was observed by means of SEM and was further analyzed.Then,the formation mechanism of the porous grooves was investigated based on the plastic deformation theory and the thermal vacancy transition theory,finding that the proposed ploughing-heat treatment method helps to successfully fabricate porous grooves on tube walls,and that,with the comprehensive action of thermal energy and hydrogen disease during the heat treatment,the formation of porous grooves is mainly due to the complex influences of both the micro-crackers and the lattice defects of groove surface occurring in the ploughing process.Finally,all these above-mentioned findings were verified by metallographic analysis.