摘要
提高铝活塞环槽表面强度的方法有多种 ,再熔化强化工艺是目前最有发展前途的一种提高铝活塞使用寿命的工艺方法。它是利用等离子弧、氩弧、电子束、激光的高温 ,重新熔化铝合金活塞环槽区一定体积的金属并同时渗入合金元素 ,在活塞环槽区形成铝基新合金 ,它同活塞体形成可靠的冶金结合 ,然后在此环形区车削活塞环槽 ,达到提高铝活塞使用寿命的目的。本文采用横流 5KWCO2激光器对HBS32 0铝活塞环槽两岸直接进行镍基合金粉末激光合金化的试验研究 ,获得了无气孔、裂纹、组织细小均匀的合金化层。SEM研究表明合金化层与基体铝合金形成了牢固的冶金结合 ,合金化层组织为靠近基体铝合金的具有定向凝固特征的树枝晶 +细小均匀的等轴晶 ,组织过渡均匀。表面硬度达到 6 5 0HV ,是基体铝合金的 5～ 6倍 ,实际使用表明 ,使用寿命较未经处理的铝活塞得到较大提高。
There are many kinds of method to improve the groove strength and hardness of aluminium alloy piston. The remelting and alloying process has the potential to be an effective and economic technique to improve the surface properties of groove of aluminium alloy piston with the view of significantly extending the performance of the material as a whole. It use the high temperature that generated by plasma arc, tungsten inert gas process, electron beam or laser to melt the surface groove and meanwhile to add some another alloy to the melted zone to form a new kinds of Al-based alloy in the groove of aluminium alloy piston. It can best improve the groove strength and hardness of aluminium piston. In this article, using a transverse flows 5KW CO2 laser, one kinds of Ni-Cr-Si-B alloy was remelted on the groove surface of 320HS aluminium alloy piston. A scanning electron microscope (SEM) was used to analyze the microstructure of the laser-clad zone. Experimental results showed that a porosity-free and crack-free surface was achieved and the interface revealed good metallurgical bonding between the alloyed. At the bottom of the layer was the dendrite morphology that had character of directional solidification and at the middle and upper layer the dendrite space was decreasing rapidly to form a fine equiaxial structure. Vickers hardness tester showed that the surface alloys is high owing to the large amount of intermetallic compound. It varied from 480 to 650 HV, was 5 or 6 times of ZL108 cast aluminium alloy, depended on the volume fraction and dendrite spacing of Al3Ni, and the laser-clad Ni-Cr-Si-B alloy exhibited the higher wear resistance than ZL108 cast aluminium alloy.
出处
《应用激光》
CSCD
北大核心
2004年第2期77-80,共4页
Applied Laser
基金
湖北省博士后基金 ( 2 0 0 2 - 3)资助
