40Cr钢加碳激光合金化研究

对40Cr钢进行表面加碳激光合金化处理，得到深0.25-0.35mm的白口铸铁层，白口铸铁层主要由莱氏体和树枝状结晶组织组成，晶粒明显细化，显微硬度高达1200HV以上，热影响相变区组织为马氏体，并存在有针状马氏体到隐晶马氏体的分层，硬度为710－780HV,比常规淬火明显提高，采用高的激光密度，快的扫描速度，有助于晶粒的细化，从而使硬度提高。磨损实验表明，白口铁层的磨损性能比常规淬火样品提高约50％。

Laser Surface Alloying of 40Cr Steel With Carbon

The 40Cr steel has been surface - alloyed with a pre deposited carbon powder layer by the laser beam. White cast iron is obtained on the surface of the sample with the depth of 0. 25 -0. 35mm. The mi-crostructure of the melted zone is pre - dendrite and eutectic ledeburite whose size are refined obviously by the rapid quench. Micro - hardness over 1200HV can be obtained. The microstructure of heat affected zone is martensite. It can be divided into two sub- layers. The first is composed of pin -like martensite and the sec-ond non - pin martensite. It reveals that the higher the scanning speed and power density, the finer the grain, hence the higher the micro - hardness. The wear test shows that the wear resistance of the specimens increased by 50% compared with the general quenched samples.