脆性球铁板料激光热应力成形

通过改变工艺参数,用2.5kWRS2000SM快轴流CO2激光器的激光束对球墨铸铁板条进行扫描;并以X-350A型X射线应力测定仪,HVS-1000显微硬度测试仪及扫描电镜(SEM)等为工具,研究了脆性材料激光热应力成形的规律。结果表明,激光束能量较高、扫描速度较低、扫描次数较多和板材厚度较小时都有利于显著增加弯曲变形。成形后的试样在变形区表层有铁素体、渗碳体产生,试样内部表层的石墨团数量减少,试样上表层的最大残余拉应力在250MPa左右,试样下表层的残余应力值接近零。试样断面硬度在700～200HV之间变化,上表层硬度最高。激光束能量较大时,变形区内部产生了微裂纹。

Forming of Brittle Nodular Cast Iron Plate by Laser Thermal Stress

Using RS2000SM CO2 laser of 2.5 kW to irradiate the nodular cast iron(QT-450)plate,and altering the process parameters during laser forming,and analyzing test samples with the X-ray stress analysis instrument(type:X-350A),digital microhardness tester HVS-1000 and scanning electric microscope(SEM)respectively,laser forming regularity of brittle material is studied.The results show that increasing the laser power and the feed number of the beam,decreasing the scanning speed,and the thickness of the test sample eventually result in the increase of the bending angle.There are ferrite and cementite in the surface layer of the test sample after laser forming.The number of ball graphite in the surface layer decreases;The maximum tensile stress of the upper surface in test sample is about 250 MPa,the residual stress value of the lower surface in test sample is about zero.The hardness of the test sample in cross section varies between 700HV and 200HV,the hardness near the upper surface is the greatest.The microcrack inside the deforming area appears when the energy of laser beam is quite strong.