YG6硬质合金渗硼层厚度对抗弯强度的影响

Effect of the boronizing thickness of YG6 hard alloy on bending strength

为获得合适的渗硼层厚度 ,使硬质合金既保持一定的硬化层 ,又保持较高的抗弯强度 ,采用改进了的B4C质量分数为 2 5 %的渗硼剂配方 ,对YG6硬质合金进行了固体粉末表面渗硼试验。加热温度 90 0～ 10 0 0℃ ,渗硼时间 2～ 6h。渗硼后在XJG 0 5金相显微镜下观察合金组织 ,测量渗硼层厚度及其显微硬度。以三点弯曲法进行弯曲试验 ,测量试样抗弯强度。结果表明 ,随着渗硼温度的升高及渗硼时间的延长 ,试样渗硼层增厚。不同工艺条件对试样表面硬度和抗弯强度影响不大 ,但渗硼层过厚使其抗弯强度下降。渗硼层厚度为 2 0～ 4 0 μm时 ,试样抗弯强度达 990～ 1170MPa ;超过 4 0 μm时 ,其抗弯强度明显下降。

YG6 hard alloy was tested using the solid powder boronizing method with the improved recipe containing 25% B 4C. The heating temperatures ranges from 900 to 1*!000*!℃, and the boronizing time ranges from 2 to 6 h. The boronizing thickness, hardness and bending strength were measured using different boronizing technology, and the effects of the boronizing thickness on bending strength were analyzed. The results showed that the bending strength was decreased evidently when the boronizing thickness was higher than 40*!μm, and the high bending strength was still kept(990～1*!170*!MPa) when the boronizing thickness ranges from 20 to 40*!μm.