激光局部热处理Cr12模具钢硬化层形貌及硬化效率模型

针对大型冷作模具传统热处理存在的变形等问题,采用响应面法研究激光局部热处理工艺参数(激光功率、扫描速度和离焦量)对硬化层形貌(宽度、深度与面积)及效率的作用规律。试验以三因素五水平中心复合设计为基础,通过多元回归和方差分析,构建工艺参数输入与硬化层形貌、硬化效率响应的关系模型。由模型的相关系数可知,硬化层形貌及效率的响应面模型拟合精度高,预测能力强。根据宽度极大、深度极小和面积极大的目标,优化得到最佳工艺参数下的硬化层形貌响应值,较试验实际值的误差分别为1.98%、4.40%和1.58%,进一步验证了模型的准确性。

Cu含量对6061铝合金组织和力学性能的影响

借助硬度计、室温拉伸机、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等仪器,研究了6061铝合金Cu含量与合金显微组织、力学性能的关系。结果表明,当w(Cu)<0.6%时,只析出β″相;当w(Cu)=0.6%时,还析出Q′相;Cu含量越高,则时效析出相的量越多、尺寸越小,强化作用越大,合金的强度和硬度就越高,但合金的塑性越差。因此,合理控制6061铝合金中的Cu含量,有利于获得综合力学性能较好的6061铝合金产品。

Creep behavior of ageing hardened Mg-10Gd-3Y alloy

Tensile creep behaviors of the ageing hardened Mg-10Gd-3Y alloy(referred to GW103)were investigated at temperatures up to 300℃.The extruded-T5 specimen exhibited high creep resistance,i.e.the low steady-state creep rate and long creep rupture time,while the better creep properties were observed in the cast-T6 one.The low steady-state creep rate of 1.71×10- 9s -1is obtained at 200℃and 80 MPa for the extruded-T5 GW103 alloy.In addition,the microstructure development of GW103-T5 alloy was also examined after creep exposure at different temperatures.On the other hand,the stress exponent and activation energy were studied in the temperature range of 200-300℃for the extruded-T5 specimens,and the creep mechanism was also discussed.