固溶处理对机车车辆抱轴箱内壁堆焊层组织和力学性能的影响

Effect of solution treatment on microstructure and mechanical properties of surfacing layer on inner wall of rolling stock axle box

通过对固溶处理前后修复堆焊层试样进行显微组织观察、力学性能测试以及残余应力测试,分析固溶处理对修复堆焊层强度、韧性和残余应力的影响。结果表明,固溶处理前熔覆区晶粒较大且不均匀,热影响区晶粒粗大,而基材区呈现铁素体与珠光体相间分布。经900℃×3.5 h固溶处理后,基材区的铁素体占比增大且分布更均匀,热影响区和熔覆区的粗大晶粒消失,晶粒细化,显著改善了晶界特性和晶粒结构。固溶处理显著提高了堆焊层的抗拉强度,从810 MPa提升至925 MPa,增幅约为14%。此外,固溶处理导致硬度普遍降低,基材硬度从154 HV降至143 HV,热影响区从238 HV降至228 HV,熔覆区从243 HV降至226 HV,同时残余压应力峰值从232 MPa降低至182 MPa,降低幅度达到21.6%。固溶处理通过减少缺陷、改善晶粒均匀性和消除残余应力,提升了材料的塑性变形能力和整体性能。

Effects of solution treatment on the strength,toughness and residual stress of the repaired surfacing layer were analyzed by observing the microstructure,testing the mechanical properties and testing the residual stress of the specimens before and after solution treatment.The results show that before the solution treatment,the grains in the clad zone are large and uneven,the grains in the heat affected zone are thick,and the substrate zone consists of ferrite and pearlite.After solution treatment at 900 C for 3.5 h,the proportion of ferrite in the substrate zone increases and the distribution is more uniform,the coarse grains in the heat affected zone and the clad zone disappear,the grains are refined,and the grain boundary characteristics and grain structure are significantly improved.Solution treatment significantly makes the tensile strength of the surfacing layer incrense from 810 MPa to 925 MPa,with an increase of about 14%.In addition,the solution treatment results in a general decrease in hardness,from 154 HV to 143 HV for the substrate,from 238 HV to 228 HV for the heat affected zone,from 243 HV to 226 HV for the clad layer,and at the same time,the peak residual compressive stress is reduced from 232 MPa to 182 MPa,with a reduction of 21.6%.These changes indicate that solution treatment improves the plastic deformation ability and overall performance of the material by reducing defects,improving grain uniformity and eliminating residual stress.