镍基高温合金深小孔的旋转冷挤压强化工艺优化
Optimization of Rotary Cold Extrusion Strengthening Process for Deep Hole in Nickel-based Superalloy
张卿 1雷学林 1郭海龙 2何岑垚 1张显程1
作者信息
- 1. 华东理工大学机械与动力工程学院,上海 200237
- 2. 中国航发湖南动力机械研究所,株洲 412000
- 折叠
摘要
采用多级凸包硬质合金挤压工具对镍基高温合金平板中的深小孔进行旋转冷挤压及无旋转冷挤压(主轴转速为0)试验,研究了挤压率(2.4％,3.0％,3.6％)与主轴转速(0,66,200 r· min-1)对孔壁表面完整性及试样疲劳寿命的影响,确定了旋转冷挤压优化工艺.结果表明:与无旋转冷挤压强化工艺相比,旋转冷挤压强化后孔壁表面微裂纹较少,随着主轴转速的增加,微裂纹增多,表面粗糙增大,且相同主轴转速下,挤压率越大,粗糙度越小,表面硬度越高,残余压应力和压应力层厚度越大.优化旋转冷挤压工艺参数为主轴转速66 r·min-1、挤压率3.0％,该工艺下的孔壁表面微裂纹少,塑性变形层较厚(约30μm),表层硬度提升(硬度峰值为515 HV),表面粗糙度较低(Ra为0.298μm),沿深度方向形成了厚度约为450 μm、应力峰值为498 MPa的周向残余压应力层;在优化工艺下孔强化后试样的疲劳寿命约为未强化试样的6.6倍,疲劳裂纹源由孔壁表面向内部偏移了约45 μm.
Abstract
The rotary cold extrusion and non-rotary cold extrusion(spindle speed of 0)tests were conducted on deep hole in nickel-based superalloy plate with multi-stage convex hull carbide extrusion tool.The effects of extrusion rate(2.4％,3.0％,3.6％)and spindle speed(0,66,200 r·min-1)on the surface integrity of the hole wall and fatigue life of the sample were studied,and the optimal rotary cold extrusion process was obtained.The results show that compared with those under non-rotary cold extrusion strengthening process,there were fewer micro-cracks on the surface of the hole wall after strengthened by rotary cold extrusion,and with increasing spindle speed,the micro-cracks and surface roughness increased;under the same spindle speed,the larger the extrusion rate,the smaller the roughness,the higher the surface hardness and the larger the residual compressive stress and compressive stress layer thickness.The optimized rotary cold extrusion process parameters were as following:spindle speed of 66 r·min-1,extrusion rate of 3.0％.Under this process,the hole wall surface had fewer micro-cracks,thicker plastic deformation layer(about 30 μm),larger surface hardness(peak hardness of 515 HV),and lower surface roughness(Ra of 0.298 μm);a circumferential residual compressive stress layer with a thickness of about 450 μm and a peak stress of 498 MPa was formed along the depth direction.The fatigue life of the samples after hole strengthening under the optimal process was about 6.6 times that of the unstrengthened samples,and the fatigue crack source was shifted from the surface of the hole wall to the interior by about 45 μm.
关键词
镍基高温合金/深小孔/旋转冷挤压/表面完整性/疲劳性能Key words
nickel-based superalloy/deep hole/rotary cold extrusion/surface integrity/fatigue property引用本文复制引用
出版年
2024
NETL
NSTL
万方数据