Effect of shot peening on the residual stress and mechanical behaviour of low-temperature and high-temperature annealed martensitic gear steel 18CrNiMo7-6

38th Risø International Symposium on Materials Science

Yang, R.^1,2 ; Zhang, X.^3 ; Mallipeddi, D.^4 ; Angelou, N.^5 ; Toftegaard, H.L.^6 ; Li, Y.^7 ; Ahlström, J.^4 ; Lorentzen, L.^3 ; Wu, G.^1,2 ; Huang, X.^3

College of Materials Science and Engineering, Chongqing University, Chongqing

400044, China^1

State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing

400044, China^2

Section for Materials Science and Characterization, Department of Wind Energy, Riso Campus, Technical University of Denmark, Roskilde

DK-4000, Denmark^3

Industrial and Materials Science, Chalmers University of Technology, Sweden^4

Section for Test and Measurements, Department of Wind Energy, Riso Campus, Technical University of Denmark, Roskilde

DK-4000, Denmark^5

Section for Composites and Materials Mechanics, Department of Wind Energy, Riso Campus, Technical University of Denmark, Roskilde

DK-4000, Denmark^6

Nano Structural Materials Center, Nanjing University of Science and Technology, China^7

关键词: Gradient structure;    High temperature;    Low temperatures;    Mechanical behaviour;    Residual stress profiles;    Tempered martensite;    Two-materials;    X-ray sources;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/219/1/012046/pdf
DOI  :  10.1088/1757-899X/219/1/012046

来源: IOP

【 摘 要 】

A martensitic gear steel (18CrNiMo7-6) was annealed at 180 °C for 2h and at ∼ 750 °C for 1h to design two different starting microstructures for shot peening. One maintains the original as-transformed martensite while the other contains irregular-shaped sorbite together with ferrite. These two materials were shot peened using two different peening conditions. The softer sorbite + ferrite microstructure was shot peened using 0.6 mm conditioned cut steel shots at an average speed of 25 m/s in a conventional shot peening machine, while the harder tempered martensite steel was shot peened using 1.5 mm steel shots at a speed of 50 m/s in an in-house developed shot peening machine. The shot speeds in the conventional shot peening machine were measured using an in-house lidar set-up. The microstructure of each sample was characterized by optical and scanning electron microscopy, and the mechanical properties examined by microhardness and tensile testing. The residual stresses were measured using an Xstress 3000 G2R diffractometer equipped with a Cr Kα x-ray source. The correspondence between the residual stress profile and the gradient structure produced by shot peening, and the relationship between the microstructure and strength, are analyzed and discussed.