| JIANG Ke-jing,WANG Liang,ZHANG Qun-li,,HU Yong,YAO Jian-hua,LIU Rong.Laser Annealing and Softening Process of 316L Stainless Steel[J],48(2):10-16 |
| Laser Annealing and Softening Process of 316L Stainless Steel |
| Received:October 23, 2018 Revised:February 20, 2019 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2019.02.002 |
| KeyWord:316L stainless steel laser heat treatment selective annealing grain morphology strength and plasticity |
| Author | Institution |
| JIANG Ke-jing |
1.a.Institute of Laser Advanced Manufacturing, b.College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China |
| WANG Liang |
1.a.Institute of Laser Advanced Manufacturing, b.College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China |
| ZHANG Qun-li, |
1.a.Institute of Laser Advanced Manufacturing, b.College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China |
| HU Yong |
1.a.Institute of Laser Advanced Manufacturing, b.College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China |
| YAO Jian-hua |
1.a.Institute of Laser Advanced Manufacturing, b.College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China |
| LIU Rong |
1.a.Institute of Laser Advanced Manufacturing,Zhejiang University of Technology, Hangzhou , China; 2.Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa KIS 5B6, Canada |
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| Abstract: |
| The work aims to solve the problem of excessive strength and low plasticity caused by hardening in stamping. The temperature-controlled mode laser with a rectangular spot was used as the heat source. The workpiece was subjected to in-stantaneous annealing in the selected area to achieve local softening. The metallographic microscopic analysis, microhardness analysis, mechanical tensile analysis and fracture analysis were taken to evaluate the microstructure, microhardness, tensile strength, elongation after fracture and fracture morphology of samples after laser annealing and softening. The metallographic structure analysis showed that the grains exhibited deformed grains, recrystallized grains, fine grains and large equiaxed crystals under different annealing parameters. From the microhardness results, the hardness of the solid solution base material was 173HV0.2, but reached 341HV0.2 after hardening. When the laser control temperature was 1400 ℃ and the scanning speed was 5, 10, and 15 mm/s, the hardness after softening was 164HV0.2, 173HV0.2, and 257HV0.2, respectively. When the scanning speed was constant, the higher the laser control temperature was, the lower the hardness after softening was. From the tensile test, the strength of the sample was reduced after the instantaneous laser annealing but the plasticity was improved. When the temperature control temperature was 1400 ℃ and the scanning speed was 5 mm/s, the tensile strength decreased from 911 MPa to 591 MPa after hardening, which was close to 570 MPa of the solid solution parent metal, and the elongation after fracture was restored from 18.2% to 54.7% which reached 95.5% of the solid solution base metal. Laser instantaneous annealing and softening can effectively reduce the material strength after hardening, improve the plasticity of the material, and restore the strong deformation ability. The softening degree decreases with the decrease of the laser temperature control temperature and the increase of laser scanning speed. Under the optimal laser softening parameters, the performance of softened sample is even better than that of the base metal. |
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