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本文用30CrMnSi研究了不同原始组织对激光加热时所得的硬化带及热影响区的组织的影响。所用的激光加热前的预处理有:a.1280℃油淬;b.1280℃油淬并在300℃回火2h;c.1280℃油淬并在300℃回火10h;d.1280℃油淬并在700℃回火2h;e.1280℃加热并在400℃等温30min;f.880℃正火。激光加热采用CO_2激光器,除注明者外功率均为1kW,离焦量为60mm,扫描速度为600mm/min。结果得出:淬火态及淬火并在300℃回火态进行激光处理时,得到四层不同的组织,由表面开始依次命名为白亮层、第一暗环、灰环及及第二暗环。其它几种预处理的试样激光处理时,未出现上述四层组织。对这四层组织进行了仔细的观察,测出了各层显微硬度,并对其成因进行了讨论。试验结果还得出淬火态激光处理可使硬度进一步提高。本文还对激光处理时出现的组织遗传现象进行了讨论。预计对第一暗环的深入研究有助于弄清非平衡态组织超快速加热的转变机制。
In this paper, 30CrMnSi was used to study the effect of different primary structures on the microstructure of the hardened zone and the HAZ obtained by laser heating. The laser preheating before use are: a.1280 ℃ oil quenching; b.1280 ℃ oil quenching and tempering at 300 ℃ 2h; c.1280 ℃ oil quenching and tempering at 300 ℃ 10h; d.1280 ℃ oil Quenching and tempering at 700 ℃ 2h; e.1280 ℃ heating and isothermal at 400 ℃ 30min; f.880 ℃ normalizing. Laser heating using CO_2 laser, except those indicated were power 1kW, defocus amount of 60mm, scanning speed of 600mm / min. The results show that when hardened and quenched and laser tempered at 300 ℃, four layers of different microstructure were obtained, named white bright layer, first dark ring, gray ring and the second dark ring from the surface. The other four pretreatment samples were laser-treated without the above four-layer structure. The four layers of the organization were carefully observed, measured the microhardness of each layer, and its causes were discussed. The results also show quenching laser treatment can further improve the hardness. This article also discusses the tissue genetic phenomena that occur during laser processing. It is expected that an in-depth study of the first dark ring will help clarify the mechanism of transition of non-equilibrium tissue to ultra-rapid heating.