【摘要】：磨損、斷裂是引起金屬零部件失效的主要原因,且這些失效形式往往發(fā)生于材料表面,故提高金屬零部件的表面性能,延長(zhǎng)其使用壽命,具有重要的理論意義和實(shí)用價(jià)值。本文以工業(yè)中被廣泛使用的45鋼為試驗(yàn)材料,首先通過(guò)正交試驗(yàn)方法研究了離焦量、電流、掃描速度等工藝參數(shù)對(duì)淬火層硬度的影響,優(yōu)化了激光淬火工藝。然后在仿生學(xué)研究的基礎(chǔ)上,以葉片、土鱉蟲鞘翅、蜻蜓翅膀、貝殼、蜥蜴角質(zhì)鱗片等具有良好耐磨性或抵抗斷裂能力的生物體表作為設(shè)計(jì)原型,設(shè)計(jì)并制備了激光仿生強(qiáng)化單元體,并研究了各種激光仿生強(qiáng)化單元體的磨損性能和拉伸性能。結(jié)果表明：1.影響淬火層硬度的主要因素是離焦量,其次是電流；最佳的激光淬火工藝參數(shù)為離焦量22.5mm、電流210A、掃描速度300mm/min;45鋼經(jīng)最佳激光淬火工藝,搭接率為44%的多道掃描激光淬火處理后,由表及里依次為完全相變硬化層、熱影響區(qū)和基體,其中完全相變硬化層的組織為針狀馬氏體和殘余奧氏體,深度為0.48 mm,硬度為842HV,比45鋼整體淬火提高18%,熱影響區(qū)的組織由完全馬氏體逐漸轉(zhuǎn)變?yōu)橹楣怏w和鐵素體組織,厚度為0.1～0.2mm,硬度從823HV到438HV呈梯度分布；相鄰道與道之間的表面硬度從842HV到450HV呈梯度分布,熱影響區(qū)寬度為0.3mm。2.點(diǎn)狀、條紋狀、網(wǎng)格狀激光仿生強(qiáng)化單元體的磨損率分別為1.70×10-5mm3/(m·N)、 1.33×10-5 mm3/(m·N)、9.34×10-6 mm3/(m·N),基體的磨損率為2.38×10-5 mm3/(m·N),搭接試樣的磨損率為1.54×10-5mm3/(m·N)。激光仿生強(qiáng)化試樣和搭接試樣的耐磨性均優(yōu)于基體試樣。從搭接試樣和激光仿生強(qiáng)化試樣的對(duì)比可見,搭接試樣的耐磨性優(yōu)于點(diǎn)狀激光仿生強(qiáng)化試樣,低于條紋狀和網(wǎng)格狀激光仿生強(qiáng)化試樣。對(duì)比激光仿生強(qiáng)化試樣的耐磨性可知,網(wǎng)格狀激光仿生強(qiáng)化試樣的磨損率最小,耐磨性最佳,條紋狀激光仿生強(qiáng)化試樣次之。3.激光仿生強(qiáng)化試樣的抗拉強(qiáng)度和屈服強(qiáng)度均優(yōu)于基體試樣。在本文所研究的單元體形狀中,條紋狀試樣的抗拉強(qiáng)度和屈服強(qiáng)度最高,較基體試樣分別提高了10.8%和24.1%：網(wǎng)格狀仿生強(qiáng)化試樣次之,其抗拉強(qiáng)度和屈服強(qiáng)度分別提高了3.3%和16.7%;點(diǎn)狀仿生強(qiáng)化試樣的抗拉強(qiáng)度和屈服強(qiáng)度提高較低,分別為2.3%和12.2%。激光仿生強(qiáng)化處理的強(qiáng)化作用主要來(lái)源于單元體顯微組織的變化和拉伸過(guò)程中拉應(yīng)力由基體向單元體的傳遞。由于基體和單元體間的應(yīng)力傳遞,故在相同載荷下,仿生強(qiáng)化試樣基體中承受的拉應(yīng)力要低于未處理試樣,只有進(jìn)一步增加載荷才能使其達(dá)到對(duì)應(yīng)的臨界應(yīng)力,因此,激光仿生強(qiáng)化試樣獲得了更高的強(qiáng)度。
[Abstract]:Wear and fracture are the main causes of failure of metal parts, and these failure forms often occur on the surface of materials. Therefore, it is of great theoretical significance and practical value to improve the surface properties of metal parts and prolong their service life. In this paper, 45 steel, which is widely used in industry, is used as the experimental material. Firstly, the effects of defocusing, current and scanning speed on the hardness of quenching layer are studied by orthogonal test method, and the laser quenching process is optimized. Then on the basis of biomimetic research, the surface of the body with good wear resistance or resistance to breakage, such as leaves, hillbilly scabbard wings, dragonfly wings, shells, lizard horny scales, was used as the design prototype. A laser bionic strengthening unit was designed and fabricated. The wear and tensile properties of various laser bionic strengthening units were studied. The results show that: 1. The main factors affecting the hardness of the quenching layer are defocus, followed by electric current, and the optimum parameters of laser quenching are 22.5 mm, 210A, 300mm / min ~ (45) scanning speed and 44% lap ratio after laser quenching. The whole transformation hardening layer, the heat affected zone and the matrix are in order from the outside to the inside. The microstructure of the complete transformation hardening layer is acicular martensite and residual austenite. The hardness of 0.48 mm, is 842 HVV, which is 18% higher than that of 45 steel. The microstructure of the heat affected zone is gradually changed from complete martensite to pearlite and ferrite with a thickness of 0.1 ~ 0.2mm, and the hardness is distributed gradient from 823HV to 438HV. The surface hardness between adjacent channels is gradient distribution from 842HV to 450HV, and the width of heat affected zone is 0.3 mm. 2. The wear rate of point, stripe and grid laser biomimetic strengthening unit is 1.70 脳 10-5mm3/ (m N), 1.33 脳 10-5 mm3/ (m N), 9.34 脳 10-6 mm3/ (m N), matrix respectively. The wear rate of 2.38 脳 10-5 mm3/ (m N), lapping specimen is 1.54 脳 10-5mm3/ (m N). The wear resistance of the laser bionic strengthened specimen and the lapped specimen is better than that of the matrix sample. It can be seen from the comparison between the lapped specimen and the laser bionic strengthening specimen that the wear resistance of the lapped specimen is better than that of the point laser bionic strengthening specimen and is lower than that of the striped and grid laser bionic strengthening specimen. Compared with the wear resistance of the laser bionic strengthening specimen, the wear rate of the grid laser bionic strengthening specimen is the least, the wear resistance is the best, and the striped laser bionic strengthening specimen is the second. The tensile strength and yield strength of the laser bionic strengthening specimen are better than that of the matrix specimen. The tensile strength and yield strength of the striped specimen are the highest, which are 10.8% and 24.1% higher than that of the matrix sample, respectively. The tensile strength and yield strength were increased by 3.3% and 16.7%, respectively, and the tensile strength and yield strength of point bionic strengthening specimens were increased by 2.3% and 12.2%, respectively. The strengthening effect of laser bionic strengthening mainly comes from the change of microstructure and the transfer of tensile stress from the matrix to the unit during the tensile process. Because of the stress transfer between the matrix and the element body, the tensile stress in the matrix of the biomimetic strengthened specimen is lower than that in the untreated specimen under the same load, and the corresponding critical stress can be reached only by further increasing the load. The laser bionic strengthening specimen obtained higher strength.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG156.99

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 張立文,裴繼斌,陳，

本文編號(hào)：2283217