本文選題：激光淬火　切入點：Basquin模型　出處：《西南石油大學(xué)》2015年碩士論文

【摘要】：井下工具的疲勞給油田生產(chǎn)帶來嚴(yán)重的經(jīng)濟損失,如何提高其疲勞性能是一項亟待解決的問題。激光表面淬火是近年來新興的一項表面處理技術(shù),無論是其理論研究發(fā)展或?qū)嶋H生產(chǎn)應(yīng)用,都已經(jīng)較為成熟。激光表面淬火使金屬表面迅速加熱至相變點以上,金屬組織奧氏體化,而后隨著材料的自身冷卻,奧氏體迅速轉(zhuǎn)變?yōu)轳R氏體。在這整個過程中,材料心部組織不變,因此得到了心部韌性好而表面硬度較高的組織。國內(nèi)外生產(chǎn)已經(jīng)將激光表面淬火用于航天、汽車、冶金、磨具、機械生產(chǎn)等各行業(yè),一些石油工具也用激光淬火來優(yōu)化其性能。激光淬火技術(shù)應(yīng)用廣泛,然而影響激光淬火質(zhì)量的工藝參數(shù)有多個,若想要得到預(yù)期的強化效果,應(yīng)對各種工藝參數(shù)的影響規(guī)律進行具體的研究。 本文研究了激光淬火對某井下工具用鋼的疲勞性能的影響規(guī)律。激光淬火處理的工藝參數(shù)主要包括激光功率P、掃描速度v和光斑大小D等。本文根據(jù)實際調(diào)研情況,具體研究了激光功率和掃描速度對材料疲勞性能的影響。文中采用CO2激光器對旋轉(zhuǎn)彎曲疲勞試樣進行激光淬火處理,而后在PQ-6旋轉(zhuǎn)彎曲疲勞試驗機上進行疲勞實驗；按照數(shù)理統(tǒng)計方法對疲勞實驗結(jié)果進行分析,對比不同激光淬火工藝參數(shù)處理的試樣與原始試樣S-N曲線的差異；利用掃描電子顯微鏡對疲勞試樣的斷口進行分析,對比不同工藝試樣疲勞裂紋源區(qū)、擴展區(qū)和瞬斷區(qū)的差異；利用金相顯微鏡和顯微硬度分析儀確定淬硬層組織及其厚度。實驗發(fā)現(xiàn),激光淬火功率對材料的疲勞性能的影響較大,淬火功率過低,材料表面達不到強化效果,功率太高,淬火層厚度太厚,反倒使得疲勞極限降低,因此在實際操作中要選擇使淬硬層厚度在1.5mm左右的功率；在同樣功率下,不同掃描速度對激光淬火材料的疲勞性能影響較小,淬硬層厚度隨著掃描速度的增加略有減小。
[Abstract]:Fatigue of downhole tools brings serious economic losses to oil field production. How to improve their fatigue performance is an urgent problem to be solved. Laser surface quenching is a new surface treatment technology in recent years. The laser surface quenching makes the metal surface rapidly heated above the transformation point, and the structure of the metal becomes austenitic, and then with the cooling of the material itself, The austenite was rapidly transformed into martensite. During the whole process, the core structure of the material remained unchanged, so the microstructure with good core toughness and high surface hardness was obtained. Laser surface quenching has been used in aerospace, automotive, metallurgical, domestic and foreign production. In various industries such as grinding tools and mechanical production, some petroleum tools also use laser quenching to optimize their performance. Laser quenching technology is widely used, but there are many technological parameters that affect the quality of laser quenching. The influence law of various technological parameters should be studied concretely. The effect of laser quenching on fatigue properties of a underground tool steel is studied in this paper. The technological parameters of laser quenching mainly include laser power, scanning speed v and spot size D etc. The influence of laser power and scanning speed on the fatigue properties of the material was studied. In this paper, CO2 laser was used to quench the rotating bending fatigue specimen, and then the fatigue test was carried out on the PQ-6 rotating bending fatigue tester. The fatigue test results were analyzed according to the mathematical statistics method, the differences of S-N curves between the samples treated with different laser quenching process parameters and the original samples were compared, and the fracture surface of the fatigue specimen was analyzed by scanning electron microscope (SEM). The microstructure and thickness of hardened layer were determined by metallographic microscope and microhardness analyzer. The influence of laser quenching power on the fatigue properties of the material is great, the quenching power is too low, the surface of the material can not be strengthened, the power is too high, the thickness of the quenched layer is too thick, and the fatigue limit is reduced. Therefore, in practice, we should choose the power to make the thickness of hardened layer about 1.5mm, and at the same power, the different scanning speed has little effect on the fatigue properties of laser quenched material, and the thickness of hardened layer decreases slightly with the increase of scanning speed.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG665

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