Test Study of Nickel-base Superalloy 718 Superfine Deep-hole Drilling

Transcription

1 Applied Mechanics and Materials Online: ISSN: , Vols , pp doi: / Trans Tech Publications, Switzerland Test Study of Nickel-base Superalloy 718 Superfine Deep-hole Drilling Zhanfeng Liu 1, a, Shengming He 2, b 1,2 School of Mechanical Engineering, Xi'an ShiYou University, Xi'an , China a lzhfg9@163.com, b heyafei320@163.com Keywords: Nickel Base Superalloy 718, Superfine Deep Hole,Tool Wear. Abstract. Nickel-base superalloy 718 is a new kind of materials that is difficult to drilling. In this paper, the superfine deep-hole (ø mm)drilling test is based on the material. This paper analyzes the causes and laws of the tool wear, tool breakage,and the hole axis deflection from the blade material, tool geometry parameters, cutting parameters and drilling methods. Introduction Nickel base superalloy has high specific strength, high thermal strength, good chemical stability, good anti-fatigue,anti-radiation,anti-corrosion resistance and good weldability,and has high oxidation resistance at 980 C, high tensile strength, fatigue strength, creep strength and fracture resistance strength at 700 C, it can withstand greater stress in condition of oxidation and gas corrosion at high temperature(600~1000 C). Based on the above good performance,nickel-base superalloy often used in aviation industry, ships and industrial turbine blades, guide vanes, turbine disk and so on 2. But from the point of view of processing performance,the nickel base superalloy is a typical material that is difficult to machine,in the progress of cutting, it has problems of large deformation,serious work hardening, great cutting force,high cutting temperature, tool wear and serious breakage. Its ultra-fine long deep hole drilling is even more difficult, there is no specific data for deep hole drilling in China at present, In order to improve the processing efficiency of the high temperature alloy 718 materials long deep hole, considering the characteristics of the material itself, this article studies the test from the blade material, blade geometry parameters and the cutting Parameters. Drilling experiment The experimental condition. The experiment machine: Drilling machine trans-formed from CW6131D lathe,20 # machine oil. Experiment tool materials and structure: Carbide YG813 as blade material, BTA deep hole drilling as tool structure,shown in Fig.1 and table 1: Fig.1.BTA deep hole drilling marked angle All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-09/05/16,00:17:34)

2 1826 Advanced Materials and Process Technology item 0 0 Table.1.Experiment tool geometry 0 e δ1 δ2 value 3 ~5 8 ~12 12 ~15 2mm 3-3 Experimental material: The bar of nickel base superalloy 718, shown in fig.2, The chemical composition and mechanical properties is shown in table.2 and table.3: Fig.2. Bar structure sketch Table.2.The chemical composition of nickel-base superalloy 718 % N i Cr Mn Si Co Al Ti min max Mo Nb C Fe Cu S min suplus max The experiment scheme.the main purpose of this study is to ensure ultrafine deep hole drilling with nickel-base superalloy 718 working in high quality, high efficiency and low consumption. The first thing is choice of the tool,as the content of Nickel-base superalloy 718 content is from 50% to 55%,so it has large plastic deformation,high cutting temperature (1000 C)and work - hardening serious in cutting.alloy contains a lot of hard particles which accelerate the tool wear and cracks and even tool fracture. So we should choose carbide YG813 that has higher heat resistance, higher toughness, good anti-adhesion and good commonality in the drilling. Test respectively at n = 255 r / min, ƒ = 0.02mm / m; n = 255 r / min, ƒ = 0.03mm / r; n = 195r/min, ƒ = 0.03mm / r. Observe the tool wear or damage, observe the shape of iron chips, Analyze its causes and make consequential amendments or replace the tool. Timely measure the of concentricity, make correction when necessary. Drilling result and analysis Tool wear morphology and analysis. The tool wear is extremely serious when deep hole drilling with nickel base superalloy 718, Table.3 shows the tool wear state of the drilling process under different circumstances. Table.3.The results of drilling nickel-based superalloy 718 Speed Feed chip Wear breakage (r/min) (mm/r) Blocking debris Serious Damaged Normal Serious Normal Normal Slight Normal As shown in fig.3, rake face, flank face and guide block are worn so seriously that the drilling can not continue. Because nickel base superalloy 718 contains much carbide, nitride, boride and intermetallic compound, especially hard particle of γ phase(mainly silica),so wear happens.in

3 Applied Mechanics and Materials Vols addition, in the progress of drilling, the temperature and pressure is rather high, the adhesion force between the tool metal and work metal can cause chip and tool fusion welding, a part of tool material is taken away causing adhesive wearing. It is found that adjust the cutting parameters, rake angle and clearance angle timely in the drilling will get desired effect. As is shown in fig. 3,when drilling at n=195r/min, ƒ=0.03mm/r, the result is most desired. Fig.3.Wear morphology in different drilling conditions with YG813 Fig.4.Tool breakage form Tool breakage morphology and analysis. The breakage is quite easily happened in drilling nickel based superalloy 718, as shown in fig.4. The reasons of the tool breakage are a lot, but from the process of drilling nickel based superalloy 718, the main reason is the high nickel content, in condition of high temperature and pressure, adhesive phenomenon is very severe, plastic flow is easily happened on the contact layer of tool face and chip, so that cutting ability of the tool is lost, causing plastic failure. Besides,in the process of drilling, strong vibration and thermal shock, high hardness and brittleness can cause tool breakdown in early time of drilling, then cause chip block up, as a result, the drilling can not continue. So in drilling, after adjusting tool angle, rotation speed, feed amount, we can observe the chip to carry on experimental drilling. In this way, the tool can be prevent from damaging, can be sharpened to reuse. The production efficiency is improved, the production cost is reduced. In the test, when n=195r/min,ƒ=0.03mm/r, we get the best result, the drilling tool is just worn rather than break.ideal chip form is shown in Fig.5. Fig.5.Iideal chip form. Measurement and analysis of the hole axiality In deep hole drilling, the factors that influence hole axis deflection is a lot, when length diameter ratio is above 50,the deflection of the hole axis is can not be predicted and control, since currently online measurement and correction is unable to do, we can only do downtime measurement. Fig.6

4 1828 Advanced Materials and Process Technology shows deflection measurement result of drilling on nickel based superalloy 718, the test result shows that this test plan can meet the requirement of axiality when deep hole drilling with nickel based superalloy 718, besides, for the tool wear is very serious, the wall thickness is gradually increased with hole depth. So in drilling, special attention should be paid to downtime tool changing and tool breakdown when the out edge breakage due to excessive force in feeding after tool sharpening. Conclusions Fig.6.The offset of the hole axis of the drilling of nickel base superalloy 718 The following conclusions can be obtained in this experiment: It is feasible to drill (ø36mm 5440mm) nickel base superalloy 718 ultrafine long deep hole with CW6163D deep hole drilling machine and multi-blade the wrong tooth BTA deep hole drilling. As shown in Table 1,Appropriate choice of blade materials (YG813), tool angle, cuttings parameters n = 195r/min,ƒ = 0.03mm / r can be solved Superfine deep hole machining of nickel base superalloy 718. The cuttings parameters can prevent or reduce the drilling of nickel-based superalloy 718 material drilling tool wear and breakage, and ensure the hole concentricity. Tool mainly occurred hard particle wear, adhesive wear, plastic damage in the nickel-base superalloy 718 superfine deep hole drilling process. It has a guiding significance to choose rational tools material and the parameters on the production practice.if you follow the checklist your paper will conform to the requirements of the publisher and facilitate a problem-free publication process. References [1] Shiqing Wang. Deep processing,northwestern Polytechnical University Press(2003) [2] Zhang Bin, Xiao Deiming. Deep-hole machining of high temperature alloy GH4169 Status and Prospects,Mechanical study and application,19, 20(2011). [3] I.A.Choudhury,M.A.El-Baradie.Machining nickel basesupe-ralloys, Inconel 718 Materials Processing Technology (1999), pp [4] Dudzinski D, Devillez A, Moufki A, etal A review of developments towards dry and high speed machining of Inconel718 alloy. International Journal of Machine Tools& Manufacture(2004), Vol. 4, pp

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