外文翻譯---離子滲氮對馬氏體時(shí)效鋼微觀結(jié)構(gòu)和性能的影響

1、附錄一 英文翻譯原文EFFECT of ION NITRIDING ON the MICROSTRUCTURE AND PROPERTIES of MARAGING STEEL (250 GRADE)Kishora ShettyS. Kumarb,P. Raghothama Rao;Regional Centre for Military Airworthiness (Foundry and Forge), CEMILAC, DRDO

2、, Bangalore-560 037, IndiaDepartment of Materials Engineering, Indian Institute of Science, Bangalore-560 012, IndiaReceived 25 June 2008. Accepted 28 November 2008. Available online 10 December 2008AbstractIn the presen

3、t investigation, ion nitriding of Maraging steel (250 grade) has been carried out at three different temperatures i.e., at 435℃, 450℃ and 465℃ for 10 h duration in order to achieve good wear resistance along with high st

4、rength required for the slat track component of aircraft. The microstructure of the base material and the nitrided layer was examined by optical and scanning electron microscope, and various phases present were determine

5、d by X-ray diffraction. Various properties, such as, hardness, case depth, tensile, impact, fatigue properties and corrosion resistance were investigated for both un-nitrided and ion-nitrided materials. It is observed th

6、at the microstructure of the core material remains unaltered and Fe4N is formed in the hardened surface layer after ion nitriding at all the three temperatures employed. Surface hardness increases substantially after ion

7、 nitriding. Surface hardness remains almost the same but case depth increases with the increase in ion nitriding temperature due to greater diffusivity at higher temperatures. Tensile strength, fatigue strength and corro

8、sion resistance are improved but ductility and energy absorbed in impact test decrease on ion nitriding. These results are explained on the basis of microstructural observations. The properties obtained after ion particu

9、larly beneficial for complex parts. The hardened surface layer becomes an integral part of the base material and there is no significant reduction in properties of the base material. It is also known to provide the modif

10、ied surface without dimensional change and distortion of the component. Ion nitriding provides better control of case chemistry and uniformity [3],[6]and[7].Maraging steels belong to a new class of high strength steels w

11、ith the combination of strength and toughness that are among the highest attainable in general engineering alloys[8]. The term maraging is derived from martensite age hardening and denotes the age hardening of a low carb

12、on, iron–nickel lath martensite matrix [9] and [10]. These steels typically have very high nickel, cobalt and molybdenum and very low carbon content. They are strengthened by the precipitation of intermetallic compounds

13、at a temperature of about 480℃ [11] and [12]. Carbon is treated as an impurity and is kept as low as commercially feasible (<0.03wt.%) in order to minimize the formation of titanium carbide (TiC), which can adversely

14、affect strength, ductility and toughness [9] and [11]. Different maraging steels are designed to provide specific levels of yield strength from 1030 to 2420MPa (150 to 350ksi). Maraging steel (250 grade) possesses a yiel

15、d strength of 250ksi.For aeronautical components requiring high strength and good wear resistance, such as, slat track, Maraging steel possesses high strength, and good wear resistance can be achieved by ion nitriding pr

16、ocess of case nitriding. In conventional gas nitriding process the nitriding temperature is 500℃–550℃[2], which is above the ageing temperature of maraging steel and would result in the over-aging of the core. However, i

17、on nitriding can be carried out at a temperature lower than the aging temperature. Ozbaysal and Inal have demonstrated that the surface hardening of maraging steels without a reduction in core hardness is possible using

18、the ion nitriding process[13]. In the present investigation, ion nitriding of Maraging steel (250 grade) has been carried out at three different temperatures, i.e., 435℃, 450℃ and 465℃ for 10h duration. Microstructural c