Mechanism of grain refinement of an advanced PM superalloy during multiple isothermal forging

HOU Qiong; TAO Yu; JIA Jian

doi:10.13374/j.issn2095-9389.2019.02.007

Volume 41 Issue 2

Feb. 2019

Turn off MathJax

Article Contents

Article Navigation > Chinese Journal of Engineering > 2019 > 41(2): 209-215

HOU Qiong, TAO Yu, JIA Jian. Mechanism of grain refinement of an advanced PM superalloy during multiple isothermal forging[J]. Chinese Journal of Engineering, 2019, 41(2): 209-215. doi: 10.13374/j.issn2095-9389.2019.02.007

Citation:

HOU Qiong, TAO Yu, JIA Jian. Mechanism of grain refinement of an advanced PM superalloy during multiple isothermal forging[J]. Chinese Journal of Engineering, 2019, 41(2): 209-215. doi: 10.13374/j.issn2095-9389.2019.02.007

Citation:

PDF( 24064 KB)

Mechanism of grain refinement of an advanced PM superalloy during multiple isothermal forging

doi: 10.13374/j.issn2095-9389.2019.02.007

HOU Qiong^{1, 2},
TAO Yu^{1, 2
,
,},
JIA Jian^{1, 2}

1.
High Temperature Materials Research Institute, Central Iron and Steel Research Institute, Beijing 100081, China
2.
Beijing Key Laboratory of Advanced High Temperature Materials, Beijing 100081, China

More Information

Corresponding author: TAO Yu, E-mail: tao0125@sina.com
Received Date: 2018-01-17
Publish Date: 2019-02-01

Abstract

Abstract

Nickel-base powder metallurgy (PM) superalloys are widely used as high temperature components in gas turbine engines owing to their outstanding mechanical properties and workability under intense heat. In order to meet the performance requirements of a new generation aircraft engine with a higher thrust-weight ratio, the fourth generation PM superalloy has been studied at home and abroad. Its operating temperature has been raised to 815-850℃. The alloy in this study was a newly-designed fourth generation PM superalloy, which exhibited excellent high temperature stress rupture and creep properties compared with the previous three generations' PM superalloys, FGH4095, FGH4096, and FGH4098. Based on the performance characteristics of PM superalloys of different grain sizes, dual microstructure heat treatment (DMHT) has been used to produce a turbine disk which has a fine-grained bore and a coarse-grained rim. Therefore, it was first necessary to obtain a uniform fine-grained disk. It has been demonstrated that the fine-grained disk can be gained through hot isostatic pressing (HIP) and multi-steps of high temperature working. In order to study the influence of multiple isothermal forging (ITF) on the grain refinement of the advanced PM superalloy, three steps of ITF were employed; each deformation was about 40%. The effective strain distribution of the alloy during ITF was simulated by using the commercial finite element software DEFORM 2D. Microstructures of those forgings were investigated by means of the electron back scattered diffraction (EBSD) technique. The experimental results show that during ITF, the axial section of the forging is divided into three regions. Region Ⅰ, located in the upper and lower end faces, has the smallest deformation. Region Ⅱ is located at both sides of the section, and its deformation is larger than that of region Ⅰ. And region Ⅲ, located in the center of the section, obtains the maximal deformation. After three steps of ITF, Regions Ⅱ and Ⅲ of the forging are fully recrystallized, and equiaxed fine-grained microstructures with an average grain size of 2-3 μm are generated. Nevertheless, necklace structures form near Region Ⅰ of the forging. A great amount of fine recrystallized grains distribute around the non-equiaxed deformed grains. The deformed grains contain plenty of low-angle grain boundaries (LAGBs), which mean that the dislocation density is very high. Through proper heat treatment, the necklace structure in Region Ⅰ is refined. Meanwhile, grain growth occurs in Region Ⅱ and Ⅲ. These findings suggest that fine-grained disks with uniform microstructures can be achieved, and the average grain size is 6-8 μm.
- powder metallurgy superalloy,
- isothermal forging,
- low-angle grain boundary,
- necklace structure,
- recrystallization

FullText(HTML)

References(16)

References

[1]	張義文, 劉建濤. 粉末高溫合金研究進展. 中國材料進展, 2013, 32(1): 1 https://www.cnki.com.cn/Article/CJFDTOTAL-XJKB201301003.htm Zhang Y W, Liu J T. Development in powder metallurgy superalloy. Mater China, 2013, 32(1): 1 https://www.cnki.com.cn/Article/CJFDTOTAL-XJKB201301003.htm
[2]	吳超杰, 陶宇, 賈建. 第四代粉末高溫合金成分選取范圍研究. 粉末冶金工業, 2014, 24(1): 20 https://www.cnki.com.cn/Article/CJFDTOTAL-FMYG201401008.htm Wu C J, Tao Y, Jia J. Study on composition variation range of the fourth generation PM superalloys. Powder Metall Ind, 2014, 24(1): 20 https://www.cnki.com.cn/Article/CJFDTOTAL-FMYG201401008.htm
[3]	Wu C J, Tao Y, Jia J. Microstructure and properties of an advanced nickel-base PM superalloy. J Iron Steel Res Int, 2014, 21(12): 1152 doi: 10.1016/S1006-706X(14)60198-9
[4]	Reynolds P L. Superalloy Compositions, Articles, and Methods of Manufacture: US Patent, 8147749. 2012-04-03
[5]	Powell A, Bain K, Wessman A, et al. Advanced supersolvus nickel powder disk alloy DOE: chemistry, properties, phase formations and thermal stability//Superalloys 2016: Proceedings of the 13th Intenational Symposium of Superalloys. Hoboken, 2016: 189
[6]	Mourer D P, Raymond E, Ganesh S, et al. Dual alloy disk development//Superalloys 1996. Warrendale, 1996: 637
[7]	Gayda J. Dual microstructure heat treatment of a nickel-base disk alloy[J/OL]. NASA Technical Reports Server (2001-11-01)[2018-12-26]. https://ntrs.nasa.gov/search.jsp?R=20020013802
[8]	Gayda J, Gabb T P, Kantzos P T. The effect of dual microstructure heat treatment on an advanced nickel-base disk alloy//Superalloys 2004. Warrendale, 2004: 323
[9]	陶宇, 張國星, 劉建濤. 粉末渦輪盤溫度梯度熱處理工裝設計研究. 鋼鐵研究學報, 2011, 23(增刊2): 486 https://www.cnki.com.cn/Article/CJFDTOTAL-IRON2011S2127.htm Tao Y, Zhang G X, Liu J T. Study on design of the device for thermal gradient heat-treatment process of PM superalloy disks. J Iron Steel Res, 2011, 23(Suppl 2): 486 https://www.cnki.com.cn/Article/CJFDTOTAL-IRON2011S2127.htm
[10]	陶宇, 賈建, 劉建濤, 等. 超細晶鎳基粉末高溫合金的制備方法: 中國專利, CN102392147A. 2012-03-28 Tao Y, Jia J, Liu J T, et al. Preparation Method of Ultra-Fine Grain Nickel Based Superalloy: China Patent, CN102392147A. 2012-03-28
[11]	劉洋, 陶宇, 賈建. FGH98粉末冶金高溫合金熱變形過程中組織變化. 粉末冶金工業, 2011, 21(2): 14 https://www.cnki.com.cn/Article/CJFDTOTAL-FMYG201102006.htm Liu Y, Tao Y, Jia J. The microstructure evolution of FGH98 P/M superalloy after hot deformation. Powder Metall Ind, 2011, 21(2): 14 https://www.cnki.com.cn/Article/CJFDTOTAL-FMYG201102006.htm
[12]	寧永權, 姚澤坤, 吳澤, 等. 多火次鍛造對GH4133A合金組織和性能的影響. 塑性工程學報, 2008, 15(4): 98 https://www.cnki.com.cn/Article/CJFDTOTAL-SXGC200804023.htm Ning Y Q, Yao Z K, Wu Z, et al. The effects of repeated firing forging on microstructure and mechanical properties of GH4133A alloys. J Plast Eng, 2008, 15(4): 98 https://www.cnki.com.cn/Article/CJFDTOTAL-SXGC200804023.htm
[13]	寧永權, 姚澤坤. FGH4096粉末高溫合金的再結晶形核機制. 金屬學報, 2012, 48(8): 1005 https://www.cnki.com.cn/Article/CJFDTOTAL-JSXB201208018.htm Ning Y Q, Yao Z K. Recrystallization nucleation mechanism of FGH4096 powder metallurgy superalloy. Acta Metall Sinica, 2012, 42(8): 1005 https://www.cnki.com.cn/Article/CJFDTOTAL-JSXB201208018.htm
[14]	謝興華, 姚澤坤, 寧永權, 等. FGH4096合金的動態再結晶與晶粒細化研究. 航空材料學報, 2011, 31(1): 20 https://www.cnki.com.cn/Article/CJFDTOTAL-HKCB201101005.htm Xie X H, Yao Z K, Ning Y Q, et al. Dynamic recrystallization and grain refining of superalloy FGH4096. J Aeron Mater, 2011, 31(1): 20 https://www.cnki.com.cn/Article/CJFDTOTAL-HKCB201101005.htm
[15]	He G A, Liu F, Huang L, et al. Microstructure evolutions and nucleation mechanisms of dynamic recrystallization of a powder metallurgy Ni-based superalloy during hot compression. Mater Sci Eng A, 2016, 677: 496 http://www.sciencedirect.com/science/article/pii/s0921509316311650
[16]	張北江, 趙光普, 焦蘭英, 等. 熱加工工藝對GH4586合金微觀組織的影響. 金屬學報, 2005, 41(4): 351 https://www.cnki.com.cn/Article/CJFDTOTAL-JSXB200504004.htm Zhang B J, Zhao G P, Jiao L Y, et al. Influence of hot working process on microstructures of superalloy GH4586. Acta Metall Sinica, 2005, 41(4): 351 https://www.cnki.com.cn/Article/CJFDTOTAL-JSXB200504004.htm