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- Singh, Sukhdeep, 1988, et al.
(author)
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Hot cracking in cast alloy 718
- 2018
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In: Science and Technology of Welding and Joining. - : Informa UK Limited. - 1743-2936 .- 1362-1718. ; 23:7, s. 568-574
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Journal article (peer-reviewed)abstract
- Hot cracking susceptibility of the Fe–Ni-based precipitation hardening cast superalloy Alloy 718 was studied by Varestraint weldability testing. The effect of two hot isostatic pressing (HIP) treatments commonly employed in the aerospace industry was investigated in reference to the as cast condition. It was found that the heat affected zone (HAZ) liquation cracking susceptibility increased for samples with pre-weld HIP treatments. The as cast condition disclosed the best response for liquation cracking followed by HIP-1120 (1120°C/4h (HIP) + 1050°C/1h and furnace cooling to 650°C/1h in vacuum + 950°C/1h) and HIP-1190 (1190°C/4h (HIP) + 870°C/10h and furnace cooling to 650°C/1h in vacuum + 950°C/1h). The amount of the secondary precipitates and base metal grain size was found to be important parameters influencing the cracking susceptibility. Regarding solidification cracking susceptibility, the three conditions appear to behave similarly.
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| 2. |
- Singh, Sukhdeep, 1988, et al.
(author)
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Investigation on effect of welding parameters on solidification cracking of austenitic stainless steel 314
- 2018
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In: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; , s. 351-357
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Journal article (other academic/artistic)abstract
- This study investigates the solidification cracking susceptibility of the austenitic stainless steel 314. Longitudinal Varestraint testing was used with three different set of welding test parameters. Weld speed, current and voltage values were selected so that the same heat input resulted in all the test conditions. From the crack measurements it was seen that the test condition with the lowest current and welding speed value also produced the least amount of cracking with very good repeatability.
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| 3. |
- Singh, Sukhdeep, 1988, et al.
(author)
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Varestraint Weldability Testing of ATI 718Plus® : Influence of Eta Phase
- 2018
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In: Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives. - Cham : Springer. - 9783319894799 - 9783319894805 ; , s. 929-937, s. 929-937
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Conference paper (peer-reviewed)abstract
- This study investigates the effect of eta phase on hot cracking susceptibility of ATI 718Plus®. Two heat treatment conditions of 950 °C/1 h and 950 °C/15 h having different amounts of eta phase were tested by longitudinal Varestraint testing method. The heat treatment at 950 °C/15 h exhibited the highest amount of cracking. This was related to the higher amount of eta phase precipitation during the long dwell heat treatment which aided to extensive liquation during welding.
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| 4. |
- Singh, Sukhdeep, 1988
(author)
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Varestraint Weldability Testing of Cast Superalloys
- 2018
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Licentiate thesis (other academic/artistic)abstract
- Precipitation hardened Ni- and Ni-Fe- based superalloys, used in hot structural components for aero engines, are subjected to hot cracking phenomena during manufacturing and specifically in welding. This type of cracking involves metallurgical reactions from the liquid phase in concomitance to weld restraints. Hot cracking is more pronounced during the welding of cast superalloys compared to its wrought counterparts owing to the larger inhomogeneity in the cast material. Cast structural components must therefore undergo a hot isostatic pressing (HIP) treatment prior to welding for closing any pores from the casting process and homogenizing the material. The current study is about the effect of two HIP treatments commonly employed in the aerospace industry on the weldability of the cast Alloy 718. Moreover, the weldability of the recently introduced cast version of ATI® 718PlusTM is also addressed, including the assessment of five different pseudo-HIP treatments and the weldability of the two cast superalloys is compared. Testing was conducted using the Varestraint (Variable-Restraint) weldability testing technique, where test plates were welded by a robot and at the same time bended to achieve external restraint. Welding and test parameters were the same for all the conditions. The hot cracking susceptibility of cast Alloy 718 was found to be worse with increasing HIP treatment temperature. It was found that HIP treatment conducted at 1190°C/4h gave higher crack susceptibility than the one at 1120°C/4h. Cast ATI® 718PlusTM was heat treated using short dwell heat treatments for 4h at 1120°C, 1160°C and 1190°C and long dwell heat treatments for 24h at both 1120°C and 1190°C, respectively. The cracking susceptibility was found to be related to the heat treatment dwell time rather than the temperature. The heat treatment at 4h dwell time exhibited lower amount of cracking than the 24h dwell heat treatment. Considering the comparative heat treatments at 1120°C/4h and 1190°C/4h, the new cast superalloy ATI® 718PlusTM was found to have lower cracking susceptibility than the cast Alloy 718.
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