Comparison of Hot Cracking Susceptibility of TIG and Laser Beam Welded Alloy 718 by Varestraint Testing

Metals

Noelia Ruiz¹  Pedro Rodríguez¹  Fernando Santos²  Andrea Niklas²  Ana Magaña²  Lexuri Vázquez³  Pedro Alvarez³ 

[1] Alfa Investigación, Desarrollo E Innovación, Torrekua 3, 20600 Eibar, Spain;IK4-AZTERLAN, Aliendalde Auzunea 6, 48200 Durango, Spain;IK4-LORTEK Technological Centre, Arranomendia kalea 4A, 20240 Ordizia, Spain;

关键词: hot cracking;    Ni superalloys;    alloy 718;    varestraint test;    TIG welding;    laser beam welding;    grain size;   

DOI  :  10.3390/met9090985

来源: DOAJ

【 摘 要 】

Reduced hot cracking susceptibility is essential to ensure the flawless manufacturing of nickel superalloys typically employed in welded aircraft engine structures. The hot cracking of precipitation strengthened alloy 718 mainly depends on chemical composition and microstructure resulting from the thermal story. Alloy 718 is usually welded in a solution annealed state. However, even with this thermal treatment, cracks can be induced during standard industrial manufacturing conditions, leading to costly and time-consuming reworking. In this work, the cracking susceptibility of wrought and investment casting alloy 718 is studied by the Varestraint test. The test is performed while applying different welding conditions, i.e., continuous tungsten inert gas (TIG), low frequency pulsed TIG, continuous laser beam welding (LBW) and pulsed LBW. Welding parameters are selected for each welding technology in order to meet the welding quality criteria requested for targeted aeronautical applications, that is, full penetration, minimum cross-sectional welding width and reduced overhang and underfill. Results show that the hot cracking susceptibility of LBW samples determined by the Varestraint test is enhanced due to extended center line hot cracking, resulting in a fish-bone like cracking pattern. On the contrary, the minor effect of material source (wrought or casting), grain size and pulsation is observed. In fact, casting samples with a 30 times coarser grain size have shown better performance than wrought material.

【 授权许可】

Unknown