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Affiliation of Author(s):材料科学与技术学院

Title of Paper:Research on the microstructure and properties of laser-MIG hybrid welded joint of Invar alloy

Journal:OPTICS AND LASER TECHNOLOGY

Key Words:Laser-MIG hybrid multi-layer welding Invar alloy Thick plate Micro-structure Mechanical property

Abstract:In order to solve the problem of large deformation, low production efficiency and high tendency of hot cracking in welding 19.05 mm thick plates of Fe36Ni Invar alloy, laser-MIG hybrid multi-layer welding technique (LMHMW) has been developed. To investigate the influence of different welding parameters on the joint properties, optical microscope observation, SEM, EDS and microhardness measurement were conducted. Experimental results illustrated that different matching of welding parameters significantly affected the depth-to-width ratio, formation of defects and HAZ width. Besides, weld zone were consisted of two regions according to the different grain shape. The region near center of weld seam (region 1) was columnar dendrite induced by laser, while the region far away from weld seam center (region 2) was cellular dendrite which was mainly caused by MIG arc. The peak value of microhardness appeared at the center of weld seam since the grains in region 1 were relatively fine, and the lowest hardness value was obtained in HAZ. In addition, results showed that the sheets can be welded at optimum process parameters, with few defects such as, surface oxidation, porosity, cracks and lack of penetration in the welding seam: laser power of backing weld P = 5500 W, welding current I = 240 A, welding speed v =1 m/min. laser power of filling weld P = 2000 W, welding current I = 220 A, welding speed v = 0.35 m/min. laser power of cosmetic weld P = 2000 W, welding current I = 300 A, welding speed v = 0.35 m/min. (C) 2017 Elsevier Ltd. All rights reserved.

ISSN No.:0030-3992

Translation or Not:no

Date of Publication:2017-12-01

Co-author:Zhang Dan,Wei Yanhong,Wang, Yuhua

Correspondence Author:Xiaohong Zhan