Shielded metal arc welding

About: Shielded metal arc welding is a research topic. Over the lifetime, 4462 publications have been published within this topic receiving 40560 citations. The topic is also known as: manual metal arc welding & flux shielded arc welding.

Numerical simulation of keyhole welding of aluminium thick plate with plasma arc

Abstract: Plasma arc welding can realize high-speed welding, deeper weld penetration and, furthermore, smaller thermal distortion. For these reasons, plasma arc welding is employed for keyhole welding. However, it has been pointed out that it is difficult to obtain the stability of the welding. In this study, we have developed a unified plasma arc welding model for analysing the welding mechanism and influence of the torch design and operation conditions of the arc on the welding process. In this paper, the keyhole welding of a thick aluminium plate employing the plasma arc was numerically analyzed for clarifying the mechanism determining the keyhole size which is important for improving the stability of the process. As a result, it was found that the keyhole size is determined mainly by a force balance between the surface tension of a weld pool and metal vapour pressure.

Laser build-up welding equipment and method

Abstract: PROBLEM TO BE SOLVED: To provide laser build-up welding equipment and method for repair welding of members composed of a single crystal material or unidirectionally solidified material, the equipment and method keeping height of reinforcement weld of a build-up welding zone constant thereby performing stable welding, even in the occurrence of variation in a reinforcement weld height in a build-up welding zone such as change in the surface condition or shape of a material to be welded. SOLUTION: The laser build-up welding equipment includes a laser beam irradiation mechanism which has an optical fiber 11 for transmitting a laser beam and a lens system 13 for forming a laser beam emitted from the optical fiber, a filler metal feeding mechanism for feeding a filler metal to a weld zone, and a shielding mechanism for blowing an inert gas to a weld zone. The apparatus further includes a displacement sensor 22 installed in a rear part relative to a scanning direction 19, a measuring instrument 24 for obtaining the reinforcement weld height of a build-up weld zone from the height of a material to be welded 21 surface before the build-up welding and from the height of the build-up welding zone 20 surface each measured by the displacement sensor 22, and a controller 25 for controlling welding conditions for the purpose of keeping the reinforcement weld height constant. COPYRIGHT: (C)2010,JPO&INPIT

Improvement of wear resistance of hot working tool steel by hardfacing Part 1 – Effect of microstructure and hardness

Abstract: Hardfacing is one of the most useful and economical ways to improve the performance of components subjected to severe wear conditions. The aim of the present work was to investigate the influence of hardfacing on the hardness and wear resistance of a hot working tool steel. Two cobalt based and one nickel based superalloys were used as hardfacing materials. Stellite 6 and 21 were deposited on H11 steel via tungsten inert gas (TIG) and shielded metal arc welding and Inconel 625 was deposited by TIG welding techniques. The pin on disc high temperature wear tests were carried out on hardfaced materials. The worn surfaces were also characterised using SEM and X-ray diffraction methods. The results showed that TIG hardfacings process having a low dilution, owing to the refined solidification structure and high capacity of work hardening enhances better wear resistance.

Investigation of the microstructure and impact properties of the high nitrogen stainless steel weld

Abstract: The high nitrogen stainless steel(HNS) is widespread attention in recent years because of the high strength,good toughness and corrosion resistance.Weld ability and welding efficiency are received extensive attention in the HNS welding.Using the double shielded TIG welding method,the active element,oxygen,was transferred into weld pool so as to change the convection of the liquid metal from outward to inward.This proposed welding process could effectively reduce the width of the pool surface,which is beneficial to reducing the overflow of nitrogen content in the weld.The influence of heat input(different welding current) on the weld pool shape and the impact properties of welds were investigated.The weld penetration increased with the increasing heat input and the 10 mm thick work piece was welded thoroughly under the 250 A welding current.The XRD test and calculation results showed that the 5 ferrite content in the welds was increased with the increasing welding current,while the impact properties of welds change little.The poor impact properties of the weld are another focus of this study.The fracture surfaces of the Charpy V-notch specimens were characterized using the scanning electron microscope(SEM).A large number of short-deep cracks and "skeleton-like" surfaces were observed on the fracture surfaces where were identified as containing (?) ferrite under energy spectrum analysis(EDS) using SEM.The interface between the (?) ferrite and austenite with low binding strength is considered to be the location of the cracks initiation.The cracks propagate along the interface between the two phases,and then causing brittle fracture of weld joints.