Welding Metallurgy of

Characterizing the magnetic memory signals on the surface of plasma transferred arc cladding coating under fatigue loads

In this investigation, a nickel-base powder mixed with tungsten carbide particles was applied by Plasma Transferred Arc welding (PTA) on the surface of the D2 cold work tool steel to improve surface quality and to extend its lifetime during applications. The Design of Experiment (DoE) method was applied to obtain the appropriate combination of hardfacing parameters and to run the minimum number of tests. Current, travel speed and preheat were considered as variable parameters. These parameters are important to reach a final layer with an appropriate bead geometry accompanied with good metallurgical properties. All samples were prepared for metallurgical investigations and the effect of process parameters on the weld bead geometry was considered. For each experiment run, weld bead geometry parameters were measured including dilution, penetration and reinforcement. Microstructures and the distribution of tungsten carbide particles after welding were analyzed by Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) equipped with an EDS microprobe. In addition, hardness tests were performed to evaluate the mechanical properties of the weld bead layers. Finally, among all the experiments, the best sample with appropriate bead geometry and microstructure was selected.

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Metallurgical Characterization of a Weld Bead Coating Applied by the PTA Process on the D2 Tool Steel

This work is dedicated to optimization of carbide particle system in a weld bead deposited by PTAW technique over D2 tool steel with high chromium content. The paper reports partial melting of the original carbide grains of the Ni-based filling powder, and growing of the secondary carbide phase (Cr, Ni)
 $$_3$$
 W
 $$_3$$
 C in the form of dendrites with wide branches that enhanced mechanical properties of the weld. The optimization of bead parameters was made with design of experiment methodology complemented by a complex sample characterization including SEM, EDXS, XRD, and nanoindentation measurements. It was shown that the preheat of the substrate to a moderate temperature 523 K (250 
 $$^\circ $$
 C) establishes linear pattern of metal flow in the weld pool, resulting in the most homogeneous distribution of the primary carbides in the microstructure of weld bead.

Characterization and Optimization of Ni-WC Composite Weld Matrix Deposited by Plasma-Transferred Arc Process

Code of project : A-6/2561 Project name : Study on CMT welding technology of a steel in automotive manufacturing: weld bead geometry mechanical property and welding metallurgy Researcher name : Asst. Prof. Niwat Mookam, Dr.Uraiwan Pongsa and Mr.Phoometh Sangrayub In this research, the objective was to investigate and measure the weld bead geometry, mechanical property, and welding metallurgy when JIS G3113 steel are welded using CMT. The study examines a number of welding variables, including weld current (10, 12, 14, 16, and 18 V), and weld travel speed (25, 50, 75, 100, and 125 mm/min). The experiment was run using a CMT welding machine under an argon atmosphere. The quality of welded specimens was determined by their weld bead height, bead width, penetration, strength and microstructure. The optimal welding conditions were found to be 12 V of weld current and 25 mm/min of weld travel speed. The optimal welding conditions provided weld bead geometry and strength of quality which were able to pass the specifications of the making and inspecting welds on automotive steel. However, the welding travel speed no influence on the bead geometry, while the weld bead height, bead width and penetration exhibited a non-uniform pattern. After welding, only an Fe0.9Si0.1 intermetallic compound was observed in the microstructures. In addition, the larger degree of preferred orientation was detected at the {100} plane with a increase residual strain in the microstructure.

Study on CMT welding technology of a steel in automotive manufacturing: weld bead geometry mechanical property and welding metallurgy

Plasma Transferred Arc (PTA) process is increasingly used in applications where enhancement of wear, corrosion and heat resistance of metals surface is required. The shape of weld bead geometry affected by the PTA welding process parameters is an indication of the quality of the weld. PTA is a versatile method of depositing high-quality metallurgically fused deposits on relatively low cost surfaces. The overlay deposited is an alloy that is hard and more corrosion resistant than counterparts laid down by Gas Tungsten Arc Welding (GTAW) or Oxy Fuel Welding (OFW) processes. Weld deposits are characterized by very low levels of inclusions, oxides, and discontinuities. This process produces smooth deposits that significantly reduce the amount of post weld machining required. Metal-Mechanic industry continuously requires recovering tool steel components subjected to severe wear. The steel known as D2 is considered to be a high carbon, high chromium cold work tool steel. In this research, weld beads were deposited on D2 steel by using PTA process with different parameters as welding current and travel speed using base nickel filler metal. In order to evaluate the metallurgical features on the weld beads/substrate interface a microstructural characterization was performed by using Scanning Electron Microscopy (SEM) and to evaluate the mechanical properties was conducted the wear test.

Analysis of Weld Bead Parameters of Overlay Deposited on D2 Steel Components by Plasma Transferred Arc (PTA) Process

Among the different surface treatments used to improve the wear resistance of metallic materials, plasma transferred arc (PTA) is an attractive alternative to conventional techniques due to the intrinsic properties of its higher deposition rate, lower heat input and especially for the wide applicability of materials. The wide range of materials makes it possible to produce metallurgical bonding between the hardfacing layer and substrate material with very low dilution and distortion. Weld deposits are characterized by less level of inclusions, oxides, discontinuities and wear resistance. Metal-mechanic industry continuously requires recovering tool steel components subjected to severe wear. In this research Fe-based filler metal was deposited on D2 steel by using plasma transferred arc (PTA) process. The influence of Cr and Nb on Fe-based filler metal microstructure was investigated using scanning electron microscopy (SEM). In order to evaluate the mechanical properties were performed wear and hardness tests. The wear resistance and hardness values were compared with the results of a weld bead using nickel-based filler metal.

B. Vargas-Arista

Papers

Analysis of Weld Bead Parameters of Overlay Deposited on D2 Steel Components by Plasma Transferred Arc (PTA) Process

Influence of Cr and Nb on the Overlay Deposited on D2 Steel by Plasma Transferred Arc Process