Welding Metallurgy of

Processing of dual phase steel with fine ferrite grains containing nanometric carbides and chain-like morphology of martensite from a 0.035C-0.005N-0.035Si-0.268Mn mild steel was realized via application of high cold rolling reductions, intercritical heat treatment, and room-temperature aging, which showed a yield stress (YS) of 450 MPa and ultimate tensile strength (UTS) of 700 MPa. It was revealed that significant enhancements in tensile properties can be achieved compared to the separate effects of intercritical annealing (YS of 130 MPa and UTS of 385 MPa), cold rolling and intercritical annealing (YS of 300 MPa and UTS of 600 MPa), and quench aging (YS of 275 MPa and UTS of 520 MPa). The results were rationalized based on the grain size strengthening, aging effect, and work-hardening behavior.

Improved mechanical properties of mild steel via combination of deformation, intercritical annealing, and quench aging

The void formation and plastic deformation micromechanisms of a cold-rolled DP600 steel during tensile loading were studied by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The SEM observations revealed that the main void nucleation mechanism in the DP600 steel is decohesion at the ferrite–martensite interfaces. The voids were mostly observed between the closely spaced martensite islands situated at the boundaries of relatively finer ferrite grains. The EBSD results indicated a strain gradient developed from the ferrite–martensite and ferrite–ferrite interfaces into the interior of ferrite grains during the tensile deformation, which led to a stress concentration at these interfaces. Moreover, it was demonstrated that local misorientation inside the finer ferrite grains surrounded by martensite islands was higher than that for the coarser ferrite grains, which made the former more prone to void initiation.

Void Formation and Plastic Deformation Mechanism of a Cold-Rolled Dual-Phase Steel During Tension

Texture, microstructure and mechanical properties of laser beam welded AISI 2507 super duplex stainless steel

Study and selection of most appropriate filler rod for GTAW of S32750 super duplex steel joints: A comprehensive study on microstructural, mechanical and corrosion properties

The Effect of Welding Heat Input on the Structure–Property Relationship of a New Grade Super Duplex Stainless Steel

Comparison of Microstructure and Tensile Properties of Dual Phase Steel Welded Using Friction Stir Welding and Gas Tungsten Arc Welding

Effect of Welding Parameters on the Microstructure and Tensile Properties of Friction Stir-Welded DP600 Steel

High-strength low alloy steels are a class of steels used in applications that require high strength and good weldability, including ship hulls, gas pipelines and oil industry. One way to build parts is fusion welding that create areas with a large grain size in the heat-affected zone and increased susceptibility to hydrogen cracking. One way to solve this problem is to use solid state friction stir welding process. In this study, microstructural evaluation and mechanical properties of friction stir welding X-60 cross sections examined by optical microscope and by tensile and micro-hardness tests. The results indicate that changing welding parameters and thereby, change the heat input during friction stir welding have a great impact on maximum temperature and cooling rate that cause creating ferrite and bainitic ferrite in the weld zone. This change in microstructure of weld zone cause to improve mechanical properties that increase yield strength from 380 MPa to 420 MPa .Also, the friction stir process cause increasing hardness of 220 Vickers to an average of 280 Vickers and uniform distribution of hardness in the cross-section of friction stir joints.

Effect of Heat Input on Microstructure and Mechanical Properties in Friction Stir Welding of HSLA-60

In this research, in situ ultrafine Al–Ni intermetallics were fabricated as reinforcement in the aluminum matrix by Friction Stir Process (FSP). Activated and non-activated powders were used as reinforcement agents. The FSP was performed under the rotating speed of 1250rpm, traverse speed of 24, 32, 44 and 62mm/min to fabricate composite. Scanning Electron Microscopy, Optical Microscopy and XRD patterns were used for microstructural observations and phase analysis of fabricated composite, respectively. In this study, it is shown that by using nickel powder (non-activated), only Al3Ni compound is formed during FSP. But in the fabricated composite with activated powder because of increasing grain boundaries and dislocation during ball milling, Al3Ni2, Al3Ni and AlNi may be formed. Using activated powder creates ultrafine intermetallic reinforcements and causes more uniform distribution of intermetallics.

M. Shamanian

Papers

The Effect of Welding Heat Input on the Structure–Property Relationship of a New Grade Super Duplex Stainless Steel

Comparison of Microstructure and Tensile Properties of Dual Phase Steel Welded Using Friction Stir Welding and Gas Tungsten Arc Welding

Effect of Welding Parameters on the Microstructure and Tensile Properties of Friction Stir-Welded DP600 Steel

Effect of Heat Input on Microstructure and Mechanical Properties in Friction Stir Welding of HSLA-60

Fabrication of in situ nickel intermetallic compound dispersed aluminum matrix composites by friction stir process