Additive friction stir processing and hybrid metal additive manufacturing of high melting point materials: A review

Ever since the beginning of 4th industrial revolution, metal additive manufacturing has revolutionized the paradigm of printing high melting point materials. In this context, this paper reviews experimental and computational aspects of friction stir processing and hybrid techniques applied for metal additive manufacturing of high melting point materials like steel, and titanium alloys. Initially, friction stir processing working principle has been discussed. Secondly, friction stir processing is compared with other severe plastic deformation techniques and summarized their advantages, disadvantages and applications in a tabular form. Then based on the state-of-the-art of literature, additive friction stir processing and hybrid metal additive manufacturing processes are discussed for high melting point materials and results have been presented with respect to their microstructural developments, mechanical behavior, etc. Finally, gaps are highlighted for high melting point materials that shows importance of selecting process parameters, tooling capacity, computational analysis, mathematical modelling, etc., and presented these as future scope of work

Experimental and numerical investigation of laser-FSW hybrid welding technique for high strength materials

Friction stir welding (FSW) of high-strength materials and thicker plates has a number of challenges that are preventing widespread industry application such as (i) premature tool failure, (ii) selection of tool material and design, and (iii) weld productivity. A finite element (FE) based analysis for Laser-FSW hybrid welding technology is carried out in ABAQUS, commercially accessible FE software, to solve these typical difficulties. The thermal analysis of Laser-FSW hybrid technique is done using two moving heat sources for the case of 3.2 mm thick S45C steel plate. A negative moving heat source is placed as a replacement of the backing plate material in the high contact pressure region under the FSW tool. It was shown that the laser heat source needs to be 10 mm ahead of the FSW tool for achieving the duplex phase (Ferrite + Bainite/Martensite) microstructure. © 202

Stir zone anisotropic work hardening behavior in friction stir processed EN8 medium carbon steel

The SZ anisotropic work hardening behavior in duplex ferrite-martensite phase (DFM) microstructures has not been investigated yet. It is an important consideration for the selection of the stretch formability direction of the friction stir processed blank used for sheet metal forming applications. The anisotropic work hardening behavior is characterized by using miniature tensile specimens prepared along longitudinal (LD) and transverse (TD) directions. The tribological parameters such as coefficient of friction (COF) and wear rate at LE value of 6 are 0.57 and 0.5×10−10 m3/Nm. The effect of surface texture on the work hardening response is observed to be negligible. The plastic anisotropy in terms of three and multi-stage work hardening behaviors is investigated at a linear energy (LE) value of 6. The global true stress-strain responses and fracture surface morphologies suggested that the deformation occurs in different stages. In the initial stage, the deformation is mainly localized in the soft ferrite phase followed by the distinct work hardening stages in the plastic flow curves. In the elastic and elastoplastic region of the flow curve, the soft ferrite phase plastically deformed, followed by stress transfer to the martensite/retained austenite phases in the fully plastic region. The (110) and (111) pole figure suggested that the active in-habit-plane slip system is (110) and [11‾1]. The strain localizes more in the V19 + V22 block having the critical resolved shear stress (CRSS) value of 445.5 MPa. The retained austenite (RA) is having (−11−1)A//(0−11)F and [011]A//[111]F type Kurdjumov-Sachs (K–S) orientation relationship with the ferrite phase. A BCC {112} -type twinned laths is found to be present within the martensite laths. The recommended stretch formability direction (SFD) should coincide with the longitudinal or processing direction of the friction stir processed blank