Microstructure and Mechanical Properties of 34CrNiMo6 Steel Repaired by Friction Stir Processing

Wang, Zhongwen; Huang, Chunping; Liu, Fencheng; Xia, Chun-hong; Ke, Liming

doi:10.3390/ma12020279

Cited by 5 publications

(2 citation statements)

References 21 publications

(21 reference statements)

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“…34CrNiMo6 steel is a typical medium-carbon low-alloy steel widely used in the automobile industry for its high strength, good ductility, and excellent corrosion resistance [1][2][3]. However, its surface properties are often considered inadequate for certain engineering applications requiring high resistance to wear such as ring gears, valve stems, connecting rods, shackle pins, etc.…”

Section: Introductionmentioning

confidence: 99%

Metallurgical Characterization and Kinetics of Borided 34CrNiMo6 Steel

Uçar

Yigit

Çalık

2020

Advances in Materials Science

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Boriding of 34CrNiMo6 steel was performed in a solid medium consisting of Ekabor-II powders at 1123, 1173 and 1223 K for 2, 4 and 6 h. Morphological and kinetic examinations of the boride layers were carried out by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The thicknesses of the boride layers ranged from 22±2.3 to 145±4.1 depending on boriding temperature and time. The hardness of boride layer was about 1857 HV0.1 after boriding for 6 h at 1223 K, while the hardness of the substrate was only around 238 HV0.1. Growth rate constants were found to be between 1.2×10−13 – 9.8×10−13 m2/s depending on temperature. The activation energy for boron diffusion was estimated as 239.4±8.6 kJ mol−1. This value was comparable to the activation energies reported for medium carbon steels in the literature.

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Section: Introductionmentioning

confidence: 99%

Metallurgical Characterization and Kinetics of Borided 34CrNiMo6 Steel

Uçar

Yigit

Çalık

2020

Advances in Materials Science

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“…The applied powder particles bond to the substrate by mechanical clamping, which leads to tensile residual stresses and reduces the fatigue life of the deposited layers. Wu et al [7] studied the feasibility of repairing AISI 4340 components through friction stir processing (FSP). In this study filling blocks were used as filling material.…”

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confidence: 99%

Extreme High-Speed Laser Material Deposition (EHLA) of AISI 4340 Steel

Zhang

Bultel

et al. 2019

Coatings

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A variant of conventional laser material deposition (LMD), extreme high-speed laser material deposition (German acronym: EHLA) is characterized by elevated process speeds of up to 200 m/min, increased cooling rates, and a significantly reduced heat affected zone. This study focuses on the feasibility of using EHLA to apply material onto Fe-based substrate materials with AISI 4340 as a filler material. We studied how three different build-up strategies-consisting of one, three, and five consecutive deposited layers and hence, different thermal evolutions of the build-up volume-influence the metallurgical characteristics such as microstructure, porosity, hardness, and static mechanical properties. We propose a thermo-metallurgical scheme to help understand the effects of the build-up strategy and the thermal evolution on the microstructure and hardness. The tensile strength of the build-up volume was determined and is higher than the ones of forged AISI 4340 material.Coatings 2019, 9, 778 2 of 16 layer and substrate. The applied powder particles bond to the substrate by mechanical clamping, which leads to tensile residual stresses and reduces the fatigue life of the deposited layers. Wu et al. [7] studied the feasibility of repairing AISI 4340 components through friction stir processing (FSP). In this study filling blocks were used as filling material. The filler blocks were first fixed to the substrate by electron beam welding, then the filler blocks were joined to the material to be repaired using a friction stirrer. The results showed no defects in the repaired zone. The measured maximum tensile strength was 91.8% compared to that of a forged structure and a ductile-brittle fracture was observed.LMD has also widely been used to repair parts made of this low-alloy steel. LMD can be used to repair and functionalize surfaces thanks to its advantages, such as the metallurgical bonding between the deposited layer and the substrate [8], the defined and well controlled energy deposition [9], and the reduced heat affected zone (HAZ) [10]. Shi et al. [11] used laser cladding as a repair process for AISI 4340. They investigated the tensile strength of the samples after cladding. The specimens were prepared by adding a notch with the dimensions of 13.73 mm in length and 0.7 mm in thickness to the center of a plate-shaped substrate, and filling the notch with the AISI 4340 filler by LMD. Then, the excess cladded layer was removed by a CNC machine to generate a flat surface finish. The specimens were taken out from the plate and machined by wire cutting. Tensile test results indicated that the elongation of the specimen was 0.6%. An explanation for the brittleness was given by the detection of untempered martensite in the cladded area and the HAZ zone, which leads to high hardness and low ductility and toughness. Chew et al. [12] investigated the fatigue performance after cladding AISI 4340 on substrates out of the same material. The authors prepared the specimens by adding a pre-clad groove, filling the groove with AISI 43...

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