Effect of heat treatment temperature on microstructure and tensile properties of austenitic stainless 316L using wire and arc additive manufacturing

In the present study, effects of heat treatment on microstructures and tensile properties of the cylindrical bars of Ti-48Al-2Cr-2Nb (at.%) alloy with unique layered microstructure consisting of equiaxed γ grains region (γ band) and duplex-like region fabricated by electron beam melting (EBM) were investigated. We found that it is possible to control width of the γ bands (Wγ) by heat treatments at 1100°C and 1190°C. The Wγ increases with decreasing heat treatment temperature. The bars heat-treated at 1190°C exhibit high elongation of 2.9% at room temperature (RT) with maintaining high strength. The RT elongation increases with increasing the Wγ because of increasing deformable regions. In contrast, the RT elongation of the bars decreases with increasing the Wγ when Wγ is very large. This is because the large γ band leads intergranular fracture. These results indicate that there is appropriate width for the γ band to obtain excellent tensile properties at RT.

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Research on the influence of heat treatment temperature on bearing capacity of high steel grade pipeline during in-service welding

MATEC Web of Conferences ◽

10.1051/matecconf/202135301020 ◽

2021 ◽

Vol 353 ◽

pp. 01020

Author(s):

Yan Xu ◽

Yinglai Liu ◽

Xianghui Nie ◽

Zhenjun Feng ◽

Liang Li ◽

...

Keyword(s):

Heat Treatment ◽

Tensile Strength ◽

High Temperature ◽

Yield Strength ◽

Bearing Capacity ◽

Tensile Properties ◽

Heat Treatment Temperature ◽

Heating Temperature ◽

Treatment Temperature ◽

Steel Grade

During the welding of in-service pipeline, natural gas is continuously transported in the pipeline, which maintains a high gas pressure. Therefore, the welding process is completed under strong cooling conditions, and welding delay crack is easy to occur. Preheating before welding and heat treatment after welding can effectively control the hardened microstructure, reduce the residual stress and ensure the welding quality. In this study, the influence of heating temperature on the bearing capacity of high steel grade pipe during in-service welding repair was studied. The high temperature tensile test was used to simulate the bearing capacity of the pipe under heating and high temperature environment. It is found that when the heating temperature is below 400°C, the pipe strength remains at the original level. With the increase of heating temperature, when the test temperature is higher than 400°C, the yield strength and tensile strength of the pipe decrease significantly. When the test temperature is 450°C, the yield strength and tensile strength of the material decrease by 15.8% and 11.1%, respectively, compared with the normal temperature, which are lower than the pipe standard requirements. Therefore, it is suggested that when the heat treatment temperature is higher than 400°C during in-service welding repair, it is necessary to consider reducing the pipeline pressure. At the same time, the box furnace heat treatment method was adopted to heat treat the pipe, and the tensile properties of the pipe after heat treatment were tested to analyze the bearing capacity of the pipe after heat treatment. It is found that when the heating temperature is higher than 700°C, the tensile properties of high grade pipeline steel pipe decrease sharply. It is suggested that when the heat treatment temperature is higher than 700°C, the risk assessment of the service safety of the heat treated pipeline should be carried out.

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Cold Sprayed Additive Manufacturing of SiC/Al Metal Matrix Composite: Synthesis, Microstructure, Heat Treatment and Tensile Properties

Materials Science Forum ◽

10.4028/www.scientific.net/msf.932.62 ◽

2018 ◽

Vol 932 ◽

pp. 62-75 ◽

Cited By ~ 4

Author(s):

L. Gyansah ◽

N.H. Tariq ◽

J.R. Tang ◽

X. Qiu ◽

J.Z. Gao ◽

...

Keyword(s):

Heat Treatment ◽

Tensile Strength ◽

Additive Manufacturing ◽

Tensile Properties ◽

Metal Matrix Composite ◽

Matrix Composite ◽

Metal Matrix ◽

Treatment Temperature ◽

X Ray ◽

Treatment Conditions

In this study, cold spray technique was used as a solid-state additive manufacturing route to deposit a 5 mm thick SiC /Al metal matrix composite. Microstructure and tensile properties were analyzed via different heat treatment conditions (200 oC, 300 oC, 400 oC and 500 oC). Microstructure evolutions were characterized via scanning electron microscopy, X-ray diffraction (XRD) and energy-disperse X-ray spectroscopy (EDS), whilst mechanical properties were investigated via micro-tensile and hardness tests. It was established that the as-sprayed deposit fractured in a brittle manner and had appreciable tensile strength (85 MPa) mainly associated with intensive work hardening effect. At heat treatment conditions, tensile strength (104 MPa) and plasticity (1.5 %-5.2 %) were enhanced due to coarsening of pure Al splat through recrystallization-recovery-grain growth mechanisms. The splat size which controls strength changes from 30.9 ± 2.6 μm to 40.9 ± 4.8 μm, an appreciation of 32 % as heat treatment temperature increased. The main fracture mode at the heat treatment state was a ductile fracture. For plastically deformed splats, the flattening ratios (FR) revealed the top (1.5), middle (1.9) and near interfacial regions (2.2) due to peening effect of SiC particles. The Young moduli were in agreement with the experimental results.

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