Effect of Heat Treatment Conditions on Microstructure and Mechanical Properties of Long Term Serviced Fe25Cr-35Ni Alloy

2012 ◽  
Vol 54 (6) ◽  
pp. 376-382 ◽  
Author(s):  
Kannika Hemmatad ◽  
Patama Visuttipitukul ◽  
Panyawat Wangyao ◽  
Gobboon Lothongkum
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Microstructure And Mechanical Properties ◽  
Treatment Conditions

scholarly journals Effect of heat treatment on the microstructure and mechanical properties of a low-carbon X80 pipeline steel

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
B.C. Acosta-Cinciri ◽  
N.M. López-Granados ◽  
J.A. Ramos-Banderas ◽  
C.A. Hernández-Bocanegra ◽  
P. Garnica-González ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Pipeline Steel ◽  
American Petroleum Institute ◽  
The Other ◽  
Low Carbon ◽  
Electron Backscattered Diffraction ◽  
X80 Pipeline Steel ◽  
Microstructure And Mechanical Properties ◽  
Treatment Conditions

Abstract In this work, the effect of heat treatment conditions on the microstructure and mechanical properties of an American Petroleum Institute (API) X80 steel with a low carbon content of ~0.02% wt., destined for the manufacture of pipelines and pipeline transmission systems by welding, was investigated. Samples were heat treated under different conditions and then were characterized by scanning electron microscopy (SEM), orientation image microscopy (OIM), and electron backscattered diffraction (EBSD). The results showed that when the steel is fastly cooled from the austenitic field (990°C), the mechanical properties increase significantly [ultimate tensile strength (UTS) >1,100 MPa, yield strength (YS) 900 MPa, and elongation 27%] due to the high percentage of martensite (M) present in the microstructure (95%). In contrast, when the cooling rate decreases and the treatment conditions remain at/or above the bainitic/martensitic transformation (from 990°C to 600°C and 450°C), the mechanical properties are decreased by almost 50% because of the decrease in the percentage of martensite (18%). However, the percentage of elongation increases significantly (38%) due to the presence of other micro-constituents resulting from the phase transformation. On the other hand, the best combination of mechanical properties (UTS above 800 MPa and YS between 610 MPa and 720 MPa) was obtained when the steel acquired a dual-phase microstructure [(martensite/austenite)-(ferrite/martensite)] since the amount of martensite is conserved between 45% and 82%, in combination with the other micro-constituent present in the steel that allows us to achieve elongation percentages close to 30%.

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