Name: MARIANA BERTONCELI SILVA
Type: MSc dissertation
Publication date: 29/04/2016
Examining board:
Name |
Role |
|---|---|
| MARCELO CAMARGO SEVERO DE MACÊDO | Internal Examiner * |
Summary: Supermartensíticos stainless steels are used in the oil and gas industry. They represent an economic alternative to duplex steels in the construction of pipelines "onshore" and "offshore" by offering lower production costs. These steels provide good corrosion resistance in environments containing CO2 and H2S. The unique combination of relatively low cost, high mechanical strength and corrosion resistance as well as good weldability becomes very attractive material. Other applications of stainless steels are related to turbine components, marine propellers, aircraft parts and ducts. The steel study was submitted to different thermal treatments of quenching and tempering, obtaining different microstructures characterized by thermodynamic analysis, optical microscopy and scanning electron. These were in turn related to corrosion resistance, by making use of electrochemical polarization tests with cyclic potentiodynamic polarization, and reactivation solution containing chloride [0.6M NaCl]. As regards the mechanical behavior, it was used as tools to Vickers hardness test and the Charpy instrumented. Only in simple quenching condition to 1000 ° C was observed sensitization and in some samples could be detected two potential pitting. As regards the mechanical behavior, due to tempering brittleness, the samples tempering at 500 ° C showed weak as to fracture propagation, different from the other heat treatment conditions studied.
Key-words: Supermartensitic Steel, Heat treatments, Microstructures, Corrosion, Hardness, Instrumented Charpy.
