M Yousefieh
,
M Shamanian
,
A Saatchi
钢铁研究学报(英文版)
The high corrosion resistance of duplex stainless steel (DSS) is due to elements such as Cr, Mo and N, but also depends on the microstructure. The best general properties are obtained with approximately equal amounts of austenite and ferrite and the absence of third phases such as σ (sigma) and Cr2N. In the present work the effect of heat input variations on the microstructure and corrosion resistance of a DSS UNS S32760 in artificial sea water media were studied. The corrosion resistance in 3.5% of NaCl solution was evaluated by potentiostatic polarization tests at room temperature. It is found that the presence of sigma phase and Cr2N decreases the corrosion potential. The specimen with heat input of approximately 0.95 kJ/mm have the best corrosion characteristics, which is the result for the lack of deleterious phases such as sigma and Cr2N and balanced ferrite-austenite proportion.
关键词:
steel
,
microstructure
,
corrosion
,
heat input
,
pulse current GTAW
Manpreet Singh Marwah
,
Vajjala Srinivas
,
Ajoy Kumar Pandey
,
Shyam Ranjan Kumar4
,
Koushik Biswas
,
Joydeep Maity5
钢铁研究学报(英文版)
Steel containing carbon of 02% was coated with Ni and Cr through electrodeposition, and subsequently annealed at 400 and 600 ℃ for 5 min, 30 min, 1 h and 2 h. During annealing at 400 ℃, the formation and growth of oxides occurred in the form of petals along with voids, cracks and porosities. However, at 600 ℃, the nucleation and growth of chromium oxide whiskers produced a surface almost free from crack, porosity and void for 1 h and 2 h of holding. In accordance with the surface morphology, the bare steel, as-deposited steel, all specimens deposited and annealed at 400 ℃, and specimens deposited and annealed at 600 ℃ for 5 and 30 min exhibited continuous corrosion in 3% of NaCl solution. However, the specimens deposited and annealed at 600 ℃ for 1 and 2 h exhibited an improved corrosion resistance in 3% of NaCl solution with high pitting potential due to presence of a dense passive oxide film almost free from voids at the surface.
关键词:
steel
,
electrodeposition
,
annealing
,
corrosion resistance
WEI Min-xian
,
WANG Shu-qi
,
WANG Lan
,
CHEN Kang-min
钢铁研究学报(英文版)
Elevated-temperature wear tests under atmospheric conditions at 400 ℃ were performed for a hot working die steel H21 on a pin-on-disk wear tester. The phase and morphology of worn surfaces were examined using XRD and SEM, and the relation of wear resistance to tempered microstructures was studied for H21 steel. XRD patterns exhibit that oxidative wear is a predominated wear mechanism with Fe3O4 and Fe2O3 on worn surfaces. It is found that with increasing normal load, obvious plastic deformation of substrate appears on worn surfaces. Microstructures start to affect apparently wear resistance of the steel with an increase of load. Under loads of 50-100 N, wear losses of steel retain low values and relatively approach for steels with various microstructures. As loads are increased to 150-200 N, wear losses of steel start to increase obviously and present apparent difference for steel with various microstructures. Wear resistance is found to increase in the sequence as follows: tempered sorbite, tempered martensite, tempered troostite without secondary hardening and tempered troostite with secondary hardening or upcoming one. Higher strength and microstructural stability are required for steels with excellent wear resistance.
关键词:
steel
,
heat treatment
,
microstructure
,
wear
,
wear resistance
