Experimental investigation on mechanical and metallurgical properties of super duplex stainless steel joints using friction welding process

The present study focuses on the metallurgical and corrosion characterization of post weld heat treated duplex stainless steel joints. After friction welding, it was confirmed that there is an increase in ferrite content at weld interface due to dynamic recrystallization. This caused the weldments prone to pitting corrosion attack. Hence the post weld heat treatments were performed at three temperatures 1080[Formula: see text]C, 1150[Formula: see text]C and 1200[Formula: see text]C with 15[Formula: see text]min of aging time. This was followed by water and oil quenching. The volume fraction of ferrite to austenite ratio was balanced and highest pit nucleation resistance were achieved after PWHT at 1080[Formula: see text]C followed by water quench and at 1150[Formula: see text]C followed by oil quench. This had happened exactly at parameter set containing heating pressure (HP):40 heating time (HT):4 upsetting pressure (UP):80 upsetting time (UP):2 (experiment no. 5). Dual phase presence and absence of precipitates were conformed through TEM which follow Kurdjumov–Sachs relationship. PREN of ferrite was decreasing with increase in temperature and that of austenite increased. The equilibrium temperature for water quenching was around 1100[Formula: see text]C and that for oil quenching was around 1140[Formula: see text]C. The pit depths were found to be in the range of 100[Formula: see text]nm and width of 1.5–2[Formula: see text][Formula: see text]m.

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Sensitivity Analysis of Flux Cored arc Welding Process Variables in Super Duplex Stainless Steel Claddings

Procedia Engineering ◽

10.1016/j.proeng.2013.09.180 ◽

2013 ◽

Vol 64 ◽

pp. 1030-1039 ◽

Cited By ~ 8

Author(s):

B. Senthilkumar ◽

T. Kannan

Keyword(s):

Sensitivity Analysis ◽

Stainless Steel ◽

Duplex Stainless Steel ◽

Arc Welding ◽

Welding Process ◽

Super Duplex Stainless Steel ◽

Process Variables ◽

Flux Cored Arc Welding ◽

Arc Welding Process

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Enhancing fatigue resistance of activated tungsten inert gas welded UNS S32750 super duplex stainless steel by optimizing its technological properties

Transactions of the Canadian Society for Mechanical Engineering ◽

10.1139/tcsme-2019-0246 ◽

2020 ◽

pp. 1-11

Author(s):

A. Arunmani ◽

T. Senthilkumar

Keyword(s):

Stainless Steel ◽

Fatigue Life ◽

Duplex Stainless Steel ◽

Fatigue Resistance ◽

Process Parameters ◽

Gas Flow ◽

Welding Process ◽

Travel Speed ◽

Inert Gas ◽

Super Duplex Stainless Steel

In engineering industries and heavy manufacturing plants, fatigue life of joints plays a pivotal role in determining the overall life span of the welded joint. In this paper, an advanced fusion joining technique, namely activated tungsten inert gas welding, was used for joining UNS S32750 super duplex stainless steel, with ZnO as activation flux. For the enhancement of fatigue resistance of joints, important welding process parameters were fluctuated according to a developed central composite design model. Empirical relationships were developed between the process parameters and the fatigue strength of the joints, which was correlated with the number of cycles to failure (NCF). Using analysis of variance, the significance of the developed fatigue model was ascertained. Using response surface methodology, optimization of process parameters for enhancement of fatigue resistance was done. It was observed that at the optimized activated tungsten inert gas weld process parameters of travel speed of welding torch at 69.85 mm/min, weld current at 125.20 A, and shielding gas flow rate at 14.77 L/min, a high fatigue life of 7.66396 × 108 NCF was obtained and the model was validated to very high predictability. Microstructural variations in the fatigue-tested specimens were evaluated for identifying the grain modifications.

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