Evolution of δ ferrite in a CF3 cast stainless steel upon neutron irradiation to 3, 5, 10, 20, and 40 dpa

Heat-affected zone (HAZ) of welding joints critical to the equipment safety service are commonly repeatedly welded in industries. Thus, the effects of repeated welding up to six times on the microstructure and mechanical properties of HAZ for AISI 304N austenitic stainless steel specimens were investigated by a Gleeble simulator. The temperature field of HAZ was measured by in situ thermocouples. The as-welded and one to five times repeated welding were assigned as-welded (AW) and repeated welding 1–5 times (RW1–RW5), respectively. The austenitic matrices with the δ-ferrite were observed in all specimens by the metallography. The δ-ferrite content was also determined using magnetic and metallography methods. The δ-ferrite had a lathy structure with a content of 0.69–3.13 vol.%. The austenitic grains were equiaxial with an average size of 41.4–47.3 μm. The ultimate tensile strength (UTS) and yield strength (YS) mainly depended on the δ-ferrite content; otherwise, the impact energy mainly depended on both the austenitic grain size and the δ-ferrite content. The UTS of the RW1–RW3 specimens was above 550 MPa following the American Society of Mechanical Engineers (ASME) standard. The impact energy of all specimens was higher than that in ASME standard at about 56 J. The repeated welding up to three times could still meet the requirements for strength and toughness of welding specifications.

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The effects of morphology of ferrite and non-metallic inclusions on corrosion behaviour of as-cast 304 stainless steel

CORROSION ◽

10.5006/3763 ◽

2021 ◽

Author(s):

Danbin Jia ◽

Liangcai Zhong ◽

Jingkun Yu ◽

Zhaoyang Liu ◽

Yuting Zhou ◽

...

Keyword(s):

Stainless Steel ◽

Corrosion Resistance ◽

Corrosion Behaviour ◽

Solidification Process ◽

Inclusion Size ◽

304 Stainless Steel ◽

Experimental Conditions ◽

Quenching Temperature ◽

Δ Ferrite ◽

Metallic Inclusions

The effects of morphology of ferrite and non-metallic inclusions on corrosion resistance of as-cast 304 stainless steel (304 SS) were investigated. With the decrease in quenching temperature from 1723 K to 1648 K, the different microstructures of the as-cast 304 SS were obtained as the following series: austenitic-lathy δ ferrite, austenitic-colony δ ferrite and austenitic-blocky δ ferrite, and the average inclusion size increased. The electrochemical results show that the sample with the microstructure of austenitic- lathy δ ferrite and smaller size inclusions had a higher corrosion tendency and the lower pitting resistance. Furthermore, the effect of morphology and content of ferrite on corrosion resistance was greater than that of inclusion size under the current experimental conditions. Therefore, a promising method was developed to improve the corrosion resistance of as-cast 304 SS by changing the solidification process.

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FEM Simulation of Waves Excited by Array Probe Propagating in Centrifugally Cast Stainless Steel With Hexagonal Column

10.1115/qnde2021-75766 ◽

2021 ◽

Author(s):

Shan Lin ◽

Yasushi Ikegami

Keyword(s):

Stainless Steel ◽

Fem Simulation ◽

Transversely Isotropic ◽

Primary Coolant ◽

Centrifugally Cast ◽

Anisotropic Property ◽

Array Probe ◽

Columnar Grains ◽

Promising Solution ◽

Cast Stainless Steel

Abstract Centrifugally cast stainless steel (CCSS) is widely used in PWR primary coolant systems. However, ultrasonic testing for such material is very challenging because its coarse grains and anisotropic property. The phased array ultrasonic technology (PAUT) is considered the most promising solution to the problem mentioned. To improve the accuracy of PAUT for CCSS with columnar grains, we used the voxel-based finite element method to perform simulation of wave propagation in CCSS, where waves were excited by a linear array. We modeled columnar grains in CCSS with hexagonal columns and introduced a side-drilled hole. It was easily to have different inclined columnar grains by rotating the crystal axes. All column crystals were considered cubic crystals while CCSS with columnar grains was macroscopically transversely isotropic. Wave propagations were computed for different focal laws and their results were compared. Waves exactly propagated toward and focused at the targeted SDH when focal laws were calculated according to the anisotropic property of CCSS, but deviated the target for focal laws based on isotropy.

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Identification and Location of Small Lead Particles Dispersed in As-Cast Stainless Steel / Bestimmung und Lokalisierung kleiner, in rostfreiem Stahl dispergierter Bleipartikeln

Practical Metallography ◽

10.1515/pm-1971-080505 ◽

1971 ◽

Vol 8 (5) ◽

pp. 300-308

Author(s):

Mario Sarracino ◽

Filippo S. Rossi

Keyword(s):

Stainless Steel ◽

Cast Stainless Steel

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377. Corrosion by commercial sodium hypochlorites and its inhibition

Journal of Dairy Research ◽

10.1017/s0022029900005240 ◽

1949 ◽

Vol 16 (1) ◽

pp. 23-38 ◽

Cited By ~ 9

Author(s):

G. H. Botham ◽

G. A. Dummett

Keyword(s):

Stainless Steel ◽

Sodium Silicate ◽

Sodium Hypochlorite ◽

Storage Conditions ◽

Simple Equation ◽

Nickel Silver ◽

Copper Nickel ◽

Dairy Equipment ◽

Cast Stainless Steel ◽

Bactericidal Efficiency

Commercial sodium hypochlorites, whether containing KMnO4 or not, are shown to be corrosive at 150 p.p.m. available chlorine and 40° C. to metals such as aluminium, tinned copper, nickel silver and cast stainless steel (18 Cr, 8 Cu, 3 Mo) which are used in dairy equipment. Hypochlorites containing KMnO4 when aged are potentially dangerous to wrought 18/8 stainless steel. The attack is by pitting and therefore especially dangerous to all the metals investigated, and, in general, increases with increase of time of exposure and temperature.Decay of sodium hypochlorite solutions results in conversion of NaOCl to NaCl and NaC103, which reaction is shown to follow a simple equation fairly closely in various storage conditions.Attack on metals by sodium hypochlorite can be efficiently inhibited by addition of sodium silicate, which has a specific action in addition to the effect exerted by increase of alkalinity. NaOH and Na2CO3 additions to the same pH are not so effective and increase attack on aluminium.Increase of pH from 9 to 10·5 by addition of Na2CO3 or sodium silicate reduces bactericidal efficiency of hypochlorites to the same extent.

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