RELAXATION PEAKS OF COLD WORKED 304L STAINLESS STEEL

Abstract Microstructure development is examined for a specialized spot weld that is used as a solid-state closure process for stainless steel tubing, referred to as pinch welding. In order to elucidate the microstructural evolution of the weld, a series of test welds were made at nominal conditions using both tubes, used in test articles and production like components. These pinch welds normally terminate after twelve cycles of a 60 Hz AC weld process. In this study, tubes with different thermal processing history were welded from one to twelve cycles and the microstructure and weld variables after each individual weld cycle number were characterized using radiography and optical metallography. Two etchants were used that highlighted different microstructural features. The study revealed that: (1) this type pinch weld is largely complete after about six cycles of 60 Hz AC current, half the weld time utilized; (2) the resistance, deformation, and closure length approach “steady state” conditions after six cycles; and (3) both oxalic and nitric acid electrolytic etchants are useful for highlighting specific microstructural attributes of type 304L stainless steel. Finally, two distinct microstructural regions can be identified for these welds: the edge of the weld which is driven by concentrated deformation, recrystallization and grain growth and the center region which is more typical of forge welding and micro-asperity breakdown followed by diffusion and grain-growth. The bond line of annealed tubes exhibits fewer indications and less contamination than that of the partially annealed and as-received cold worked tubes.

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Fatigue Crack Growth of Cold Worked 304L Stainless Steel in Gaseous Hydrogen

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.378.140 ◽

2013 ◽

Vol 378 ◽

pp. 140-144

Author(s):

T.C. Chen ◽

C.T. Hsieh ◽

L.W. Tsay

Keyword(s):

Stainless Steel ◽

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Surface Hardness ◽

Base Plate ◽

Gaseous Hydrogen ◽

304L Stainless Steel ◽

Strain Induced Martensite ◽

Cold Worked

The fatigue crack growth behaviors of cold worked 304L stainless steel (SS) in air and gaseous hydrogen were evaluated, and further compared with the base plate. Cold rolling caused a rise in surface hardness and induced austenite to martensite transformation of 304L SS. Despite of testing environment, the fatigue crack growth rate (FCGR) of the cold worked specimen was higher than that of the base metal. Furthermore, both kinds of specimens were susceptible to hydrogen-accelerated crack growth. Mainly quasi-cleavage fracture related with the strain-induced martensite together with separation along twin boundaries accounted for the accelerated crack growth of the specimens in hydrogen.

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J&L TYPE 309

Alloy Digest ◽

10.31399/asm.ad.ss0896 ◽

2003 ◽

Vol 52 (12) ◽

Keyword(s):

Stainless Steel ◽

Corrosion Resistance ◽

High Temperature ◽

Elevated Temperature ◽

Physical Properties ◽

Heat Treating ◽

Good Combination ◽

Resistance To Oxidation ◽

Cold Worked ◽

Specialty Steel

Abstract Type 309 (UNS S30900) is an austenitic chromium-nickel stainless steel widely used for elevated-temperature services. It has a good combination of oxidation resistance and corrosion-resisting properties. The alloy is essentially nonmagnetic when annealed and become slightly magnetic when cold worked. It is intended primarily for high-temperature applications at 816 deg C (1500 deg F) or higher where resistance to oxidation and/or corrosion is required. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as creep. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-896. Producer or source: J & L Specialty Steel Inc.

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CARPENTER PROJECT 70+ TYPE 304/304L

Alloy Digest ◽

10.31399/asm.ad.ss0875 ◽

2003 ◽

Vol 52 (2) ◽

Keyword(s):

Stainless Steel ◽

Corrosion Resistance ◽

Physical Properties ◽

Heat Treating ◽

General Purpose ◽

304L Stainless Steel ◽

Type 304 ◽

Complex Parts

Abstract Carpenter Project 70+ Type 304/304L is a modified version of Type 304/304L stainless steel with improved machinability when compared to conventional 304 (Alloy Digest SS-418, revised September 1997) and 304L (Alloy Digest SS-513, revised November 1997). The alloys are nonhardenable austenitic chromium-nickel steels and are good general-purpose materials for simple and complex parts. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-875. Producer or source: Carpenter Specialty Alloys.

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