304 Stainless Steel Tube

304 Stainless Steel Tube is one of the most sought-after austenitic stainless steels. It finds application in a range of applications that need high corrosion resistance and strength, such as food processing equipment, industrial machinery, chemical process/petrochemical vessels and marine products. As an economical yet versatile material choice for structural requirements such as food processing equipment, industrial machinery, chemical process/petrochemical vessels or marine products requiring excellent durability; 304 stainless steel tube makes an excellent choice.

Stainless steel tubes come in an extensive selection of shapes and sizes, having become the go-to material for stainless steel fabrication. Not only is stainless tubing easily weldable and machineable, but its mechanical properties make it suitable for many mechanical tasks.

Commonly employed in manufacturing and construction, 304 stainless steel tubes can be cold forged at low temperatures to provide added strength. They’re also capable of being machined with traditional subtractive processes like turning, milling, and grinding as well as modern cutting equipment like EDM or ECM.

Type 304 stainless steel is a chromium-nickel alloy renowned for its outstanding corrosion resistance and tensile strength. When annealed, this nonmagnetic metal cannot be magnetic but can be cold worked to increase hardness and tensile strength.

Its high chromium and nickel content make it an ideal choice for applications involving pitting, crevice or general corrosion resistance. This alloy can withstand most service temperatures while having a low carbon content that prevents carbides from forming harmful carbides.

A common defect in 304 stainless steel is grain boundary sensitization, which leads to the formation of chromium carbides at grain boundaries and destruction of austenite phase. This issue often stems from improper welding of alloy and exposure to high temperature for too long. The objective of this study was to identify whether there could be a potential mitigation strategy employed to avoid this issue from arising.

The ductile fracture theory was applied to the analysis of 304 stainless steel tubes subjected to pressure. Experimental creep tests at 9*32 and 7*36 MPa explored the influence of notch position on tube rupturing time; etched tubes experienced significant decreases in their radial wall thickness while unetched ones remained unchanged.

As the axial notch distance increased, X-ray diffraction (XRD) revealed a decrease in chromium content within a’-martensite, as indicated by its increasing volume fraction. This matches up perfectly with Kurdjumov-Sachs’ relationship for lattice coherency.

On hydraulic bulging, AISI 304 stainless steel tubes underwent a strain-induced austenite to martensite transformation within the hollow shaft. This transformation resulted in the formation of an ‘-martensite phase’ within austenite, maintaining lattice coherency throughout. Furthermore, twin crystallographic nature of AISI 304 stainless steel tubes at different positions after hydraulic bulging was discussed.

On a THF-1500T CNC internal high-pressure forming machine, an annealed 304 stainless steel tube was subjected to pressure-induced strain in order to create a hollow shaft. This experiment sought to investigate how a’-martensite affects both austenite-to-martensite transition behavior and hollow shaft composition.