High Pressure Fatigue Testing of 160 KSI Yield Strength Stainless Steel Tubing
High pressure processes like water-jet cutting, hydroforming or LDPE production require high pressure tubing with nominal sizes of 2 to 90 mm for pressures of up to 4,000 bar. The most common materials for these applications are either cold drawn austenitic steels type 304 / 316 or low alloy martensitic steels from the A723 series. Recent developments in material technology made it possible to increase the yield strength of the cold drawn austenitic steel from 700 MPa to 1100 MPa maintaining high toughness values, even for relatively large tube sizes. This steel grade, referred to as “HP160” (nitrogen strengthened 21Cr 10Ni 3Mn 2.5Mo stainless steel), is now increasingly being utilised in the high pressure industry. In this paper the fatigue performance of HP160 under pulsating internal pressure will be compared to fatigue results from conventional steels. The results will also be compared with the requirements of the ASME high pressure code Section VIII Division 3.