Changes of Microstructure and Grainsize of Martensitic Stainless Steel during the Processes of Hot Reversed Extrusion, Broaching and Heat Treating

Abstract:

The field of high pressure steel cylinders (HPSC) used for the variety of applications, such as storage of technical gases, compressed natural gas (CNG), medical gases and special applications like scuba diving cylinders is still significantly expanding. With increasing safety requirements, the need of new techniques applied in field of HPSC structural and materials innovations comes into place.Speaking mainly about the field of scuba diving cylinders, the need of corrosion protection of inner surface comes in place due to the possible risk of valve blockage by metal corroded particles of inner surface. Even such a risk occurs in extremely rare occasions, there was until now no generally applied solution (such as inner wet, powder or Teflon coating, etc.) due to significantly high costs of such additional inner surface protection. Another problem that occurs so far are significant visual imperfections of scuba diving cylinders caused by the rough treating by scuba divers during the use and manipulation that causes chipping of outer surface painting and subsequent corroded areas.The breakthrough solution is the scuba diving cylinder made of a stainless steel by the processes of reversed extrusion and broaching from billet without any need of an additional coating. No such a product was made so far by these methods of production and no evidence of an evolution of the microstructure and grainsize changes during such manufacturing with subsequent heat treating was ever documented and analysed.

• Periodical: Materials Science Forum (Volume 891)
• Pages: 143-148
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.891.143
• Online since: March 2017
• Authors: Pavel Kučera*, Eva Mazancová
• Keywords: Broaching, Heat Treatment, High Pressure Steel Cylinders, Reversed Broaching, Reversed Extrusion, Stainless Steel

References

[1] P. Kučera, E. Mazancová, 34CrMo4 steel resistance against the SSS after controlled cooling process, Mater. Eng. 21 (2014) 61-67.

[2] R. Kunc, I. Prebil, Low-cycle fatigue properties of steel 42CrMo4, Mat. Sci. Eng. A 345 (2003) 278-285.

DOI: 10.1016/s0921-5093(02)00464-1

[3] ISO 9809-4: 2014, Gas Cylinders – Refillable seamless steel gas cylinders – Design, construction and testing – Part 4: Stainless steel cylinders with an Rm value of less than 1100 MPa, Geneva, ISO, (2014).

DOI: 10.3403/30251284

[4] S.V.S. Far, M. Ketabchi, M.R. Nourani, HPT deformation characteristics of 34CrMo4 steel, J. Iron Steel Res. 17 (2010) 65-69.

DOI: 10.1016/s1006-706x(10)60199-9

[5] P. Kučera, E. Mazancová, Mechanical and structural response of AISI 4135 steel after controlled cooling process, Metalurgija 55 (2016) 165-168.

[6] F. Nűrnberger, O. Grydin, Z. Yu, M. Schaper, Microstructural behaviour of tempering steels during precision forging and quenching from hot-forming temperatures, Metall. Mining Ind. 3 (2011) 79-86.

[7] A. Alvino, A. Antonini, D. Lega, Failure analysis on a fractured 34CrMo4 steel high pressure cylinder filled with a mixture of inert gases, Eng. Fail. Anal. 38 (2014) 49-57.

DOI: 10.1016/j.engfailanal.2014.01.004

[8] L. Schäfer, Influence of delta ferrite and dendritic carbides on the impact and tensile properties of martensitic chromium steel, J. Nuclear Mater. 258-263 (1998) 1336-1339.

DOI: 10.1016/s0022-3115(98)00200-1

[9] P. Wang, S.P. Lu, N.M. Xiao, D.Z. Li, Y.Y. Li, Effect of delta ferrite on impact properties of low carbon 13Cr-4Ni martensitic stainless steel, Mater. Sci. Eng. A 527 (2010) 3210-3216.

DOI: 10.1016/j.msea.2010.01.085

[10] ISO 9809-2: 2010, Gas Cylinders – Refillable seamless steel gas cylinders – Design, construction and testing – Part 2: Quenched and tempered steel cylinders with tensile strength greater than or equal to 1100 MPa, Geneva, ISO, (2014).

DOI: 10.3403/30085141

[11] M. Boniardi, A. Casaroli, Stainless Steels, first ed., Politecnico di Milano, Dep. di Meccanica, Milano, (2014).

[12] A.J. Sedriks, Corrosion of stainless steels, second ed., John Wiley & Sons, NewJersy, (1996).