Stainless steel 17-7PH, AISI 631, 1.4568, X7CrNiAl17-7 and UNS S17700 age hardened in accordance with ASTM A693, A313, A564, A705, EN 10088.

17-7PH, AISI 631, X7CrNiAl17-7, 1.4568 - specification and application

Stainless steel from the group of age-hardened PH with the highest content of Chromium - 17% and Nickel - 7% in relation to PH of grades 15-5 and 17-4. It has excellent strength properties, high hardness and elasticity, good corrosion resistance and resistance to high temperatures and deformation.
In terms of chemical composition, the corrosion resistance equals that of AISI 301 / 1.4310 steel, in terms of mechanical properties it is a much better choice for responsible parts and components exposed to fatigue. In the annealed state, the steel has an austenitic structure, after heat treatment of ageing it turns into martensite, increasing its strength properties along with obtaining magnetic properties.
The material is used on valve parts, tanks, springs, spring washers, food knives, diaphragms, low and high temperature parts, heat exchangers, special fittings and installations, machine constructions and components. Steel is intended for the aerospace, petroleum, chemical and petrochemical industries, energy, food and cryogenic industry in the form of strips, wires, sheets and bars.

17-7PH, S17700 according to ASTM A1082 - mechanical properties

• Annealed condition, saturated - Cond A
  • Rm: >1035 MPa
  • Rp0,2: >380 MPa
  • Elongation, A: >20%
  • Hardness: <92 HRB
• Hardened condition after ageing - Cond TH1050
  • Rm: >1170 MPa
  • Rp0,2: >965 MPa
  • Elongation, A: >6%
  • Necking, Z: >25%
  • Hardness: >38 HRC / >352 HB
• Hardened condition after ageing - Cond RH950
  • Rm: >1280 MPa
  • Rp0,2: >1030 MPa
  • Elongation, A: >6%
  • Necking, Z: >10%
  • Hardness: >41 HRC / >388 HB
• Condition after cold rolling - Cond C
  • Rm: >1380 MPa
  • Rp0,2: >1205 MPa
  • Elongation, A: >1%
  • Hardness: >41 HRC
• Condition after cold rolling + ageing - Cond CH900
  • Rm: >1655 MPa
  • Rp0,2: >1580 MPa
  • Elongation, A: >1%
  • Hardness: >46 HRB

X7CrNiAl17-7, 1.4568 - mechanical properties

• Delivery condition for sheets / strips +AT
  • Rm: < 1030 MPa
  • Elongation, A: >19%
• Delivery condition for sheets / strips + P1450
  • Rm: >1450 MPa
  • Rp0,2: >1310 MPa
  • Elongation, A: >2%
• Delivery condition for bars +AT
  • Rm: < 850 MPa
  • Hardness, HB: <255

Heat treatment of 17-7PH, S17700, AISI 631:

• Cond. A - Saturation at 1065O C
• Cond. TH1050 - Saturation at 1400 F (760 C) for 1.5 hours, cooled for 1 hour to 55 F (15 C) for 0.5 hours, then aged at 1050 F (566 C) for 1.5 hours
• Cond. RH950 - Saturation at 1750 F (954 C) for 10 minutes with air cooling, product cooling to -100F (-73 C) for about 1.5 hours, aging at 950 F (510 C) for 1 hour
• Cond. C - Condition after cold rolling
• Cond. CH900 - Cold rolled condition after ageing at 900 F (482 C) for 1.0 hours with air cooling