Stainless Steel 329

Chemical Analysis
C Carbon
Mn Manganese
2.00 max
P Phosphorus
0.035 max
S Sulfur
0.015 max
Si Silicon
1.00 max
Cr Chromium
25.00 – 28.00
Mo Molybdenum
1.30 – 2.00
Ni Nickel
4.50 – 6.50
N Nitrogen
0.05 – 0.20

General characteristics of Stainless Steel 329

Type 329 is a duplex, austenitic – ferritic stainless steel, with good resistance to pitting and stress corrosion cracking.


The grade may be used for forged valve parts and pumps and for centrifugal machines


This grade should be forged between around 2280/1900ºF (1250/1050ºC.) Parts may be air cooled after forging.

Heat treatment


Parts should be solution annealed between 1870/2010ºF (1020/1100ºC) and water quenched. Approximately equal amounts of austenite and delta ferrite will be formed after solution annealing.


This grade is quite difficult to machine, perhaps more so than the normal 18/8 austenitics. Type 309 has only about 50 percent of the machinability index of type 316. It is recommended that the best possible machines and tooling be used for machining of parts made from this grade.


The duplex structure of this grade makes welding difficult. If welding is deemed necessary it is recommended professional advice be sought regarding filler metals, heat input rates and post weld heat treatment.


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