SUS 321 vs SUS 316 Stainless Steel Pipe: High Temperature

Are you selecting stainless steel pipes for high-temperature service where long-term stability matters?Both SUS 321 and SUS 316 stainless steel pipes are widely used in industrial systems, but their performance differs significantly when exposed to continuous heat, welding stress, and thermal cycling. This guide helps buyers choose the right grade based on temperature limits, cost efficiency, and lifecycle performance.

What is SUS 321 stainless steel tubing?
SUS 321 is a titanium-stabilized austenitic stainless steel. The addition of titanium prevents the precipitation of chromium carbide at high temperatures, making it ideal for welded pipes operating in the temperature range of 450–870°C, suitable for heat exchangers, superheaters, exhaust systems, and expansion systems.

 

What is SUS 316 stainless steel tubing?
SUS 316 stainless steel tubing is an austenitic stainless steel tubing based on 304 stainless steel with the addition of molybdenum (Mo). It has excellent corrosion resistance, especially in environments containing chlorine and salt water (such as seawater) and at high temperatures. Its resistance to pitting and crevice corrosion is far superior to 304, and it is widely used in chemical engineering, food processing, marine engineering, medical devices, and other fields.

 

 

SUS 321 is titanium-stabilized, resistant to carbide precipitation, and maintains its integrity at temperatures up to approximately 900°C, making it ideal for continuous high-temperature use; while SUS 316 has a temperature limit of approximately 870°C and lower creep resistance. Therefore, 321 is more suitable for applications requiring long-term high-temperature stability, while 316 is more suitable for corrosive chloride environments at moderate temperatures.

Property	SUS316	SUS321
Oxidation Resistance Limit Temperature	870°C (Short-term: 980°C)	925°C (Short-term: 1050°C)
Continuous Operating Temperature	650°C (Corrosion-free environment)	800°C (Stress-bearing environment)
Creep Strength (700°C/1000h)	40 MPa	65 MPa
Intergranular Corrosion Sensitivity	Prone to corrosion in sensitization temperature range (450–850°C)	Excellent resistance due to titanium stabilization treatment

 

SUS321 vs Alloy 316：Equivalent materials

Stainless Steel Grade	UNS Number	ASTM/EN Standard	Japanese (JIS)	Other International Equivalents
316	S31600	ASTM A193 B8M / EN X5CrNiMo17-12-2	SUS316	STS316, 1.4401, 04Cr17Ni12Mo2
321	S32100	ASTM A240 Type 321 / EN X6CrNiTi18-10	SUS321	AFNOR Z6CNT18-10, DIN X6CrNiTi18-11, GB 0Cr18Ni10Ti, Swedish 2337,  GOST X6CrNiTi18-10

 

SUS321 vs Alloy 316：Chemical Composition

Grade	C (%)	Cr (%)	Ni (%)	Mo (%)	Ti (%)	Key Purpose
SUS321	≤0.08	17.0–19.0	9.0–12.0	-	≥5×C	Stabilized against carbide precipitation
316 (Alloy 316)	≤0.08	16.0–18.0	10.0–14.0	2.0–3.0	-	Superior corrosion & chloride resistance

 

SUS321 vs Alloy 316：Mechanical Properties

Property	SUS 321	Alloy 316
Tensile Strength (MPa)	515	490–620
Yield Strength (MPa)	205	≥170
Elongation (%)	40	35–40
Hardness	≤217 HB	≤217 HB
Max Service Temperature	Up to 900°C	Up to 550°C

 

SUS316 vs SUS321 stainless steel：Corrosion resistance

The addition of molybdenum (Mo) in SUS316 stainless steel enables SUS316 to form a stable oxide film at the grain boundary, especially in acidic environments containing chloride ions (such as seawater and chemical media), its resistance to pitting and crevice corrosion is significantly better than that of ordinary austenitic stainless steel. For example, in a 3.5% NaCl solution, the critical pitting temperature (CPT) of SUS316 can reach 70°C, while that of SUS304 is only 40°C.

 

What is the difference between ss316ti and ss321?

SS316Ti offers superior resistance to chloride corrosion (PREN value of approximately 23-27) and is suitable for moderately high-temperature environments (approximately 870°C). SS321, on the other hand, exhibits better high-temperature stability, reaching up to approximately 900°C, and possesses higher creep resistance. Therefore, for continuous use in environments above 800°C, SS321 is the better choice; while for more corrosive, lower-temperature environments, SS316Ti is more suitable.

 

GNEE has over 20 years of experience in stainless steel pipe manufacturing, providing globally trusted piping solutions. We are committed to quality, reliability, and customer satisfaction.
We offer:
ISO 9001, CE, PED, SGS, and BV certifications
In-house welding, annealing, and non-destructive testing facilities
Strict quality control and 3.1/3.2 test certificates
Fast delivery and global logistics support
Customized OEM services for engineering projects

Contact now