SS vs SUS – What are the Differences?

“Stainless steel” (SS) and “Steel Use Stainless” (SUS) are types of metal used in many products. They are the same material, just with different naming systems. Besides, SS vs SUS differs in a few parameters.

SUS 304 are softer compared to SS 304. Moreover, SS 304 is the American standard, while SUS 304 is the Japanese equivalent. Other key differences are cost, availability, finish options, etc. 

You will gain clarity on these metal terms by reading this guide. Thus, you can select the right material for various applications, from cookware to industrial equipment.

SS vs SUS – Comparison Chart

Both stainless steel grades are austenitic and have similar elements. However, they have key differences due to the specific production methods or treatments preferred by each standard body.

What are the Differences between SS and SUS?

Let’s look through the differences between SUS 304 and SS 304 in detail from below.

Hardness

SUS 

Japanese manufacturers often use annealing to make SUS 304, as many Japanese products need this softness. Annealing heats the metal and cools it slowly. The process makes the metal softer, making SUS easier to shape. 

For example, kitchenware, auto parts. CNC machining parts are made of SUS 304. Soft SUS is also less likely to crack or break.

SS

American companies usually follow American Society of Testing and Materials (ASTM) standards for SS 304. The standards often lead to harder steel. Hard SS is great for many uses. It resists wear and tear better. Builders like it for strong structures. 

Factories use it for tough machine parts. Hard SS keeps its shape well under pressure. But it can be trickier to work with than softer metals.

Cost

SUS

304 SUS are mostly produced in Asian industries, particularly in Japan. Local production makes the Steel use Stainless 304 for cheaper. Thus, companies there can sell SUS for less money. 

SS

304 SS costs more in Asia because it’s often shipped from far away. Shipping adds to the price.Buyers in America find SS to be a cost-effective choice for their needs as SS 304 is manufactured mostly in the US.

Trace Elements

SUS

JIS standards guide SUS making in Japan. These rules allow some small changes in tiny bits of other metals.

SUS might have more or less of these elements. The changes are very small. You can’t see them, but they can affect how SUS works. Some SUS might be different from other SUS.

SS

ASTM rules are strict about Stainless steel 304 (SS) in America. The rules say exactly how much of each tiny metal bit should be in SS. Manufacturers follow the rules carefully.

Thermal Conductivity

SUS

SUS has thermal conductivity of 16.2 W/m. As a result, it can resist heat well. So, it is a popular metal for metal castings including valve and pump components, food processing equipment, etc.

However, continuous heating at a temperature between 797-1580 °F may cause corrosion. At the same time, exposure to high heat may compromise the hardness of this metal.

SS

Thermal conductivity of SS 304 is similar to the SUS 304. Thus, it is also used mainly for an application that requires high temperature. 

Weldability

SUS

SUS 304 is a commonly used welded fabrication in the welding industry. This stainless steel grade contains Nickel  8%~10% and Chromium 18%~20%, making it a good choice for strong joints. It can be readily welded using TIG, MIG, SA and MMA welding processes.

SS

SS is super easy to join together. You can use lots of different ways to weld SS. Most common welding tools work great with SS. Welders don’t need special training for joining SS. Moreover, the connections are strong. People prefer working with SS because of its simplicity.  

Availability

SUS

SUS is perfect for many Asian products.You can find it easily in countries like Japan and China. 

SS

SS is widely available in America and Europe. Manufacturers of machinery parts, food and beverages, dairy, etc. prefer SS. People see SS every day in their homes. From sinks to skyscrapers, SS is a top choice. 

Finish Options

SUS

SUS 304 stainless steel has a wide range of surface finishes. Some are shiny; others are matte. Many SUS products have a special look. Japanese kitchens often use SUS for good thermal conductivity. Asian cars might use SUS, which doesn’t show fingerprints.

SS

SS is super shiny, like a mirror. Some SS looks brushed, with tiny scratches all over. Many people like SS, which is easy to clean. 

In America, you’ll see lots of SS with a satin finish. European buildings often use SS that’s been sandblasted. Western makers offer SS that fits right in with local styles.

Tensile Strength

SUS

The tensile strength of SUS steel is lower (515 MPa – 625 MPa) . This happens because of the different ways it is processed. The lower strength might make it less durable under stress. However, it still works well for many uses. It is a solid choice but only sometimes the strongest.

SS

The maximum and minimum tensile strength of SS 304 is 515 MPa and 625 MPa, respectively. Such a lower tensile strength makes it susceptible to stress cracking. When cracks form and grow in a corrosive environment, SS 304 may break.

Oxidation Resistance

SUS

SUS steel does a good job of resisting oxidation. It holds up well against rust, but how it performs can depend on how it’s made. Some batches might resist rust a little less. Even with these small differences, SUS steel is still a reliable choice for most environments.

SS

SS steel often does better at resisting oxidation. This is because it’s made under strict ASTM guidelines. These rules help ensure the steel is extra resistant to rust. SS steel is often picked when you need something that will stay strong and shiny for a long time.

Final Product

SUS

Stainless use steel is often found in Asian-made electronics, car parts, and local machines. Many factories in Asia use SUS because it fits their needs well. It’s strong enough for everyday products and machinery. SUS steel is a common choice in these industries, offering reliability and good performance.

SS

Stainless steel is mostly used in Western-made heavy machinery, buildings, and household items. It is often chosen for big projects because it is strong and durable. SS Steel is trusted in these areas for its quality. It’s found in things like bridges, appliances, and other everyday items.

Summing Up

Stainless steel is versatile, used in both decorative and industrial settings. Learning the differences between SS vs SUS is crucial for ensuring durability, safety, and cost-efficiency. 

Understanding these differences helps in selecting the right material for the job while optimizing performance and expenses.