304 and 304L Stainless Steel Pipes

The Distinction Between 304 and 304L Stainless Steel Pipes: A Comprehensive Analysis

In the realm of stainless steel pipes, two prominent grades stand out: 304 and 304L. These two variants, while sharing several similarities, possess distinct characteristics that set them apart. This article aims to elucidate the differences between 304 and 304L stainless steel pipes, delving into their unique properties, applications, and advantages.

At the outset, it is crucial to understand that both 304 and 304L stainless steel pipes belong to the austenitic family of stainless steels. This family is renowned for its exceptional corrosion resistance, formability, and weldability, making it the preferred choice for a plethora of applications across various industries.

The primary distinction between 304 and 304L stainless steel pipes lies in their chemical composition. While both grades contain a similar percentage of chromium (18-20%) and nickel (8-10.5%), the 304L variant has a lower carbon content, typically not exceeding 0.03%. This seemingly minute difference in carbon concentration has a significant impact on the material’s properties and performance.

The reduced carbon content in 304L stainless steel pipes confers several advantages, particularly in terms of weldability. The lower carbon concentration minimizes the risk of carbide precipitation, a phenomenon that occurs during welding and can lead to intergranular corrosion. Consequently, 304L stainless steel pipes exhibit superior resistance to intergranular corrosion, especially in welded sections, compared to their 304 counterparts.

Furthermore, the diminished carbon content in 304L stainless steel pipes enhances their formability, rendering them more malleable and ductile. This property is particularly advantageous in applications that necessitate complex shaping or extensive bending, as it reduces the likelihood of material cracking or fracturing.

Despite these advantages, 304 stainless steel pipes should not be dismissed, as they possess their own set of merits. For instance, the higher carbon content in 304 stainless steel pipes imparts greater strength and hardness, making them suitable for applications that demand robustness and durability. Additionally, 304 stainless steel pipes exhibit exceptional resistance to a wide range of corrosive environments, including exposure to oxidizing acids, alkalis, and various organic compounds.

In terms of cost, 304 and 304L stainless steel pipes are relatively comparable, with minor fluctuations depending on factors such as market conditions and supplier pricing. Ultimately, the choice between these two grades hinges on the specific requirements of the application in question.

In conclusion, both 304 and 304L stainless steel pipes boast a myriad of beneficial properties, owing to their austenitic nature and unique chemical compositions. While 304 stainless steel pipes offer superior strength and corrosion resistance, 304L stainless steel pipes excel in weldability and formability.

We provide the product range in the table below

Material	Stainless Steel Pipes
Standard	ASME, ASTM, EN, BS, GB, DIN, JIS, etc
Steel Grade	200 Series: 201,202 300 Series: 301,304,304L,316,316L,316Ti,309,310,317,321 400 Series: 409,410,420,430,436,444,441,440c Duplex Steel: 904L,2205,2507,2101,2520,2304
Wall Thickness	0.01-50mm
Diameter	1mm-4500mm
Manufacturing Method	Cold Rolled, Hot Rolled
Manufacturing Technique	Seamless, Welded (ERW,EFW,Seamless,Spiral Welded)
Shape	Round, Square, Rectangular, Oval
Surface	Primary, Bright Polished, Hairline, Mirror
Color	Golden, Champagne gold, Rose gold, Brown, Bronze, Brass, Black, etc.
Delivery Time	In stock: 5-10 days Not in stock: 10-20 days
Payment Terms	T/T, L/C, Paypal, Credit Card, Trade Online
MOQ	1 Ton

Machinability

The use of chip breakers is advised since the chips can be stringy. Stainless steel work hardens rapidly, heavy positive feeds, sharp tooling, and a rigid set-up should be used.

Chemical Properties

	C	Mn	Si	P	S	Cr	Ni
304	0.07max	2.0max	1.00max	0.045max	0.03max	min: 17.5 max: 19.5	min: 8.0 max: 10.5
304L	0.03max	2.0max	1.00max	0.045max	0.03max	min: 17.5 max: 19.5	min: 8.0 max: 10.5

Mechanical Properties

Properties quoted below are guideline figuresonly nad should not be used for any design purposes.

Grade	Tensile Strength ksi (min)	Yield Strength 0.2% ksi (min)	Elongation %	Hardness (Brinell) MAX	Hardness (Rockwell B) MAX
304 / 304L	75	30	40	201	92

Physical Properties

Density lbm/in3	Thermal Conductivity (BTU/h ft. °F)	Electrical Resistivity (in x 10-6)	Modulus of Elasticity (psi x 10-6)	Coefficient of Thermal Expansion (in/in)/ °F x 10-6	Specific Heat (BTU/lb/°F)	Melting Range (°F))
at 68°F: 0.285	9.4 at 212°F	28.3 at 68°F	28	9.4 at 32 – 212°	0.1200 at 68°F to 212°F	2500 to 2590
	12.4 at 932 °F	39.4 at 752°F		10.2 at 32 – 1000°F
		49.6 at 1652 °F		10.4 at 32 – 1500°F

Here is a technical parameter table for Grade 304/304L stainless steel:

Parameter	Value
Applications	Grade 304/304L stainless steel is commonly used in a wide range of applications, including:
	– Food processing equipment
	– Kitchen appliances
	– Chemical processing equipment
	– Heat exchangers
	– Architectural trim and molding
	– Automotive and aerospace structural components
Corrosion Resistance	Grade 304/304L stainless steel offers good corrosion resistance in a variety of environments, including:
	– Atmospheric conditions
	– Chemical and food processing environments
	– Marine environments
Heat Resistance	Grade 304/304L stainless steel has good heat resistance up to temperatures of around 870°C (1600°F).
Welding Characteristics	Grade 304/304L stainless steel can be welded using all standard welding techniques.
Machinability	Grade 304/304L stainless steel has good machinability, but it can be difficult to machine in hard or tough conditions.
Chemical Properties	Grade 304/304L stainless steel has the following chemical properties:
	– Chromium (Cr): 18-20%
	– Nickel (Ni): 8-12%
	– Manganese (Mn): 2%
	– Silicon (Si): 1%
	– Carbon (C): 0.08%
	– Phosphorus (P): 0.045%
	– Sulfur (S): 0.03%
Physical Properties	Grade 304/304L stainless steel has the following physical properties:
	– Density: 8.0 g/cm³
	– Melting point: 1400-1450°C (2550-2640°F)
	– Electrical resistivity: 72 microhm-cm (20°C)
	– Thermal conductivity: 16.2 W/m-K (100°C)
	– Thermal expansion: 17.2 μm/m-K (20-100°C)

Knowledge related to stainless steel:
What is sensitization and how does it affect the performance of stainless steel ?

Sensitization is a phenomenon that occurs in certain types of stainless steel, where the material becomes susceptible to intergranular corrosion due to the precipitation of chromium carbides at the grain boundaries. This can occur when the stainless steel is exposed to high temperatures (in the range of 450-850°C) for an extended period of time, such as during welding, heat treatment, or prolonged exposure to elevated temperatures in service.

When sensitization occurs, the chromium in the stainless steel combines with carbon to form chromium carbides, which depletes the chromium content at the grain boundaries. This results in a localized loss of corrosion resistance, as chromium is a key element that provides the stainless steel with its resistance to corrosion. The affected areas become vulnerable to attack by corrosive agents, which can lead to cracking, pitting, and ultimately, failure of the material.

Sensitization can significantly reduce the performance and reliability of stainless steel, particularly in corrosive environments. To prevent sensitization, it is important to use stainless steel grades that are designed to resist sensitization, such as Grade 304L or Grade 316L. Additionally, proper welding and heat treatment procedures should be followed to minimize the risk of sensitization in stainless steel components.