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303 stainless steel is improved on the basis of 304 stainless steel sulfur-containing easy-to-cut steel, through the addition of sulfur (S), phosphorus (P) and other elements to optimise the cutting performance, while retaining the basic characteristics of austenitic stainless steel. Compared with ordinary stainless steel, 303 flat steel has outstanding advantages, such as the addition of sulfur elements significantly reduce tool wear, especially for automatic lathes, CNC machining and other high-speed cutting scenarios, which can improve machining efficiency by more than 30%. Stable performance in dry atmosphere, weak acid and alkali environment, meet the general industrial environment needs. Excellent cold working moulding ability, can make complex parts by stamping, bending and other processes. After polishing treatment, it can reach mirror effect, which is suitable for decorative parts.

Product Parameter (Specification)

Products description:

Product information	Parameter	Product intormation	Parameter
Product name	Stainless steel round bar	Standard	ASTM, JIS, DIN, EN
Length	Customised to customer requirements	Certification	ISO, SGS
Grade-ASTM	201, 202,302, 303, 304, 304L, 310, 310S, 316, 316L, 321, 410, 431, 430F, 904L & other	Price term	FOB,CIF
Technique	Cold rolled hot rolled	Payment terms	T/T L/C
Packaging and delivery
Note : bundle, plastic bags, thin film, wooden pallet, standard seaworthy export packing or as customer demands

Product Feature and Application

Precision Machinery Manufacturing

In the field of automation equipment and precision instruments, 303 stainless steel flat steel is widely used in the manufacture of high-precision, small tolerance core components:

Transmission system parts: such as gear shafts, cams, couplings, etc., its easy-to-cut characteristics can significantly shorten the machining cycle, reduce tool loss.

Valve components: ball valve spools, globe valve stems and other key parts, the medium corrosion resistance of the material can be adapted to water, steam and other media environment.

Pump body structural components: pump casing support moulded by cold bending or stamping process, taking into account the needs of light weight and strength.

Automotive Industry

The automotive industry has stringent requirements for wear resistance, processing efficiency and cost control of components, and the application of 303 flat steel covers a number of sub-systems:

Engine accessories: fuel injection system nozzles, sensor housings and other small parts that require precision turning.

Transmissions: Wear-resistant parts such as transmission synchronising rings, clutch pins, etc., which can be produced quickly in large batches due to the improved machinability of sulphur.

Fasteners: Bolts and gaskets for non-high-load environments, replacing some chrome-plated carbon steel parts to reduce weight.

Technical advantage: material ductility supports cold heading process to meet the automotive industry's need for one-off forming of complex shaped parts.

Food Processing Equipment

In the food industry, although 303 flat steel is not in direct contact with food, it performs well in the following scenarios:

Conveyor systems: conveyor belt supports, sorting robotic arms, the material is resistant to weak acids and alkalis characteristics to adapt to the environment of frequent rinsing of cleaning agents.

Packaging machinery: mould guide posts, cutter bases, high hardness and wear resistance to extend the life of the equipment.

Temperature control device: oven lining bracket, freezing equipment frame, maintain dimensional stability in the temperature range of -50 ℃ ~ 300 ℃.

Technical advantages: passivation treatment can further enhance the surface corrosion resistance, in line with GB 4806.9 food safety mechanical material specifications.

Electronics and Semiconductors

The miniaturisation trend of electronic components puts higher demands on material processing accuracy:

Connector terminals: SIM card slot, Type-C interface metal parts, precision stamping and moulding to ensure signal transmission stability.

Heat sink module: LED lamp substrate, chip heat sink, moderate thermal conductivity and easy to process complex fin structure.

Precision moulds: injection mould inserts, jig positioning blocks, material hardness HRB 85-90 to ensure long-term use without deformation.

Technical advantage: support micron-level precision etching process, suitable for the ultra-thin design needs of optoelectronic devices.

Energy Equipment

In energy extraction and power equipment, 303 flat steel is used in non-extreme corrosion scenarios:

Oil and gas drilling: instrumentation valve housings, sensor sheaths for moderately corrosive downhole media.

Wind power equipment: internal nacelle brackets, junction box fixings, lightweight design to reduce tower loads.

Nuclear auxiliary systems: cooling pipe supports, maintenance tools, low magnetic properties of the material to avoid interference with precision instruments.

Technical advantage: the hardness of the material can be adjusted through heat treatment to meet the mechanical properties required under different loading conditions.

Production Details

303 stainless steel is based on 304 stainless steel with the addition of sulfur (S) and phosphorus (P) to improve the cutting performance of easy-to-cut austenitic stainless steel. Its standard chemical composition is as follows:

1.Major Elements:

Element	Chromium (Cr)	Nickel (Ni)	Carbon (C)	Manganese (Mn)	silicon (Si)	sulfur (S)	phosphorus (P)
Content(%)	17-19	8-10	MAX 0.15	MAX 2	MAX 1	0.15-0.35	MAX 0.20

2.Mechanical properties

Condition	Tensile strength (MPa)	Yield strength (MPa)	Elongation (%)	Hardness (HB)
Data	≥500	≥190	≥40	≤187

3.Physical properties

Condition	Density	Melting point	Thermal conductivity	Resistivity
Data	7.93 g/cm³	1400-1450°C	16.3 W/m-K (at 100℃)	0.72 Ω-m

4.Temperature resistance characteristics

Long-term working temperature: -20℃~+400℃, short-term up to +800℃, but will oxidise.

Low temperature properties: maintain toughness to -196℃, no brittle transformation.

High temperature attention: Above 500℃, carbides may precipitate at grain boundaries, need to avoid sensitisation interval 450~850℃. Sulfur (S) may cause thermal embrittlement at high temperatures, avoid hot forging or welding.

Product specifications and forms

Item	Parameter range	Description
Material grade	304 (06Cr19Ni10)	Conformity standard: GB/T 1220-2007 (national standard), ASTM A240/A240M (American standard).
Cross-section shape	Rectangle	Thickness and width of the combination of different specifications, edges can be right-angled or rounded processing
Thickness (mm)	3 ~ 20	Common thickness: 3, 5, 6, 8, 10, 12, 15, 20 (can be customised non-standard size)
Width (mm)	20 ~ 200	Common width: 20, 30, 40, 50, 60, 80, 100, 120, 150, 200 (on request)
Length (m)	1 ~ 6	Commonly specified size is 6 metres, support section cutting or special length customisation
Surface condition	2B, BA, No.4, brushed, sandblasted, etc.	2B (cold rolled bright), BA (mirror), No.4 (brushed) is commonly used in industry, and the decorative scene can be polished or colour-plated treatment.

Surface treatment options

Type	Description	Applicable Scene
Pickled surface	Matte grey-white, remove oxide skin	General industrial parts, subsequent processing
Polished surface	Mechanically polished to Ra≤0.8μm (mirror surface)	Medical devices, food equipment
Grinding surface	Precision grinding, dimensional tolerance ±0.02mm	Shafts, precision parts

FAQ

Q: Why choose 303 over 304 or 316 stainless steel?

A: The addition of sulphur (S) to 303 stainless steel significantly improves cutting performance and makes it suitable for high-volume precision machining, while 304 and 316 are more corrosion-resistant, and 316 in particular contains molybdenum, which makes it resistant to chloride corrosion but more difficult to cut. If there is no need for strong corrosion and efficient machining, 303 is more cost-effective.

Q: How to choose the cutting tool when cutting 303 stainless steel?

A: Recommended carbide tools, such as YG8 or high-speed steel tools, cutting speed control at 20-35m/min, feed 0.1-0.2mm/r. The use of oil-based coolant can reduce tool wear and extend life.

Q: What should I do if tiny cracks appear on the surface after machining?

A: It may be thermal embrittlement caused by elemental sulfur. It is necessary to reduce the cutting temperature, enhance cooling, and avoid sudden cooling after machining. It is recommended to clean the surface of sulphide residue after machining.

Q: Will 303 stainless steel rust in humid environment?

A: It is not easy to rust under normal humidity environment, such as indoor, but the corrosion resistance is weaker than 304/316 when exposed to seawater, high chlorine environment, such as swimming pool or acidic medium for a long time.It is recommended to clean it regularly and apply antirust oil.

Q: Can it be used in direct food contact scenarios?

A: Not recommended. 303 Stainless Steel has a high sulphur content and may release trace amounts of sulphides, and is only suitable for structural parts that are not in direct contact with food, such as equipment supports.

Q: What do I need to pay attention to when welding 303 stainless steel?

A: Due to its high sulfur content, welding is prone to thermal cracking. It is recommended to use small current TIG welding, using 309L welding wire, and passivation treatment is required after welding to restore corrosion resistance.

Q: Is it suitable for cold bending moulding?

A: Yes. 303 stainless steel has good ductility, can be stamping, bending and other cold processing, but need to pay attention to the bending radius should not be too small, it is recommended ≥ 2 times the thickness to avoid cracking.

Q: How to deal with rust spots on the surface?

A: Use stainless steel special cleaner with nitric acid content to wipe, or use a soft cloth dipped in a mixture of white vinegar + baking soda to gently wipe, after which rinse with water and dry.

Q: What is the price of 303 stainless steel flat steel?

A: The price is lower than 304 and 316, about 80-85 per cent of 304, making it suitable for scenarios where budgets are limited but efficient processing is required.

Q: Does it need special protection when storing?

A: It needs to be stored in a dry and ventilated place, avoiding contact with carbon steel and preventing contamination by iron ions, and in rainy season it is recommended to seal the package and place desiccant.

Q: How is the performance of 303 flat steel under high temperature?

A: Long-term use temperature is recommended ≤ 400 ℃, short-term can withstand 800 ℃, but will be oxidation discolouration. The strength decreases under high temperature, need to avoid the application of load-bearing parts.