What is Stainless Steel?

Bobby Brown

Post 2023-12-13

Overview

Stainless steel doesn't mean it doesn't rust; it means it's less prone to rusting. The grade choice should match the specific requirements, not just go for higher numbers.
Steel can be categorized as "carbon steel" and "stainless steel & alloy steel" based on its material. Steel is an alloy known for its high strength, corrosion resistance, and malleability.
The steel industry supply chain includes upstream, midstream, and downstream segments. Carbon steel is commonly used in construction, machinery manufacturing, and transportation, while stainless steel is often applied in food processing, household items, and marine engineering.

Is Stainless Steel Truly Rustproof? What is Stainless Steel
What is AISI 303 306 steel?
Steel Industries
Steel Industry Supply Chain
- Carbon Steel
- Stainless Steel & Alloy Steel:
Valuable Aids in the Steel Manufacturing Process - Nozzles and Flow Meters

Is Stainless Steel Truly Rustproof? What is Stainless Steel

Stainless steel, commonly used in the semiconductor, LCD, and precision electronics industries, is not entirely rustproof but highly resistant to corrosion. Originating from the steel industry, stainless steel is produced from iron extracted from iron ore, with added alloy elements like chromium (Cr), nickel (Ni), manganese (Mn), and molybdenum (Mo). These elements give stainless steel its corrosion resistance and antioxidation properties, making it durable and easy to clean. This is why stainless steel is a popular choice for kitchen utensils. The semiconductor industry specifically requires ultrapure water, which is 1000 times cleaner than tap water, for delicate processes like photomask cleaning, wafer washing, etching, and mechanical polishing. The preparation of pure water for these processes combines various techniques, including distillation, ion exchange resins, reverse osmosis (RO), electrodialysis, and filtration, to ensure the water's high purity.

In the broader context, the stainless steel market is experiencing growth, especially in Asia Pacific regions like China, due to infrastructure development and technological advancements in steel. Stainless steel's properties, such as corrosion resistance and strength, make it suitable for modern construction, automotive exhaust systems, and electronic machinery.

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What is AISI 303 306 steel?

We often see labels like "food-grade 304 stainless steel" or "medical-grade 316 stainless steel" on the market. What do the numbers before stainless steel mean? Stainless steel is assigned different numbers based on metal composition and alloy ratios. The AISI304 and 316 stainless steels mentioned above are part of the numbering system developed by the American Iron and Steel Institute (AISI) and are common general-purpose designations.

Cr - Forms a chromium oxide protective layer on the metal surface, key to stainless steel's corrosion resistance.

Ni - Increases stainless steel's strength and ductility, improving its resistance to corrosion in high hydrogen ion concentration environments.

Mn - Enhances steel hardness and strength while improving processability and corrosion resistance.

Mo - Enhances stainless steel's corrosion resistance in extreme environments, such as seawater containing chloride ions.

The numbering of stainless steel alloys is based on the proportion of alloying elements. For example, AISI 304 stainless steel contains 18% chromium and 8% nickel (18-8), offering excellent corrosion resistance and a polished finish. It is commonly used in kitchenware and furniture manufacturing. AISI 316 stainless steel, on the other hand, contains approximately 16% chromium, 10% nickel (18-10), and 2% molybdenum, providing even higher corrosion resistance than 304, albeit at a higher price. Besides kitchenware, it is used in marine structures and ship components due to its superior resistance to saltwater. AISI 440 stainless steel has the highest hardness but less corrosion resistance, making it suitable for high-end cutlery and surgical instruments. Therefore, the stainless steel grade selection depends on specific requirements such as corrosion resistance and hardness, rather than a higher numerical value or food-grade/medical-grade distinctions.

Steel Industries

How is stainless steel produced? Stainless steel originates from the steel industry, a backbone of various sectors like infrastructure, transportation, manufacturing, and an important economic indicator. The steel industry encompasses various industrial fields such as smelting, casting, forging, and rolling. Steel is an alloy primarily composed of iron, carbon, manganese, silicon, etc., known for its high strength, corrosion resistance, and malleability. It can be categorized as "carbon steel" and "stainless steel & alloy steel" based on its material. Taiwan produces around 20 million tons of steel annually, ranking 12th globally (World Steel Association, 2022). Currently, the steel industry tends towards small and medium-sized structures, is capital-intensive, and employs a high percentage of technical personnel, making it a technology-intensive industry.

Steel Industry Supply Chain

In the steel industry, iron is categorized into two main types based on the material of the finished product: "Carbon Steel" and "Stainless Steel & Alloy Steel." These categories further break down into upper, middle, and lower segments based on different market roles.

Carbon Steel

| Carbon steel is commonly used as the foundational material for construction, roads, machinery manufacturing, and transportation equipment

Upstream: Raw materials for carbon steel include coal, iron, sand minerals, and scrap steel. Primary processes involve blast furnace smelting (heating iron ore and reducing it to produce raw iron) or electric arc furnace (EAF) refining, both focusing on enhancing steel strength and hardness. Products include billets, blooms, and slabs. Carbon content differentiates carbon steel from stainless steel, without added corrosion-resistant elements like chromium.

Midstream: This includes various processes such as cold/hot rolling for steel plates, rebar, coils, wire coils, and more. It also covers various types of steel and angle steel produced through rolling, cutting, trimming, and processing.

Downstream:
1.Construction Industry: Cold and hot-rolled steel plates and rebars are used in constructing buildings, bridges, roads, and other structures.
2.Machinery Manufacturing: Steel coils and wire rod coils are extensively applied in manufacturing machinery equipment, vehicle components, and various industrial machinery.
3.Processing and Manufacturing: Processed and cut steel forms various types of steel and angle steel, used in producing components, assemblies, crafts, and more.
4.Energy and Transportation: Steel materials find wide applications in the energy production and transportation sectors, including steel bars, pipelines, and more.

Stainless Steel & Alloy Steel:

| Stainless steel is frequently employed in everyday life, including the food and beverage industry, medical machinery, and home decoration

Upstream: Raw materials for stainless steel include iron ore, chromium, nickel, cobalt, etc. Iron ore, a natural ore containing iron, primarily consists of iron oxides, carbonates, and sulfates. In stainless steel production, iron is extracted from iron ore through an electric furnace process. Nickel, molybdenum, copper, titanium, niobium, and other alloy elements are added to create stainless steel, imparting corrosion resistance and oxidation resistance.

Midstream: Due to specific demands (corrosion resistance, food-grade applications, etc.), this sector may include additional processes such as cutting, pipe manufacturing (extrusion, stretching, bending, etc.), surface treatment (polishing, pickling, chrome plating, etc.), welding, and connection (TIG welding, laser welding, etc.).

Downstream:
1.Food Processing and Catering: Highly corrosion-resistant stainless steel utensils are widely used in food production and catering, including stainless steel trays, bowls, and cutlery.
2.Medical Instruments: Stainless steel's corrosion resistance and biocompatibility make it a preferred material for manufacturing surgical instruments and medical equipment.
3.Chemical and Marine Engineering: Stainless steel pipes and containers are common in the chemical industry and marine engineering due to their corrosion resistance in harsh environments.
4.Home and Decoration: Stainless steel's high-temperature resistance, ease of cleaning, durability, and eco-friendliness make it popular in furniture production, such as lamps and kitchen utensils.

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Valuable Aids in the Steel Manufacturing Process - Nozzles and Flow Meters

Application 1: The Use of Nozzles in the Steel Industry

Nozzles serve as invaluable tools in the steel industry, not only for cooling steel billets but also for precise control of coolant flow during the steelmaking process, ensuring even distribution of alloy elements. In blast furnace operations, nozzles efficiently utilize thermal energy, enhancing production efficiency. Additionally, nozzles find wide application in surface treatments for steel, such as plate cleaning, coating, and corrosion protection, ensuring superior product quality and surface integrity.

| Nozzles used to spray cooling water on electrode rods to cool them after the electric furnace steelmaking process

Case: A Taiwanese Rebar Manufacturer Producing 600,000 Tons Annually

Situation: The company utilizes electric arc furnace technology for rebar production, requiring the use of graphite electrode rods for conductivity to generate high-temperature steelmaking furnaces. After the electrode rods have served their purpose, cooling water is sprayed through nozzles for temperature reduction. The company initially used brass nozzles for cooling, but brass is susceptible to deformation under high-temperature conditions, resulting in short nozzle lifespans and frequent replacements, increasing costs.

Solution: LORRIC - KG Solid Conical Nozzles for the Steel Industry
LORRIC recommended switching to stainless steel nozzles to extend product lifespan. LORRIC's KG specialized solid conical nozzles for the steel industry feature an X-type nozzle turbulence plate design, reducing fluid turbulence to ensure uniform spray particles, thereby enhancing cooling efficiency. LORRIC's stainless steel nozzle material ensures a longer lifespan compared to typical manufacturer nozzles. The company validated our nozzle's spray effectiveness through practical testing, leading them to choose KG nozzles as dedicated spray heads for electrode rod cooling fixtures.

| Nozzles used in the pickling process at a steel mill to spray pickling solution

Case: Leading Manufacturer in Greater China for Wire and Cable, and Special Steel Industries

Situation: Founded in Taiwan in 1966, the company initially focused on wire and cable production. Today, it has become a prominent player in the Greater China region's wire and cable and special steel industries. Within its core businesses, the wire and cable segment includes copper materials, power, and communication cables. The stainless steel segment produces stainless steel billets, coils, cold-finished bars, seamless steel tubes, making it a leading producer of long stainless steel products in Asia. The company faced challenges in its pickling process, where it used nozzles from European and American brands. The pickling solution employed in the process contained highly corrosive agents - nitric acid (HNO3) and hydrofluoric acid (HF), leading to nozzle clogging issues. As a result, the equipment required bi-monthly shutdowns for maintenance and nozzle replacements. The high cost of European and American brand nozzles escalated the maintenance expenses, prompting the company to seek a suitable alternative.

Solution: LORRIC - KAD Multi-piece Fan Nozzle
Upon understanding the customer's requirements, we recommended the KAD multi-piece fan nozzle. The KAD fan nozzle adopts a three-piece design, making it easy to maintain, clean, and replace. Its unique positioning design between the nozzle and base ensures that every replacement maintains the original positioning. Even with frequent replacements, it does not affect the overall performance of the production line.

Application 2: The Application of Flow Meters in the Steel Industry

Flow meters are a crucial technical tool in the steel industry. In the iron smelting process of blast furnaces, flow meters are widely employed to monitor the flow of cooling water, fuel, and coolant, ensuring system stability and efficient utilization of energy and resources. Furthermore, their use in stages like heat treatment, continuous casting, and rolling facilitates precise control of cooling rates and process parameters, achieving precise steel regulation. In the realm of steel surface treatment, the application of flow meters further ensures accurate fluid ratios in processes such as coating, corrosion prevention, and cleaning, ultimately guaranteeing product quality and cost-effectiveness.

| Installing flow meters on stainless steel pipes in steel mills to detect pipeline blockages

Case: A Leading Stainless Steel Manufacturer in Taiwan

Situation: This company is Taiwan's first vertically integrated stainless steel plant with a complete process of smelting, hot rolling, and cold rolling. Their stainless steel products not only meet domestic market demands but are also exported to numerous countries in Asia, Africa, Europe, and America. Processed products have extensive applications in the automotive industry, household items, machinery manufacturing, and construction. The company wanted to install flow meters on 1-½" stainless steel pipes to detect any blockages without the risk of leakage from cutting the pipes. They sought advice on a suitable solution from our company.

Solution: LORRIC FU-TX310 Clamp-On Ultrasonic Flow Meter
Taking the customer's work environment into account, LORRIC recommended the FU-TX310 Clamp-On Ultrasonic Flow Meter. LORRIC's FU-TX310 features external installation, allowing customers to install and start flow monitoring without interrupting equipment operation. Its non-intrusive, no-pipe-cutting characteristics mean the flow meter can be easily installed, removed, maintained, or calibrated, significantly reducing maintenance costs. During the installation of ultrasonic flow meters, improper probe placement can affect data accuracy. To address this difficulty in installing ultrasonic flow meters, LORRIC has patented metal fasteners for probe positioning. These fasteners make it easy for customers to identify the correct probe placement, simplifying the installation process. After trying the FU-TX310 Clamp-On Ultrasonic Flow Meter, the company was highly satisfied with its accuracy. The external installation design eliminated concerns about the risk of leakage and pressure loss associated with cutting pipes, perfectly addressing their needs.