Introduction To Stainless Steel Performance And Application Range

2 Piece Ball Valve is a common steel type. As a widely used steel, it has good corrosion resistance, heat resistance, low temperature strength and mechanical properties; it has good hot processing properties such as stamping and bending, and no heat treatment hardening phenomenon (non-magnetic, convenient use temperature -196℃～800℃).

Scope of application of 304 stainless steel

Household items (1, 2 types of tableware, cabinets, indoor pipelines, water heaters, boilers, bathtubs)

Auto parts (windshield wipers, mufflers, molded products)

Medical equipment, building materials, chemistry, food industry, agriculture, ship parts

304L stainless steel (L for low carbon) performance introduction

As a low-carbon 304 steel, its corrosion resistance is similar to that of 304 steel in general state, but after welding or stress cleaning, its resistance to intergranular corrosion; without heat treatment, it can also maintain good corrosion resistance, and the use temperature is -196℃～800℃.

Scope of application of 304L stainless steel

Applied to outdoor open-air machines in the chemical, coal, and petroleum industries with high requirements for intergranular corrosion resistance, heat-resistant parts of building materials, and parts that are difficult to heat treat.

Introduction to the performance of 316 stainless steel

Due to the addition of molybdenum, 316 stainless steel has particularly good corrosion resistance, atmospheric corrosion resistance, and high-temperature strength, and can be used under harsh conditions; excellent work hardening (non-magnetic).

Scope of application of 316 stainless steel

Equipment for seawater, chemical, dye, papermaking, oxalic acid, fertilizer and other production equipment; photography, food industry, coastal facilities, ropes, CD rods, bolts, nuts.

Introduction to the performance of 316L stainless steel (L for low carbon)

As a low-carbon series of 316 steel, in addition to having the same characteristics as 316 steel, it has excellent resistance to intergranular corrosion.

Scope of application of 316L stainless steel

Products with special requirements for resistance to intergranular corrosion.

316 and 316L stainless steel are molybdenum-containing stainless steels. The molybdenum content in 316L stainless steel is slightly higher than that in 316 stainless steel. Due to the molybdenum in the steel, the overall performance of this steel is better than that of 310 and 304 stainless steel. Under high temperature conditions, when the concentration of sulfuric acid is less than 15% and greater than 85%, 316 stainless steel has a wide range of uses. 316 stainless steel also has good resistance to chloride corrosion, so it is usually used in marine environments. The maximum carbon content of 316L stainless steel is 0.03, which can be used in applications where annealing cannot be performed after welding and maximum corrosion resistance is required.

Corrosion resistance of 316 and 316L stainless steel

316 stainless steel has better corrosion resistance than 304 stainless steel and has good corrosion resistance in the production process of pulp and papermaking. Moreover, 316 stainless steel is also resistant to corrosion by marine and corrosive industrial atmospheres.

Generally speaking, there is little difference between 304 stainless steel and 316 stainless steel in terms of chemical corrosion resistance, but there are differences in certain specific media.

The first stainless steel developed was 304, which is sensitive to pitting corrosion under certain circumstances. An additional 2-3% of molybdenum can reduce this sensitivity, thus giving rise to 316. In addition, this additional molybdenum can also reduce corrosion from certain hot organic acids.

316 stainless steel has become almost a standard material in the food and beverage industry. Due to the worldwide shortage of molybdenum and the higher nickel content in 316 stainless steel, 316 stainless steel is more expensive than 304 stainless steel.

Pitting corrosion is a phenomenon mainly caused by deposit corrosion on the surface of stainless steel, which cannot form a protective layer of chromium oxide due to lack of oxygen.

Especially in small valves, the possibility of deposits on the valve plate is small, so pitting corrosion rarely occurs.

In various types of aqueous media (distilled water, drinking water, river water, boiler water, seawater, etc.), the corrosion resistance of 304 stainless steel and 316 stainless steel is almost the same, unless the chloride ion content in the medium is very high, then 316 stainless steel is more suitable.

In most cases, the corrosion resistance of 304 stainless steel and 316 stainless steel is not much different, but in some cases it may be very different, which requires specific analysis of specific circumstances. Generally speaking, valve users should be aware of this, because they will choose the material of the container and pipeline according to the medium. It is not recommended to recommend materials to users.

Heat resistance of 316L and 316 stainless steel

316 stainless steel has good oxidation resistance in intermittent use below 1600 degrees and continuous use below 1700 degrees. In the range of 800-1575 degrees, it is best not to use 316 stainless steel continuously, but when 316 stainless steel is used continuously outside this temperature range, the stainless steel has good heat resistance. 316L stainless steel has better resistance to carbide precipitation than 316 stainless steel, and the above temperature range can be used.

Heat treatment of stainless steel

Anneal in the temperature range of 1850-2050 degrees, then anneal rapidly, and then cool rapidly. 316 stainless steel cannot be hardened by overheating.

Welding of stainless steel

316 stainless steel has good welding performance. It can be welded by all standard welding methods. When welding, 316Cb, 316L or 309Cb stainless steel filler rods or electrodes can be used for welding according to the application. In order to obtain the best corrosion resistance, the welded section of 316 stainless steel needs to be annealed after welding. If 316L stainless steel is used, welding annealing is not required.