Contact
vi
Reply:

In metallurgy, stainless steel is defined as an iron-carbon alloy with a minimum of 10.5%chromium content.[1] The name originates from the fact that stainless steel does not stain, corrode or rust as easily as ordinary steel (it "stains less", but is not actually stain proof). This material is also called corrosion resistant steel when it is not detailed exactly to its alloy type and grade, particularly in the aviation industry. As such, there are now different and easily accessible grades and surface finishes of stainless steel, to suit the environment to which the material will be subjected in its lifetime. Common uses of stainless steel are everyday cutleryand watch straps.


Stainless steels have higher resistance to oxidation (rust) and corrosion in many natural and man made environments; however, it is important to select the correct type and grade of stainless steel for the particular application.


High oxidation resistance in air at ambient temperature is normally achieved with additions of a minimum of 13% (by weight) chromium, and up to 26% is used for harsh environments.[2] The chromium forms a passivation layer of chromium(III) oxide (Cr2O3) when exposed to oxygen. The layer is too thin to be visible, which means that the metal remains lustrous. It is, however, impervious to water and air, protecting the metal beneath. Also, this layer quickly reforms when the surface is scratched. This phenomenon is called passivation and is seen in other metals, such as aluminium and titanium. When stainless steel parts such as nuts and bolts are forced together, the oxide layer can be scraped off causing the parts to weld together. When disassembled, the welded material may be torn and pitted, an effect that is known as galling.


Nickel also contributes to passivation, as do other less commonly used ingredients such as molybdenum and vanadium.

Reply: According to an article recently published in the New York Times around 70 percent of all pots and pans currently used in the American market is stainless steel with nonstick surface. Most users prefer this as it is easier to clean and better for use during the cooking process. 

There are also many other materials available for use in kitchen and cookware. For example, cookware made form polished aluminum is very popular because of its light weight. Teflon coatings are also popular as the coating makes the cleaning process much easier and reduces food sticking to the pot or pan during cooking. Iron pots with ceramic coatings are also still being used while cast iron pots used to be quite popular, but they are very heavy. Stainless steel cookwares have become increasingly popular, because of the purity of the metal. 

The bulk of a person’s nickel intake comes from the intake of foods that naturally contain nickel. Studies have recently been trying to establish the amount of nickel that is absorbed as a result of the use of s stainless steel utensils. There has been concern that that nickel could cause allergic reactions or could pose even more serious health risks such as cancer. But there has so far been no evidence to show that nickel absorbed in food during the cooking process, will cause serious harm. Some recent media reports have suggested that stainless steel pots should be avoided and scientific studies have confirmed that nickel found from such pots is merely undetectable, even for particularly aggressive foodstuffs. As the result, the nickel from stainless steel cookware relative to our daily intakes of nickel is generally insignificant and should not cause either allergic reactions or other harmful health effects. 

Looking at the possible harmful effect that some other materials used in the stainless steel manufacturing process could have on a person, it must firstly be said that stainless steel itself doesn’t hold a significant health threat and has as such not been classified as a material that is hazardous to your material. For different grade of stainless steel, people who are already allergic to nickel may have a low risk of an allergic skin reaction following direct and prolonged skin contact with this grade according to a skin doctor at Chang Gung Hospital Taiwan. Secondly, there is no indication from the available data that the manufacturing of stainless steel causes adverse effects on the health of workers. Third, according to Institute of Occupation Health of University of Birmingham reported that the welding of stainless steel does not cause any increase in the risk of lung cancer over and above the increased risk from any steel welding. However, the welding process in general may be associated with increased reporting of respiratory symptoms such as coughing, but there is no evidence of increased risk of developing lung function abnormalities, nor of any specific association with the welding of stainless steel. Meanwhile, statistics and studies showed that the published workplace exposures to potentially harmful materials were generally well-controlled, so minimizing the possibility of any risk to health. Finally, the grinding and cutting of stainless steel also do not appear to cause any harmful to our health effects. 

In conclusion, stainless steel is considered the best cooking surface, especially, used in modern cookware.
Reply: Stainless steel springs represent the ultimate in appearance and corrosion resistance. They also offer some unique properties not obtainable in carbon steel springs.

When 12% or more chromium is added to steel, it becomes resistant to rusting. The chromium inhibits rusting by causing a microscopic layer of oxygen to become attached to the metal surface. This layer acts as a barrier to further oxidation/rusting. Other elements are also added to stainless steel spring material, particularly nickel. The addition of nickel results in the material becoming non-magnetic in the annealed condition. This change happens at the atomic level and the resultant crystal structure is known as austenite, thus the term “austenitic stainless steels”. The austenitic structure is non magnetic, very stable, and will not transform into a stronger martensitic structure by heat treatment. It can, however, be strengthened by cold working. 

Austenitic Stainless Steel Grades

The most common grade of austenitic stainless steel, type 304, contains 18% chromium and 8% nickel, with the balance being iron. Generically, this grade is known as “18-8” and is part of a larger industry classification known as “300” series stainless steels. One of the most common spring grades is 302 stainless, which contains 18% chrome, 9% nickel. The more corrosion resistant grade 316 contains 17% chrome, 12% nickel, 2.5% molybdenum.

Advantages of Stainless Steel Springs Compared to Carbon Steel

Corrosion Resistance of Stainless Steel Springs
This property is probably the most common reason for choosing stainless steel. In addition to being resistant to rusting, the austenitic stainless springs are resistant to a wide variety of chemical media and suitable for use in the food processing industry. 

Elevated Temperature Advantages of Stainless Steel Springs
Austenitic stainless steel springs can be used at temperatures of up to 650° F, compared to music wire or oil tempered springs, which are only good to about 250° F. 

Magnetic Properties
Austenitic stainless springs are not magnetic to the same degree as carbon steel springs but exhibit varying degrees of magnetic properties, depending on the amount of cold work in the wire. 

Tensile Strength
Although austenitic stainless springs can not be strengthened by heat treatment, high tensile strength can be developed by cold drawing the wire. The smaller sizes will exhibit the higher tensile strengths, with strength levels comparable to carbon steel class 1 hard drawn or oil tempered wire in diameters .20” and smaller.

Thermal Properties
Stainless steel springs exhibit a coefficient of thermal expansion approximately 15% less than carbon steel springs and thermal conductivity is only about 30% of carbon.
Kết quả hình ảnh cho baosco

Contact & Advice: 

Please leave your information here
and TYGICO will be in touch.