In the past 30 years, global stainless steel output has been an average of more than 5% growth rate. In recent years, different regions of the world steel production is different, while the stainless steel production in Asia has a remarkable increase. Although the development of stainless steel in less than 100 years, but the stainless steel has been shown to be a metal material production growth is the fastest, and its production in recent years the growth rate even more than the plastic production growth rate. Stainless steel production has such a high growth rate of driving force lies in it has some of the characteristics of: resistance to corrosion and oxidation resistance and high strength to weight ratio, good rolling formability, weldability and low-temperature toughness etc..
In the past 10 years, the average growth rate of the stainless steel consumption Chinese and India were more than 20% and 10%. However, stainless steel consumption per capita in the two countries were only 4.1kg and 1.1kg, is still very low, which indicates that the stainless steel consumption in these two countries, there is still much room for growth. Recently, Chinese has become the world’s stainless steel market development center. China stainless steel production capacity is increasing, and in 2010 Chinese stainless steel crude steel production is expected to reach 10 million tons. Chinese and India will be the world’s two stainless steel production capacity increased substantially in the country. Because China is greatly expanded stainless steel production capacity, so the number of Chinese net imports of stainless steel will continue to decrease, resulting in the use of many stainless steel exporter stainless steel production capacity rate is low.
Consumption consumption of different varieties of stainless steel stainless steel in different countries have great differences, such as the western developed country and India are quite different. In the western developed countries, white appliances and utensils industry used stainless steel accounted for total stainless steel consumption reaches the highest proportion of 37%, followed by the processing industry for 19%, transport industry is 15%, welding steel pipe industry was 12%, the construction industry is 11% and other industries is 6%. In India, up to 75% of the stainless steel for white goods and utensils, followed by the processing industry is 12%, the rest of the industry’s stainless steel consumption is less than 10%. Based on the stainless steel structure, stainless steel is generally divided into 4 categories: ferritic stainless steel, martensitic stainless steel, austenitic stainless steel, duplex stainless steel (ferrite + austenite).
Austenitic stainless steel can be further subdivided for chromium nickel stainless steel (AISI 300 series stainless steel) and Cr Mn stainless steel (AISI 200 series stainless steel), it depends on the addition of the accounting for the status of major alloying elements: the number of nickel and manganese. Chromium nickel stainless steel currently accounts for 2/3 of the world’s stainless steel production. As a result of manganese and chromium stainless steel and chromium nickel stainless steel are the same as the same organization structure, similar in many physical and mechanical properties. Therefore, under the high nickel prices in recent years, Cr Mn stainless steel production also increased steadily. In the past 5 years, the production of chromium manganese stainless steel production accounted for almost doubled the proportion of stainless steel production. While the world’s supply of nickel has not been synchronized with stainless steel production growth.
The nickel ore grade is very low, generally between 1% to 3% grade, and the nickel refining project needs huge investment. Although nickel in stainless steel plays the role of the austenitic elements, but as in the two series of stainless steel in the main role of the alloy elements of the price but there is a huge difference. Therefore, the price of nickel chromium stainless steel with nickel price changes. Therefore, stainless steel industry to healthy development and made of stainless steel with competitiveness, we should vigorously develop without nickel and low nickel ferrite stainless steel, Cr Mn austenitic stainless steel and duplex stainless steel. In addition to the stainless steel with high strength, good formability and good welding performance quality, it also has good corrosion resistance, can be used in many corrosive environments. The pitting index can be used as a measure of corrosion resistance.
Adding nitrogen and lower carbon content can be easily double phase stainless steel has good welding performance. As of now, the super resistance to stress corrosion cracking performance based on the application of duplex stainless steel has been expanded to the oil and gas industry, petrochemical industry, papermaking industry, desalination plant, pollution control equipment etc.. In many applications, dual phase stainless steel containing 22%Cr, 5%Ni and 3%Mo 2205 have replaced some of the austenitic stainless steel series, such as 317L and higher nickel content 904L.
Resistant to pitting index more than 40 super duplex stainless steel, such as 2507 has been used for shipbuilding, chemical and oil industries with high strength and in extreme environment use, such as containing chloride solution in use. Despite the nickel and molybdenum content is low, but its resistance to corrosion resistance equivalent to 5% to 6% Mo high alloyed super austenitic stainless steel containing. Based on its high yield strength, duplex stainless steel and super duplex stainless steel can greatly reduce the use of the steel weight.
In recent years, a number of nickel – dual phase stainless steel has been developed. In this kind of duplex stainless steel, some nickel is replaced by manganese and nitrogen. This kind of dual phase stainless steel for oil and deep sea pipeline containing 20%Cr, 16%Ni, 5% Mn, 002%C and 013%N 19d UNSS32001 and for water desalination plants, paper industry, dam and bridge containing 21%Cr, 15%Ni, 5% Mn and 022%N ldx2101 UNSS32101. Other low molybdenum, nickel free dual phase stainless steel can be comparable with the expensive 316, with super strength, wear and corrosion resistance, while reducing the weight of containing 23%Cr, 4%Ni dual phase stainless steel. It is widely used in the paper industry as well as near shore equipment.
Ferritic stainless steel has a high chromium content and contains 1% to 2% of the molybdenum, the relatively traditional ferrite has a good corrosion resistance. The carbon and nitrogen content of the super ferrite stainless steel must be very low (usually less than 100ppm), in order to reduce the ductile brittle transition temperature. This can be achieved by vacuum decarburization process. 30%Cr super ferritic stainless steel containing 22%, 24%, 26% and Ti/Nb with molybdenum and carbide stabilizing effect has been developed. In addition, the corrosion resistance of the super ferritic stainless steel containing 15%Mo and 22%Cr can be comparable to 316, while the Cr content is much higher. These super ferrite material is the first choice for the roof and exterior wall of the building, such as the coast, the reason is that these stainless steel has a high corrosion resistance and compared to the austenitic stainless steel has a lower coefficient of thermal expansion.
Cr Mn stainless steel has been in Germany for a long time of commercial production. When the Korean War began a shortage of nickel, prompting enterprises to further develop chromium manganese stainless steel. After the end of the war, the shortage of nickel has improved, and the company has returned to the development of the stainless steel. At that time, 200 series of stainless steel production costs are relatively low. With the advent of argon oxygen decarburization process, people can use cheaper high carbon ferromanganese and gaseous nitrogen alloying.
In fact, in the production process of Cr Mn stainless steel, the consumption of expensive argon is lower than that of Cr Ni stainless steel. AISI201 Cr Mn stainless steel has produced in many countries, including the United States and Japan, and has successfully application in the following areas: Food and beverage industry (cutlery, kitchen utensils), white home appliance industry (oven, washing machine, microwave oven, refrigerator, beverage vending machine), construction (partition, stair handrail, support structure), transportation (wagon, trucks, trailers, subway cars, trams, piston ring).
By alloying with copper, the drawing ability of Cr Mn series stainless steel can be improved, so as to further expand its application field. Adding 15% to 2% of the copper in the AISI201 stainless steel, the stainless steel has a very good drawing property.
AISI201 and 202 are developed in the process of using ingot. With the continuous casting process, argon oxygen decarburization process and use ladle furnace were more precise composition control and in the rolling of better control of casting billet heating temperature can produce more saving alloying elements in the strip.
These alloying elements endow the stainless steel with a higher strength, good drawing, welding and corrosion resistance.
Super martensitic stainless steel
Super martensitic stainless steel is the latest entry into the “super steel” family of steel. Although the super martensitic stainless steel has a very low carbon content and a martensitic structure, it combines high strength and excellent low temperature toughness and can be welded, and has sufficient corrosion resistance in many applications. The application of the super martensite containing 13% to 17%Cr and the content of nickel and molybdenum in the petroleum and natural gas industry is increasing continuously.
India stainless steel production in the past 15 years, India stainless steel production with an average annual growth rate of 14%, while the world’s average annual growth rate of only 6%. During this period, India stainless steel production accounted for the percentage of the world’s total output has increased from 2% to 7%, and the varieties of stainless steel production in India also occurred in the rapidly changing, the 200 series stainless steel production increased by a large margin, the 300 series stainless steel production is from 1990 to 2002 accounted for 95% of the total output dropped to 22% in 2004 – 05. A large number of India AOD furnace completed and put into operation to promote the production of chromium manganese stainless steel in India.
In India, 75% of the market share of stainless steel tableware, kitchen supplies and white home appliances. And in the last century 80’s, the industry accounted for 85% of the market share.
India’s transport industry, the consumption of stainless steel is expected to be greatly improved. At present, the transportation industry of stainless steel consumption is 230 thousand T, to 16 to 2015 years will increase to 250 thousand T. India auto production in recent years has been greatly increased, while the auto parts industry is also involved in global competition, the export volume has also increased dramatically. Because of the strict emission standard of automobile exhaust, the use of stainless steel in automobile and motorcycle exhaust system will be more and more. In railway passenger cars, many of the equipment and furnishings are also consumed stainless steel. Each car subway car consumption of stainless steel about 12t; and to the 2010 Delhi city underground railway will need 1000 buses and other major cities in India also in plans to use the transportation mode for Derry City underground railway, which will consume a large number of stainless steel. The new truck all coal in the future will also be made of stainless steel or aluminum. So, in the stainless steel to provide users with more value and maintain its position before the face more challenges.
1 Asian stainless steel consumption has increased significantly.
2 global stainless steel production capacity in excess of the case, the future of new production capacity will be mainly in China and India.
3. Argon oxygen decarburization technology and vacuum oxygen decarbonization technology based on the emergence and the improvement, the new super stainless steel in the future will get continued development, with a very low carbon and nitrogen content of super martensitic stainless steel and super iron (steel will appear; high nitrogen content, can be more economical production, with super performance of new austenitic stainless steel, double phase stainless steel, the new super austenitic stainless steel and new super duplex stainless steel will be available.
. expensive some varieties of stainless steel will be replaced by the appropriate, cheap varieties: replaced with double phase stainless steel will be almost no alloy super martensitic stainless steel; austenitic chromium nickel stainless steel and nickel chromium molybdenum austenitic stainless steel will be ferritic stainless steel, Cr Mn austenitic stainless steel and nickel duplex stainless steel replaced; super austenitic stainless steel will be lower alloy content of super duplex stainless steelalternative.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)