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Current Position:Home > Industry news > DUPLEX STAINLES

DUPLEX STAINLESS STEEL TUBE (MANUFACTURER&SUPPLIER)

Release Date:2017-04-15

Duplex stainless steel tube has good welding performance, compared with the ferritic stainless steel and austenitic stainless steel, it is neither like ferritic stainless steel weld heat affected zone, as grain coarsening and make the plastic toughness sharply lower, also don't like austenitic stainless steel, the welding thermal crack is more sensitive.

Duplex stainless steel because of its special advantages, is widely used in petroleum chemical industry equipment, water and waste water treatment equipment, oil gas transmission pipeline, paper making machinery and other industrial areas, has also been used for bridge bearing structure field in recent years, has the very good development prospect.

Duplex stainless steel is in its solid quenching organization ferrite and austenite facies each half, general minimum phase content may be as high as 30%.

Chinese name Duplex stainless steel tube foreign names Duplex stainless steel tube steel tube points class stainless steel pipe can welding performance optimal point resistance to stress corrosion cracking Should be in petroleum and chemical equipment Directory 1 duplex stainless steel tube

Forced the introduction

Duplex stainless steel tube safety use restrictions and requirements

2 the characteristics of duplex stainless steel

Much as compared with austenitic stainless steel, duplex stainless steel

Much as compared with austenitic stainless steel, the weakness of the duplex stainless steel

Forced compared with ferritic stainless steel, duplex stainless steel

Forced compared with ferritic stainless steel, the weakness of the duplex stainless steel

Duplex stainless steel tube duplex stainless steel tube  editor of duplex stainless steel tube

Duplex stainless steel tube has good welding performance, compared with the ferritic stainless steel and austenitic stainless steel, it is neither like ferritic stainless steel weld heat affected zone, as grain coarsening and make the plastic toughness sharply lower, also don't like austenitic stainless steel, the welding thermal crack is more sensitive.

Duplex stainless steel because of its special advantages, is widely used in petroleum chemical industry equipment, water and waste water treatment equipment, oil gas transmission pipeline, paper making machinery and other industrial areas, has also been used for bridge bearing structure field in recent years, has the very good development prospect.

Duplex stainless steel is in its solid quenching organization ferrite and austenite facies each half, general minimum phase content may be as high as 30%.

Duplex stainless steel tube duplex stainless steel tube safety use restrictions and requirements

1. The need to control the phase ratio, the most appropriate proportion is ferrite and austenite meet each half, including a number of not more than 65%, so as to ensure the best comprehensive performance. If two phase imbalance, such as too many ferrite phase, it is easy to form in welding HAZ, single-phase ferrite in some medium is sensitive to stress corrosion cracking.

2. Need to master organization change law of duplex stainless steel tube, and familiar with each steel grade TTT CCT curve, this is the correct guidance for duplex stainless steel heat treatment, hot forming technology is the key, such as precipitation of duplex stainless steel brittle phase are much more sensitive than austenitic stainless steel.

3. Continuous use of duplex stainless steel tube - 50 ~ 250 ℃ temperature range, the lower limit depends on the brittle transition temperature, steel cap is limited by 475 ℃ brittleness, the maximum temperature should not exceed 300 ℃.

4. The duplex stainless steel tube after solid solution treatment need to be fast, slow cooling leads to the precipitation of brittle phase, which can lead to the toughness of the steel, especially the local corrosion resistance.

5. High chrome molybdenum hot working of duplex stainless steel tube and the lower limit of thermoforming temperature not lower than 950 ℃, super duplex stainless steel is not less than 980 ℃ low chromium molybdenum duplex stainless steel is not less than 900 ℃, avoid caused by brittle phase separation in the process of surface crack

6. You can't use of austenitic stainless steel commonly used 650-800 ℃ eliminating stress processing, generally USES solid solution annealing treatment. For surfacing duplex stainless steel in low alloy steel, the need for 600-650 ℃ the overall elimination should be processing, must be considered due to the precipitation of brittle phase of toughness and corrosion resistance, especially the resistance to local corrosion performance degradation, as far as possible, shorten the heating time in this temperature range. Heat treatment of low alloy steel and duplex stainless steel clad plate problems also want the same consideration. [1]

7. Need to be familiar with understand the laws of duplex stainless steel tube welding, all not to use the welding of austenitic stainless steel, duplex stainless steel equipment safe use and can correctly grasp the welding process of steel has a lot to do, the failure of some equipment are often related to welding. Is the key to energy and interpass temperature control, correct selection of welding material is also very important. Welded joint (weld metal and welded HAZ) of two phase proportion, especially the number of austenitic weld HAZ maintain necessary, to ensure the performance of the welded joint is equal to parent metal is very important.

8. Selection of duplex stainless steel in different corrosion environments, to pay attention to the corrosion resistance of steel is always relative, in spite of duplex stainless steel has good resistance to local corrosion performance, in terms of a duplex stainless steel, he is also the applicability of a medium conditions, including temperature, pressure, medium concentration, pH, etc., need to choose carefully. Access to the data from literature and manual is a lot of laboratory corrosion test results, often with the project actual conditions gap, so need to pay attention to when select material, when necessary, need to be at the scene of the actual corrosion test of medium or coupon test, under the condition of even simulator test. [2]

The characteristics of duplex stainless steel tube duplex stainless steel  editor Due to the features of the two phase, with proper control of chemical composition and heat treatment process, make the DSS has both the advantages of ferritic stainless steel and austenitic stainless steel.

Duplex stainless steel tube compared with austenitic stainless steel, duplex stainless steel

(1) the yield strength is more than twice as tall as ordinary austenitic stainless steel, and has enough plastic molding need toughness. Using the duplex stainless steel storage tank and pressure vessel wall thickness than the commonly used austenitic reduce 30-50%, reducing the cost.

(2) has excellent resistance to stress corrosion cracking ability, even the lowest of duplex stainless steel alloy content than austenitic stainless steel has a higher resistance to stress corrosion cracking ability, especially in the environment of the chlorine ion. Stress corrosion is common austenitic stainless steel is difficult to solve the outstanding problems.

(3) the most widely used in many medium of 2205 duplex stainless steel corrosion resistance is superior to the ordinary 316 l austenitic stainless steel, and super duplex stainless steel has high corrosion resistance, and then some medium, such as acetic acid, formic acid and even can take the place of austenitic stainless steel, high alloy and corrosion resistant alloy.

(4) has a good resistance to local corrosion performance, compared to the alloy content quite austenitic stainless steel, its wear resistance corrosion and corrosion fatigue performance is better than that of austenitic stainless steel.

(5), lower than the linear expansion coefficient of austenitic stainless steel and carbon steel, suitable for connecting with carbon steel, has important engineering significance, such as production of composite panels or lining, etc.

(6) no matter under the condition of dynamic load and static load, than austenitic stainless steel has higher energy absorption capacity, the structure to cope with sudden accidents such as collision, explosion, etc., obvious advantages, duplex stainless steel has practical application value.

Duplex stainless steel tube compared with austenitic stainless steel, the weakness of the duplex stainless steel

(1) application of universality and multifaceted than austenitic stainless steel, such as its temperature must be controlled under 250 ℃.

(2) the plastic toughness was lower than those of austenitic stainless steel, cold and hot working process and mechanical properties than austenitic stainless steel.

(3), medium temperature brittleness area need to strictly control the process of heat treatment and welding system, in order to avoid the occurrence of harmful phase, damage performance.

Duplex stainless steel tube compared with ferritic stainless steel, duplex stainless steel

(1) the comprehensive mechanical properties are better than ferritic stainless steel, plastic toughness, in particular, is not sensitive to brittle like ferritic stainless steel.

(2) in addition to the stress corrosion resistance and other local corrosion resistance are better than ferritic stainless steel.

(3) the cold working process and cold forming performance is far better than that of ferritic stainless steel.

(4) the welding performance is far better than ferritic stainless steel, generally do not need to preheat before welding and without heat treatment after welding.

(5) the application scope is wide ferritic stainless steel.

Duplex stainless steel tube compared with ferritic stainless steel, the weakness of the duplex stainless steel

Alloy element content is high, the price is relatively high, general ferrite does not contain nickel.