1, the corrosion resistance of chromium stainless steel with a certain (oxidizing acids, organic acids, cavitation), heat and wear resistance. Typically used for power plants, chemical, oil and other equipment and materials. Chromium stainless steel welding is poor, should pay attention to Welding Electrode, heat treatment conditions and the selection of suitable welding.
2, Cr 13 stainless steel weld hardening of large, easy to crack. If using the same type of chromium stainless steel electrodes (G202, G207) welding must be carried out more than 300 ℃ 700 ℃ preheat and post weld around the slow cooling process. If the weldment can be postweld heat treated, chrome-nickel stainless steel welding rod should be used (A107, A207).
3, 17 chromium stainless steel to improve corrosion resistance and weldability increased amount of stability and appropriate elements Ti, Nb, Mo, etc., welding of stainless steel better than the chrome 13. Using the same type of chromium stainless steel electrodes (G302, G307), should be above 200 ℃ preheating and post-weld tempering around 800 ℃. If the weldment can not be heat treated, chrome-nickel stainless steel welding rod should be used (A107, A207).
4, chrome-nickel stainless steel electrodes with good corrosion resistance and oxidation resistance, widely used in chemical, fertilizer, petroleum, medical equipment manufacturing.
5, chrome-nickel stainless steel welding, carbide precipitation by repeated heating to reduce corrosion resistance and mechanical properties.
6, chrome-nickel stainless steel with titanium calcium type of drug skin and low hydrogen type. Titanium calcium type can be used for AC-DC, AC welding penetration but shallow, and easy to redness, so as far as possible the DC power supply. Diameter of 4.0 and below can be used for all position Flux Cored Welding Wire parts, 5.0 and above for flat welding and fillet welding.
7, the electrode should be used to keep dry, titanium calcium type shall be 150 ℃ drying 1 hour, low-hydrogen type should be dried by 200-250 ℃ for 1 hour (can not be repeated drying, easy to crack or peel off the skin drugs), to prevent the electrode viscous oil and other drug skin dirt, so as not to increase the carbon content and the resulting impact of the weld weldment quality.
8, in order to prevent corrosion of heat generated between the eyes, the welding current is not too large, less than about 20% carbon steel electrode, the arc should not be too long, the layer between the fast-cooling, in order to narrow weld is appropriate.
Stainless steel is mainly used for corrosion-resistant, but also as a heat-resistant steels and low-temperature steel. Therefore, the welding of stainless steel, the electrode performance must be consistent with the use of stainless steel. Stainless steel electrode and the base material must be based on working conditions (including temperature and exposure to media, etc.) to use.
1, in general, the choice of electrode material can refer to the base metal, base metal component selection and the same or similar electrode. Such as: A102 corresponding 0Cr19Ni9; A137 corresponding 1Cr18Ni9Ti.
2, the carbon content on corrosion resistance of stainless steel have a great impact, therefore, generally used in the carbon content of deposited metal is not higher than the base material of stainless steel electrode. If you must use A022 316L electrodes.
3, austenitic stainless steel weld metal mechanical properties should be guaranteed. Can be verified by the welding procedure qualification.
4, for work in high-temperature heat-resistant stainless steel (austenitic heat-resistant steel), the choice of electrode should be able to meet the main thermal crack resistance of weld metal and welded joints of high-temperature performance.
(1) of the Cr / Ni ≥ 1 of the austenitic heat-resistant steel, such as 1Cr18Ni9Ti, etc., generally are used austenitic - ferritic stainless steel welding rod to weld metal ferrite containing 2-5% is appropriate. Ferrite content is too low, the weld metal cracking and poor; if too high, or long-term use in high temperature heat treatment is easy to form σ-phase embrittlement, resulting in cracks. Such as A002, A102, A137.
In some special applications, may require the use of fully austenitic weld metal, can be used such as the A402, A407 electrodes and so on.
(2) of the Cr / Ni <1 the stability of the austenitic heat-resistant steel, such as Cr16Ni25Mo6, etc., generally should be to ensure the weld metal and base metal with similar chemical composition roughly the same time, increase the weld metal Mo, W, Mn and other elements of content, making the heat to ensure a strong weld metal at the same time, improve weld crack resistance. Such as the use of A502, A507.
5, for work in a variety of corrosive media in the corrosion resistance of stainless steel, the temperature should be medium to select the electrode and work, and to ensure its resistance to corrosion (corrosion of welded joints to do test).
(1) For operating temperature over 300 ℃, there is a strong corrosive media, shall be stabilized with Ti or Nb elements or ultra-low carbon stainless steel electrode. Such as A137 or A002.
(2) media containing sulfuric acid or hydrochloric acid, often used with Mo and Cu or Mo-containing stainless steel electrode, such as: A032, A052 and so on.
(3) work, corrosive pollution weak or just to avoid corrosion of equipment, may use non-stainless steel welding Ti or Nb.
To ensure the weld metal resistance to stress corrosion, the use of ultra-alloyed welding consumables, that the corrosion resistance of weld metal alloying elements (Cr, Mo, Ni, etc.) were higher than the base metal. Such as the use 00Cr18Ni12Mo2 types of welding material (such as A022) welding 00Cr19Ni10 weldment.
6, for work in low temperature conditions, austenitic stainless steel, welded joints should be used to ensure that the temperature of the low-temperature impact toughness, so pure austenitic electrodes. Such as A402, A407.
7, can also be used nickel-based Low Alloy Steel Electrodes. Such as the use of 9% Mo welding consumables welding of nickel-based super austenitic stainless steel Mo6.
8, electrode selection of drug skin type:
(1) The two-phase austenitic steel weld metal itself contains a certain amount of ferrite, with good ductility and toughness, crack resistance of weld metal from the point of comparison, alkaline drug skin leather with titanium calcium type Unlike carbon steel electrode welding difference as significant. Therefore, in practical applications, from welding performance, focus more, mostly by drug skin type code 17 or 16 of the electrode (eg, A102A, A102, A132, etc.).
(2) only in the rigid structure of a large crack or poor weld metal (such as certain martensitic chromium stainless steel, pure austenitic chromium-nickel stainless steel, etc.) only when considering the selection of drug, code-named 15 of the skin alkaline drug skin stainless steel electrode (eg, A107, A407, etc.).
In summary, the austenitic stainless steels have their own unique characteristics, austenitic stainless steel welding electrode selection of particular note, the only way to achieve the implementation of different materials for different welding methods and different electrode materials, stainless steel electrode must be based on the base metal and working conditions (including temperature and contact media, etc.) to use. It was possible to achieve the desired weld quality.