In pressure vessel of heterogeneous steel solder

One, heterogeneous steel solders the overview reachs his to solder characteristic between the steel with two kinds of different names solder say solder for heterogeneous steel, it is a kind of connect with the most wide application in belonging to heterogeneous metal to solder. Solder to heterogeneous steel contact can be divided again for two kinds of circumstances, the first kind is the joint that congener and heterogeneous steel forms, although the capable person of two side mother of this kind of connect is chemical composition is different, but belong to ferrite kind steel or belong to austenite kind steel; The 2nd kind of connect is an alien heterogeneous steel composition, namely the mother capable person of two side does not belong to contact same kind of steel, exemple if a side is ferrite kind steel, another side is austenite kind steel (like) of austenite stainless steel. Belong to ferrite to mother capable person kind steel, the connect that its welding line uses welding rod of austenite stainless steel or nickel radical welding rod solders, also belong to the 2nd kind of connect. As a result of heterogeneous steel connect no matter the mother capable person of two side goes up from chemical composition there still is difference on physics, chemical function, accordingly, when soldering, should compare same kind between steel oneself solder should complex much. The characteristic solders under the existence when heterogeneous steel solders: The inhomogenous sex that there is chemical composition in ① connect is heterogeneous steel solders inhomogenous sex reachs the chemical part of contact from this and the tissue that cause and mechanical performance are uneven sexual issue is very outstanding, especially contact of heterogeneous to the 2nd kind steel is more such. Not only the composition of welding line and mother capable person often differs, the part that connects welding line itself also is inhomogenous, this basically is caused as a result of the existence of attenuant rate when soldering. The integral function impact of the head of inhomogenous sex butt joint of this kind of chemical composition is bigger. ② connect bond is organized and the instability of function is in because the bond between mother capable person and welding line metal is existing clear macroscopical and chemical part is inhomogenous quality, because this causes constituent huge inhomogenous sex, the physico-chemical performance that gives contact, mechanical function brings very big impact. Solder with welding rod of austenite stainless steel for instance the heterogeneous steel connect between low-alloy steel and austenite stainless steel, existing in bond " carbon is migratory " phenomenon, make bond relies on welding line a side to form carburet layer, and low-alloy steel a side forms decarburized layer, change of the hardness inside area is here acuteness, at the same time mechanical function drops, cause craze even. The heat treatment after ③ solder is more unmanageable problem the heat treatment after the solder of heterogeneous steel connect is a problem that deals with harder, if deal with undeserved, can serious damage is heterogeneous the mechanical function of steel connect, cause craze even. For example to connect of congener and heterogeneous steel, intensity of capable person of a side mother is inferior, temperature of the heat treatment after the solder of the requirement is inferior also, and intensity of capable person of another side mother and alloying element content are higher, temperature of the heat treatment after the solder of the requirement is higher, right now if PWHT temperature choice is undeserved, the intensity of capable person of a side mother that can make intensity low drops excessive. 2, heterogeneous steel solders craft point 1.

Solder material chooses to choose solder capable person correctly is to solder the key of heterogeneous steel, solder closely related the quality of contact and performance characteristics and choose solder capable person. The welding line of heterogeneous steel connect and bond, because alloying element is reached by dilute of carbon migratory wait for a reason to exist an intermediate zone, in intermediate zone not only organization of chemical composition, metallographic is inhomogenous, and physical function, mechanical function also have very big difference normally, may cause weld defects (wait like crackle) or reduce performance badly. Must mix according to form of the composition of mother capable person, function, connect for this use requirement will choose solder capable person correctly. The basic principle that its solder material chooses has the following: ① is soldering below the premise that contact does not produce the limitation such as crackle, the intensity that is like welding line metal and plasticity cannot when give attention to two or morethings, should choose the solder capable person with plasticity and nicer tenacity. Function of metal of ② welding line needs a medium kind to accord with capable person of two kinds of mothers only, can think contented use technology asks. Usually, choose solder material to make the function of mechanical function etc of welding line metal not under neutral of mother capable person the index of can inferior a side, thought to satisfy technical requirement namely. But still answer below certain circumstance from solder technical properties (wait like crack resistance) the respect will consider. When the heterogeneous steel grade of ③ structure steel solders, to the structural steel welding rod of same intensity grade, should choose the low hydrogen welding rod with can good crack resistance commonly. To metallographic constituent difference compares big heterogeneous steel connect, be like pearlite - austenite is heterogeneous steel connect, criterion must mature fill metal is soldered contact function to still get ensuring after dilute. Below the condition that ④ asks in contented function, choose the solder capable person that good, price gets technical properties lowly, easily. ⑤ is heterogeneous to the alien steel connect, all choose welding rod of stainless steel of austenite of tall chromic nickel or nickel commonly base alloy welding rod. To the main contact with working slashing requirement, head choose uses welding rod of nickel radical alloy, because although its price is more expensive, but can decrease or avoid carbon migratory, and the interpose of linear expansion coefficient of metal of its welding line is mixed at ferrite steel between austenite steel, the organization of butt joint head and mechanical function have profit. 2.

Solder temperature of warm-up requirement warm-up is decided really, solder certainly commonly by a side with warm-up high demand warm-up temperature, but connect of heterogeneous to the alien steel, can drop warm-up temperature appropriately, decide via experiment hind when necessary. 3.

Solder to decide connect of heterogeneous to the alien steel normatively, solder in the choice when the standard, because try,lower penetration ratio. For this, should choose small diameter welding rod or welding wire, choose small electric current as far as possible fast solder. 4.

Use the method that piles edge solder beforehand to undertake soldering to handle difficult issue to solve warm-up of heterogeneous steel connect and solder postheat sometimes, often use the method that piles edge solder beforehand to undertake soldering. Its craft order is: Pile layer of edge solder 1 ~2 and welding line beforehand first in the groove of capable person of a side mother that needs heat treatment this side undertakes the welding rod → of akin steel PWHT → cold conditions solders whole welding line, next contact undertakes PWHT no longer. This kind of practice, can reduce a few issues that inhomogenous place brings bond class status, the heat treatment that also gives contact is brought convenient, but the ply that is sure to keep in mind to pile edge solder layer beforehand right now must assure to be more than or be equal to 4mm, in order to have the effect to separator. 5.

Temperature of the heat treatment after solder is according to heat treatment temperature asks talent of high a side mother comes commonly surely really make choice of is heterogeneous the PWHT temperature of steel connect, must do welder beforehand right now art assess, the intensity of capable person of a side mother that makes intensity low in case drops badly, occurrence intensity is unqualified. Of nextpage3, compound armor plate solder compound armor plate is by alloy of stainless steel, nickel radical, cupreous radical alloy or titanium board for answer layer, pearlite steel is basic level, the bimetallic board that makes with the method such as explosive solder, compound rolling, v. The basic level of compound armor plate should satisfy the requirement of contact intensity and stiffness, answer layer should be satisfied be able to bear or endure the requirement such as corrode. Do not lose original integral performance to assure compound armor plate, must undertake soldering respectively with answer layer to basic level, choice of material of its weldability, solder, welder art wait to be decided by material of basic level, answer layer. Of basic level and answer layer boundary solder belong to heterogeneous steel to solder, its weldability basically depends on composition of basic level and the physical function of answer layer, chemical composition, metal of contact form, fill. Always heterogeneous steel solders the problem of existence is likewise when compound armor plate solders, elaborate a few problems that the attention answers when compound armor plate solders only for this section. Application is at present more is the compound armor plate that austenite stainless steel is basic level for answer layer, pearlite, it is the compound armor plate that ferrite steel is basic level for answer layer, pearlite next. 1.

Solder method according to clad steel plank dimension of ply of qualitative, connect, groove reachs the condition that apply solder to wait to solder certainly method, normally gas of solder of the welding rod arc welding, solder that bury arc, arc of tungsten pole argon, CO2 protects solder and plasma arc solder to wait. Current and commonly used tungsten extremely argon arc solder or welding rod arc welding solder answer layer, solder with the solder that bury arc or welding rod arc welding basic level. 2.

Form of groove of connect of groove form butt joint sees JB/T 4709 " steeliness pressure vessel solders regulations " graph A1. Can use groove of V form, X form, V and U combination form. Also can be in contact the reverse side undertakes machining inside a paragraph of small distance, metal of layer of take out answer, in order to ensure when solder, solder basic level does not make solder of flesh of basic level solder arrives on answer layer. Use X form groove as far as possible commonly double-faced solder, first solder basic level, again solder transfers layer, final solder answer layer. With assuring to solder contact has better corrosion resistance. At the same time the consideration transfers of the layer solder characteristic, the welder that reduces answer layer a side as far as possible makes an amount. Horn receives contact groove form to see JB/T 4709 " steeliness pressure vessel solders regulations " in graph A2. No matter answer layer is located in inside or outside side, all solder first basic level. When answer layer is located in inside, in solder answer layer should is opposite from inside before root of basic level solder has clear root. Answer layer is located in outside when side, answer basic level final solder path undertakes repairing burnishing. When solder answer layer, first solder transfers layer, again solder answer layer. When the fused temperature of the steel of basic level of fused temperature prep above of answer layer metal, and when two kinds of metals are antipathic on metallurgy, answer layer metal must use pad in order to maintain the integrality of answer layer. After basic level solder is over, use fillet weld to solder gasket with answer layer. 3.

Fill metal chooses basic level to use appropriate fill metal to undertake soldering, make contact has the mechanical performance that anticipates use place needs. Below most circumstance, choose appropriate intermediate fill metal to regard the transition of steel as the layer, control answer layer metal thereby the quantity containing iron that final solder, avoid answer layer and generation of path of solder of basic level place fragile change, crackle, assure what answer layer solder to be able to bear or endure the special function such as corrode, wear-resisting. 4.

Solder to reach solder material to choose ① orderly normally first solder basic level, the first basic level (carbolic steel, low-alloy steel) welding line not Ying Rong penetrates answer layer metal, in case welding line metal happens fragile change or produce crackle. Measure is to use appropriate joint design, frit of metal of limitative steel welding line is appeared; From contact the reverse side purify answer layer, this also increased the workload of solder answer layer of course, rose to solder cost. ② solder (v) when answer layer a side, must consider attenuant impact. No matter which kind of v methods, the welding line metal of ground floor v is the fusion of metal of mother capable person that enters by the frit apply metal of v material and frit and become. Because the alloying element content of mother capable person is very low, so it has attenuant effect to the alloy composition of metal of ground floor welding line. Accordingly, the likelihood makes the austenite in welding line metal and ferrite form elemental content inadequacy, result v metal may appear many martensite organization, produce crackle possibly, bring about v layer tenacity to reduce at the same time. With handiwork welding electrode is a specification below. The penetration ratio of manual welding electrode is 20 ％ left and right sides commonly. If use 308 model welding rod (Cr18 ％ , Ni 8 ％ ) model welding electrode, after classics mother capable person is attenuant, the composition of welding line metal of v will become 15-7 model, the likelihood in such welding line is austenite + martensite organization. If be in in real operation when penetration ratio control is bigger, many fragile hard martensite arises likely in welding line, no matter such v layer is mechanical function, be able to bear or endure corrode function, or crack resistance can be very poor. As a result of attenuant action, the Ni content in welding line is inferior, around weld junction the martensite with wider generation transfers layer. Same v method, if choose 309 model v material, after classics mother capable person is attenuant, the composition of welding line metal of v is 19-9 or 18-8 model, such ground floor achieve the requirement of v composition basically, and welding line organization is austenite + ferrite organization, such welding line metals are had taller fight hot tearing function and corrosion resistance can. Soldering so answer when the answer layer of plywood, should choose appropriate fill metal first v one layer or multilayer transfer layer, next again solder answer layer. Transfer the fill metal of the layer must the dilute of steel of can concessional basic level. With the 16MnR+304 with common pressure vessel answer plywood is exemple, solder use normally when answer layer 309 model solder material first v, use next 308 model solder material solder builds facing. Plane of air of usable carbon arc, shovel cuts ③ root ministry or filing has clear root. Transfer in v before the layer, must keep clear of any odd-come-short in clear root groove. The heat treatment after ④ wants solder solders with eliminating leftover stress, choose Lv of the take an examination when heat treatment temperature: Basic level and the difference with the normative heat treatment of answer layer; Be able to bear or endure to answer layer the influence of corrode sex; The element of basic level and answer layer interface diffuses to whether can produce brittleness photograph, bring about plate performance aggravation; Manage as a result of basic level and the content of answer layer function difference, process of heat treatment refrigeration produces leftover stress, edge ply direction forms tensile stress on answer layer, bring about answer layer to produce stress to corrode craze to wait. Eliminate stress heat treatment to be able to be over in solder undertake after basic level, next solder transfers layer, again solder answer layer. Heat treatment temperature takes floor, extend heat preservation time. CNC Milling