A method of manufacturing a weldment made of ductile iron
(57) Abstract:Usage: for arc welding products from high-strength nodular cast iron in the oil and gas industry, power engineering, shipbuilding, utilities. The inventive welding carry out TIG method non-consumable electrode with additional filler wires. And for welding the root pass of the wire has a composition, wt.%: iron is 1.0-10.0; manganese 0,5-9,0; Nickel else, when the Nickel content of at least 90 wt.%, and for subsequent welding seams use a wire of the following composition, wt. %: Nickel 40,0-55,0; iron 30,0-45,0; chromium of 0.1-7.0 and manganese else. As a result of implementing the proposed method of welding weld withstands pressure up to 10-25 MPa. 2 C.p. f-crystals, 2 Il. The invention relates to welding, in particular for arc welding products from high-strength cast iron, and can find application in the oil and gas industry, power engineering, shipbuilding, utilities.There is a method of mechanized cold arc welding of cast iron, which are consumable electrode, mild steel and weld pool serves a filler rod of alertsa of the conditions are good welding weld metal with cast iron body parts. This method does not provide high-quality welds and is not applicable for non-welding joints.There is a method of welding with non-consumable electrode of nodular cast iron with pre-heating and subsequent heat treatment 
However, this method does not provide high quality welding curved joints in the manufacture of shaped articles from high-strength cast iron.This method is the closest to the claimed and accepted as a prototype.The purpose of the invention, the quality of the welding seam in arc welding of articles made of ductile iron, providing the possibility of making shaped articles from high-strength cast iron.This objective is achieved in that in the method of manufacturing a weldment of high-strength nodular cast iron, including preparation of edges for welding, preheating to a temperature of 250-500oC, welding in argon non-consumable electrode and the weld heat treatment, characterized in that the welding of the root pass are using filler wire of the following composition, wt.Iron is 1.0-10.0
Nickel OS the following chemical composition, wt.Nickel 40,0-55,0
Chromium is 0.1-7,0
Heat treatment after welding by heating the welded connection at speeds of no more than 20oC/C to 950-970oC, cooling in air to a temperature of 700-720oWith, re-heating at a rate not exceeding 20oC/C to a temperature of 950-970oC and subsequent cooling in air to ambient temperature. When the heat treatment in the furnace welded joint is heated to temperature 950-970oWith speeds of no more than 20oWith a/C, maintained at that temperature for 8-12 min, then cooled to a temperature 730-740oC, maintained at that temperature for at least 8 min and cooled in air to ambient temperature.Novelty and inventive step of the claimed technical solution is confirmed by the fact that only by using this method it is possible to manufacture welded fittings made of ductile iron, having a minimum burst pressure of 10-25 MPa.In Fig. 1 shows an example of cutting welding joint; Fig. 2 is a graph of the temperature of the weld by heat treatment.The proposed method for the manufacture of welded products RUB cleaned from oil, dirt, rust, moisture and other contaminants. Then on the ends of the edges of the chamfer angle 273oto the end surface, after which obtochuyut the inner surface of the billet width not less than 7 mm from the welded end and a depth of not less than 0.7 mm, the Outer surfaces of the workpieces stitch width not less than 10 mm from the welded end and a depth of not less than 0.1 mm, an Inner surface abutting the ends of the blanks be ground to the same diameter. Fit-up welding is no gap between the blade edges. Pets local gap width of not more than 0.6 mm for a length of not more than 1/3 of the circumference. Allowable offset edges relative to each other is not more than 0.8 mm on the site no more than 1/3 of the circumference. The Assembly of the welding joint, it is desirable to produce the lairs, the alignment - regulating pricedoc under lairs. Preheating is carried out by a gas flame. Possible induction heating with a heating rate of not more than 20oWith a/C. the Width of the heated portion is not less than 80 mm and heating at full depth. Preheating temperature of 250-500oC. After warming up, perform the welding of the root pass of a consumable electrode in argon using a filler wire is Oka composition, wt. Ni 52; Fe 36; Cr 7; Mn 5.Post-weld heat treatment of welded site is produced as follows. In field conditions, the heating of the weld to produce an oxygen-propane torch. For pipes with a diameter of 150 mm is required at least two burners. Heating is carried out to a temperature of 950-970o, Then cooled to 700-720oWith and heated to 950-970oWith subsequent cooling in air. The heating rate and cooling is maintained equal to the 20oWith/sIn workshop conditions the heat produced in the furnace. The product is placed in an oven with a temperature of 1000oC until the welded Assembly is heated, the temperature in the furnace drops to 960oSince, at this temperature, incubated 10 min, after which the welded Assembly is transferred into a furnace with a temperature 730-740oC and incubated for 9 minutes and Then the product is removed from the furnace and cooled in air to the shop temperature.Produced by the proposed method welded joints of pipes and fittings made of high-strength nodular cast iron has stood the test of high pressure. Thus, the welded connection of pipes with a diameter of 100 mm with wall thickness of 6.1 mm withstood the pressure of 15 MPa. According to the claimed method provides welding natvig is S="ptx2">1. Method of making welded articles from high-strength nodular cast iron, including preparation of edges for welding, preheating to 250 To 500°C, welding in argon non-consumable electrode and the weld heat treatment, characterized in that the welding of the root pass are using filler wire of the following composition, wt.Iron 1 10
when the Nickel content of at least 90% and for subsequent welding seam filler wire take the following composition, wt.Nickel 40 55
Iron 30 45
Chromium is 0.1-7,0
Manganese Else.2. The method according to p. 1, characterized in that the heat treatment of the weld is produced by heating the welded connection at a speed of not more than 20 deg./with up to 950 970°C, cooling in air to 700 720°C, re-heating at a rate of not more than 20 deg./with up to 950 970oC and subsequent cooling in air to ambient temperature.3. The method according to p. 1, characterized in that the heat treatment of the weld is produced by heating the welded connection to 950 970°C at a rate of not more than 20 deg. /s isothermal holding at this temperature for 8 to 12 min, ohlazhdeniya air to ambient temperature.
FIELD: restoration of parts cast of aluminum alloys with use of fusion welding.
SUBSTANCE: method comprises steps of cutting out flaw containing portion spaced equidistantly by distance (3 - 8)n from boundary of flaw; making insert of deformed aluminum alloy welded with casting alloy of restored part at relation of coefficients of percentage elongation Gd/Gc = 9 - 25, where Gd and Gc coefficients of percentage elongation respectively of deformed and casting aluminum alloys, n - thickness of cast part in restoration zone.
EFFECT: lowered labor consumption at restoring parts of aluminum alloys.
3 dwg, 1 tbl
FIELD: processes for making large-size thick-sheet orthotropic plates of carbon low-alloy steels in different branches of industry, particularly for bridge building.
SUBSTANCE: method comprises steps of relative orienting members of orthotropic plates; tack welding oriented members by means of non-consumable tungsten electrode in mixture of shield gases Ar (95 - 97)% + (3 - 5%) CO2 ; performing automatic continuous-seam welding and then trimming surface of welded seam. It allows simplify method for making welded large-size thick-sheet orthotropic plates of carbon low-alloy steels.
EFFECT: lowered labor consumption, shortened time cycle for making enhanced-quality plates, improved reliability of welded structures.
6 dwg, 1 ex
FIELD: electric arc welding of materials by means of non-melting electrode, namely methods for automatic argon-arc pulse welding of steel tubes.
SUBSTANCE: method comprises steps of preliminarily dressing tube butts and forming annular chamfers on inner surfaces of butts; abutting tubes; moving welded edges relative to electrode by step axial rotation of abutted tubes at revolution number 1 -1.5 rev/min; igniting arc 2 - 5 s before starting rotation of tube in order to heat welded seam zone; performing welding by means of torch inclined to tube axis by angle 60 - 85° relative to vertical line; sustaining electric current intensity in range 110 - 155 A for pulse duration 0.7 - 0.9 s; keeping electric current at pause period in range 10 - 30 A for pulse duration 0.5 - 0.7 s. Overlapping value of welded seam is in range 10 - 25 mm. It allows eliminate cracking of welded seam of tubes at bending samples by angle exceeding 160°.
EFFECT: enhanced quality of welded seam of tubes.
3 dwg, 1 tbl
FIELD: automatic welding increased-thickness joints of titanium alloys in inert gas by means of submerged tungsten electrode.
SUBSTANCE: method comprises steps of forming in welded edges cutout which is in the form of П-shaped dressing of edges at welding parts with slit gap; keeping relation of depth of dressing to its width less than 1; rounding acute angles of dressing; before welding introducing granulated additive material into slit gap and performing first pass at minimally admissible value of shape factor of fusion. In order to provide guaranteed fusion of walls, second and third passes are realized in the same mode. Electrode is placed in such a way that it is shifted relative to butt axis. At double-side welding passes are realized according to next order: first and second passes, then third, fourth and fifth passes.
EFFECT: enlarged manufacturing possibilities of method due to increased limit thickness of welded parts.
3 cl, 5 dwg
FIELD: machine engineering, possibly gas-shield electric arc welding by means of non-consumable electrode.
SUBSTANCE: method comprises steps of alternatively feeding several gases or their mixtures by pulses; at each next pulse feed using gases (gas mixtures) having ionization potentials different in comparison with those of gases or gas mixtures of previous pulse feed; periodically changing electric arc gap simultaneously with gas feed pulses; setting basic voltage of electric arc equal to optimal voltage in medium of gas or gas mixture with minimum ionization potential; setting difference between maximum and minimum voltage values of arc at periods of previous and next pulse feed of gases or gas mixtures in range 1 - 7 V.
EFFECT: enhanced quality of welded joints, possibility for adjusting fusion depth.
1 tbl, 1 ex
FIELD: gas-shield welding process with use of non-consumable electrode, namely torches for such welding.
SUBSTANCE: torch includes body of collet chuck holder. Said body has cylindrical surface near its working end and it is welded to electrically conducting gas conduit. Collet chuck is mounted in body for securing non-consumable electrode. Nozzle has cylindrical surface passing to cone surface and then again passing to cylindrical surface near its working end. Asbestos-cement insulator is arranged on surface of body of collet chuck holder; brass sleeve is put onto said insulator. Insulator is fixed to body by means of pressure ring-splitter having cylindrical surface passing to cone surface with radial openings.
EFFECT: possibility for making small-size torch for welding butts of metallic structures in hard-to-reach places of installation zone.
FIELD: plastic working of metals, namely processes for forming butt welded seams on tubes at making tube studs of U-shaped tube bundles using effect of localized hot plastic deforming of welded seam and near-seam zones.
SUBSTANCE: method comprises steps of preliminarily working tube ends by expanding them from cylinder to cylinder; assembling tubes with use of mandrel and placing intermediate member of additive material between joined end surfaces of end portions of tubes sized by expansion and end surfaces of step ring. Welded seams are formed by argon-arc welding due to melting material of intermediate member at its both sides adjacent to tube ends. The intermediate member is heated up and it is subjected to hot radial squeezing while concentrating its initial deformation in surface layers according to position of ring steps, welded seams and near-seam zones on mandrel for providing size of their outer diameter equal to initial outer diameter of tubes.
EFFECT: improved quality of welded seams.
FIELD: mechanical engineering; argon-arc welding.
SUBSTANCE: invention relates to methods of automatic argon-arc welding of austenitic steel pipes in manufacture of important constructions, such as high-pressure pipes used at nuclear power stations. Proposed method includes mechanical preparation of welding surface zone, veeing edges to miter of 3.0-3.5 mm and subsequent multiple-pass welding with nonconsumable negative electrode using filler wire. Welding edges are veed to miter of 2.7-3.0 mm. Welding at first pass is carried out with heat input of 0.35-0.55 MJ/m by impulse current. Welding at second pass is done with heat input of 0.6-0.86 MJ/m by impulse current at cross oscillations of electrode. Welding at third and subsequent passes is carried out with heat input of 0.62-1.16 MJ/m by steady current with cross oscillations of electrode.
EFFECT: increased capacity art welding and quality of weld joint owing to reduction of intercrystalline cracking of weld joint.
FIELD: mechanical engineering; welding.
SUBSTANCE: invention relates to design of torches for gas-shielded arc-welding by nonconsumable electrode. Proposed head of torch contains chuck with hole for electrode secured in body and gas fed channels, nozzle and partition arranged inside nozzle and formed by pack of gauzes. Gauze partition is made convex relative to welding arc flame. Head is furnished additionally with partition made of pack of gauzes arranged between chuck and gauze convex partition and made concave relative to flame of welding arc. Packs of gauzes are made of stainless steel of 3 to 5 layers. Gauze mesh is 0.3-0.5 mm.
EFFECT: provision of high quality of welding at relatively simple design.
5 cl, 2 dwg