Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
  • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
  • B23K35/24—Selection of soldering or welding materials proper
  • B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
  • B23K35/3053—Fe as the principal constituent
  • B23K35/308—Fe as the principal constituent with Cr as next major constituent
  • B23K35/3086—Fe as the principal constituent with Cr as next major constituent containing Ni or Mn

Definitions

• the invention relates to a welding electrode for electric arc welding intended for joint welding and builtup welding stainless steels, particularly steels with a ferrite-martensitic, ferrite-martensite-austenitic or martensite-austenitic structure, and is characterized in that the electrode in the shape of a bare wire or a wire with a coating deposits a weld metal whose alloying constituents affecting the structure lie within the following analysis limits: 0.01-0.05 percent carbon, 0.1-0.9 percent silicon, 0.5-4.5 percent manganese, 15.0-18.0 percent chromium, 4.5-7.5 percent nickel, 0.2-2.5 percent molybdenum, 0.02-0.12 percent nitrogen and 02-35 percent tungsten, the remainder iron apart from the unavoidable impurities.
• the alloying constituents shall be adapted manually in such a way that the following two equations with the chromium equivalent (Cr,,) and the nickel equivalent (Ni are satisfied:
• Certain types of stainless steels particularly steels with a ferrite-martensitic, ferrite-martensite-austenitic or martensite-austenitic structure, obtain high mechanical strength characteristics, partly owing to their chemical composition and partly by the heat treatment they undergo prior to being used.
• Austenitic stainless steels in a heat-treated condition on the other hand, have a low yield limit, but they may be given a higher yield limit and ultimate strength values by cold work, e.g., by stretching.
• the elongation value of the weld metal may be regarded as a gauge of the welds cracking resistance.
• the risk of contraction cracks in the weld is great.
• ferrite-martensitic, ferritemartensite-austenitic or martensite-austenitic steel with the corresponding electrodes one has therefore normally applied a method which implies both the preheating of the basic material and the stress-relieving of the welded structure in order to reduce the risk of cracks.
• a weld metal with a high yield limit and ultimate strength in combination with very good elongation and impact value by using an electrode which, in the shape of a wire or a wire with a coating deposits a weld metal which contains the following alloying constituents affecting the structure: 0.01-0.05 percent carbon, 0.1-0.9 percent silicon, 0.5-4.5 percent manganese, 15.0-18.0 percent chromium, 4.5-7.5 percent nickel,
• the alloying constituents affecting the structure shall be adapted mutually in such a way that the following two equations with the chromium equivalent (Cr and 0 the nickel equivalent (Ni are satisfied:
• Equation 1 Cr +Ni 26.0 and S 32.0
• tungsten acts as a kind of modulator which in combination with nickel, manganese and nitrogen gives the desired balance to the ratio between the martensite part and the ferrite plus austenite parts.
• the martensite part of the weld structure shall lie between 5 and 50 percent and the ferrite plus austenite parts between 50 and 95 percent.
• the present invention relates to an electrode or a filler for joint-welding or built-up welding stainless steels, particularly steel with a ferrite-martensite-austenitic structure, e.g., steel of type 16 Cr 5 Ni 1 Mo, as well as steel of a ferrite-martensitic or martensite-austenitic structure, e.g., steel of type 12-14 Cr, 0-3 Ni and 0-2 Mo.
• the weld metal in itself does not require any heat treatment after the welding in order to achieve maximum toughness.
• the basic material may require stress-relieving in order to eliminate welding stresses or in order to level out the hardness tops which the latter types of steel show in heat-affected zones close to the weld.
• the electrode described it is also possible to carry out stress-relieving within the temperature range 550-700C without causing the strength values of the weld material to decrease to any great extent.
• the electrode is suitable for welding certain austenitic stainless steels, provided that the corrosion conditions to which the welded object is subjected, suit the weld metal of the electrode.
• the electrode is particularly suitable suited for joint welding stainless steels of identical or almost identical composition containing at least 13 percent chromium, and 3.5 percent nickel; they are then merged by means of arc welding and melting of a coated or an uncoated electrode whose composition lies within the composition according to claim 1.
• the electrode is also very suitable for coating a surface on work-pieces of unalloyed, low-alloyed or stainless steels; the hardfacing then takes place with an electrode which, coated or uncoated, has a composition according to that of claim 1.
• the welding electrode according to the present invention may be made in the shape of coated electrodes or uncoated wire for melting in an inert protective gas atmosphere or under a protective blanket of granulated welding powder, so-called flux.
• the bare wire in its turn may be homogeneous or so-called pipe-wire.
• the covering of coated manual-welding electrodes consists of fluxing material, arc-stabilizing, deoxidizing and alloying elements as well as some plasticizer for making the substance ductile.
• the composition of the covering may be varied and may have a lime-basic, rutile-basic or rutile-acid character all according to the welding properties desired.
• the covering should contain a certain amount of one or several of the following alloying elements: chromium, nickel, molybdenum, tungsten, manganese, silicon and nitrogen, partly in order to compensate the loss by burning which normally occurs in connection with the transport of material through the arc and partly in order to provide the weld with that part of the alloying elements which possibly for practical reasons has not been alloyed into the core wire.
• the composition of the wire in the case mentioned first shall conform as nearly as possible to the desired weld analysis and in the latter case be adapted to the composition of the welding powder.
• Table I chemical analysis The chemical analysis has been made in the manner prescribed in different standards, e.g., DIN 8556, Blatt 2 (Deutsche Industrie Normen), i.e., one makes a weld on plate with a great number of beads and determines the chemical analysis of that part of the weld which is further than 10 mm from the plate. In doing so the effect of the basic material is eliminated.
• Table II characteristics of strength The values indicated above represent an average of several tests. The welding tests have been carried out with a coated electrode in the manner prescribed in DIN 1913, Blatt 2.
• test specimens of type 10C50 according to SIS 1121 13 (SIS The Swedish Standard Association) and for the impact tests Charpy V-notch specimen according to SIS 1123 51 have been used.
• the F2 test indicated above is heat-treated at 600C with subsequent aircooling.
• a method of arc welding high strength stainless steels comprising the steps of melting an electrode in an electric are, said electrode having the following composition: 0.01-0.05 percent carbon, 0.l-0.9 percent silicon, 0.5-4.5 percent manganese, 15.0-18.0 percent chromium, 4.5-7.5 percent nickel, 0.2-2.5 percent molybdenum, 0.02-0.
• the constituents being adapted so that the chromium equivalent plus the nickel equivalent is not less than 26.0 and not more than 32.0, and 1.4 times the chromium equivalent minus the nickel equivalent is not less than 15.0 and not more than 20.0, the chromium equivalent being the sum of the percent chromium percent molybdenum percent silicon 0.5 times percent tungsten and the nickel equivalent being the sum of the percent nickel 0.5 times percent manganese 30 (percent carbon percent nitrogen 0.03) so as to obtain a weld metal having a microstructure comprising ferrite, martensite, and austenite, the martensite comprising from 5 percent to 50 percent thereof and the sum of the ferrite and austenite comprising from 50 percent to percent thereof.
• the welding electrode is a wire having a coating comprising fluxing material, arc-stabilizing material, deoxidizing material, and at least one material selected from the group of alloying elements consisting of chromium, nickel, molybdenum, tungsten, manganese, silicon and nitrogen.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Arc Welding In General (AREA)
• Nonmetallic Welding Materials (AREA)

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Citations (10)

• 1968
  • 1968-12-16 AT AT1223268A patent/AT291708B/de not_active IP Right Cessation
  • 1968-12-17 CH CH1874668A patent/CH514392A/de not_active IP Right Cessation
  • 1968-12-18 DE DE19681815274 patent/DE1815274A1/de active Pending
  • 1968-12-20 FR FR1597986D patent/FR1597986A/fr not_active Expired
  • 1968-12-20 GB GB60775/68A patent/GB1248985A/en not_active Expired
  • 1968-12-20 BE BE725830D patent/BE725830A/xx unknown
  • 1968-12-20 NL NL6818455A patent/NL6818455A/xx unknown
• 1971
  • 1971-06-24 US US156534A patent/US3700851A/en not_active Expired - Lifetime

Patent Citations (10)

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