CN1160618A

CN1160618A - Repair method and welding wire for repairing defect on the machined plane of iron casting

Info

Publication number: CN1160618A
Application number: CN 96103149
Authority: CN
Inventors: 陈友兰
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-03-21
Filing date: 1996-03-21
Publication date: 1997-10-01
Anticipated expiration: 2016-03-21
Also published as: CN1042604C

Abstract

The present invention relates to the CO2 protected arc welding and electric welding wire. The wire contains: C 0.01-0.049%, Si 0.01-0.05%, Mn 0.03-0.55%, Al 0.01-0.5%, Ni 0.05-0.2%, Cr 0.02-0.1%, Cu 0.05-0.2%, S less than 0.03%, P less than 0.02% and the rest Fe. The repair process includes beveling at the place to be welded, welding through small-current cold welding and annealing the welded area to be machined. Compared with available fusion welding for cold welding casting iron, the present invention has improved cracking resistance and machinability, bond Hbmax lower than 220 and other merits.

Description

The restorative procedure and the welding wire of ironcasting machined surface defective

The present invention relates to a kind of CO to ironcasting ₂Shielded arc welding and welding wire thereof.

The reparation of ironcasting has number of ways and method, the nickel-base welding rod welding technology that propositions such as the U.S. are arranged that has been widely used; The argon arc welding technology that the former Soviet Union proposes with the pure nickel welding wire; The method that prevents of the disclosed component of machine crackle of Japan Patent (clear 39-18230 bulletin), this method is at the local bevel that crackle takes place, mother metal is carried out 150～200 ℃ of preheatings, imbed pure nickel electrode in the groove and carry out arc welding, the welding back is incubated 4h in 540～560 ℃, and carries out machining after the cooling in stove.Above-mentioned these methods generally can solve the reparation problem of ironcasting, but nickel-base welding rod and welding wire cost an arm and a leg, and the welder is required height, if weld improperly, then still have the bad problem of processability.And complex process, productivity ratio are difficult to improve.And CO ₂The former welding that is mainly used in steel part of shielded arc welding.

Propose welding agent in the CNGK87102464 patent application and be used for the restorative procedure of ironcasting; A kind of cast iron CO is proposed in the CN1038961A patent application ₂Semi-automatic cold welding wire, these welding materials are used for cold welding of cast iron, and the processability of its postwelding all can not satisfy the requirement that last processing line carries out metal cutting processing.

At publication number is the welding wire that proposes in the patent application of CN1065617A, the processability of its postwelding generally can satisfy upward, and processing line carries out the requirement of finish-milling, but near the welding zone melt run, because of the hardness of its hardness number and mother metal (HT250) itself differs more, and a white band appears, go to touch with hand, can feel has " projection " at the white band place, influences machining accuracy.Welding zone is as boring aperture, the more difficult precision that meets the requirements of.

The method that the object of the present invention is to provide a kind of welding wire and adopt this welding wire that ironcasting machined surface defective is repaired, not preheating before weldering, under the not heat treated prerequisite of postwelding, postwelding can directly be gone up machine line and carry out machining, comprise and to bore aperture and tapping at welding zone, and guarantee its machining accuracy, also can make the welding zone color consistent with mother metal more conveniently.

Said welding wire among the present invention, its chemical composition are (by 100% calculating, down together) C:0.01%～0.049%, Si:0.01%～0.5%, Mn:0.03%～0.55%, Al:0.01%～0.5%, Ni:0.05%～0.2%, Cr:0.02%～0.1%, Cu:0.05%～0.2%, impurity content are restricted to S＜0.03%, P＜0.02%, surplus is Fe, and gage of wire is φ 0.8mm to φ 0.5mm.

The restorative procedure of ironcasting machined surface defective is to leave groove at position to be welded, and groove face processing makes lustrous surface, is convenient to make welding arc to burn groove face Anywhere; To all places that will process of postwelding, all use normalizing pass topped; The principle of selecting for use of welding conditions is under the prerequisite of guaranteeing to fuse, and adopts said welding wire of the present invention and little electric current (70～40A) CO ₂The protection cold welding, welding job will make by cold welding of cast iron to be carried out.

Owing to contain a small amount of Al, for cast iron, it is strong graphite element in the said welding wire of the present invention, has certain preventing welding the effect that the fusion area produces white structure.So just needn't add welding agent and can obtain better welding effect, have better crack resistance, processability, can guarantee its fusion area H than the melting technology of existing various cold welding of cast iron in groove bottom _BMax＜220; The welding zone color is compared more with mother metal and is reached unanimity; Technical process is simpler, and the welder is more convenient for grasping, not preheating before weldering, and under the not heat treated prerequisite of postwelding, postwelding can directly be gone up machine line and carry out machining, and production efficiency is higher, more saves Master Cost and electric energy.For example, the present invention is used for the reparation of internal combustion engine ironcasting machined surface defective, can solve soldering and postwelding processing to aperture, and easier machining accuracy and quality of guaranteeing to guarantee to keep in good repair copy obtains satisfied result and tangible more economic benefit.

Fig. 1 is the screwed hole on the internal combustion engine machined surface.

Fig. 2 is the groove at screwed hole place.

Embodiment 1: gets chemical composition (calculating) and is C:0.049% by 100%, and Si:0.5%, Mn:0.55%, Al:0.5%, Ni:0.2%, Cr:0.1%, Cu:0.20%, S:0.030%, P:0.020%, surplus is the welding wire of the φ 0.8mm of Fe, uses CO ₂Shielded arc welding carries out soldering to the defective at H250 ironcasting M6 screwed hole place, and getting welding current is 70A, and weldingvoltage 19V, gas flow are 5～10L/min.During soldering, the weld seam in all places that will process is topped with normalizing pass.

Postwelding carries out hardness test to the fusion area after machinings such as polishing, its H _BMax=195～210 through boring and tapping, can reach desired precision.

Embodiment 2: getting chemical composition is C:0.01%, Si:0.015%, Mn:0.030%, Al:0.01%, Ni:0.05%, Cr:0.02%, Cu; 0.05%, S:0.015%, P:0.012%, surplus is the welding wire of the φ 0.5mm of Fe, uses CO ₂Shielded arc welding carries out soldering to the defective at HT250 ironcasting M6 screwed hole place.Getting welding current is 40A, weldingvoltage 18V, gas flow 5L/min.During soldering, topped with normalizing pass to the weld seam in all places that will process.Postwelding carries out hardness actual measurement, its H through machining to the fusion area _BMax=190～195 (mother metal hardness HB=180～185), through processing experiment, ground auger aperture and tapping smoothly.

Embodiment 3: getting chemical composition is C:0.025%, Si:0.01%, and Mn:0.3%, Al:0.3%, Ni:0.1%, Cr:0.05%, Cu:0.1%, S:0.018%, P:0.012%, surplus is the welding wire of the φ 0.6mm of Fe, uses CO ₂Shielded arc welding carries out soldering to the defective at HT250 ironcasting M6 screwed hole place, and getting welding current is 50A, weldingvoltage 19V, gas flow 10L/min.During soldering, the weld seam at all positions that will process is all topped with normalizing pass.

Postwelding carries out hardness test to the fusion area after machining, its H _BMax=195～205 through boring and tapping, can reach desired precision.

Embodiment 4: the Repair Welding that the present invention is used for M6 screwed hole place on the diesel-engine body machined surface.Its material is HT250, has finished whole machining (see figure 1)s.Require welding repair process not destroy shape, position, the precision of body.Postwelding, the processing again in double thread hole will reach the specification requirement of regulation, and requires to eliminate the vestige of soldering.

The method of head it off is:

(1) with φ 10 bit bores, the degree of depth is 17mm, and concentric with M6, is processed into groove shown in Figure 2 with electric mill again;

(2) use welding wire of the present invention, carry out CO ₂The protection weldering, gage of wire is φ 0.8mm, when carrying out the bottom welding, I=50～60A, U=18～19V, gas flow is 5～10L/min, one-time continuous piles with.

(3) position that weld seam protrudes machined surface is polished earlier with electric angle grinder, again with electric mill polish, the file filing, oilstone polishes, and eliminates until the soldering vestige.

(4) boring, tapping on request.

Claims

1. welding wire, its chemical composition contains C, Si, Mn, Ni, Cr, S, P, Fe, it is characterized in that also containing Al, Cu, the chemical composition of welding wire is (calculating by 100%) C:0.01%～0.049%, Si:0.01%～0.5%, Mn:0.03%～0.55%, Al:0.01%～0.5%, Ni:0.05%～0.2%, Cr:0.02%～0.1%, Cu:0.05%～0.2%, impurity content is restricted to S＜0.03%, (0.02%, surplus is Fe to P, and gage of wire is φ 0.8mm to φ 0.5mm.

2. the restorative procedure of ironcasting machined surface defective is characterized in that

1) leave groove at position to be welded, groove face processing makes lustrous surface;

2) to all places that will process of postwelding, all use normalizing pass topped;

3) principle of selecting for use of welding conditions is under the prerequisite of guaranteeing to fuse, and adopts described welding wire of claim 1 and little electric current (70～40A) CO ₂Protect cold welding, will make by cold welding of cast iron and welding.