From Table III, it will be seen that it is necessary to use filling material of the proper composition if the weld is to be the same in composition as the original article. By merely using electrodes and melt bars with an excess of such elements as silicon, carbon, etc., this can be controlled to a very small variation from the desired amount. Unless the operator burns his metal by using too much current or applying it too long, there will be no appreciable difference in color between the weld and the rest of the piece; so finished surfaces may be welded in many cases.

Fig. 86. Test Plates.Showing Strenght.of Electric Welds.

Table V. Relative Strength Of Joints

Samples and Preparation

Breaking Strain Pounds

Length After

Breaking Inches

Per Cent Efficiency

Original piece of plate ..........................

58,600

8.80

97.66

Lap joint, are welded ............................

54,800

8.94

91.33

Lap joint, riveted and welded .................

54,200

9.22

90.33

Butt joint, are welded ..................

47,800

8.28

79.66

Butt joint, acetylene welded.........

36,800

8.23

61.33

Lap joint, riveted only ................................

35,000

• • • •

58.33

Strength Of Weld. Butt- Weldedjoints

The strength of the weld can be made the equal of the article welded by reinforcing, or it can be made very nearly equal by using filling material of high strength and welding flush with the surface of the piece, Fig. 86, this being especially true of steel plates. Some tests made by the author on steel plates of various thicknesses (with a nominal strength of 56,000 lbs. per square inch) showed the results given in Table IV.

The elongation in the filling material was less than in the original material, of course, owing to its being really a steel casting, but its ductility can be improved by hammering after welding and this is frequently done when welding heavy sections.

Comparative Test

In order to test the relative strengths of riveted, electric-arc-welded, and acetylene-welded joints, a set of steel samples were made up and tested as follows, each piece being 3/8 inches by 2 13/32 inches in cross section and 8 inches long in the straight portion, Table V.

The steel plate used had a nominal strength of 60,000 pounds per square inch but was actually not up to standard, although it showed clearly the relative advantages of the various methods of making joints. Some tests recently made in England are shown in Table VI. Strength of welded piece was 88.43 per cent of original plate.

Table VI. Relative Strength Of Original And Welded Plate

Size of Sample

INCHES

Breaking Strain Pounds

PER CENT

Elongation in 4 Inches

Per Cent

Reduction of Area

Welded piece ..................................

.125X1.48

42,702

10.93

5.23

Original piece...........

.125X148

48,290

32.03

29.63

Table VII. Time And Cost Of Welding

Anticle Welded

Time

Cost

Steel casting, shrinkage crack 6'long by 1' deep........

8 min.

$00.04

Steel casting, riser 4" by 4" cut off ...............................

4 min.

.05

Forged steel locomotive frame, broken in 2 places .........................

20 hrs..

18.28

12" crack in back sheet of locomotive boiler .........................

9 hrs .

5.47

Building up worn driving wheel instead of turning down.. ............

2 hrs.

.72

Welding 67 cracks in old fire box (saving over $1000).....

2 wks.

52.60

Cast-steel tender frame broken, in 3 places ..............................

27 hrs.

19.00

Steel shaft. 2" diameter, broken, welded ready to finish..

1 hr.

.60

Broken railway type motor case, cast steel, welded ........................

3 hrs.

1.95

Enlarged holes in brake levers, steel bars ....................

4 min.

.05

Building up 2' armature shafts, worn in journals.......

3 hrs.

1.80

Air brake piston rods, broken, welded ready to finish ................................

30 min.

.35

Leaking axle boxes, cracks, welded in position..........

15 min

.15

Cost Of Arc Welding

The cost of arc welding will vary according to the nature of the work, the skill of the operator, and the cost of labor and current, but it is much less than for similar work done by any other process. It ranges from about three-fourths down to one-tenth that of the cost of acetylene welding, for various jobs, and the time required is much less. With the electric arc it is not necessary to keep a large portion of the work heated in order to prevent the chilling of the filling material, because the work forms the hottest (positive) terminal of the arc and a sufficient volume of heat is generated at the point which is being worked upon to insure perfect fusion.

Cost Data In Steam Railroad Shops

The figures in Table VH show the cost of several actual jobs done with arc welders, the labor being paid at the rate of 30 cents per hour and the current costing 2 cents per kilowatt hour, with the filling material figured at 8 cents per pound.

Comparison With Old Methods

The figures in Table VII will give a fair idea of the class of work and the costs of welding in steam railroad shops and car shops, and those in Table VIII will show the savings effected through the use of arc welding instead of making repairs by the old methods, of whatever kind.

Street Railway Repairs

Repairs to electric railway apparatus are also important in order to keep the rolling stock in useful service. The figures in Table IX, which give average costs for performing typical repair jobs in street car shops, are based upon the relation between the cost of electric welding as opposed to replacement because that is usually the alternative.

Table VIII. Relative Costs Of Repairs

Article Welded

Welding

Old Cost

Saving

Engine main frames, both broken ........................

$11.80

$56.20

$44.40

Driving wheel built up 3/16" on tread...........

.72

8.00

7.28

General repairs on fire box aide sheets..........

66.51

342.62

276.11

Filling worn knuckle joint bushing hole........

.75

7.50

6.75

Welding 7 cracks in locomotive cylinder ...........................

22.35

367.15

344.50

Broken mud ring on locomotive boiler ................................

32.07

118.06

85.99

One of the electric railway companies claimed that they repaired about 1600 articles a year which, if replaced by new pieces, would cost them nearly $15,000.00, and had also the benefit of the large amount of time saved by doing the work quickly and keeping their rolling stock in service a larger portion of the time. The use of electric-arc welding apparatus is not confined to the railway field, but equally interesting figures could be given as applying to work done in foundries, machine shops, boiler and tank shops, garages, and other places. These few will serve, however, to show the possible savings through using the arc for repair work in general.

In conclusion, it should be remembered that in order to weld with the arc it will require some practice in starting the arc, especially with the metallic electrode. The "trick" consists in touching the work and getting away as quickly as possible to the required distance, and yet not going so far as to rupture the arc. If the electrode is of metal, it will heat and stick to the work unless withdrawn quickly, but it can easily be broken loose by a twisting motion of the hand. Care should also be exercised to see that the eyes and face are fully protected from the glare and heat of the arc, as it is hard on the eyes and affects the skin like bad sunburn. On the other hand, some men have done arc welding for years with no injury.

Table IX. Street Railway Repairs

Article Welded

Welding

New Part

Saving

Armature shaft, repaired in place ..............

$ 1.70

$ 4.72

$ 3.02

Armature shaft, large, repaired in place........

1.97

15.13

13.16

Railway motor axie cap, large ....................................

.22

3.51

3.29

Railway motor armature bearing cap ..................................

.27

6.07

5.80

Railway motor gear case, top half ............................

.48

7.30

6.82

Truck side frame, Brill 27.G..................

.72

44.40

43.68

Truck side frame, peckham 14-B ................

.90

46.98

46.08

Brake head, building up worn socket ...................................

.06

1.15

1.09

Motor frame, G. E. 90, railway type motor.....

2.88

16.80

13.92