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and the furnace is so efficient that the product is actually cheaper than open-hearth steel and very much cheaper than converter steel.

In one case where a rapid type electric foundry furnace of 3 tons replaced two 2-ton converters, the cost of the steel at the spout was reduced $35 per ton, even though the power cost was approximately 1/2c per kilowatt-hour; the converter practice, too, had been well standardized after several years use and the electric furnace was then new and further improvements were expected.

MR. BALLARD.-The quality of steel which we were called upon to produce to our mind called for the lowest possible phosphorus and sulphur content. We naturally turned to the basic for that reason. I am not defending the basic process over the acid; we merely exercised our judgment in the matter of furnace lining, results of which we feel have justified our action.

A MEMBER. This matter of freedom from serious cracks is rather interesting and I do not suppose the checks are absolutely absent in the case of electric steel, but I was wondering about what the reduction would be compared with the open hearth.

MR. BALLARD.—This question was recently answered some few days ago by the writer, stating that to my mind metal plays a secondary part in the question of checks, assuming that the processes of acid open hearth, and electric steel making are properly performed. Generally speaking open-hearth steel is made under ordinary supervising conditions. With the electric furnace keener supervision and closer attention must be paid to the furnace operation, resulting in a somewhat improved product. To my mind the question of checks is more often one of mold troubles rather than of metal. I firmly believe that with the same close attention paid to operation of the open hearth that is now given the electric furnace, there would be little difference between the product of the two furnaces. Without question the temperature is under better control in the electric than in the open hearth, together with the fact that the steel is much freer from oxides.

Electric Versus Converter Steel

By John H. Hall and G. R. Hanks

At our High Bridge plant we have a 3-ton heroult electric furnace and a 3-ton bottom-blown bessemer converter working side by side. The electric furnace is operated on a basic bottom, which enables us to turn out steel very low in sulphur and phosphorus.

During the war we had orders for castings for the army and navy, and in order to use our converter for castings of this class we installed the Stoughton oil-burning process on our cupolas, by which we were enabled to turn out steel sufficiently low in sulphur to meet the government's specifications and in many cases to get sulphur considerably below 0.06 per cent.

We had always been able to meet the tensile tests for Classes 1, 2 and 3 army and navy A, B, C and D steel with converter metal and after we had the oil on the cupolas working successfully we undertook to turn out army and navy work with converter steel as well as with electric steel.

We had not gone very far with the more intricate castings before we were faced with the fact that the converter steel, even when the sulphur was around 0.05 per cent, was much more subject to hot cracks and tears than the electric steel and apparently it was not always true that the lower sulphur heats were any better in this respect than the high sulphur heats.

Kept a Record In order to throw some light on this question we kept very careful records on one of the cradle-band castings for 240-millimeter howitzer. These castings were of Class 3 steel but in our practice we poured them with steel running from 0.25 to 0.35 per cent carbon and secured the desired high tensile strength by heat treatment. The table

on

page 223 gives the analyses of a number of converter and clectric heats from which castings of this pattern were poured and shows clearly the large proportion of cracked and torn castings on the converter steel. An examination of this table will show that in the converter heats on which no castings were lost the sulphur was as high or higher than on the heats on which castings were rejected for hot cracks. It will also be noted that at least one of the electric furnace heats (No. E491) is not very low in sulphur and on this heat we lost no castings. In fact electric heat No. E491 with 0.032 per cent sulphur is directly comparable with converter heat No. 68528 with 0.038 per cent sulphur, on which a casting cracked.

were

Resorted to Stunts In our efforts to overcome the hot tears in the foundry we used all of the "stunts” that could be worked out with any reasonable theory behind them and some of them were as follows: The castings were made in both green and dry sand; they were taken out of the molds hot; were allowed to cool over night, etc. Some of these same molds were relieved to allow free shrinkage by destroying the sand grip, while other molds merely had the cope lifted and allowed to remain until they were cold. During our experiments as above enumerated we determined that the castings poured from electric steel could be handled in most any manner that time and equipment would allow and our results produced very few rejections, whereas with castings poured from converter steel we were unable to produce any large proportion of good castings regardless of the manner in which they were cared for.

Somewhat later we undertook the manufacture of rudder stocks and stern frames for merchant ships, and our experience on these castings was even more illuminating than on the smaller castings for ordnance work. The reason for this, of course, was that the castings were so long as to give a very great total shrinkage amounting to 5 inches. Our first really conclusive test these castings came when

on

we

were

obliged to pour a rudder stock from two heats of converter steel which analyzed as follows: Carbon, 0.29 and 0.31 per cent; silicon, 0.51 per cent; manganese, 0.77 and 1.01 per cent; sulphur, 0.066 and 0.057 per cent; and phosphorus, 0.052 and 0.056 per cent.

This casting was scheduled to be poured from one converter heat and one electric furnace heat, mixed, but owing to trouble with the electric furnace we were obliged to pour it entirely of converter steel. Every precaution was taken to relieve this casting so that the shrinkage would not result in hot checks, the sand being dug out from around the heads and the cope lifted off the casting about 30 minutes after pouring. We were naturally somewhat afraid that we would have hot checks in this casting, but when the cope was lifted off and we found the casting torn in three pieces our feelings may be more easily imagined than described. Within a few days the same casting was poured successfully of electric furnace steel which analyzed as follows: Carbon, 0.30 per cent; silicon, 0.38 per cent; manganese, 0.85 per cent; sulphur, 0.021 per cent; and phosphorus, 0.019 per cent.

We afterward successfully poured these large castings and also large stern frames, sometimes with electric furnace steel alone and sometimes with electric steel and converter steel mixed. The analyses of several heats on which we successfully poured castings of this class are given below:

Carbon Silicon Mang'se Sulphur Phosph'us Kind of heat

Per cent Per cent Per cent Per cent Per cent Electric

0.26 0.38 0.82 0.02 0.024 (Electric

0.37 0.42 0.94 0.019 0.033 1 Converter

0.37 1.10 1.51 0.047 0.045 S | Electric

0.27

0.78 0.94 0.030 0.036 Converter

0.27
0.24

0.67 0.045 0.046 Examination of these analyses shows that the average sulphur in the two castings poured of electric and converter steel mixed is 0.033 per cent in one case and 0.038 per cent in another.

Naturally, in the rush of war work we were too busy to keep very complete records, but our experience convinced lis that the electric steel was superior to the converter steel from the standpoint of hot checks and we had several cases besides those given above where steels of practically identical analyses as regards sulphur ran true to form in the matter of hot checks, the converter steel giving considerably more trouble than the electric.

so much

Experiences at Easton Our Easton shop at the same time was running a 6-ton basic electric furnace side by side with a 2-ton converter. In their electric furnace practice they did not work for as low sulphur as we did at High Bridge, but after they had been running a couple of months they were convinced that the electric steel castings were

more free from hot checks that there was practically no comparison between the two steels. They had an experience on a large stern frame which was practically the same as ours at High Bridgea converter steel casting cracked so badly in the molds that it could not be used at all. The same casting poured from electric steel with a little converter steel to fill up the heads came out practically free from hot checks.

At Easton one of the regular lines of manufacture is castings for track work which are poured from a hard grade of carbon steel. These castings are of intricate design and the men in charge of that foundry have been making them regularly for 15 or 20 years. In talking with them they remarked that during the 15 years they had poured them of converter steel they had grown to regard hot checks in these castings as a matter of course, but that after a short experience with the electric furnace steel they were able to turn out these castings practically free from checks with no more care in handling, and in fact, in many cases, with less care than was used for the converter steel.

We do not wish to be understood as stating that we believe that sulphur has nothing to do with hot checks in steel castings, but we do feel that sulphur is by no means the only thing which makes converter steel liable to these defects. In fact our own individual opinion is that although sulphur is a contributing cause it does not have as great an

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