How to break the nose of a Soviet tank
Welding quality is satisfactory
There are different ways to evaluate the quality of tank builders' work. If we touch on the level of armored hull production, we can fire on the finished product. For example, in 1959, Omsk Plant No. 174 took танк T-54B and fired at it with 85-mm high-explosive fragmentation grenades and 100-mm armor-piercing shells. The tank had a hard time. The report, in particular, points out the blow-off of the driver's hatch cover after an 85-mm shell hit the turret's front. The strength of the observation device unit and azimuth indicator was insufficient - they were blown off by an armor-piercing shell that hit the hull's front. They also noted the unsatisfactory armor protection of the exhaust, which was blown off after a 100-mm shell hit the side.
By the way, the test firing was not just organized, but after design changes - they introduced a tenon-free connection of the frontal parts of the hull using automatic welding, changed the protection of the exhaust pipe by welding it to the side, and introduced the welding of the flange of the "Luna" sight. Not that these were fundamental design changes, but they required transporting the tank to the Kubinka proving ground for a thorough firing. In the end, it turned out that the innovations almost justified themselves (the commission allowed changes to the series), but new vulnerabilities were revealed. In conclusion, they summed up the results:
"All measures developed by Plant No. 183 (Kharkov) and No. 174 (Omsk) to eliminate the identified deficiencies must be implemented for testing by firing on the hull and turret of the T-55 tank, which will be shipped from Plant No. 174 to the NIIBT GABTU testing ground for the next control tests by firing in the third quarter of 1959."
It remains only to express the hope that in modern times all innovations in tank design are tested in a similar manner.
But the military testers were not limited to firing at serial tanks. The strength and quality of welds were also assessed using a simple test – breaking the tank's nose assembly under pressure. The details of this matter can be revealed in the repositories of the Russian State Archive of Economics. The background to the event states that at the end of 1957, tank factories introduced tenon-free joints for frontal plates. This was faster and more technologically advanced, but potentially less durable. A year later, in mid-November, a frontal assembly identical to that of the T-54 was specially welded for testing. Further, according to the declassified report (spelling and punctuation were subject to minimal editing):
«The purpose of the test: to check the quality of welded seams in the fracture, made by automatic welding, by breaking the welded joints of the unit under pressure. To practice the modes of automatic welding of the nose sheets, a standard sample 500 mm long was welded. The welding of the sample was performed on an ABS machine with 6-5 mm welding wire of the EI-613 brand under flux of the AN-22 brand.
The welding modes are as follows:
Current strength…………………...450-500 A
Voltage ………………...34-36 V
Welding speed…………….21,5 m/hour
Wire feed speed 95 m/h.
The first layer of the internal and external seams was welded using a 5 mm filler wire of the EI-613 brand. The subsequent layers were welded without the filler wire. Both seams — internal and external — were welded in 7 passes.
The sample was broken under a press. The fracture occurred along the deposited metal of the internal and external welds. In the fracture of the internal weld, a lack of fusion was found at the top of the weld over a length of 40 mm and a lack of fusion of layers over a length of 35 mm. In the fracture of the external weld, a lack of fusion was found at the top of the weld over a length of 50 mm and a lack of fusion of layers between the third and fourth over a length of 145 mm.
The fractures revealed that the current was insufficient, so the current was increased for welding the next sample.
The second sample was welded in the following modes:
Current strength………………….. ……500-550 A
Voltage………………. ……34- 38 V
Welding speed…...............21,5 m/hour
Wire feed speed……95 m/hour.
Two drill holes were made on the second sample. No defects in the welds were found in the drill holes. A section was cut out from the middle part of the sample for macro- and micro-examination.
The remaining sections of the welded joint were broken under pressure. No defects were found in the fractures of the internal and external seams.
According to drilling, micro-examination and fractures, the quality of welded seams is satisfactory.
To clarify the welding modes, a third sample was welded using the same modes as the second sample.
The third sample was broken under the press. In the fractures of the third sample in the internal seam, a lack of fusion was found between the 3rd and 4th layers at the end of the seam 20 mm long, which was caused by the displacement of the electrode when the train was ignited. No defects were found in the external seam.
In the fractures of all three samples, the weld metal is dense, fibrous, gray-matte in color, without defects, with the exception of the defective areas described above.
Based on the satisfactory results obtained on the last two samples, the NOS unit was welded under the same conditions for failure testing.
The tested tenonless NOS unit was welded on November 5, 1958 by auto welder Comrade E.A. Imatov using automatic welding under a layer of AN-22 flux with 5 mm diameter EI-613 welding wire.
The welding modes are as follows:
Current strength…………………500.550 A
Over the course of…................34.38 B
Welding speed...…………..21,5 m/hour
Wire feed speed..95 m/hour.
The first layer of the internal and external seam was welded using a 5 mm diameter EI-613 filler wire.
The welding procedure was adopted as follows:
First, 4 layers of the internal seam were welded, then the external seam was completely welded in 7 layers, after which the remaining 3 layers of the internal seam were welded.
Before the failure, the welded seams connecting the nose sheets were illuminated with gamma rays.
When X-raying, a crack was assumed to be a defect in the outer weld. When the "NOS" unit broke, a chip in the base metal was detected in the place of the assumed defect when X-raying. To facilitate the breakage and obtain fractures along the welds, the unit was interrupted by gas cutting into three different sections, which were then broken under a press.
The nature of the fractures and the quality of the welds in the fracture are as follows:
Section #1:
The destruction occurred approximately in the middle of the deposited metal of the external and internal welds. The tops of the grooves of the internal and external welds were welded along the entire length. Two gas pores measuring 2x5 mm were found in the fracture of the internal weld. In the fracture of the external weld, a lack of fusion between the 2nd and 3rd layers was found over a length of 15 mm and a height of 2 mm.
Section #2:
The destruction occurred approximately in the middle of the deposited metal of the external and internal welds. The tops of the grooves of the internal and external welds were welded along the entire length of the welds. In the fracture of the external weld, a lack of fusion was found between the third and fourth layers over a length of 25 mm and a height of 2 mm. No defects were found in the fracture of the internal weld.
Plot No. 3
The destruction occurred approximately in the middle of the deposited metal. The tops of the inner and outer welds were welded along the entire length.
A slag inclusion measuring 15 x 6 mm was found in the fracture of the internal weld. In the fracture of the external weld, at the top of the weld, a chip was found along the base metal over a length of 210 mm, up to 6 mm high, and a lack of fusion between the layers at the end of the weld over a length of 15 mm, 2 mm high.
In all weld fractures, with the exception of defective areas, the pressed metal is fibrous, gray-matte in color, without columnarity.
CONCLUSIONS:
I. The defective sections of the welds found in the fractures are small in size and are scattered. The total length of the defective areas is 70 mm, which is equal to the length of the welds of 3648 mm.
It is: 70: 3648 = 0,0189 = 1,89% The total area of defective sections is 290 sq. mm, which is equal to the total area of weld seam fractures – 115440 sq. mm.
is: 220 : 115440 = 0,0019 = 0,19%.
2. The quality of the deposited metal in the fractures of welded seams is good.
3. The quality of the internal and external seams at the fracture is satisfactory.
CONCLUSION:
The quality of welds made by automatic welding under a flux layer is satisfactory. The welded unit NOS passed the test.
Based on the satisfactory results of the test of the NOS unit with breakage under the press, a second tenon-free NOS unit was welded in addition to the 1958 program according to the letter of the Head of the State Committee Directorate, Comrade Kucherenko N.A., dated 12/01941 from 2/UP-1958, which was installed on the hull of the T-54 tank going for testing at the NIIBT testing ground of the GBTU."
T-55 nose under pressure
In September 1959, it was time to break the front part of the more advanced T-55 tank, whose front parts were welded without spikes. According to the text of the report:
«Purpose of the test: To test the quality of welded seams in a fracture, made by automatic welding, by breaking the welded joints of the unit under pressure.
The tested unit was welded on August 24, 1959 by the auto welder Comrade I.S. Oreshin using automatic welding under a layer of flux grade AN-22 with welding wire F-5 grade EI-613.
The welding modes are as follows:
Current strength…………........ 500-550 A
Voltage…................................. 32-36 volts
Welding speed………………..16 m/hour
Wire feed speed…...95 m/hour.
The first layer of the internal and external seams was welded using a 5 mm diameter filler wire of the EI-613 brand.
The welding order was as follows: first, 3 layers of the internal seam were welded, then the external seam was welded completely in 5 layers, after which the remaining 2 layers of the internal seam were welded.
Before the failure, the welded seams connecting the nose sheets were illuminated with gamma rays.
When X-raying the internal weld, a defect in the form of lack of fusion was assumed. When the "Nose" unit broke, lack of fusion was detected at the place of the assumed defect when X-raying.
To facilitate breakage and obtain fractures along the welded seams, the unit was cut using gas cutting into three equal sections, which were then broken under a press.
The nature of the fractures and the quality of the welds in the fracture are as follows:
Section No. 1 - The destruction occurred approximately in the middle of the deposited metal of the external and internal welds. The tops of the grooves of the internal and external welds are welded along the entire length. Three gas pores were found in the fracture of the internal weld, 5 pieces measuring 10x2 mm and one piece measuring 5x7 mm. There are no defects in the fracture of the external weld.
Section No. 2 The failure occurred approximately in the middle of the deposited metal of the external and internal welds. The tops of the grooves of the internal and external welds were welded along the entire length. Slag inclusions were found in the fracture of the internal weld in two places, measuring 10x15 mm and 10x12 mm. No defects were found in the fracture of the external weld.
Section No. 130. The destruction occurred approximately in the middle of the deposited metal of the external and internal welds. In the fracture of the internal weld, a lack of fusion was found at the top of the weld over a length of 10 mm, 20 mm high. In the fracture of the external weld, a hot crack measuring 10xXNUMX was found on the tack weld performed by manual arc welding with austenitic electrodes.
In all weld fractures, with the exception of defective areas, the deposited metal is fibrous, gray-matte in color, without columnarity.
CONCLUSIONS:
1. The defective sections of the welds found in the fractures are small in size and are scattered. The total length of the defective areas is 172 mm, which to the length of the welds = 3648 mm. This is: 172 : 3648 = 0,04717 = 4,72 percent.
The total area of defective areas = 1905 sq. mm, which equals the total area of weld seam fractures = 115440 sq. mm.
is: 1905 : 115440 = 0.0165 = 1,65 percent.
2. The quality of the deposited metal in the fractures of welded seams is satisfactory.
3. The quality of the internal and external seams at the fracture is satisfactory.
Conclusion.
The quality of welds made by automatic welding under a flux layer is satisfactory. The welded unit passed the test. For continuous quality control, make 2 drills on each unit».
The document was signed by the plant’s chief technologist, the head of the armored hull workshop, and the senior military representative for armored hull production.
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