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The Static NotchBar Tensile Test

The Static NotchBar Tensile Test INSPECTION The Static Notch-Bar and the fourth is generally similar to several standard steels, including B.S.S. S.5 V7 (En.l5). Tensile Test In preparation for the tests, the relationship between the tempering temperatures and ordi­ nary tensile strengths of the four steels was de­ An Indication of Tensile Strength, termined. The steels were then treated at tem­ peratures selected from the data obtained to give tensile strength levels of from 89 to 122 tons Hardness, Ductility and Toughness per square inch. The first steel was heated in an electric furnace in every case, and the remainder open hearth. By G. Fitzgerald-Lee, M.I.E.I., A.R.Ae.S. The results of the static notched-bar tensile tests showed that this type of test differentiates with a high degree of sensitivity between the different steels at identical levels of mechanical ARIOUS steels, or even different heats of out in an ordinary tensile testing machine in the strength, and even between different heats of the same steel, with identical mechanical normal manner with the exception that instead any one steel at a given strength or hardness. In properties when determined by ordinary of employing a standard tensile test-piece a the higher hardness ranges studied the first two tests, vary considerably in behaviour in service; modification is used. A sharp sixty degrees cir­ steels show much higher static notch tensile and such differences of performance are neither cumferential vee-notch is machined at the centre values than the third steel, which, in turn, is due to any variation in composition nor to any of the gauge length, the radius at the root of the markedly superior to the fourth steel. The dif­ other known factors. That these differences exist notch being less than 0·0015 in. The diameter of ferences are depicted in the nomogram. is now known but their causes are still very the test piece is half an inch, and the diameter at The nomogram, evolved from the test figures, much matters for metallurgical conjecture. It is the root of the notch is 0·35. When the eccentric is based on the Ultimate Tensile Strength figures, known that steels tempered from the austenitic loading test is carried out the same notched ten­ in tons per square inch, which are given on the range and tempered to give a martensitic struc­ sile specimen is used as in the concentric loading top line and exactly repeated on the bottom line. ture become increasingly ductile with rise of test but bending is superimposed on the tensile The second line gives the Brinell Hardness Fac­ temperature. The ordinary tests, however, fail to stress by means of a wedge-shaped washer under tors which were found to correspond with the give any indication of the variations in be­ the shoulder of the head of the test-piece. various tensile strength figures. This is followed haviour, on tempering, between even different A series of tests on four different steels has en­ by the concentric and eccentric notch strength, low-alloy steels, to say nothing of different heats abled a comparison to be made between the in tons per square inch, separated by the notch- of any one particular steel. The notched-bar im­ static notched-bar tensile test figures and the ductility figures, in percentages, for each steel in pact-bend test is capable of revealing differences tensile strength and Brinell hardness figures ob­ turn, numbered according to the composition in impact properties among steels which have tained on standard machines. The results are table already given. Many interesting facts may been tempered to levels of mechanical strength depicted and correlated in the accompanying be deduced from the nomogram, as, for ex­ identical with the results obtained by ordinary nomogram. ample, the instability of the fourth steel, the high tensile tests. The notched-bar test is, however, The composition of the four steels was as concentric notch strength stability of the first highly complex, involving a certain amount of follows: (with only 17 per cent loss throughout the scale), tension, compression, bending and shear, and its and the unstable notch-ductility of the fourth No. C. Ni. Cr. Mo. | Mn. P. S. Si. full significance is not yet clearly understood. Of steel, involving a strength loss of 93 per cent be­ 0.41 3.5 0.02 0.83 0.016 0.014 its three characteristic features: high speed, 0.03 0.27 tween the tensile strength limits given. Although 0.39 3.46 0 0 0.79 0.018 0.029 2 0.23 notch, and bend action, the notch is the most 0. 4 0 1 0 0.69 0.014 0.023 3 0.16 the notched-bar impact-bend test is not yet quite potent embrittling factor. Recent investigations 0.42 0 0 0 1.81 0.023 0.022 4 0.24 understood, even less is known at present about have shown that static notched-bar tensile tests the static notched-bar test, which, however, is give more fully understandable results and The first two steels approximate to B.S.S. S.69, likely to be proved one of the most useful of all evaluate metals in very much the same manner which has slightly more chromium, phosphorus, mechanical tests once its technique has been per­ as impact tests. sulphur and silicon; the third differs from fected and its implications become more fully The static notched-bar tensile test is carried D.T.D.167 only in that it has no molybdenum; understood. September 1949 301 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

The Static NotchBar Tensile Test

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb031810
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Abstract

INSPECTION The Static Notch-Bar and the fourth is generally similar to several standard steels, including B.S.S. S.5 V7 (En.l5). Tensile Test In preparation for the tests, the relationship between the tempering temperatures and ordi­ nary tensile strengths of the four steels was de­ An Indication of Tensile Strength, termined. The steels were then treated at tem­ peratures selected from the data obtained to give tensile strength levels of from 89 to 122 tons Hardness, Ductility and Toughness per square inch. The first steel was heated in an electric furnace in every case, and the remainder open hearth. By G. Fitzgerald-Lee, M.I.E.I., A.R.Ae.S. The results of the static notched-bar tensile tests showed that this type of test differentiates with a high degree of sensitivity between the different steels at identical levels of mechanical ARIOUS steels, or even different heats of out in an ordinary tensile testing machine in the strength, and even between different heats of the same steel, with identical mechanical normal manner with the exception that instead any one steel at a given strength or hardness. In properties when determined by ordinary of employing a standard tensile test-piece a the higher hardness ranges studied the first two tests, vary considerably in behaviour in service; modification is used. A sharp sixty degrees cir­ steels show much higher static notch tensile and such differences of performance are neither cumferential vee-notch is machined at the centre values than the third steel, which, in turn, is due to any variation in composition nor to any of the gauge length, the radius at the root of the markedly superior to the fourth steel. The dif­ other known factors. That these differences exist notch being less than 0·0015 in. The diameter of ferences are depicted in the nomogram. is now known but their causes are still very the test piece is half an inch, and the diameter at The nomogram, evolved from the test figures, much matters for metallurgical conjecture. It is the root of the notch is 0·35. When the eccentric is based on the Ultimate Tensile Strength figures, known that steels tempered from the austenitic loading test is carried out the same notched ten­ in tons per square inch, which are given on the range and tempered to give a martensitic struc­ sile specimen is used as in the concentric loading top line and exactly repeated on the bottom line. ture become increasingly ductile with rise of test but bending is superimposed on the tensile The second line gives the Brinell Hardness Fac­ temperature. The ordinary tests, however, fail to stress by means of a wedge-shaped washer under tors which were found to correspond with the give any indication of the variations in be­ the shoulder of the head of the test-piece. various tensile strength figures. This is followed haviour, on tempering, between even different A series of tests on four different steels has en­ by the concentric and eccentric notch strength, low-alloy steels, to say nothing of different heats abled a comparison to be made between the in tons per square inch, separated by the notch- of any one particular steel. The notched-bar im­ static notched-bar tensile test figures and the ductility figures, in percentages, for each steel in pact-bend test is capable of revealing differences tensile strength and Brinell hardness figures ob­ turn, numbered according to the composition in impact properties among steels which have tained on standard machines. The results are table already given. Many interesting facts may been tempered to levels of mechanical strength depicted and correlated in the accompanying be deduced from the nomogram, as, for ex­ identical with the results obtained by ordinary nomogram. ample, the instability of the fourth steel, the high tensile tests. The notched-bar test is, however, The composition of the four steels was as concentric notch strength stability of the first highly complex, involving a certain amount of follows: (with only 17 per cent loss throughout the scale), tension, compression, bending and shear, and its and the unstable notch-ductility of the fourth No. C. Ni. Cr. Mo. | Mn. P. S. Si. full significance is not yet clearly understood. Of steel, involving a strength loss of 93 per cent be­ 0.41 3.5 0.02 0.83 0.016 0.014 its three characteristic features: high speed, 0.03 0.27 tween the tensile strength limits given. Although 0.39 3.46 0 0 0.79 0.018 0.029 2 0.23 notch, and bend action, the notch is the most 0. 4 0 1 0 0.69 0.014 0.023 3 0.16 the notched-bar impact-bend test is not yet quite potent embrittling factor. Recent investigations 0.42 0 0 0 1.81 0.023 0.022 4 0.24 understood, even less is known at present about have shown that static notched-bar tensile tests the static notched-bar test, which, however, is give more fully understandable results and The first two steels approximate to B.S.S. S.69, likely to be proved one of the most useful of all evaluate metals in very much the same manner which has slightly more chromium, phosphorus, mechanical tests once its technique has been per­ as impact tests. sulphur and silicon; the third differs from fected and its implications become more fully The static notched-bar tensile test is carried D.T.D.167 only in that it has no molybdenum; understood. September 1949 301

Journal

Aircraft Engineering and Aerospace Technology – Emerald Publishing

Published: Sep 1, 1949

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