DE2030400A1 - High tensile steel - Google Patents

Description

Nippon Kokan Kabushiki Kaisha f June 9, 1970

Tokyo, Japan

High tensile steel

The invention relates to a high tensile strength steel.

The steel according to the invention consists of 0.12-0.21 % carbon, 0.70-1.00 % manganese, 0.20-0.35 % silicon, 0.40-0.65 % chromium, 0.15-0 , 25 % molybdenum, 0.0J - 0.08 % vanadium, 0.01 - 0.0J $ titanium, 0.0005-0.005 $ boron, 0.020 - Ο, ΟβΟ % aluminum, 0.008. - 0.020 % nitrogen, remainder iron and impurities »After treatment by hardening and tempering, this alloy produces a steel with a yield point of more than 70 kg / mm » a tensile strength of more than 80 kg / mm with excellent notch toughness and weldability,

Under the standard designation ASTM A 5I7 GrB, USS T-1 Type A Steel, only similar steels are known. However, if such a high tensile strength steel with a nickel-containing When comparing steel with the same high tensile strength, it turns out that it lacks the necessary notch toughness «One such known steel is therefore not suitable as a high tensile strength Steel for use in adverse conditions.

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109818/1183

The invention, however, creates a steel; which both the high tensile strength as well as the notch toughness of the known steels containing expensive nickel, however, which can be manufactured at a lower cost and industrially. The steel is after the nitrogen and Aluminum addition for precipitation or segregation of nitrided aluminum, hardened and tempered.

W The upper limit of the aluminum content is set at Ο, ΟβΟ % because more than Ο, ΟβΟ $ aluminum could damage the purity of the steel. The upper limit of the nitrogen content is set at 0.020 % in order to set this content in relation to the above-mentioned upper limit value for the aluminum content. The lower limit of the aluminum content is set at 0.020% , because below this value no deoxidation of the steel and no complete binding of the dissolved nitrogen can be expected. The lower limit of the nitrogen content is set to 0.008 % , taking into account the ratio between the amount of aggregate aluminum and the required

| borrowed amount of nitrided aluminum.

example

Table I shows an example of the chemical composition of a steel according to the invention, the remainder being iron and impurities. Table II illustrates the mechanical properties of a steel produced by rolling of the steel according to Table I into a plate 25 mm thick and after heat treatment in the form of hardening and tempering was obtained.

109810/1103

Table I.
MY

C Si Mn P S -Cr Mo V Ti B Al N 0.17 0.26 0.93 0.01-5 0.007 0.63 0.24 0.04 0.01 0.002 0.040 0.012

Table II

Plate tensile strength test

thick yield point tensile elongation vEO vE-60 ~ vTs (mm) (kg / mm ² ) strength ($) (kgm / cnr) (kgm / cm) (C)

(kg / mm ² )

71. 82 19 16.3 9.4 -58

Notes to Table II:

The materials subjected to the tensile strength test possessed a sample length of 50.8 mm and a diameter of 14 mm.

The materials subjected to the impact tests had a V-shaped notch 2 mm deep. -

An investigation of the above example shows that the steel of the invention the known high tensile strength steels, both in the yield point as is also superior in the tensile strength. In addition, it has high notch toughness even at a temperature of -60 C. Accordingly, the steel according to the invention is comparable to the known, but expensive, nickel-containing, high-tensile steel and is extremely suitable as a high-tensile steel for low-temperature conditions.

109818/1183 - ^ -

Claims (2)

Claims 1. High tensile steel, characterized in that it is made of 0.12-0.21 # carbon, 0.70-1.00 $ manganese, 0.20-0.35 $> silicon, 0.40-0.65 % Chromium, 0.15-0.25 % molybdenum, 0.0} - 0.08 # vanadium, 0.01-0, OJ % titanium, 0.0005-. 0.005% boron, 0.020 - 0,0β0% aluminum, 0.008 - 0.020% nitrogen, balance iron and impurities, and is treated by hardening and tempering. 2. High tensile steel, characterized in that it consists of 0.17 % carbon, 0.93 # manganese, 0.26 % silicon, 0.63 % chromium, 0.24 % molybdenum, 0.04 % vanadium, 0.01 % Titanium, 0.002 % boron, 0.040 % aluminum, 0.012 % nitrogen, the balance iron and impurities. 109818/1183