DE1758593C2 - Steel with high toughness and high tensile strength - Google Patents

Description

The invention relates to a steel that due to its high toughness, especially high notched impact strength at low temperatures, and. characterized by high tensile strength.

Due to recent advances in welding together at low temperatures too using constructions and devices which are used for the storage of liquid gas steels are required that have improved toughness. Tensile strength, flow strength, Have impact resistance, weldability, and machinability.

Much effort has been made to improve the notch ductility of steels at low temperatures. For example, the The rolling temperature of a steel plate was set to a special value, or nitride compounds were such as B. aluminum nitride and the like., Added to the steel in order to improve the fine grain size, or have been added large amounts of nickel worked into the steel.

The present invention has for its object to provide steels which have an improved mechanical strength and especially high toughness at low temperatures, high Have tensile strength and high flow strength.

Another object of the invention is to provide steels G5 to create, which are used for the production of structures and devices, which at low TeiriDeratures should be used.

593 ^ ₂

The subject of the invention is therefore ";" Steel with high toughness, high tensile strength and high flowability, which is composed of 0.05 to 025 percent by weight carbon; 0.1 to 07 percent by weight silicon, 02 to ίο percent by weight manganese, OJS to 3.0 percent by weight nickel. Aluminum in a content of less than 08 percent by weight. OXi 1 to 0.025 percent by weight tellurium. The remainder consists of iron and incidental impurities, and which can additionally contain less than * »0 percent by weight of chromium, less than 1.0 percent by weight of molybdenum and / or less than 0.6 percent by weight of copper.

The invention further relates to a steel of high toughness, high tensile strength and high flow strength, which is made from 005 to 025 percent by weight of carbon, 0.1 to 07 percent by weight of silicon, 0.2 to 2.0 percent by weight manganese, alumine »sa in content up to less than 008 percent by weight and optionally up to less than 3.0 percent by weight nickel, less than 2.0 percent by weight of chromium, less than 1.0 percent by weight of molybdenum, less than 0.6 percent by weight of copper, one or more components from the following group:

Gewichlspio / ent Vanadium 0.005 to I). 15th

Titanium 0.005 to 0.15

Zirconium 0.005 to 0.2

Niobium 0.005 to 0.3

Tantalum. ' 0.003 to 0.3

Boron 0.0005 to 0.006

and 0.01 to 0.025 percent by weight tellurium and im remaining 3us consists of iron and incidental impurities.

As a result of long development work, it was found that steels with a low carbon content, in terms of their toughness, especially at low temperatures, and with regard to the deformability of welded parts without adversely affecting their mechanical properties, e.g. B. Tensile strength, can be improved by adding a small amount of tellurium to them, and it new steels were developed, which in Japanese patent application 52 173 of August 16 1967 are given.

Attempts were also made to improve the notched impact strength of steels with high tensile strength, which Alloying elements contained in small amounts to improve, and as a result of many attempts has been made It has now been found that the steel defined above is improved in terms of its notch ductility by Tellurium is added to it in the amounts specified above. The result is new steels with a high level of quality Notched impact strength at low temperatures, a high tensile strength and a high flow strength wedge.

Tellurium salts for steels are known from US Pat. No. 2009 716, but they are said to improve machinability. The tdlur content is included these steels between 0.03 and 2%.

The steels produced according to the invention must contain the components in the quantities specified above contain. The reasons for this are as follows:

The carbon content of the steel should be so small because of the impact strength and weldability be as possible, but a steel needs a carbon content of more than 0.05% in order to achieve the mechanical Properties to improve. The Kerbsthlagzähigkcil and the weldability of the steel are

1768

Way affected when the steel has a high Has carbon content. Accordingly, the carbon content of the steel according to the invention is 0.05 defined up to 0.25%.

Silicon is used as a deoxidizer in the manufacture of conventional steels and has the effect of increasing the tensile strength of such steels. However, a silicon content of more than 0.7% is not desirable for improving the toughness of the steels of the present invention. Accordingly jst defines the silicon content as 0.1 to 0.7%.

Manganese is also used as a deoxidizer and has the effect of improving the normalizing properties, but when manganese is in is used in an amount less than 0.2%, the corresponding effect is not satisfactory. Accordingly, the manganese content is defined as 0.2 to Z0%.

Nickel increases the normalization properties

steel according to the invention adversely affected, and it also becomes brittle when hot-rolled.

The tellurium-containing steel of the present invention is used in terms of its mechanical properties and mutual effects and effects of tellurium and aluminum, which is present in an amount below 0.08%. What corresponds to the aluminum content of conventional steels, improved.

It has been found that tellurium is used in an amount of 0.01 to 0.15 weight percent should to the high toughness of the steels according to the invention, which carbon in an amount of less than 025% included.

The component belonging to the vanadium group. Titanium, zirconium, niobium. Tantalum and boron is selected, improves the notched impact strength of the steels according to the invention in the presence of tellurium. It is pointed out that cmc has such com-

and toughness, but this effect is reduced. _ "

when the nickel is used in an amount of less than 20 ponente in the amounts given above 05% is used. When nickel needs to be in a big one. If such a component is in a Amount is used, then it possesses the inclination. Amount used below the lower limit Increase the amount of retained austenite for what will. Then it is not expected to have any effect Structure of the steel according to the invention shows undesirable. The notched impact strength of the is also serious. Accordingly, the upper limit value of the nickel steel according to the invention is not increased or impaired defined as 3.0%. tiut.'if such a component is in a lot

- · "- · - · - ■ = - ■ - ■ ■ ·.-.- use above the upper limit value ·, is.

It is further pointed out that boron improves the normalization property of the steel and that vanadium titanium, zirconium, niobium and tantalum increase the strength of the steel according to the invention and the tempering of carbide at high temperatures, which is why the hardness of the steel is reduced in welded areas and its weldability is improved ability of steel against corrosion and its 35 will.
Yield strength, but when it is in amounts above The invention is illustrated by the following examples

0.6% is used, the toughness of the is explained in more detail.

Chromium and molybdenum cause an increase in the strength wedge, but the toughness and weldability of the steel according to the invention are adversely affected if they are used in larger amounts be used. Accordingly, the upper limit of the chromium and molybdenum content is 2.0 and 1.0% defined.

Copper causes an increase in the resistance

Examples 1 to

Nine steels labeled A, B, C. D. E. F. G. H and I are shown in Table 1 below listed.

Table I.

Slahl no.

A (example I).
B (example 2).
C (example 3).
D (example 4).
E (example 5).
F (example 6).

0 (comparison). H (comparison).

1 (Comparison).

C. Si Mn l> S. Ni Cr Mon Cu ΛΙ CoI l% l PnI l "<l | (% l ("Oil _T / o) (% | J ° J> ± (%> _ 0.12 0.34 1.20 0.012 COlO 0.77 0.20 0.03 0.27 0.025 0.10 0.25 1.18 0.014 0.012 1.20 0.06 0.45 0.25 0.038 0.12 0.21 0.90 0.012 0.013 0.89 0.40 0.36 0.21 0.018 0.14 0.26 0.58 0.010 0.010 1.15 0.68 0.23 0.22 0.041 0.09 0.29 0.57 0.015 0.014 1.84 0.30 0.42 0.30 0.038 0.10 0.38 0.80 0.012 0.015 1.40 1.02 0.56 0.18 0.040 0.12 0.36 1.19 0.013 0.010 0.78 0.22 0.03 0.25 0.026 0.13 0.25 0.85 0.013 0.011 0.90 0.38 0.34 0.21 0.020 0.10 0.34 0.78 0.011 0.015 1.41 1.03 0.52 0.19 0.042

Tj
(% l

0.019 0.014 0.022 0.018 0.021 0.018

Steels A through F are steels according to the invention, and Steels G through I are comparative steels, which are conventional steels. All steels were heated to 900 ° C and tempered at 650 ° C »Ie tested for their mechanical properties. The test results are given in Table 2 below.

table

Steel no.

A (example Ij
B (example 2)
C (example 3)
D (example 4)
E (example 5)
F (example 6)
G (comparison)
H (comparison)
I (comparison)

FHeB strength

(kg / mm ¹ )

53.0
55.4
62.9
63.1
65.2
75.0
53.3
63.9
75.4

61.6 64.3 70.9 71.3 7Z2 82.2 62.3 72.5 82.8

ftohnunt! fcin-
lacing l-.l <"»! 30.2 76.5 28.9 74.6 26.4 72.1 26.8 72.8 27.8 72.8 21.6 62.3 29.4 76.1 25.6 72.6 20.4 61.4

<tfrbsthUy-
/ ahigkcti TrE at O t -89 lCharp) -V- -95 Genetic test) -98 | cg-m cm ^J -100 25.4 -115 23.2 -82 22.5 -66 22.2 -72 21.5 -67 12.8 22.5 22.1 12.4

Transition temperature no

ι η

TrIS 7> 3C -128 -109 -133 -118 <-140 -Ul <-140 -120 <-I40 -132 -120 -96 -109 -91 -130 -93 -102 -80

The steels were tested for their Charpy-Shlagfeytiukeil at 0 "C, whereby 2-mm-V-notches were used. Furthermore, the transition temperatures" TrE ", " Tr 15 ", " Tr 30 "and" 7VS "were determined from the transition temperature curves The temperature "TrE" is the energy transition temperature which indicates one half of the maximum absorption energy, and the temperatures "Tr 15" and "7>3O" indicate the absorption energy for 15 ft-Ib and 30 ft-lb, respectively. The symbol "7>S" indicates the break transition temperature at which a 50% break developed. It can be seen from the data given in Table 2 that the steels according to the invention - 85 -90 -95 -98 -112 -80 - 62 -67 -63

high tensile strengths and very good notch toughness at low temperatures compared to the strings of conventional comparative steels.

B e i s ρ i e 1 7

A steel of the composition according to the invention, of 0.12% C, 0.37% Si, 1.33% Mn, 0.011%>. 0.013% S. 0.52% Ni. 0.24% Cr, 0.21% Cu, 0.06% Mo. 0.11% Nb. 0.002% B, 0.034% Al and 0.018% Te. The remainder contained iron was compared with the known tellurium-free steels given in Table 3. All steels were normalized at 900 ° C.

table

Steel no.

23 (example 29)

1 (comparison).

2 (comparison).

C. Si Mn P. S. Ni Ct C; (%> ("oil 1%) I ⁰ ol (% l 1%) (V.) (%) 0.13 0.34 1.21 0.010 0.013 0.35 0.05 0.27 0.12 0.25 0.53 0.012 0.010 0.28 0.06 0.26 0.12 0.35 1.20 0.011 0.013 0.29 0.06 0.24

Steel no.

1 (comparison).

2 (comparison).

Ti table Nb Ta B. Λ1 V (%) Zr '"ill <% l (V.) (%) (% l 0.030 0.035 -

Mon

0.07 0.03 0.06

Ic

The strength values given in Table 4 were determined.

table

Chair no.

According to the invention
steel

1 (comparison)

2 (comparison)

IMcU- Train- (λ l There- lcslißkcit strength Dcniiiinu sthiuirun)! (kg mm ') (kB mm'l (% l 41.3 53.3 41.2 76.4 33.0 45.9 37.1 71.1 36.4 53.8 37.8 67.4

Final

bci 0 C lC'h; irpy-V-Kcrhprobtt

Ιίμ-rn cm ²

nbcrgiingstcmpcriiliir

TrH

-100
-32
-26

Door 15

<-l30
-63
-66

TrM)
-127

.-53
-49

IrS -83

-20 -19

.1. ItMI. 4 meta. ** ■ * - .1 *

«T

Values.

table

Steel no

According to the invention

steel

(Comparison)

liießfcsligkcil

(kg nmr)

52.3 51.0

Tensile strength iy.kei

(kg mm ² l 60.8

59.1

Elongation (V.)

29.6 30.4

Constriction

78.5 77.1

Notch

toughness

atO C

(Charpy-V-

Notch test)

kg-m / cm ²

26.0 22.0 * in TM.

Obcrgangstemnerutur (C)

TrE

-120
-40

TVI5

- 130

-87

7> 3O

-130 -68

TfS

-107
-31

From the given ^^ "gbdteSbtg ggg ^ UUiUiJSS" ÄÄe zt SOS given, with the steels Ni, Cr, Mo etc. in large M nth.

it is evident that the e ^ iner mechanical prop

and notched impact strength, is improved when it is of animal origin

e ^ n7u ^U niimä examples are in the following

The test results are in the table below? specified. table Examples 8-19

14 steels, which were designated with the numbers 1 to 14, are given in Table 6 below. The steels No. 1 to 12 are fictional * conventional steels, and steels Nos. 13 and 14 are well-known comparative steels.

All steels were normalized at 900 ° C and then tempered at 65O ° C and tested for their mechanical properties.

Steel no.

1 (example 8) ..

2 (example 9) ..

3 (example 10).

4 (example 11), 5 (example 2). 6 (Example 3).

7 (example 14).

8 (example 15).

9 (example 16).

10 (example IT)

11 (example 18)

12 (example 19)

13 (comparison).

14 (comparison).

SIaM No.

1 (example 8).

2 (example 9}.

3 (example 10)

4 (example 11)

C. Si (V.) (V.) 0.12 0.26 0.13 0.21 0.10 0.30 0.09 0.27 0.12 0.35 0.15 0.34 0.14 0.29 o; i3 032 0.10 0.26 0.11 030 0.09 038 0.10 0.32 0.13 0.25 0.10 034

Mn

1.01

0.63

0.58

0.61

0.93

1.09

0.89

1.00

0.83

130

0.76

0.82

0.85

0.78

Table 6 (continued)

P. I / l Ni Cr Cu Mon (V.) (V.) (%) (%) (V.) (V.) 0.012 0.013 0.85 0.44 0.22 033 0.013 0.010 UO 0.67 0.20 0.25 0.010 0.010 1.80 0.36 0.27 0.40 0.014 0.012 1.92 032 0.30 0.42 0.009 0.013 1.07 0.42 0.20 0.32 0.014 0.011 0.96 037 0.21 0.45 0.013 0.01) 0.87 0.51 0.20 035 0.010 0.012 om 0.40 0.22 032 0.013 0.012 1.12 0.62 0.18 0.28 0.011 0.014 1.05 036 0.20 030 0.011 0.013 1.43 1.06 0.13 0.57 0.010 0.014 138 1.01 0.20 033 0.013 0, OU 0.90 0.38 0.21 034 0.011 0.015 1.41 1.03 0.19 032

0.05

Nb Ta B. Al Te CA) (%> (%) (V.) 0.003 0.035 0.018 _ i- 0.003 0.640 0.015 ■ τ 0.021 0.022 0.04 - - 0.032 0.020 Zr (%) 0.02 -

Ti W.

0.02 -

continuation

10

Slaiil No.

5 (example 12) ..

6 {example 13) ..

7 (example 14) ..

8 (example 15) ..

9 (example 16) .. 10 (example 17) .. It (example 18) ..

12 (example 19) ..

13 (comparison) ...

14 (comparison) ...

V Ti / l Nh Ta η ΛΙ (%) (% l 1 ¹ Vn) (%) (% l 0.03 --- 0.041 - 0.02 - 0.021 - 0.06 0.002 0.025 - - - .__ 0.06 0.020 - 0.01 - 0.04 - - 0.016 - - - 0.03 0.03 - 0.022 - - - - 0.004 0.038 - - - 0.04 - 0.003 0.033 - - - - - 0.020 - - - - - - 0.042

0.019 0.017 0.018 0.017 0.020 0.016 0.018 0.017

table

Slah! No

1 (example 8) ..

2 (example 9) ..

3 (example 10).

4 (example 11).

5 (example 12).

6 (example 13).

7 (example 14).

8 (example 15).

9 (example 16).

10 (example 17).

11 (example 18).

12 (example 19).

13 (comparison) ..

14 (comparison) ..

63.3 63.6 65.0 66.0 64.2 65.1 66.0 65.2 64.0 66.9 75.3 75.4 63.9 75.4

71.5 71.8 72.5 74.0 7Z9 73.2 74.1 72.8 72.2 74.7 82.4 82.0 72.5 82.8

Constriction

26.3 26.6 27.6 25.5 26.0 26.0 25.4 26.2 26.7 25.6 21.7 21.5 25.6 20.4

72.1 72.6 73.0 71.8 72.2 71.7 71.5 72.0 72.4 71.7 62.6 62.5 72.6 61.4

Notched impact strength at O C t Charpy-V-notch test c) kg-m cm ²

23.0 22.1 21.8 21.5 22.2 22.0 24.1 23.5 23.2 22.7 13.0 12.9 22.1 12.4

transition temperature t C)

TrE

-98 -101 -117 -106 -97 -101 -96 -98 -103 -96 -83 -85 -72 -67

TrIS TrJO <- 140 -112 <-140 -122 <-140 -134 <-140 -122 <-140 -114 <-140 -120 <-140 -111 <- 140 -113 <-140 -117 <-140 -113 -123 -98 -122 -97 -130 -93 -102 -80

TrS

-96

-98

-113

-102

-

-96

-93

-96

-100

-92

-81

-81

-67

-63

From the figures given in Table 7 it can be seen that the steels according to the invention have high impact strengths exhibit at low temperatures, while their tensile strength accordingly dei Amount of the alloy component contained changes.

The steels according to the invention are used as building materials for the manufacture of a wide variety of constructions and especially used for devices that are used at low temperatures. the Steels according to the invention can be used after they have been rolled, or rolled and tempered, or after they have been rolled normalized or normalized and tempered or quenched and tempered.

Claims (1)

1758 Patent claims: l.SlabJ, characterized. that he 0.05 to 025 weight percent carbon. 0.1 s up to 0.7 percent by weight silicon, 0.2 to 2i) percent by weight manga ». 05 to 3JD weight percent nickel. Aluminum in columns to less than 0.08 weight percent. 001 to 0025 percent by weight tellurium, optionally to less than 2.0 percent by weight chromium, less than 1.0 percent by weight molybdenum, less than 0.6 percent by weight copper and the remainder iron and Contains incidental impurities Z steel, characterized in that it is 0.05 to 0.25 percent by weight carbon, 0.1 to 0.7 percent by weight silicon, 0.2 to 2.0 percent by weight manganese, aluminum, in contents up to less than 0.08 percent by weight, optionally less than 3.0 percent by weight nickel, less than 2.0 percent by weight of chromium, less than 1.0 percent by weight of molybdenum, less than 0.6 percent by weight of copper, one or more components from the following group: Weight percent Vanadium 0.005 to 0.15 Titanium 0.005 to 0.15 Zirconium 0.005 to 0.2 Niobium 0.005 to 0.3 Tantalum 0.003 to 0.3 Boron 0.0005 to 0.006 as well as 0.01 to 0.025 percent by weight tellurium and the remainder iron and incidental impurities contains.