US3644144A - Coated electrode for electric arc welding of steel of various structure - Google Patents

Abstract

The present invention relates to welding coated electrodes and is used for welding steel of various structure. The electrode comprises a rod containing carbon, silicon, manganese, molybdenum, nickel, titanium and iron, and a coating of the fluoric-calcium type.

Description

United States Patent Timofeev et a1.

[54] COATED ELECTRODE FOR ELECTRIC ARC WELDING OF STEEL OF VARIOUS STRUCTURE [72] lnventors: Mikhail Mikhailovich Timofeev, ulitsa Velozavadskaya, 11/1, kv. 323, Moscow; Vladimir Leonidovich Sokolov, ulitza Komsomolskaya 5, kv. 96, Reutovo, Moskovskaya Oblast; Samuil Iosifovich German, ulitsa Mayakovskogo, 11, kv. 21; Ninel Efimovna Levenberg, ulitsa Galana, 3, kv. 58, both of, Kharkov; Nikolai lvanovichPopov, ulitsa Kovskkova 8/50, kv. 36, Elektrostal, Moskovskaya Oblast, all of USSR.

[22] Filed: July 24, 1970 [21] Appl.No.: 58,208

[52] US. Cl ..ll7/205, 117/206, 117/207, 117/224, 148/26 1 Feb. 22, 1972 [51] Int. Cl. ..B23k 35/ 22 [58] Field of Search ..l17/205, 206, 207, 202; 148/26; 219/146 [56] References Cited UNITED STATES PATENTS 3,184,577 5/1965 Witherell ..l17/205 X Primary Examiner-William L. Jarvis Attorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT The present invention relates to welding coated electrodes and is used for welding steel of various structure.

The electrode comprises a rod containing carbon, silicon, manganese, molybdenum, nickel, titanium and iron, and a coating of the fluoric-calcium type.

1 Claims, No Drawings COATED ELECTRODE FOR ELECTRIC ARC WELDING OF STEEL OF VARIOUS STRUCTURE The present invention relates to coated electrodes for electric arc-welding of steel of various structure, and, more particularly, for welding defects of castings from heat-resistant cast steel without heating and subsequent thermal treatment.

At present, electrodes having a nickel base and alloyed with carbon, silicon, manganese, molybdenum, chromium, tungsten and other elements acquire ever greater use in electric arc-welding of heterogenous steel without subsequent thermal treatment.

One of the electrodes used for such purposes is an electrode comprising a rod containing (taken by weight percent) not more than 0.12 percent of carbon, not more than 0.8 percent of silicon, not more than 0.7 percent of manganese, 78 percent of nickel, 0.15-0.35 percent of titanium, 19-22 percent of chromium and the rest of iron, and a coating of the fluoriccalcium type, containing 25-35 weight percent of molybdenum.

The metal built up by means of the aforedescribed electrode is alloyed with great amounts of intensive carbide-forming elemoms-chromium (19-22 percent) and molybdenum (14-15 percent), that penetrates into it from the coating, as a result of which in case the joints are kept at high temperatures for a long period of time the built-up metal is provided with low plastic properties since the joints are greatly liable to precipitation hardening.

Besides, the metal built up by this electrode is liable to for mation of pores in the course of welding.

An object of the present invention is to provide an electrode having a nickel base to obtain heterogenous joints and, more particularly, to weld defects of castings from heat'resistant steel, ensuring obtaining of built-up metal possessing high plastic properties.

There is proposed a coated electrode for welding heterogenous steel, preferably for welding castings from heatresistant cast steel, comprising a rod containing carbon, silicon, manganese, nickel, titanium, iron and a coating of the fluoric-calcium type.

A characteristic feature of the present electrode lies in that the rod composition includes molybdenum. In its specific embodiment the rod contains the following components (taken by weight percent):

0.04-0.08 percent of carbon 0.2-0.5 percent of silicon -10 percent of manganese 6.0-7.5 percent of molybdenum 55.0-65.0 percent of nickel 0.25-0.9 percent of titanium, and

the rest is iron.

The employment of the aforesaid electrode whose rod contains no chrome and 6.0-7.5 percent of molybdenum, makes it possible to obtain a built-up metal which is less alloyed with intensive carbide-forming elements.

The presence of 55-65 percent of nickel in the built-up metal precludes formation of brittle transition crystallization interlayers in the zone of welding of heterogenous joints and provides for high operational characteristics of the metal in case the main metal is added to the latter.

At the same time, the decreased amount of the carbideforming agents in the built-up metal minimizes formation of diffusion interlayers at the side of the built-up metal, raises its plastic properties and makes the joints less liable to ageing in the course of their use at high temperatures.

The employment of the aforesaid electrode considerably decreases the level of alloying the built-up metal, which, in its turn, brings down its cost.

The electrode is manufactured in accordance with conventional technological processes.

To make the subject matter of the present invention readily understood, given below are examples of compositions of electrode rods having a nickel base (taken by weight percent).

EXAMPLE 1 The rod has the following chemical compositions:

carbon 0.04 percent silicon 0.2 percent manganese 5.0 percent molybdenum 6.0 percent nickel 55.0 percent titanium 0.25 percent iron the rest.

Presence of molybdenum (6.0 percent), manganese (5.0 percent) and titanium (0.25 percent) attributes to obtaining a built-up metal which is resistant to formation of hot cracks and precludes formation of pores in the course of welding. The presence in the built up metal of at least 55.0 percent of nickel provides for obtaining joints possessing high operational characteristics without brittle crystallization and diffusion interlayers in the zone of welding of heterogenous joints.

EXAMPLE 2 The rod can have the following chemical composition:

carbon 0.06 percent silicon 0.30 percent manganese 7.5 percent molybdenum 7.0 percent nickel 60.0 percent titanium 0.60 percent Tem erature 81; in 50.2 in art in ottes ,ln0 C. kg./mm. kgJmm. 6 percent t: percent kgJmn.

20 52. 0-56. 0 28. 2-33. 3 89. 7-45. 5 60. 1-50. 8 16. 6-16. 5 Average.- 54.4 30.1 42. a 54. 2 m 16.1

Average.- 42.6 31. 2 35. 2 43. 5

Norm-Where BB is tensile strength; 80.2 is yield strength; 5 1s relative elongation; w is relative narrowing; an is impact strength.

After the ageing of 10,000 hours at 565 C. the impact strength of the built-up rod of the present composition of the metal is equal to l 1.9 kg./cm

EXAMPLE 3 The rod can also have the following chemical composition:

carbon 0.08 percent silicon 0.5 percent manganese 10.0 percent molybdenum 7.5 percent nickel 65.0 percent titanium 0.90 percent iron the rest.

With the present correlation of the components, a built-up metal resistant to formation of hot cracks and pores is ob tained in the rod.

With the maximum content of nickel in the rod equaling 65.0 percent, the linear expansion coefficient of the built-up metal is rather close to the linear expansion coefficient of Temperature range, in C.

Matellel 20-100 20-200 20-300 20-400 20-500 20-565 Built up metal 14.3 14.4 14.15 14.55 14.6 14.8 Steeloipearlltlcclass... 12.0 12.09 12.85 13.46 14.73 15.20

Electrodes with the rods of the aforesaid compositions can have a coating containing:

marble 20-40 percent fluorite 15-30 percent metallic manganese 10-20 percent titanium dioxide l0-20 percent potash I-2 percent,

and soluble glass used as a binding component.

The welding carried out with the aid of an electrode having a coating of the aforesaid composition ensures obtaining a built-up metal having no pores and hot cracks, provides for good separation of slag crust, makes it possible to carry out the process of welding in all the space positions and provides for a high stability of arcing.

To improve the conditions of manufacturing the coating and placing it onto the electrode rod, potash is added in the amount of l-2 percent.

Interacting in the course of the manufacture of the coating with the soluble glass used as a binder, potash performs the function of a plasticizer and makes it possible to prepare an elastic and at the same time rigid soldering mass. Besides, potash affects favorably the conditions of arcing by increasing the stability of arcing and bringing down the potential of ionization of the arc gap.

What we claim is:

1. A coated electrode for electric arc-welding of steel of various structure, mainly for welding defects in castings from heat-resistant cast steel, comprising a rod containing the following components (taken by weight percent):

carbon 0.04-0.08 percent silicon 0.2-0.5 percent manganese 5.0-10 percent molybdenum 6.0-7.5 percent nickel 55.0-65.0 percent titanium 0.25-0.9 percent iron the rest,

and a coating of the fluoric-calcium type.

l l I