SU664800A1 - Core wire composition - Google Patents

Description

Iron powder0.01-20

Fluorspar 0,5-3

Scandium containing

component0.1 -1.5

Low carbon steel sheath. The remaining Scandium is introduced as a metal powder or as part of nickel, magnesium, aluminum, titanium based master alloys with a content of scandium up to 30%. Scandium has mrdification, ruyush, its effect in quantities of 0.1% and above. When more than 1% of scandium is introduced into the wire, the opposite effect is observed: in the structure of the weld iron, along with spherical, there appears snowflake-like and irregularly shaped graphite.

In order to reduce chill-off of the deposited iron, the number of input elements of the graphitizer: carbon and silicon should be rather high. The sum is equal to; their components of the charge of graphite and ferrite cored wire are 11–12%, a higher content of graphite corresponds to a lower content of ferrosilicon, and vice versa. the content in the wire of more than 10% of graphite carbon is not absorbed in the weld pool and is released in the form of graphite sang. The upper limit for ferrosilicon. Due to the fact that the amount of silicon in the cladding should be limited to obtain high plastic properties.

Introduction to the composition of fluorspar contributes to better absorption of scandium, reducing its loss and improves the welding and technological properties of the wire. With a content of more than 3% fluorspar, the bath is slagged and slag inclusions are found in the cladding.

The introduction of iron powder into the wire improves its technological properties and improves the performance of smelting. While ensuring the chemical composition of the wire according to the modulus, im (scandium) and graphitization, they (carbon, silicon) elements - should strive to enter the maximum possible amount of iron powder, which is up to 20% of the sheath, of its wire weight.

Scandium, introduced into the cored wire, changes the conditions of crystallization of the deposited iron and contributes to the formation of graphite beads of a ball-shaped form. As a result, the weld metal or the cladding, as well as the joint as a whole, have high mechanical properties.

Powder wire with a diameter of 3 mm is made from a low-carbon steel strip and powdered charge on conventional pulling machines. Butt hem joints. Welding and cladding is carried out in direct current polarity. Standard semi-automatic machines and power sources are used. The following are examples of application for the cored wire.

Example 1. Powder wire was used, the components of which were taken in the following 5 weight ratio,%: graphite 8.0, ferrosilicium 4.5, iron powder 14.0, metal scandium 0.2, fluorspar 0.7, low carbon steel cladding rest. Surfacing mode: welding current 400-420 A, arc voltage 34–35 V, wire feed speed 159 m / h. The structure of the surfacing: spherical graphite (GSHD-2, GSHD-3) evenly distributed, the base of perlite and separate scattered inclusions of cementite, ferrite core around the globules. Hardness of cladding NU 320-350, transition zone NU 460-480. After annealing at a temperature of 800 ° C for 2 hours and with a furnace, the base structure becomes ferritic with hardness NU 195-205.

Example 2. Powder wire was used, the components of which are taken in the following weight ratio,%: trafit 9.0, ferrosilicon 3.0, iron powder 15.0, metal scandium 0.8, fluorspar 1.0, low carbon with hoist shell else. Surfacing mode: welding current 410-430 A, arc voltage 0 33-34 V, wire feed speed 159 m / h. The structure of the nanlava: graphite-spherical (GSHD-3) and compact, evenly distributed, the base of perlite and ledeburite areas. Hardness of cladding 5 NU 370-380, transition zone NU 490-500. After annealing (in the same mode), the base structure is perlite-ferrite, hardness NU 220-250.

In all cases the x-process was 0 stable, without splashing. The weld iron was dense, without pores and undercuts.

The mechanical properties of cast iron (after annealing at 800 ° C for 5–2 hours) are at the level of the properties of high-strength cast iron: tensile strength 50–62 kgf / mm, yield strength 38–50 kgf / mm, elongation 3–6%; impact viscosity 2-5 kgf-m / cm2.

0 The introduction of scandium contributes to the p-ferlitization of the metallic cast iron base, which makes it possible to use such flux-cored wires for welding high-strength cast irons with pearlite metallic base 5 (without additional input of elements stabilizing perlite), as well as for surfacing parts operating under wear conditions and frequent heat change.

The action of scandi as a globular torus of graphite in the deposited iron is stronger than yttria, cerium and other rare-earth metals. tal, and taking into account the degree of assimilation is many times more efficient than magnesium and calcium. Despite the increased cost compared to other modifiers

scandi, the economic effect is achieved due to the use of very small amounts of it in the cored wire (0.1-0.2%).

This ensures high hygienic characteristics of the welding process. Gross dust emissions (solid component of aerosol) when welding with powdered prdvolokoy containing scandium, do not exceed 15 g / kg, while when welding with a wire with the necessary amount of magnesium 30 g / kg or more; Calcium 24.5 g / kg. The concentration of carbon monoxide and nitrous oxide in the welder's breathing zone is many times lower than the maximum permissible concentrations. Waste dust and gases do not contain toxic substances.

Claims (2)

1. US patent number 38E8246, cl. 219-146, 1974. 2. USSR author's certificate number 526477, cl. In 2EK, 1977.