CN1050569A - Ferrochrome exothermic - Google Patents

Abstract

A kind of wear-resistant and corrosion-resistant ferrochrome exothermic, its composition (weight %) is: 34-50 chromium, 1.5-2.5 carbon ,≤5 manganese ,≤5 silicon ,≤5 molybdenums ,≤10 nickel ,≤5 bronze medals, one or more trace alloying elements of every kind of content≤1: titanium, zirconium, niobium, boron, vanadium and tungsten, all the other are iron and institute's incidental impurities.The microstructure of this alloy is the eutectic chromium carbide in containing one or more cable bodies, residual austenite and martensitic matrix.In addition, this microstructure also on matrix, contain chromium carbide, ferrite or once austenitic one of them.

Description

Ferrochrome exothermic

The present invention relates to a kind of ferrochrome exothermic, the particularly a kind of wear-resisting corrosive of anti-damage ferrochrome exothermic.

Alloy of the present invention is used for making the part of in-line pump, pipeline, nozzle, agitator and allied equipment, and it can stand to contain the erosion of corrosive fluid and abradability granular mixture when work.

The typically used of these parts comprises that part is exposed to flue gas desulfurization (FGD) in sulfuric acid and the Wingdale and part and is exposed to chemical fertilizers production in phosphoric acid, nitric acid and the gypsum.

Transfer gives the United States Patent (USP) 4 of Abex company, 536,232 and 4,080,198(" Abex United States Patent (USP) ") disclosed ferrochrome exothermic contains about 1.6%(weight) carbon and 28%(weight) chromium, it is characterized in that chromium carbide and ferrite are distributed in the martensite or austenitic matrix that contains solid solution chromium.Chromium content in the alloy should make alloy present excellent corrosion resisting performance.But with regard to it was corrosion-resistant, very order was dissatisfied for the performance of this alloy.

The purpose of this invention is to provide a kind of ferrochrome exothermic, with the alloy phase ratio of Abex U.S. Patent Publication, it has better wear-resistant corrosion resistance nature.

In the Abex United States Patent (USP) alloy of disclosed the sort of type in acidic medium in acidic medium wearing and tearing and Corrosion Mechanism be since the abradability particle in the liquid stream constantly except that the depassivation anticorrosion layer, thereby accelerated corrosion.

In order to replenish purification layer, in matrix, need high as far as possible chromium concn.

But, increasing chromium content simply and can cause forming the σ phase to improve its erosion resistance, σ can cause fragility mutually, is undesirable therefore.

The present invention is based on following understanding and finishes, increase the chromium of Abex U.S. Patent Publication alloy and the concentration of carbon simultaneously, this may increase the percent by volume of chromium carbide phase, and can improve the wear resistance of this ferrochrome exothermic, keep chromium concn in the matrix in certain level simultaneously, and do not cause forming the σ phase.As mentioned above, according to wearing and tearing and Corrosion Mechanism take place, the wear resistance of estimation improvement ferrochrome exothermic may be improved the wear-resistant and corrosion resistance nature of ferrochrome exothermic.

Composition (weight %) wear-resistant and corrosion-resistant ferrochrome exothermic provided by the invention is as follows:

34-50 chromium

1.5-2.5 carbon

≤ 5 manganese

≤ 5 silicon

≤ 5 molybdenums

≤ 10 nickel

≤ 5 bronze medals

One or more trace alloying elements of every kind of content≤1 are selected from titanium, zirconium, niobium, boron, vanadium and tungsten.

All the other are iron and institute's incidental impurities,

Its microstructure is the eutectic chromium carbide in matrix, its matrix be following defined ferrite, residual austenite and martensitic one or more.

Term " ferrite " refers to such an extent that be the body-centered cubic iron (α and/or δ form) that contains solid solution chromium.

Term " austenite " refers to such an extent that be the face-centered cubic iron that contains solid solution carbon and chromium.

Term " martensite " refers to such an extent that be austenitic transmutation product.

Preferably matrix contains 25-35%(weight) solid solution chromium.

Preferred microstructure is also to contain once chromium carbide in matrix, ferrite or once austenitic one of them.

(weight %) is as follows for the preferred content of elemental chromium, carbon, manganese, silicon, molybdenum, nickel and copper:

36-40 chromium

1.9-2.1 carbon

1-2 manganese

0.5-1.5 silicon

The 1-2 molybdenum

1-5 nickel

1-2 copper

For above-mentioned preferred composition, preferred substrate contains 29-32%(weight) solid solution chromium.

According to the present invention, the chromium and the carbon content that increase ferrochrome exothermic simultaneously make it to be higher than disclosed content in the Abex United States Patent (USP), make the hard carbide that forms more volume percentage ratio to improve wear resistance.More particularly, preferable is that the chemical equilibrium that increases chromium and carbon content makes the chromium carbide that forms more volume percentage ratio and do not increase matrix chromium content and make to reach and produce more than the mutually brittle threshold value of σ.

As can be seen, the preferred alloy of the present invention presents the antiwear anti-corrosion more superior than the alloy of Abex U.S. Patent Publication.This can be by following table 1 explanation, and table 1 has been listed the standard electrokinetic potential corrosion of Abex U.S. Patent Publication alloy and preferred alloy of the present invention and the result that the garden mill decreases test.The composition of alloy is provided by table 2.

Table 1. corrosion and wearing test result

Corrosion^*Wearing and tearing^*

(millimeter/year) (millimeter³/ hour)

Abexalloy 1^*5.60 488

Abex alloy 2^*2.50 614

Foundry goods 1^#0.07 370

Foundry goods 2^#0.43 444

* 10% sulfuric acid, 25 ℃ to ASTM G61

* 40%(weight) silica sand mud 18 meter per seconds

The composition of table 2 table 1 interalloy

Cr C Mn Si Mo Ni Cu Fe

Abexalloy 1^*28.4 surplus in the of 1.94 0.97 1.48 2.10 2.01 1.49

Abex alloy 2^#**27.5 surplus in the of 1.65 1.21 1.47 2.00 2.00 1.39

Foundry goods 1^#35.8 surplus in the of 1.95 0.96 1.48 2.10 2.04 1.48

Foundry goods 2^#40.0 surplus in the of 1.92 0.96 1.59 1.95 1.95 1.48

* United States Patent (USP) 4,536, the casting alloy in 232 the composition range

In the composition range of * United States Patent (USP) 4,536,232 through heat treatable alloy

As can be seen from Table 1, the corrosion-resistant and abrasion resistance properties of preferred alloy of the present invention is more far better than Abex alloy.

Alloy of the present invention has the microstructure of the alloy that is different from the Abex U.S. Patent Publication, and its difference can be proved by the accompanying drawing of the Photomicrograph that contains Abex U.S. Patent Publication alloy and preferred alloy of the present invention.

Fig. 1 represents the microstructure of Abex alloy, and this alloy contains 28.4% chromium, 1.94% carbon, 0.97% manganese, 1.48% silicon, 2.10% molybdenum, 2.01% nickel, 1.49% bronze medal, and all the other are iron basically.This microstructure comprises an austenite dendrites (50% volume) and is included in the eutectic structure of the eutectic carbides in eutectic ferrite, residual austenite and the martensitic matrix.

Fig. 2 represents a kind of microstructure of preferred alloy of the present invention, and this alloy contains 35.8% chromium, 1.94% carbon, 0.96% manganese, 1.48% silicon, 2.06% molybdenum, 2.04% nickel, 1.48% bronze medal, and all the other are iron basically.This microstructure is hypereutectic, and it has a ferrite dendrite (20% volume) and is included in the eutectic structure of fully decentralized eutectic carbides in the ferritic matrix of eutectic.As can be seen, when comparing with the microstructure of Figure 1A bex alloy, Fig. 2 microstructure reflects that the volume of a dendrite reduces, and the volume of eutectic matrix increases, because this eutectic matrix has a more a high proportion of carbide, when with the Abex alloy phase than the time, the percent by volume of the hard carbide in this alloy increases generally.Can see that Fig. 3-5 is compared with the microstructure shown in Fig. 1, and above-mentioned in the larger context phenomenon also clearly.

Fig. 3 represents the microstructure of the preferred another kind of alloy of the present invention, and this alloy contains 40.0% chromium, 1.92% carbon, 0.96% manganese, 1.59% silicon, 1.95% molybdenum, 1.95% nickel, 1.48% bronze medal, and all the other are iron basically.This microstructure is the eutectic carbides in the eutectic ferrite matrix.

Fig. 4 represents the microstructure of the preferred another kind of alloy of the present invention, and this alloy contains 40.0% chromium, 2.30% carbon, 2.77% manganese, 1.51% silicon, 2.04% molybdenum, 1.88% nickel, 1.43% bronze medal, and all the other are iron basically.This microstructure is hypereutectic, and it has M one time₇C₃Carbide and the eutectic structure that is included in the eutectic carbides in the eutectic ferrite matrix.

Fig. 5 represents the microstructure of the preferred another kind of alloy of the present invention, and this alloy contains 43% chromium, 2.02% carbon, 0.92% manganese, 1.44% silicon, 1.88% molybdenum, 1.92% nickel, 1.2% bronze medal, and all the other are iron basically.Microstructure in this case is hypereutectic, and it has M of trace₇C₃Carbide and the eutectic structure that is included in the eutectic carbides in the eutectic ferrite matrix.

Casting of any suitable routine and heat treatment technics can be used for production alloy of the present invention.Yet, preferably cast, thermal treatment under 600-1000 ℃ temperature then, air cooling is produced this alloy subsequently.

Many variations can be arranged and do not break away from the spirit and scope of the present invention for above-mentioned alloy.

Claims (5)

1, a kind of wear-resistant and corrosion resistant ferrochrome exothermic is characterized in that the composition (weight %) of this alloy is:

34-50 chromium

1.5-2.5 carbon

≤ 5 manganese

≤ 5 silicon

≤ 5 molybdenums

≤ 10 nickel

≤ 5 bronze medals

One or more trace alloying elements of every kind of content≤1: titanium, zirconium, niobium, boron, vanadium and tungsten.

All the other are iron and institute's incidental impurities,

Its microstructure is the eutectic chromium carbide in containing ferrite, residual austenite and martensitic one or more matrix.

2, the alloy of determining according to claim 1, it is characterized in that its microstructure also be contained in a chromium carbide in the matrix, ferrite or once austenitic one of them.

3, the alloy of determining according to claim 1 is characterized in that its matrix contains 25-35%(weight) solid solution chromium.

4, the alloy of determining according to above-mentioned each claim is characterized in that the composition (weight %) of this alloy is:

36-40% chromium

1.9-2.1 carbon

1-2 manganese

0.5-1.5 silicon

The 1-2 molybdenum

1-5 nickel

1-2 copper

5, according to the production method of the definite alloy of above-mentioned each claim, it is characterized in that alloy thermal treatment, air cooling then in 600-1000 ℃ of temperature range.

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