CN103757543A

CN103757543A - Rare earth reinforced copper precipitation strengthened steel and preparation method thereof

Info

Publication number: CN103757543A
Application number: CN201410038855.3A
Authority: CN
Inventors: 王海燕; 高雪云; 安治国; 任慧平; 金自力
Original assignee: Inner Mongolia University of Science and Technology
Current assignee: Inner Mongolia University of Science and Technology
Priority date: 2014-01-27
Filing date: 2014-01-27
Publication date: 2014-04-30
Anticipated expiration: 2034-01-27
Also published as: CN103757543B

Abstract

The invention discloses rare earth reinforced copper precipitation strengthened steel and a preparation method thereof. The steel comprises the following chemical components in percentage by weight: 0.01%-0.045% of C, 0.05%-0.15% of Si, 0.2%-1.2% of Mn, 0.8%-1.65% of Cu, 0.015%-0.02% of Al, 0.05%-0.15% of Ni, 0.005%-0.08% of RE, not more than 0.004% of P, not more than 0.0025% of S and the balance of Fe. The preparation method comprises the following steps: smelting and casting, adding rare earth elements, and casting, wherein the total oxygen content of molten steel is not more than 150 ppm before the rare earth elements are added in the smelting and casting step, and the time interval between the rare earth element adding process and the casting process is not more than 30 seconds. According to the method, an effect of strengthening low-alloy steel is achieved by ageing precipitation of Cu; due to the addition of the rare earth elements, the mechanical performance of the steel and the toughness of a welding heat affected zone can be remarkably improved.

Description

A kind of rare earth reinforced cupric precipitation strength steel and preparation method thereof

Technical field

The present invention relates to a kind of rare earth reinforced cupric precipitation strength steel and preparation method thereof, belong to metallurgical technology field.

Background technology

Along with the development of Metallurgical Industry technology, the precipitation strength effect of copper in steel more and more causes widely to be paid close attention to.

Due to high-ductility and the strengthening effect of Cu precipitated phase itself, thereby it has good plasticity Harmony with surrounding environment under complex stress strained condition, simultaneously near Cu precipitated phase, be difficult for generating causing high stress concentrations district or the crackle of material failure, thereby be conducive to improve steel work-ing life.

Utilize the aging precipitation sclerization of copper, Copper Bearing Steel is obtaining the high-intensity while, can greatly reduce carbon content in steel, thereby obviously improves plasticity and toughness and the weldability of steel.

Therefore the intensity that the strengthening effect that, utilizes the Precipitation of Cu to produce ferrite improves steel is necessary.

Research shows, in Cu Precipitation process, and the also trend of oriented α-Fe/Cu interface segregation of alloying element such as Si, Al, Ni and Mn in steel, along with the carrying out that segregation and Cu separate out, the over-all properties of steel also improves constantly.

In smelting process, add rare earth element, can cleaning molten steel, the solidified structure of refinement steel, improve form and the distribution of inclusion, and can purify crystal boundary, thereby can effectively improve the mechanical property of steel, especially have positive effect putting forward heavy alloyed toughness and improve aspect the toughness of welded heat affecting zone.

Summary of the invention

The technical issues that need to address of the present invention are just to overcome the defect of prior art, a kind of rare earth reinforced cupric precipitation strength steel and preparation method thereof is provided, it passes through Cu precipitate reinforced alloys matrix, and adds rare earth element to improve mechanical property and the welding heat influence area toughness of steel.

For addressing the above problem, the present invention adopts following technical scheme:

The invention provides a kind of rare earth reinforced cupric precipitation strength steel, the chemical composition of described steel is by weight percentage: C 0.01～0.045, Si 0.05～0.15, Mn 0.2～1.2, Cu 0.8～1.65, Al 0.015～0.02, Ni 0.05～0.15, RE 0.005～0.08, P≤0.004, S≤0.0025, Fe surplus.

The present invention provides a kind of preparation method of described rare earth reinforced cupric precipitation strength steel simultaneously, comprise smelting and casting, add rare earth element and casting step, in smelting and casting step, add before rare earth element, total oxygen content≤the 150ppm of molten steel, interval time≤30 second when rare earth element adds afterwards to casting.

It is rare earth La or Ce wire iron sheet cored-wire that institute adds rare earth, and rare earth La and Ce hybrid metal silk iron sheet cored-wire, and in La and Ce hybrid metal silk iron sheet cored-wire, La massfraction is 35%, and Ce massfraction is 65%.

The present invention also comprises solid solution, Precipitation and quenching heat treatment, the steps include: that solution heat treatment is that alloy is heated to 840～920 ℃, is incubated 0.5～5 hour; By alloy air cooling to 550～650 ℃ insulation 0.5～3 hour, realize Precipitation thermal treatment subsequently; Finally alloy is carried out to shrend.

The present invention utilizes the Precipitation of Cu, and in conjunction with alloying elements such as Si, Al, Ni and Mn to α-Fe/Cu interface segregation, jointly reach strengthening low alloy steel effect.Rare earth element add mechanical property and the welding heat influence area toughness that not only can significantly improve steel.

Accompanying drawing explanation

Fig. 1 is the transmission electron microscope picture that technique is prepared alloy described in embodiment 1.

Specific embodiment

According to design mix, smelt, be cast into strand.

Adopt vacuum induction furnace to smelt; Adding the total oxygen content≤150ppm that controls molten steel before rare earth element, before tapping casting, add rare earth element, rare earth element joins the timed interval≤30 second between casting.It is Rare-Earth Ce wire iron sheet cored-wire that institute adds rare earth.

Pouring temperature is 1500～1650 ℃;

Strand composition is: C 0.02, Si 0.06, Mn 0.2, Cu 1.5, Al 0.018, Ni 0.09, Ce 0.036, P 0.008, S 0.0005, Fe surplus.Strand is of a size of 200 × 80 × 30mm(length × wide × height).

Strand is heated to 1000 ℃ of insulations 15 minutes, and start rolling temperature is 980 ℃, through 4 passage rollings, rolled piece is rolled to 8mm thick, 820 ℃ of finishing temperatures, water-cooled after rolled piece air cooling to 750 ℃.With wire cutting machine, rolled piece is cut into 15mm × 10mm × 6mm sample afterwards.The sample of well cutting is carried out to solid solution and ageing treatment: solution heat treatment, for alloy is heated to 880 ℃, is incubated 1.2 hours; By alloy air cooling to 630 ℃ insulation 2 hours, realize the Precipitation of Cu-rich particle subsequently; Finally sample is carried out to shrend.

The sample preparing is carried out after grinding and polishing, and testing its surface hardness mean value is 213HV.Sample from thermal treatment is reached the standard grade and is cut out the thin slice that 0.2mm is thick, through mechanical polishing, arrive 0.08mm, be washed into the disk that diameter is 3mm, with 90% ethanol+10% perchloric acid solution electrolysis pair, spray and be thinned to perforation, under JEOL JEM-2010 type transmission electron microscope, observe, obtain the transmission electron microscope picture of sample as shown in Figure 1.The rich copper particle that in figure, the darker particle of color is Precipitation, these particle dispersions are distributed in light farmland district, and shape such as is mostly at the axle shape, and diameter is approximately 5-20nm.

Finally it should be noted that: obviously, above-described embodiment is only for example of the present invention is clearly described, and the not restriction to embodiment.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here without also giving exhaustive to all embodiments.And the apparent variation of being amplified out thus or variation are still among protection scope of the present invention.

Claims

1. a rare earth reinforced cupric precipitation strength steel, it is characterized in that, the chemical composition of described steel is by weight percentage: C 0.01～0.045, Si 0.05～0.15, Mn 0.2～1.2, Cu 0.8～1.65, Al 0.015～0.02, Ni 0.05～0.15, RE 0.005～0.08, P≤0.004, S≤0.0025, Fe surplus.

2. the preparation method of rare earth reinforced cupric precipitation strength steel claimed in claim 1, it is characterized in that: comprise smelting and casting, add rare earth element and casting step, in smelting and casting step, add before rare earth element, total oxygen content≤the 150ppm of molten steel, interval time≤30 second when rare earth element adds afterwards to casting.

3. the preparation method of rare earth reinforced cupric precipitation strength steel as claimed in claim 2, it is characterized in that: it is rare earth La or Ce wire iron sheet cored-wire that institute adds rare earth, and rare earth La and Ce hybrid metal silk iron sheet cored-wire, in La and Ce hybrid metal silk iron sheet cored-wire, La massfraction is that 35%, Ce massfraction is 65%.

4. the preparation method of rare earth reinforced cupric precipitation strength steel as claimed in claim 3, is characterized in that, comprises solid solution, Precipitation and quenching heat treatment, the steps include: that solution heat treatment is that alloy is heated to 840～920 ℃, is incubated 0.5～5 hour; By alloy air cooling to 550～650 ℃ insulation 0.5～3 hour, realize Precipitation thermal treatment subsequently; Finally alloy is carried out to shrend.