A method of manufacturing steel mechanical parts and steel to fabricate these parts

 

The invention relates to metallurgy, in particular to the manufacture of steel machine parts using cementation or carbonitrile (cyanidation). The claimed method includes obtaining a steel workpiece, the workpiece processing by cementation or carbonitrile perhaps high temperature. While the composition of the steel comprises, in weight%: carbon - 0,15-0,35; silicon is not more than 0.6; manganese, chromium and molybdenum in an amount of not more than 5.0; aluminum is not more than 0.1; copper - not more than 0.5; sulfur is not more than 0.15; phosphorus - not more than 0,03; it is possible to 0.02 tellurium; to 0.04 selenium; to 0.07 lead; up to 0.005 calcium, the remainder iron and impurities. Curve hardenability by Jomini for this steel must satisfy the conditions of 45 HRCJ350 HRC; 39 HRCJ1147 HRC; 31 HRCJ2540 HRC; and the average values of J3cpI , J11cpI , J15cpand J25cpfive samples of Jomini must satisfy the conditions: | (J11cp-J3cp14/22-J25cp8/22|2,5 HRC; J3cp-J15cp9HRC. The technical result of the invention Entitiy or carbonitrile. 2 C. and 13 C.p. f-crystals., table 4.

The invention relates to the manufacture of parts made of steel, at least a part of which surface hardened by carburizing or carbonitridation, followed by oil or gas quenching.

Many steel machine parts, such as gears, reinforce with the surface cementation and or carbonitridation. For the sake of this part is placed in an atmosphere rich in carbon or carbon and nitrogen, at temperatures above 900oWith a few hours to enrich steel carbon or carbon and nitrogen at a certain depth from the surface by diffusion of these elements on the surface, after which the parts are immersed in cold, warm or hot oil, or gas, to increase surface hardness. Cementation or Carboniferous can also be carried out at temperatures above 1000oWith; in this case we speak of high-temperature or high-temperature carburizing carbonitriding.

For the production of such parts using steel with a carbon content of 0.15% to 0.35% in the alloy with chromium or chromium and molybdenum, or chromium and manganese. This technology, which allows to obtain a higher surface hardness and neighboring areas, which, it can cause deformities that can cause rejection of parts or the need for more costly treatment.

The closest technical solution according to the essential features and the achieved result is a method of manufacturing parts made of cemented or carbonitriding steel and steel for these parts, known from the application of Japan JP 09 053 149 And published 25.02.1997.

The known method includes obtaining billet parts from steel, then the cementation or Carboniferous possibly a high temperature, at least part of the surface of the workpiece parts.

Known steel contains components in the following ratio, wt.%: With - 0,05-0,5; Mn - 0,3-3,0; Al - 0,015-0,06; N is from 0.005 to 0.03; Fe - rest and inevitable impurities. Known steel may further contain one or more components, wt.%: Cr - 3.0; Mo to 1.0; N - 3.0; Si - 0.5; R - up 0,030; S up to 0,035.

However, the known method and the known are inherent in the above-mentioned disadvantages.

The basis of the invention is to create a method of manufacturing parts and steel for their manufacture, which can eliminate the above disadvantages.

The problem is solved in that in sporeback by cementation or carbonitridation, perhaps a high temperature, at least part of the surface of the workpiece parts, according to the invention, the chemical composition of the steel, which consists of the item includes, in weight ratio: 0,15%0,35%; 0%Si0,6%; 0%Mn+Cr+Ni+Mo5%; 0%Al0,1%; 0%Cu0,5%; 0%S0,15%; P0,03%; it is possible to 0.02% of tellurium, to 0.04% of selenium, up to 0.07% lead, up to 0.005% of calcium, while the rest is represented by the iron and impurities from the manufacturing process; the chemical composition was adjusted so that the curve Gemini steel was such that 45 HRCJ350 HRC; 39 HRCJ1147 HRC; 31 HRCJ2540 HRC; and to the average values of J3cpI , J11cpI , J15cpand J25cpfive samples of Jomini were such that |J11cp-J3cp14/22-J25cp8/22|2,5 HRC; img src="https://img.russianpatents.com/chr/8804.gif">8 HRC.

Better if curve Gemini such that satisfies at least one of the following conditions - average values of J7cpI , J11cpI , J15cpand J25cpfive samples of Jomini such that 10(J7cp-J11cp)/(4(J15cp-J25cp)2,15; 10(J7cp-J15cp)/(8(J15cp-J25cp))<2.0,26%; 0,05%Si0,5%; 1%Mn1,6%; 0,4%Cr1,5%; 0,08%Mo0,27%; 0%Ni0,6%; 0,003%Al0,06%; 0%Cu0,3%; 0%S0,1%; P0,03%.

In addition, and even better, if the chemical composition of steel: 0,21%0,25%; 0,1%Si0,45%; 1.1% ofMo0,26%; 0%Ni0,6%; 0,005%Al0,05%; 0%Cu0,3; 0,02%S0,09%; P0,03%.

Preferably, the titanium content in the steel is from 0 to 0.05%, and nitrogen from 0.004 to 0.02%.

The invention concerns were also subjected to carburizing or carbonitriding, the chemical composition in which the weight ratio of the following: 0,2%0,26%; 0,05%Si0,5%; 1%Mn1,6%; 0,4%Cr1,5%; 0,08%Mo0,27%; 0%Ni0,6%; 0,003%Al0,06%; 0%Cu0,3%; 0%S0,1%; P0,03%, it is possible to 0.02% of tellurium, to 0.04% of selenium, up to 0.07% lead, up to 0.005% of calcium, while the rest is represented by the iron and impurities from the manufacturing process; hee>/img>J350 HRC; 39 HRCJ1147 HRC; 31 HRCJ2540 HRC, with average values of J3cpI , J11cpI , J15cpand J25cpfive samples of Jomini such that |J11cp-J3cp13/22-J25cp8/22|2,5 HRC and J3cp-J15cp9 HRC, preferably8HRC.

Preferably, the steel after carburizing or carbonitrile had a chemical composition such that, 0.21%0,25%; 0,1%Si0,45%; 1.1% ofMn1,5%; 0,9%Cr1,4%; 0,09%Mo0,26%; 0%Ni0,6%; 0,005%Al0,05%; 0%Cu0,3%; 0,02%S0,09%; P0,03%.

Preferably, the average values of J7cpI , J11cpI , J15cpand J<://img.russianpatents.com/chr/8226.gif">(J7cp-J11cp)/(8(J15cp-J25cp))<2; 10(J7cp-J11cp)/(8(J15cp-J25cp))<2,15.

The inventors unexpectedly found that the deformation caused by hardening at the end of treatment by grouting or at the end of carbonitrile, can be significantly reduced, even eliminated, if used for production of parts steel curve Gemini which has virtually no points of bend in contrast curves Jomini normally used for these steels. More precisely, it was found that it is desirable to use steel containing from 0.15% to 0.35% of carbon to the steel it is easy to handle and to achieve sufficient viscosity in anaplerotic or decarbonation parts parts; up to 0.6% silicon, to provide sufficient desoxidation steel - alloying elements such as manganese, chromium, molybdenum, and Nickel, in such quantities that their sum was less than 5% to give a sufficient hardenability, leveling of the curve of Jomini and alignment of mechanical properties details of the promotion and control of grain; - less than 0.5% of copper, which is considered an impurity that reduces the ductility and toughness anaplerotic or decarbonation zones; perhaps from 0% to 0.05% titanium education strengthening nitrides; preferably, the content of nitrogen, an element that is always present and which reacts with aluminum or titanium with the formation of nitrides, should be from 0.004% to 0.02%; up to 0.15% sulfur to improve machinability;
- less than 0.03% phosphorus, representing an admixture of adverse ductility and toughness.

In addition, the steel may contain up to 0.02% of tellurium, to 0.04% of selenium, up to 0.07% lead, up to 0.005% calcium to improve machinability. The rest of the composition represented by the iron and impurities from the manufacturing process.

Chemical composition verify that curve Gemini steel was such that 45 HRCJ350 HRC; 39 HRCJ1147 HRC; 31 HRCJ2540 HRC,
and to the average values of J3cpI , J7cpI , J11cpI , J15cpand J25cpfive samples of Jomini were such that |J11cp-J3cp14/22-J25cp8 HRC.

Curve Gemini is a curve characterizing the water became. It is obtained by measuring the hardness along the length of the generatrix of the cylindrical sample, hardened by the jet of water aimed at one of its ends. The hardness measured at a distance of x mm from the end, which directed the stream of water, called the Jx. Engineers are very well familiar with this test. However, its characteristics are naturally scattered. That is why the shape of the curve of Jomini characterized here, on the one hand, the variations of the values for the points J3I , J11and J25and by the relation: |(J11-J3cp14/22-J25cp8/22|2,5 HRC, which introduces middle five different samples taken from the same steel. More precisely, consistently spend 5 identical measurements; for each sample was measured at least, the values of J3I , J7I , J11I , J15and J25so get five values for J3I , J7I , J11I , J15and J25calculated for each point Jxaverage Jxcpfive values. In this regard, the vertical strokes are known in itself a symbol of the absolute value. The very attitude is the curve of Jomini has no curves.

The desired shape of the curve of Gemini can be adjusted so that they meet at least one of the following relations: 10(J7cp-J11cp)/(4(J15cp-J25cp))2,15; 10(J7cp-J11cp)/(8(J15cp-J25cp))2. Such curves Gemini can be obtained, in particular, with steel corresponding to what has been defined, but a chemical composition which includes a more accurate weight expression:
from 0.2% to 0.26%, preferably from 0.21% to 0.25% carbon, to ensure not too high hardness parts to cementation or carbonitrile and to have a good ability to cementation or carbonitriding;
from 1% to 1.6%, preferably from 1.1% to 1.5% manganese to ensure good internal condition for fixation of sulfur and in combination with chromium and molybdenum to provide hardenability thus, in order to obtain a satisfactory curve Gemini;
- from 0.05% to 0.5%, preferably from 0.1% to 0.45% silicon;
- from 0.4% to 1.5% chromium, preferably from 0.9% to 1.4%, the curing cemented zoom, in order to obtain a satisfactory curve Gemini;
- from 0.08% to 0.27%, preferably from 0.09% to 0.26% molybdenum for carburized hardening or carbonitriding layer, increasing the resistance to oxidation and in combination with manganese and chromium to provide hardenability thus, in order to obtain a satisfactory curve Gemini, the lower limit is the minimum value of the content of molybdenum is necessary that this element had a significant effect;
- from 0% to 0.6% Nickel to improve the impact resistance of the parts.

Preferably, the copper content remains less than 0.3%, the sulfur content is from 0.02% to 0.1%, better if it is less than 0,09%, the aluminum content is from 0.003% to 0.06%, preferably 0.005% to 0.05%.

As mentioned above, the steel may contain, in addition, one or more items, including tellurium, selenium, lead and calcium.

To manufacture the part, according to the invention, produced from steel according to the invention the workpiece part, which is subjected to carburizing or carbonitrided at high temperatures and quenched in oil or gas, and oil can be cold, warm or hot. The workpiece parts can be created, for example, forging or turning of the economic structures. (See table. 1).

Curves Jomini these steels were such, as indicated in the table. 2.

After cementation at 995oC for 10 hours and quenching in warm oil at 98oWith the parts had no deformation, which required additional processing. Moreover, cementation differed carbon content of 0.94% for 0.1 mm below the surface.

For comparison were produced in the same conditions, identical parts in steel types MS, MS, MS, 27MC5r, 27CD4u, 30M5 and 20CD4 corresponding to the old technology.

After cementation parts require new processing. In addition, the carbon content of the carburized layer, 0.1 mm below the surface, is only 0.8%. This last result shows that, in addition to a weaker sensitivity to deformation, the steel according to the invention, carbonized better than steel, corresponding to old technologies.


Claims

1. A method of manufacturing a steel machine parts, according to which receive billet parts and conduct the treatment by grouting or carbonitridation possibly high temperature of at least part of the surface of the workpiece parts, characterized in that the chemical composition of steel img>Sito 0.6; 0Mn+Cr+Ni+Mo5; 0%Al0,1 0%Cu0,5; 0%S0,15; P0,03; it is possible to 0.02% of tellurium, to 0.04% of selenium, up to 0.07% lead, up to 0.005% of calcium, while the rest is represented by the iron and impurities from the manufacturing process; the chemical composition was adjusted so that the curve Gemini steel was such that 45 HRCJ350 HRC; 39 HRCJ1147 HRC; 31 HRCJ2540 HRC and to the average values of J3cpI , J11cpI , J15cpand J25cpfive samples of Jomini were such that |J11cp-J3cp14/22-J25cp8/22|2,5 HRC; J3cp-J15cp9 HRC.

2. The method according to p. 1, characterized in that the steel is such that J3cp-J15cp8 HRC.

3. The method according to p. 1 or 2, characterized in that the average values of J7cpI , J11cpI , J15cpand J25cpfive samples of Jomini �ttp://img.russianpatents.com/chr/8804.gif">2,15.

4. The method according to one of paragraphs.1, 2 or 3, characterized in that the average values of J7cpI , J11cpI , J15cpand J25cpfive samples of Jomini such that 10(J7cp-J11cp)/(8(J15cp-J25cp))2.

5. The method according to one of paragraphs.1-4, characterized in that the chemical composition of the steel is such that 0.2 percent0,26%; 0,05%Si0,5%; 1%Mn1,6%; 0,4%Cr1,5%; 0,08%Mo0,27%; 0%Ni0,6%; 0,003%Al0,06%; 0%Cu0,3%; 0%S0,1%; P0,03%; Fe - rest.

6. The method according to p. 5, characterized in that the chemical composition of the steel is such that 0,21%0,25%; 0,1%Si0,45%; 1.1% ofMn1,5%; 0,9%Cr0,6%; 0,005%Al0,05%; 0%Cu0,3%; 0,02%S0,09%; P0,03%; Fe - rest.

7. The method according to one of paragraphs.1-6, characterized in that the steel contains from 0 to 0.05% titanium.

8. The method according to one of paragraphs.1-7, characterized in that the nitrogen content in the steel is from 0.004 to 0.02%.

9. Steel after carburizing or carbonitrile, characterized in that its chemical composition includes wt.%: 0,20,26 0,05%Si0,5; 1%Mn1,6; 0,4%Cr1,5; 0,08%Mo0,27; 0%Ni0,6; 0,003%Al0,06; 0%Cu0,3; 0%S0,1; P0,03; it is possible to 0.02% of tellurium, to 0.04% of selenium, up to 0.07% lead, up to 0.005% of calcium, while the rest is represented by the iron and impurities from the manufacturing process, and the �hr/8804.gif">J1147 HRC; 31 HRCJ2540 HRC; however, the average values of J3cpI , J11cpI , J15cpand J25cpfive samples of Jomini such that |J11cp-J3cp13/22-J25cp8/22|2,5 HRC; J3cp-J15cp9 HRC.

10. Steel after carburizing or carbonitrile under item 9, characterized in that its chemical composition is such that 0,21%0,25%; 0,1%Si0,45%; 1.1% ofMn1,5%; 0,9%Cr1,4%; 0,09%Mo0,26%; 0%Ni0,6%; 0,005%Al0,05%; 0%Cu0,3%; 0,02%S0,09%; P0,03%; Fe - rest.

11. Steel after carburizing or carbonitrile according to any one of p. 9 or 10, characterized in that the J3cp-J15cp8HRC.

12. Steel after CEM the J15cpand J25cpfive samples of Jomini such that 10(J7cp-J11cp)/(8(J15cp-J25cp))2,15.

13. Steel after carburizing or carboniteservice on one of the PP.9-12, characterized in that the average values of J7cpI , J11cpI , J15cpand J25cpfive samples of Jomini such that 10(J7cp-J11cp)/(8(J15cp-J25cp))2.

14. The steel according to any one of paragraphs.9-13, characterized in that it contains from 0 to 0.05% titanium.

15. The steel according to any one of paragraphs.9-14, characterized in that the nitrogen content is from 0.004 to 0.02%.

 

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