DE1962504C3 - Process for the heat treatment of steel - Google Patents

Description

The invention relates to a method for heat-resistant steel has been developed (cf. Japanese patent treatment of steel with essentially the following application 75390/65), the one tensile strength of composition: 100 to 130 kg / mm * and a high internal friction less than 0, 06% C, ^{possessed by D? Iser} ^ known tough steel has in ^{general less than 10 · / Si 5} a good internal coefficient of friction, but less than LO ⁰ / Mn. has it been found in later attempts that it

3 to 10 ^c / NL ^ Eiggssehsfiss the Im ₅ SiSn friction with even ge-8 to 17 · / Cr slight fluctuation in the conditions of the melting addition

4 to 10 ° / Co * ^ ⁰¹ chg ^ren "^ e ^ ™ of these steels only eliea very 2 to 5 ° / o Mo or W in exchange" kleir ^ value of internal friction slien.

but in a ratio of ² ^ simultaneous improvement in corrosion resistance

2-i . durability and strength of certain steel alloys

Impurities and the remainder Fe. ^ «*« * £ ° «e; d» Jffiicicgeijiges ' ^ * & z USA.-

^{ö 6} patent specification 3235415 a heat treatment

In modern = rotating machine !! how Tsrbj- 15 drive known bu which, after quenching aurch nen and compressors are the blades because of the successful Martensitbildimg Iosungsgegluht wird- Since enlargement of the machines and the UtcnZäMetuö- iikrhei else w 'y''rate The regression of the inner periphery takes place in an increasing degree of a large centrifugal force, which is set according to the known method. In order to guarantee a rapid further improvement in the damping process of this rotary machine, a material (to suppress the formation of resonance) must be created, which is a soft one. rich. From the French patent 1421 299 S caused by centrifugal force it is known that the internal friction or the damping §r is able to withstand. This blade material rouS properties of special steels by a certain H in addition to improving strength and appropriate heat treatment. Apart from the * internal friction, since the Sisaiel has a high 25 clearly different chemistry of the centrifugal force under the influence of a certain known process in treated steel alloys ψ driving force. The reason for this is as follows: In the case of the heat treatment process mentioned below, if the design of a turbine or compressor additionally the second annealing with a relatively high f blade is »α generally a corresponding temperature, with iter again a practically full opposite plane is taken into account dangerous resonance - 3 ° constant dissolution of the primary martensit to be expected. is carried out, which - as already stated - in ζ For this avoidance of Rjtäoai iz already at the beginning of a particularly large and targeted discard smd, however, complicated processes and processes without the damping effect is not advantageous. I needed and it is practically impossible to list all conceivable the invention was άκ object e "n

Avoid design-related resonances. 35 Process for the heat treatment of certain steels In practice, a counter-alloy is therefore to be developed during the design process, for the steels being treated ; level only to take into account a really dangerous and made of it Werfcstäc & ea a stable inner lent resonance set while for the other. Gives friction or a high damping capacity. : not so dangerous resonances no counter level The invention was based on the knowledge that

is determined. In general, the amplitude 40 depends. or vibration stress in the case of a Resode steel alloys dnc mixed structure of softer ones nanz trains with the dampening capacity of a shovel and raJteien Komgcfägssea together, d. H. in the sense of a vibrator, in which with the subject of the Ez-invention is thus a process

small oscillation amplitude a large damping for the heat treatment of steel with essentially capacity is present. The range therefore varies with the following composition: dangerous resonance with the damping capacity """mcM · _a k o ftft" / C
of a bucket, the number or size of the blades determined by JSSS 10 · /. Si
structural means to be avoided, hazardous re lllj l ^ »u iW _M resonances *" is all the smaller, the larger the damping _ftCT j £ he is as assets. The damping capacity of such a 5 »3

i; Blade largely depends on the internal friction g

of the SchaoicrncikäiunS uh. Au diväCm Grund ~ uB eis - · ■ <· *. * ' * -

Blade material a ^^ corresponding ^ internal friction ₂ JJ 'j; «^ ^ _{w in exchange}

have to d "shovel against harmful resonance _daiür .n- _{in United} hältnts of

follow the action of a certain driving force to 55 ■, ■ 1

protection. Impurities and remainder Fe, So far, stainless steel of the type 13 Cr afe η & - - »material has been used for workpieces that have a large which is characterized by the fact that the steel must have internal friction. Steels of this type initially from. From an austenitic temperature to one, however, there is a tendency to a rapid decrease in temperature within the Martian transformation of internal friction when the strength is cooled by rich, then again due to a temperature change in the composition or by increased temperature which is increased 600 to 7Q0 ^e C above the Marserte heat treatment. The limit value 'tensi' / conversion range lies, and again up to which steels of this type can be used as a material with martensitic internal friction at room temperature or lower, is 65 cools and is ultimately subjected to crumb hardening, therefore, generally with a tensile strength of.

at most 90 kg / mm ³ . To solve this difficult- With unlimited tensile strength, the proportion of

.: wedging is already an initially formed martensite suitable for turbine blades, going up to 100%, if only

ί 962.504 ti

e, ne yield point of about 80 kg / mm * is sufficient. If the received in this way, a Mi *: hge-

the elimination adhesion can be omitted. However, if the yield point consisting of primary and secondary martensites is to reach a temperature of 100 to 130 kg / mm * for 1 to 100 hours at a temperature of 100 to 130 kg / mm * for the special advantages of the steel, 400 to 500 ° C must be maintained , learns the primary margin in primary martensit controlled 5 teasitphase due to aging in the previous, namely z. B. to at least 20 ⁵ Z ₀ , normalizing intermediate wannuag no hardness changes. d. Il. wise about 50% to have a sufficiently high internal friction - it remains as soft as it is during the secondary exercise. Martesstphase an aging hardening over one of the

When the said steel cools down from the phase obtained in the usual hardening process, it is precaustenitic Temperature occurs a Martenätujn- io table experiences the same course, whereby necessary Formation on when the cooling speed increases, for example, the hardness and strength of the steel as a whole - 10 ° C per hour or flour. Under loaf of this den. In this state the steel shows an adf of Kühluagsgeschwindigkeil results in sirf-. but only one heat treatment according to the chemical composition lower martensite base, fast-moving strength and high internal friction. The characteristic Medusa? dk - unrestricted 15 properties.

The reason for this lies in the fact that the Uraformy «^ -" üfe widely used in the aforementioned heat treatment

it depends on the temperature i * - ^! V ^ and by the subjected steel the internal time is generally bad! "E £" ird. Generally speaking, the above-mentioned refinement becomes all the greater, the greater the amount of primary steel from an aurienite transition-end martensite and the higher the temperature. On the other hand, if the temperature is appropriate, the strength or temperature is reduced below that which is the hardness. In this case the reduction of the manensite deformation can begin, and above that strength or hardness to a certain extent by reduction. at which this reshaping ceases, increase in the aggregate amount on a hardening cable by at least one part! of the austenite can be suppressed into marten- ment, such as molybdenum, in order to convert the outfit. Thereupon the steel will increase to 35 sefaeidungs- or aging hardness vennögen of the Sckuncine at 600 to 700 ⁰ C above the Martensit-Überganfis- daren 'iartensitphase za,
The temperature at a point is warmer, around the mar- The proportion of primary martensite in the Siahlsont exterior

sit to soften. At the same time, on the other hand, it remains expedient, taking into account the chemical residual austenite to see the Tefl unchanged and practically free composition, the required work of a change of state depending on the material strength and the internal irritation of the steel over time and the martensite forming will be corrected by the ao. As the forming properties Closing cooling at a corresponding temperature of the primary martensite with little fluctuation in the rature caused. The chemical composition at the beginning of the heat treatment change considerably, The martensite formed in the following is used as the "Primary martensite" is the name given to it, while the austenite can be precisely determined from the curve by measuring the residual thermal expansion after reheating of the curve of each individual melt. Primary martensite formed martensite as »Secondary With such control of the proportion of primary Mariensitr referred to as. Martensites are caused by a change in the melting

If the tempering temperature of the primary martensite conditions, changes in the steel that occur are only higher than the upper martensite transition point, 40 little influence. Dip tempering temperature of the primary becomes the primary martensite (in the case of the present steel martensite is set as high as possible so as to be above Ac ₁ ) to Tefl z. B. up to 50 · / ,, or fully dk hardness of the primary martensis as low as possible to be constantly in training. He £ sdMSgsg ^ ä & hold. In this case, a 45 nit transition temperature of each melt is preferably determined in order to ensure a sufficient heating martensite initial temperature by measuring the extent of the primary martensite. Applied as a tempering temperature such that at least this temperature is preferably transformed into a temperature part thereof. selected value at which the transformation of the primary

In this case, the martensite from the primary martensite becomes 50 ^β / _β or less,
Austenite formed by the subsequent cooling can be followed by the invention in one execution

partly CAex completely converted into martensite. 5 ° explained in more detail by way of example, without, however, wanting to restrict the invention, although this martensite has a tendency to go back to it.
retention of the residual austenite and a fairly low one in the table is the chemical composition

Äüschcjdungshäiie ^ij en !! ö »n» «am. Its eggs resemble those of a steel, indicated by ordinary properties, to those of secondary martensite. In Wannerjenanöiang no groSc inner Re x ¹ * · "";.. Unite cases it is necessary, can be lift according to the verwen- 55 A sample consisted of a material Deten cooling aiii a space under steel piece, which in a basic Hot-hfrequenj: - to advance the temperature below the temperature in order to melt the furnace into a casting of 30 Lg gcg «iSien. A satisfactory regulation or control of the proportion of the primary martensite and the deformation 40 to a rod with a square Q '^ ricriiuH \ on -40 mm was forged and cut into pieces of the secondary martensite after tempering. In this context, the rnech <s are warranted. The residence time at each temperature must have different properties and the properties of the -nnc depending on the dimensions of the thermal friction of each test specimen for each heat treatment to the workpiece to be treated as long as illustrated in FIG. 2. In FIG ge temperature distribution over the heat dissipation Ni. 1 of the samples A, RF «ine the entire interior of the workpiece is reached. This known heat treatment, during the other dwell time, can give the heat treatment material properties according to the invention in the range of 1 to 10 hours without impairment of the work positions. The internal friction will vary dun.ii riveting. of the natural oscillation steam

Sample in the form of a tuning fork determined by calculation on the basis of the value thus measured. • The maximum logarithmic damping ratio and the load or load resulting from this mean a; maximum range of the logarithmic resistance within your measuring range 'λΐηά "of a load; dinate indicate the logarithmic damping ratio and the horizontal coordinate the maximum bending load (in kg / mm ³ ), the real internal friction curve does not reach a maximum value at a best mm-th load, but simply increases with increasing load, so that the logarithmic damping ratio at the Side of a further increased load has a correspondingly higher value.

sample C. Si Chemical composition (GewkhlspraarJ) Ni Cr Mon Co W. 0.03 0.09 Mn 6.17 12.40 3.80 7.37 _ A. 0.02 0.14 0.34 5.50 11.83 3.47 6.14 - B. 0.03 0.28 0.07 6.01 11.58 3.1 * 639 - C. 0.03 0.31 0.44 5.42 12.12 2.71 6.86 - D. 0.03 0.26 0.19 5.76 i2.21 - 7.02 43 E. 0.35

In the exemplary embodiment mentioned, the method according to the invention according to FIG. 2 obviously does not have such a great influence on a sample, the by ordinary known heat treatment a large internal friction can be imparted while it however, each sample is markedly improved by the * 5 ordinary heat treatment can only impart very little internal friction; also will the internal friction is stabilized at an appropriate optimum value by the method according to the invention. ·

Although the samples used in the aforementioned embodiment have the chemical composition given in the table, dis Steels used according to the invention are not restricted to this, but can have the following composition -have: less than 0.06% C, less than 1.0% Si, less than 1.0% Mn, 3 to 10% Ni, 8 to 17% Cr, 4 to 10% Co, 2 to 5% Mo or W to replace Mo in a ratio of 2: 1, other impurities, aggregate elements and the remainder Fe. Items that are either alone or Mixtures that can be added as additives in such proportions that they do not impair the properties of the steel are, for example, Ti, Al, Zr, U, Cs, Hf, Ca, B, etc.

Claims (1)

Claim: Process for the heat treatment of steel with essentially the following composition than 0.06% C, less than 1.0% Si, less than 1.0 · / »Mn, S to 10 · /. Ni, 8 to 17% Ci, 4 to 10% Co, 2 to 5 · / »Mo or W in exchange for this in the ratio of 2: 1, Impurities and residual Fi, It is characterized by the fact that the steel is initially cooled from an austenitic temperature to a temperature within the MsxtensitumwandluEgsberckhes, then heated again to a temperature that is 600 to 700 ⁰ C above the martensitic conversion range, and then again martensitically cooled to room temperature or lower and finally one Is subject to elimination. For this purpose i sheet of drawings