DD250952B3 - MANGANE ALUMINUM MULTI-LUBRICATED BRONZE FOR HIGH-PURCHASED CONSTRUCTION PARTS - Google Patents

Description

Field of application of the invention

The invention relates to a manganese-aluminum Mehrstoffbronze for highly wear-stressed construction parts of the forming, injection and storage technology, in particular for compression molding and nozzles of the metal and plastic processing industry, molds, pistons, bearings, bearings, bricks, screws, cages. Sliding and ball bearings, worm and gear wheels, general tools z. B. wrench.

Characteristic of the known technical solutions

Alloys of copper and beryllium have been proven for years for the entire field of application. In many cases, the parts are made of semi-finished products (K.Eichhorn, low-alloyed copper alloys, German Copper Institute 1966, pp. 108-142, 282-292) or also by casting (E.Brunhuber, melting and alloying of copper materials, specialist book publisher Schiele & Schön GmbH, Berlin 1968, p.217-221). Copper-beryllium alloys are characterized by a pronounced hardening effect, on the basis of which it is possible to vary the mechanical properties within wide limits and, in particular, to achieve high wear resistance. To ensure high hardness and wear resistance wrought alloys are solution annealed after a high degree of deformation (strain hardening) and precipitation hardened.

In cast alloys, high strengths are achieved by increased beryllium contents and addition of further alloying elements. After casting, these alloys are no longer malleable because of their hardness.

Increasingly, to improve wear resistance, alloying elements such as Co (up to 2.7%) and / or Ni are used in Cu-Be alloys.

Especially in the American (DE-OS 2129101,2129102) and Japanese economy (DE-OS 1903711,1903712) alloys based on CuAI were proposed for high wear for the first time. Be, Co and / or Si, Sn, Zr, Ce, Mn, Fe, Ni, Ti were also added to these alloys. In the cited publications the importance of structural engineering is discussed. In some cases, however, the high mechanical properties of about 1000 MPa breaking strength and 400 HB hardness are only achieved if the material is cold or hot deformed. However, the elongation decreased in some cases to 0%. Due to these conditions, this material can be used predominantly only for simply designed parts.

A highly wear-resistant alloy (DD-WP 155701) with a breaking strength up to 850MPa was developed in the GDR for forming tools. It already has significant advantages over previous alloying. However, it is not yet sufficiently wear-resistant enough for special applications (eg nozzle bearing cages). An increase in the wear resistance by heat treatment is uncommon in high-strength cast alloys, since no appreciable strength and hardness increases are achieved. Heat treatments are primarily carried out on cold- or hot-strengthened parts in the sense of soft annealing or as compensation for medium-strength alloys (up to approx. 700 MPa).

The materials and processes used hitherto have a number of disadvantages:

high Cu content,

high proportion of the special alloying elements Be, Co, Ce, Cr, Ti, Zr, Sn, Ni, Si,

Use of the toxic alloying element beryllium,

- very high hardness,

heavy workability after the heat treatment,

- distortion of the finished parts by heat treatment,

low toughness and thus susceptible to dynamic and shock loads,

too low wear resistance of the CuAl based alloy,

- high workload (especially machining work) when using semi-finished products,

- the materials are load exclusively usable only in the heat-treated state,

- difficult control of the treatment processes (heat treatment, forming) to produce the desired properties,

high energy heat treatment processes are required by high temperatures,

- expensive material composition and production.

Object of the invention

The object of the invention is to eliminate the above-mentioned deficiencies and disadvantages of the known alloys and methods by the use of a suitable material, i. h., Above all, the use of the very toxic and expensive alloying element beryllium and the expensive special alloying elements, such as Co, Ce, Cr, Ti u. a. equivalent to avoid elements and also to lower the high Cu content of over 90%.

Predominantly, the material is intended to obtain good mechanical properties and high wear resistance already in the cast state. The material should continue to be used in principle in the cast state and have a good machinability.

Field of application of the invention

The object of the invention is to develop an alloy for highly wear-resistant construction parts of the forming, spraying and bearing technology on the basis of a Ma-Al multi-metal bronze, which has a minimum breaking strength of 800 MPa, a minimum elongation of 2.0% and a hardness of at least 200 HB. The following disadvantages should be excluded:

- the use of the toxic and expensive alloying element beryllium,

- large proportion in composition (over 90%),

Use of the expensive special alloying elements Cu, Ce, Cr, Ci, Zr, Sn, Ni,

low toughness (below 2.0%) and thus the shock sensitivity,

- high machining costs by working out the moldings from semi-finished products and by machining at very high hardnesses after the heat treatment,

- Cold or hot forming,

- complicated and expensive casting and finishing processes. In particular, this should be achieved:

- good processing properties,

- exclusion of the use of toxic and expensive alloying elements,

high resistance to wear,

- long service lives of the parts.

The solution according to the invention consists in that on the basis of an alloy with the chemical composition of 10.00 to 14.0% Mn 4.60 to 9.0% Zn 0.65 to 6.0% Fe 0.50 to 3, 0% Ni 6.50 to 9.0% Al 0.04 to 0.3% C residue% Cu

and the following proportions of Al: Mn = 1.0: 1.2-1.8

AhZn = 1.0: 0.6-1.3

Zn.Mn S 1.0: 1.3

Al + Mn + Zn = 24.0-28.0% Ni: Fe & 1.0: 1.3

Fe + Mn a 12.0%

a three-phase structure is present, which has at least 80% beta phase, at least 5% kappa phase (particle diameter <10μιη) and at least 10% alpha phase, wherein alpha and beta phase are finely distributed in the structure and the beta Grain boundaries with band-like alpha precipitates (width 2-10μιη) are occupied. An alloy having the above chemical composition and mixing ratios has basic mechanical properties in compliance with the proposed structure The following structure: breaking strength RM = 800-950MPa elongation _А Б = 6.0 to 2.2% Hardness HB = 230-300.

This casting alloy has a high wear resistance, and it is equally well machined and machinable in the cast state.

The cause of this positive behavior of the alloy is due to the precisely defined microstructure achieved. In the basic structure of the matrix of beta primary grains are fine needle-like microstructural constituents of the alpha phase and modification of the iron manganese-rich kappa phase of small particle size. The presence of the kappa particles simultaneously causes the formation of an overall fine-grained microstructure, whereby the strength of the alloy increases. The band-like tough alpha precipitates present at the beta-grain boundaries cause a grain boundary doctrine that has a positive effect on the toughness of the alloy.

embodiment

Below, the solution according to the invention will be illustrated in several variants in tabular list.

alloying elements

in% by weight I IH

This results in the following mechanical properties in the cast state:

Mechanical properties I Il III

Breaking strength Rm (MPa) 937 919

Elongation at break A ₅ (%) 2.5 3.3 6.2

Hardness HB 296 291

Variant I and II preferably for nozzles and tools, variant III preferably for bearings.

12,00 11.87 12.10 8.05 8.60 6.60 2.62 2.61 4.01 1.85 1.72 1.93 7.44 7.25 7.10 0.29 0.17 0.11 rest rest rest

Claims (1)

Manganese-aluminum multi-material bronze for highly stressed construction parts of forming, injection and bearing technology based on an alloy of the chemical composition of 10.00 to 14.0% Mn 4.60 to 9.0% Zn 0.65 to 6.0% Fe 0.50 to 3.0% Ni 6.50 to 9.0% Al 0.04 to 0 , 3% C rest% Cu and the following proportions of AhMn = 1.0: 1.2-1.8 Al: Zn = 1.0: 0.6-1.3 Zn: Mn g 1.0: 1.3 Al + Mn + Zn = 24.0-28.0% Ni: Fe S 1.0: 1.3 Fe + Mn ^ 12.0% and a three-phase microstructure, characterized in that the three-phase microstructure consists of at least 80% beta phase, at least 5% kappa phase (particle diameter <10μιτι) and at least 10% alpha phase, alpha and beta phase fine in the microstructure distributed and the beta-grain boundaries with band-like alpha precipitates (width 2-10 цт) are occupied.