STAINLESS BLASTING MEDIUM

Abstract

A stainless blasting medium is provided including blasting medium elements containing an austenitic chromium-manganese steel, the blasting medium comprising the austenitic chromium-manganese steel-containing blasting medium elements in a range of ≥90 wt.-% to ≤100 wt.-% relative to the total weight of the stainless blasting medium. The following further relates to the use of the stainless blasting medium for blasting surfaces, metal and non-metal surfaces, such as workpieces, in particular stainless workpieces.

Claims

1. A stainless blasting medium comprising blasting medium elements comprising an austenitic chromium-manganese steel, wherein said blasting medium comprises said blasting medium elements comprising an austenitic chromium-manganese steel in a range from ≥90 wt.-% to ≤100 wt.-%, based on the total weight of said stainless blasting medium.

2. The stainless blasting medium according to claim 1, wherein the austenitic chromium-manganese steel comprises: ≥0 wt.-% to ≤0.8 wt.-% carbon, ≥0 wt.-% to ≤1.2 wt.-% nitrogen, ≥10 wt.-% to ≤30 wt.-% chromium, ≥6 wt.-% to ≥30 wt.-% manganese, ≥0 wt.-% to ≤3 wt.-% molybdenum, ≥0 wt.-% to ≤3 wt.-% silicon, ≥0 wt.-% to ≤2 wt.-% copper, ≥0 wt.-% to ≤1 wt.-% cobalt, ≥0 wt.-% to ≥1 wt.-% nickel, ≥0 wt.-% to ≤1 wt.-% tungsten, ≥0 wt.-% to ≤1 wt.-% niobium, ≥0 wt.-% to ≤1 wt.-% vanadium, ≥0 wt.-% to ≤1 wt.-% aluminum, ≥0 wt.-% to ≤1 wt.-% titanium, and balance iron, wherein the weight percentage is based on the total weight of the austenitic chromium-manganese steel, and wherein the austenitic chromium-manganese steel comprises carbon and nitrogen together in an amount from ≥0.2 wt.-% to ≤1.3 wt.-%.

3. The stainless blasting medium according to claim 1, wherein the austenitic chromium-manganese steel comprises: ≥0.1 wt.-% to ≤0.3 wt.-% carbon, ≥0.55 wt.-% to ≤0.65 wt.-% nitrogen, ≥15 wt.-% to ≤19 wt.-% chromium, ≥17 wt.-% to ≤21 wt.-% manganese, ≥0.05 wt.-% to ≤0.15 wt.-% molybdenum, ≥0.7 wt.-% to ≤1.1 wt.-% silicon, ≥0 wt.-% to ≤0.5 wt.-% copper, ≥0 wt.-% to ≥0.5 wt.-% cobalt, ≥0 wt.-% to ≤0.1 wt.-% nickel, ≥0 wt.-% to ≤0.5 wt.-% titanium, ≥0 wt.-% to ≥0.5 wt.-% vanadium, ≥0 wt.-% to ≤0.5 wt.-% niobium, and balance iron, wherein the weight percentage is based on the total weight of the chromium-manganese steel, and wherein the austenitic chromium-manganese steel comprises carbon and nitrogen together in an amount from ≥0.7 wt.-% to ≤0.9 wt.-%.

4. The stainless blasting medium according to claim 1, wherein the austenitic chromium-manganese steel comprises substantially no martensitic structural constituents due to the primary manufacturing process or does not form martensitic structural constituents during cold working.

5. The stainless blasting medium according to claim 1, wherein the blasting medium elements are at least one of substantially concave, elliptical, or spherical.

6. The stainless blasting medium according to claim 1, wherein the blasting medium has a bulk density measured according to DIN EN ISO 60:2000-01 in a range from ≥3.5 g/cm.sup.3 to ≤5 g/cm.sup.3, or from ≥4.1 g/cm.sup.3 to ≤4.6 g/cm.sup.3.

7. The stainless blasting medium according to claim 1, wherein the blasting medium elements respectively have a shortest and a longest diameter, wherein the blasting medium has a proportion of blasting medium elements whose longest diameter is more than twice as large as their shortest diameter, measured according to DIN EN ISO 11125-5:2018-12, of ≤15%, or ≤5%.

8. The stainless blasting medium according to claim 1, wherein the blasting medium elements have an average equivalent diameter D.sub.50 measured according to DIN 66165-2:2016-08 in a range from ≤3 mm to ≥0.01 mm, from ≤2.5 mm to ≥0.05 mm, or from ≤1 mm to ≥0.09 mm.

9. The stainless blasting medium according to claim 1, wherein the blasting medium elements have a first average equivalent diameter D.sub.50 as virgin grain before use and have a second average equivalent diameter D.sub.50 as operating mixture after use, measured according to DIN 66165-2:2016-08, wherein the second average equivalent diameter is smaller, smaller by at least 5%, or smaller by at least 10%, than the first average equivalent diameter.

10. The stainless blasting medium according to claim 1, wherein the blasting medium elements have a hardness as virgin grain before use, measured according to DIN EN ISO 6507-1:2018, in a range from ≥200 HV 0.1 to ≤400 HV 0.1, ≥280 HV 0.1 to ≤360 HV 0.1.

11. The stainless blasting medium according to claim 1, wherein the blasting medium elements have a first hardness as virgin grain before use and a second hardness as operating mixture after use, measured according to DIN EN ISO 6507-1:2018, wherein the second hardness is greater than the first hardness, at least 60% greater, or at least 65% greater.

12. The stainless blasting medium according to claim 1, wherein the blasting medium in use has a lifetime, measured at an average equivalent diameter D.sub.50, measured according to DIN 66165-2:2016-08, in a range from ≤0.3 mm to ≥0.01 mm by means of a lifetime test according to SAE J 445 5.3 up to an accumulated loss of 100%, of ≥25,000 cycles, of ≥28,000 cycles, or of ≥35,000 cycles.

13. Use of a corrosion-resistant blasting medium according to claim 1, for the blasting treatment of surfaces, of metallic and non-metallic surfaces, such as workpieces, in particular of stainless workpieces.

Description

BRIEF DESCRIPTION

[0124] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0125] FIG. 1 is a diagram of the sieve analysis of virgin grain and operating mixture of the blasting medium according to embodiments of the invention according to Example A and the blasting medium made of chromium-nickel steel according to Comparative Example B,

[0126] FIG. 2 is a diagram of the hardness analysis of virgin grain and operating mixture of the blasting medium according to embodiments of the invention according to Example A and the blasting medium made of chromium-nickel steel according to Comparative Example B;

[0127] FIG. 3 is a diagram of the lifetime test of the blasting medium according to embodiments of the invention according to Example A and the blasting medium made of chromium-nickel steel according to Comparative Example B; and

[0128] FIG. 4 is a diagram of the Almen intensity of the blasting medium according to embodiments of the invention according to Example A and the blasting medium made of chromium-nickel steel according to Comparative Example B.

DETAILED DESCRIPTION

[0129] FIG. 1 shows the diagram of the sieve analysis of virgin grain and operating mixture of the blasting medium according to embodiments of the invention according to Example A (CrMn austenite) and the blasting medium made of chromium-nickel steel according to Comparative Example B (CrNi austenite). Both blasting mediums have almost identical equivalent diameters as virgin grain. Compared to the operating mixture of Comparative Example B, the operating mixture of the blasting medium according to embodiments of the invention comprises more components with a smaller equivalent diameter.

[0130] FIG. 2 shows the diagram of the hardness analysis of virgin grain and operating mixture of the blasting medium according to embodiments of the invention according to Example A and the blasting medium made of chromium-nickel steel according to Comparative Example B. Both virgin grain and operating mixture of the blasting medium according to embodiments of the invention of Example A are respectively harder than virgin grain or operating mixture of the blasting medium of Comparative Example B. In addition, the hardness increases between virgin grain and operating mixture for the blasting medium according to embodiments of the invention more than for the Comparative Example.

[0131] FIG. 3 shows the diagram of the lifetime test of the blasting medium according to embodiments of the invention according to Example A and the blasting medium made of chromium-nickel steel according to Comparative Example B. The loss plotted against the number of cycles of the blasting medium according to embodiments of the invention is much flatter compared to the loss of the Comparative Example, resulting in a longer lifetime.

[0132] FIG. 4 shows the diagram of the Almen intensity test of the blasting medium according to embodiments of the invention according to Example A and the blasting medium made of chromium-nickel steel according to Comparative Example B. After 40 cycles, both blasting mediums exhibit a saturation point at which a doubling of the number of cycles results in at most a ten percent increase in the deflection (arc height) of the Almen strip. Here, the blasting medium according to Example A exhibits an overall greater Almen intensity, from which, due to the comparability of the test conditions, a comparatively improved energy transfer during blasting can be concluded compared to Comparative Example B.

[0133] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0134] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.