YB/T 091-2019 English PDF (YB/T091-2019)

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YB/T 091-2019: Forging (rolling) steel grinding balls
YB/T 091-2019
YB
FERROUS METALLURGY INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.99
H 54
Replacing YB/T 091-2005
Forging (rolling) steel grinding balls
ISSUED ON: MAY 02, 2019
IMPLEMENTED ON: NOVEMBER 01, 2019
Issued by: Ministry of Industry and Information Technology of PRC
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Classification and code ... 6
5 Technical requirements ... 6
6 Test method ... 7
7 Inspection rules ... 9
8 Packaging, marking, transportation, storage ... 10
Appendix A (Normative) Standards for physical and chemical inspection methods for
steel products ... 12
Appendix B (Normative) Test method for grinding ball impact fatigue life ... 14
Appendix C (Normative) Calculation of breakage rate of balls and ball consumption of
steel balls ... 16
Forging (rolling) steel grinding balls
1 Scope
This standard specifies the terms and definitions, classification and code, technical
requirements, test methods, inspection rules, packaging, marking, transportation,
storage of forging (rolling) steel balls.
This standard applies to forging (rolling) steel balls, which are used as grinding media
in ball mills, semi-autogenous mills, etc.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB/T 229 Metallic materials - Charpy pendulum impact test method
GB/T 230.1 Metallic materials - Rockwell hardness test - Part 1: Test method (scales
A, B, C, D, E, F, G, H, K, N, T)
GB/T 2828.1 Sampling procedures for inspection by attributes - Part 1: Sampling
schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection
GB/T 8541 Terminology of forging and stamping
YB/T 081 Rule for rounding off of numerical values and judgement of testing values
for technical standards of metallurgy
3 Terms and definitions
The terms and definitions defined in GB/T 8541, as well as the following terms and
definitions, apply to this document.
3.1
Forging steel grinding balls
Steel grinding balls formed by forging process.
6.2 The chemical analysis and internal structure inspection of steel balls and blank
materials shall be carried out in accordance with the methods specified in Appendix A
and relevant regulations.
6.3 The test of impact energy absorption value shall be carried out using a 10 mm × 10
mm × 55 mm unnotched specimen, which is cut on the steel ball, in accordance with
the provisions of GB/T 229.
6.4 The number of drop ball tests shall be carried out in accordance with the method
specified in Appendix B.
6.5 The hardness test shall be carried out in accordance with the provisions of GB/T
230.1. When preparing the specimen, wire cutting or electric spark cutting shall be
adopted, or the surface of the ball shall be ground into a flat surface for inspection; the
grinding thickness shall be 2 mm ~ 5 mm.
6.6 The detection and calculation of the breakage rate of balls shall be carried out in
accordance with the provisions of Appendix C of this standard.
6.7 The surface defects of the steel ball shall be detected by visual inspection.
6.8 The hardness uniformity of the steel ball can be expressed by the average volume
hardness.
6.8.1 The calculation method of the average volume hardness of the steel ball is shown
in formula (1).
AVH = 0.009HRCcore + 0.063HRCr/4 + 0.203HRCr/2 + 0.437HRC3r/4 + 0.289HRCsurface
……………………………………….(1)
Where:
AVH - Average volume hardness of steel ball (HRC);
HRCcore - Hardness at measurement point of steel ball core, which is point A in Figure
1 (HRC);
HRCr/4 - Hardness at measurement point 1/4 of steel ball radius, which is point B in
Figure 1 (HRC);
HRCr/2 - Hardness at measurement point 1/2 of steel ball radius, which is point C in
Figure 1 (HRC);
HRC3r/4 - Hardness at measurement point 3/4 of steel ball radius, which is point D in
Figure 1 (HRC);
HRCsurface - Hardness value at the measuring point on the steel ball surface, which is
point E in Figure 1 (HRC);
unqualified.
7.5 Inspection of the hardness of the steel ball core: For every 200t of steel balls of the
same type and specification produced continuously (less than 200t is counted as one
batch), steel balls with a surface hardness of the lower limit specified in Table 3 shall
be sampled for inspection. If the inspection fails, it shall double the samples from this
batch for re-inspection. If the chemical composition is qualified, re-heat treatment is
allowed. If there are still unqualified results, the batch shall be unqualified.
7.6 Type inspection
If one of the following situations occurs, type inspection shall be carried out in
accordance with all technical requirements specified in this standard. Whether the type
inspection is qualified shall be determined according to the exit-factory inspection
judgment rules.
a) When a new product is trial-produced;
b) When the production process has a major change that may affect the product
quality;
c) After mass production, it shall be inspected at least once every six months;
d) When production is resumed after a long-term suspension;
e) When the exit-factory inspection results are significantly different from the
previous type inspection;
f) When the national quality supervision agency proposes a type inspection
requirement.
7.6.1 Dimensions and allowable deviations, shape and surface quality are sampled
according to the normal secondary sampling plan in GB/T 2828.1, at general inspection
level I, AQL = 6.5.
7.6.2 Randomly select 5 products, that pass the size and allowable deviation, shape and
surface quality inspection, for mechanical properties inspection. Then randomly select
1 product from the 5 for chemical composition inspection.
8 Packaging, marking, transportation, storage
8.1 Packaging
Steel balls shall be packaged in iron barrels or woven bags or in bulk.
8.2 Marking
Appendix A
(Normative)
Standards for physical and chemical inspection methods for steel products
GB/T 223.3 Chemical analysis methods for steel and alloys: Determination of
phosphorus content by diantipyryl methane phosphate aluminate gravimetric method
GB/T 223.4 Alloyed steel - Determination of manganese content - Potentiometric or
visual titration method
GB/T 223.5 Steel and iron - Determination of acid-soluble silicon and total silicon
content - Reduced molybdosilicate spectrophotometric method
GB/T 223.11 Iron, steel and alloy - Determination of chromium content - Visual
titration or potentiometric titration method
GB/T 223.12 Methods for chemical analysis of iron, steel and alloy - The sodium
carbonate separation-diphenyl carbazide photometric method for the determination of
chromium content
GB/T 223.13 Methods for chemical analysis of iron, steel and alloy - The ammonium
ferrous sulfate titration method for the determination of vanadium content
GB/T 223.14 Methods for chemical analysis of iron, steel and alloy - The N-benzoyl-
N-phenylhydroxylamine extraction photometric method for the determination of
vanadium content
GB/T 223.16 Methods for chemical analysis of iron, steel and alloy - The chromotropic
acid photometric method for the determination of titanium content
GB/T 223.17 Methods for chemical analysis of iron, steel and alloy - The
diantipyrylmethane photometric method for the determination of titanium content
GB/T 223.58 Methods for chemical analysis of iron, steel and alloy - The sodium
arsenite-sodium nitrite titrimetric method for the determination of manganese content
GB/T 223.59 Iron, steel and alloy - Determination of phosphorus content - Bismuth
phosphomolybdate blue spectrophotometric method and antimony phosphomolybdate
blue spectrophotometric method
GB/T 223.60 Methods for chemical analysis of iron, steel and alloy - The perchloric
acid dehydration gravimetric method for the determination of silicon content
GB/T 223.61 Methods for chemical analysis of iron, steel and alloy - The ammonium
Appendix B
(Normative)
Test method for grinding ball impact fatigue life
The grinding ball impact fatigue life test by falling ball method (hereinafter referred to
as the falling ball test) is to use a falling ball impact fatigue testing machine (hereinafter
referred to as the falling ball testing machine), to simulate the impact process of steel
balls in a ball mill, under laboratory conditions.
The number of impacts is displayed by a counter. The number of impact fatigue failures
reflects the impact fatigue life of the steel ball under this condition.
B.1 The falling distance of the falling ball machine is 8 m.
B.2 The specimens of the falling ball test shall be 20 steel balls randomly selected from
the batch to be inspected as test balls; another 3 or more steel balls shall be selected as
replacement balls. Marks shall be made on the surface of the replacement balls.
B.3 The falling ball test is conducted at room temperature.
B.4 The steel ball failure judgment and test procedure are as follows:
B.4.1 Steel ball failure judgment
a) The average diameter of the peeling layer on the steel ball surface (the average of
the maximum diameter and the minimum diameter) is greater than 20 mm,
meanwhile the middle thickness is greater than 5 mm.
b) The steel ball breaks along the middle.
B.4.2 Test procedure
B.4.2.1 First, put 16 test balls into the curved pipe. Start the test machine. Gradually
put the remaining 4 test balls into the circulation conveying system, from the downhill
slide.
B.4.2.2 Turn on the counter. Reset the counter. Clear the alarm. Turn the digital dial to
the preset number (10000).
B.4.2.3 The test personnel shall observe carefully on site. When it is found that one test
ball fails in accordance with the provisions of a) or b) in B.4.1, take out the failed ball
and put in a replacement ball, until the third failed ball appears. Record the cumulative
number of impacts received by the 3 test balls in the falling ball machine system when
they fail. If the number of failed balls in the test has not reached the failed ball number