The Chromium Alloy Cast Grinding Balls In Building Materials Industry (1)

Release time：2021-11-08

This standard was revised based on JC/T 533 —1994.
This standard shall replace JC/T 533-1994 since the date of the implementation.

Compared with JC/T 533-1994, the main changes in this standard are as follows:
— Normative reference documents (Chapter 2 of the 1994 edition; Chapter 2 of the Present Edition) have been updated and supplemented
— Terms and definitions revised and added: remove 1994 version 3.4 and 3.5: adding the terms and definitions that established in GB/T 17445, and definition of medium chromium cast iron grinding balls (chapter 3 of the 1994 edition; Chapter 3 of this edition)
— Revised product classification: alloy cast grinding balls are divided into three types, five grades, and two heat treatment states high chromium cast balls, medium chromium cast balls, and low chromium cast balls. Instead of the code names used in the original standard (chapter 4 of the 1994 Edition: Chapter 4 of this edition)
— Revised technical requirements: the diameter deviation of the cast grinding balls of dia10 -25mm and dia30-120mm conform to the accuracy of CT9 and CT10 in GB/T 6414-1999, respectively. The shape deviation is less than or equal to the diameter deviation of the same size of the casting ball (5.1 in 1994 version; 5.1,5.2 in this version). Revised Chemical Composition (5.2 in 1994 edition; 5.3 in this edition). The indexes of surface hardness and hardness difference of high chromium cast grinding ball in mechanical properties (5.3.1, 5.3.2 in 1994 edition; 5.4.1, 5.4.2 in this edition) are revised. Added the drop ball impact fatigue life requirement (version 5.4.3).

— Revised testing method: It is stipulated that the chemical composition of cast grinding balls shall be inspected and arbitrated in accordance with the standards specified in the normative reference documents. Test according to GB/T 5678-1985(6.2 in 1994 edition; 6.2 in this edition); Added the test method of drop ball impact fatigue life (6.7 in this edition).

— Revised Inspection Rules: Added inspection classification (version 7.2), factory inspection date (version 7.3) : type inspection content (version 7.9) ;
— Revised packaging, marking, transport and storage (1994 version 8.1.8.2: This version 8.1, 8.2) 
— Revised the requirements of the single bin broken rate and wear rate for high chrome and low chrome grinding balls in the original standard appendix A. Added the requirements of the medium chrome grinding balls broken rate and wear rate (1994 version Appendix A, this version Appendix A). 

Appendix A of this standard is an informative appendix.

This standard is proposed by China Building Materials Industry Association
This standard by the National Building Materials Industry Machinery Standardization Technical Committee is centralized 
This standard is drafted by Zhuzhou Southern Aviation casting and forging machinery plant.
This standard participated in the drafting units: Anhui Ningguo wear-resistant Materials Co., Ltd., Hebei Kaiyuan wear-resistant Materials Co., Ltd., Tangshan Jianxin Steel Ball Factory, Toyo Grinding Balls (Ma An Shan) Co., Ltd.
The principal drafters of this standard: Zheng Wenbin, Tang Shaoqi, Yao Yongmao, Sun Ping, Xiang Shaoxin, Wu Qingsong
This standard was first issued in 1994, and this is the first revision.