Tenfaye is the professional large gear rings manufacturer in China. When dealing with situations where some customers provide unclear material specifications, some customers provide niche materials that are not European or American standards, or some customers only provide hardness values combined with other technical parameters, our engineer will recommend Chinese national standard materials for girth gears to customer reference and selection before quotation.
 
The following is an analysis of the chemical composition and mechanical properties of common Chinese national standard materials for large gear rings.

1. Chemical Composition
1.1 The chemical composition of each cast steel grade shall comply with the requirements specified in Table 1.
1.2 Unless otherwise specified, residual element content shall not be used as acceptance criteria.
1.3 When required by the purchaser, finished product chemical composition analysis may be performed, and the allowable deviation of finished product chemical composition shall comply with the requirements of GB/T 222.
Table 1
Chemical Composition (Mass Fraction)                                                         %

Material Grade	C	Si	Mn	S	P	Cr	Ni	Mo
ZG35CrMo	0 . 33~0 . 37	0 . 30~0 . 50	0 . 50~0 . 80	≤0 . 025	≤0 . 025	0 . 80~1 . 20	—	0 . 20~0 . 30
ZG42CrMo	0 . 38~0 . 45	0 . 30~0 . 60	0 . 60~1 . 00	≤0 . 025	≤0 . 025	0 . 80~1 . 20	—	0 . 20~0 . 30
ZG45CrMo	0 . 43~0 . 47	0 . 30~0 . 60	0 . 70~1 . 00	≤0 . 025	≤0 . 025	0 . 90~1 . 20	—	0 . 25~0 . 35
ZG35CrNiMo	0 . 32~0 . 37	0 . 30~0 . 50	0 . 70~1 . 00	≤0 . 025	≤0 . 025	0 . 60~0 . 90	0 . 60~0 . 90	0 . 40~0 . 50
ZG40CrNiMo	0 . 37~0 . 43	0 . 30~0 . 50	0 . 70~1 . 00	≤0 . 025	≤0 . 025	0 . 60~0 . 90	0 . 60~0 . 90	0 . 40~0 . 50
ZG34Cr2Ni2Mo	0 . 32~0 . 37	0 . 30~0 . 60	0 . 60~1 . 00	≤0 . 025	≤0 . 025	1 . 40~1 . 70	1 . 40~1 . 70	0 . 15~0 . 35
ZG40CrNi2Mo	0 . 37~0 . 43	0 . 30~0 . 50	0 . 70~1 . 00	≤0 . 025	≤0 . 025	1 . 00~1 . 40	1 . 40~1 . 70	0 . 30~0 . 40
Notes: ·  Residual element content: Ni≤0.30%, Cu≤0.25%, V≤0.05%, total residual element content ≤1%. If not required by the purchaser, residual elements shall not be used as acceptance criteria. ·  Trace amounts of V, Ti, Nb, B, and Re elements may be added.

2. Mechanical Properties
The mechanical properties of each cast steel grade shall comply with the requirements specified in Table 2.
Table 2 Mechanical Properties

Material Grade	Heat Treatment	ReH/ MPa	Rm / MPa	A/ %	Z/ %	KV2/ J	Body Hardness/ HBW
ZG35CrMo	Normalizing+ Tempering	≥390	≥590	≥14	≥20	—	170~210
	Quenching + Tempering	≥490	≥680	≥13	≥25	≥25	190~230
ZG42CrMo	Normalizing+ Tempering	≥450	≥595	≥12	≥20	—	200~240
	Quenching + Tempering	≥510	≥690	≥11	—	≥20	220~260
ZG45CrMo	Normalizing+ Tempering	≥490	≥650	≥10	≥20	—	220~260
	Quenching + Tempering	≥560	≥750	≥10	—	≥18	240~280
ZG35CrNiMo	Normalizing+ Tempering	≥530	≥720	≥12	≥25	—	210~250
	Quenching + Tempering	≥610	≥805	≥12	≥25	≥25	240~280
ZG40CrNiMo	Normalizing+ Tempering	≥610	≥805	≥10	≥22	—	240~280
	Quenching + Tempering	≥660	≥855	≥10	≥22	≥20	270~310
ZG34Cr2Ni2Mo	Normalizing+ Tempering	≥550	≥730	≥12	—	—	230~270
	Quenching + Tempering	≥650	≥850	≥12	—	≥30	250~290
ZG40CrNi2Mo	Normalizing+ Tempering	≥620	≥815	≥10	—	—	260~300
	Quenching + Tempering	≥700	≥950	≥12	—	≥20	280~320
Note: The average value of test results from three impact test specimens shall comply with the requirements of Table 2. Only one specimen is allowed to have test results lower than the specified value, but it shall not be lower than 70% of the specified value.

Large gear rings are one of the most critical components in the transmission systems for rotary kilns and ball mills. The chemical and mechanical properties of girth gear will directly affect the stability of the rotary kiln and ball mills transmission system, operational stability, service life, and equipment availability.
 
If you have requirements for girth gears for mill and kilns or questions about large gear rings, please contact us at any time. As a professional large gear ring manufacturer, we are worthy of your trust.