BAIJIAN - Third party testing organization
1 Scope: This standard specifies the technical requirements for pre carburization heat treatment、 carburization primary quenching、 tempering、 high-temperature tempering、 secondary quenching、 and post tempering of carburized bearing steel rolling bearings such as G20CrMo (A)、 G20CrNi2Mo (A)、 G2OCr2Ni4 (A)、 G10CrNi3Mo (A)、 and G20Cr2Mn2Mo (A) in accordance with GB/T 3203、 as well as the inspection methods for average grain size、 depth of hardening layer、 hardness、 microstructure、 cracks、 etc. This standard is applicable to the quality inspection of carburizing heat treatment of carburized bearing steel rolling bearing parts mentioned above、 and also to the quality inspection of carburizing heat treatment of low-carbon alloy steel rolling bearing parts. The following normative references are essential for the application of this document. For dated references、 only the dated version applies to this document. Any undated reference documents. The new version (including all modification orders) applies to this document. GB/T 230.1 Metallic Materials Rockwell Hardness Test - Part 1: Test Method (A、 B、 C、 D、 E、 F、 G、 H、 K、 N、 T scales) GBT 231.1 Metallic Materials Brinell Hardness Test Part 1: Test Methods GB/T 3203 Technical Conditions for Carburized Bearing Steels GB/T 6394 Method for Determining Average Grain Size of Metals GB/T 9450 Determination and Verification of Hardened Case Depth of Carburized and Quenched Steel Parts GB/T 24606 Non destructive Testing of Rolling Bearings Magnetic Particle Testing JB/T 1255-2001 Technical Conditions for Heat Treatment of High Carbon Chromium Bearing Steels Rolling Bearing Parts JB/T 7361 Hardness Test Methods for Rolling Bearing Parts 3 Terms and Definitions The following terms and definitions Applicable to this document. 3.1 Case hardened depth (of a carburized and hardened case) The vertical distance from the surface of the part to a Vickers hardness value of 550 HV1. [GB/T 9450-2005、 Chapter 3] 4 Technical Requirements 4.1 Pre heat treatment before carburization Technical Requirements 4.1.1: Bearing parts should be prepared for heat treatment before carburization、 and the hardness after heat treatment should not exceed 229 HBW< The diameter of sputum pressure should not be less than 4.0 mm; The hardness of parts made of G20Cr2Ni4 (A) after heat treatment should not exceed 241 HBW (indentation diameter should not be less than 3.9 mm). 4.1.2 The average grain size of bearing parts before carburization should be level 5 or finer in accordance with GB/T 6394. 4.2 Technical requirements for carburizing heat treatment 4.2.1 Hardening layer depth The depth of the hardened layer of the finished parts after carburizing heat treatment should comply with the provisions of Table 1. 4.2.2 Hardness 4.2.2.1 The surface hardness and core hardness of bearing parts after carburizing、 one-time quenching、 tempering、 or secondary quenching、 tempering should comply with the provisions of Table 2
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