GB/T 41857-2022 English PDF (GBT41857-2022)

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GB/T 41857-2022: Sheet metal parts fabricated by fine blanking combined with extrusion process -- General specification
GB/T 41857-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 25.020
CCS J 32
Sheet metal parts fabricated by fine blanking combined with
extrusion process - General specification
ISSUED ON: OCTOBER 12, 2022
IMPLEMENTED ON: OCTOBER 12, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 Technical requirements ... 6
5 Test methods ... 8
6 Inspection rules ... 9
7 Marking, packaging, transportation and storage ... 10
Bibliography ... 12
Sheet metal parts fabricated by fine blanking combined with
extrusion process - General specification
1 Scope
This document specifies the technical requirements, test methods, inspection rules,
marking, packaging, transportation and storage of sheet metal parts fabricated by fine
blanking combined with extrusion process (hereinafter referred to as “fine blanking
extrusion parts”).
This document applies to steel fine blanking extrusion parts fabricated by fine blanking
combined with extrusion process.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this
document and are indispensable to its application. For dated references, only the version
corresponding to that date is applicable to this document; for undated references, the
latest version (including all amendments) is applicable to this document.
GB/T 223 (all parts), Methods for chemical analysis of iron, steel and alloy
GB/T 224, Determination of depth of decarburization of steels
GB/T 226, Test method for macrostructure and defect of steel by etching
GB/T 228.1, Metallic materials - Tensile testing - Part 1: Method of test at room
temperature
GB/T 230.1, Metallic materials - Rockwell hardness test - Part 1: Test method
GB/T 231.1, Metallic materials - Brinell hardness test - Part 1: Test method
GB/T 699, Quality carbon structural steels
GB/T 1031, Geometrical product specifications (GPS) - Surface texture: Profile
method - Surface roughness parameters and their values
GB/T 1591, High strength low alloy structural steels
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 2829, Sampling procedures and tables for periodic inspection by attributes
(apply to inspection of process stability)
GB/T 2975, Steel and steel products - Location and preparation of samples and test
pieces for mechanical testing
GB/T 3077, Alloy Structure Steels
GB/T 4335, Determination of ferrite grain size for cold rolled low carbon steel sheets
GB/T 4336, Carbon and low-alloy steel - Determination of multi-element contents -
Spark discharge atomic emission spectrometric method (routine method)
GB/T 5216, Structural steels with specified hardenability bands
GB/T 6394, Determination of estimating the average grain size of metal
GB/T 8541, Terminology of forging and stamping
GB/T 10561, Steel - Determination of Content of Nonmetallic Inclusions -
Micrographic Method Using Standards Diagrams
GB/T 13298, Inspection methods of microstructure for metals
GB/T 13299, Determination of free cementite, pearlite and Widmanstatten structure
in steel
GB/T 13320, Metallographic grading atlas and assessing method for steel die
forgings
GB/T 30573, Fine blanked parts - General technical requirements
JB/T 5074-2007, Spheroidite grade of low and medium carbon steel
JB/T 9175.2, Fine blanked parts - Part 2: Quality
JB/T 9180.1, Cold extruded steel parts - Part 1: Dimensional tolerance
3 Terms and definitions
Terms and definitions determined by GB/T 8541 and the following ones are applicable
to this document.
3.1 Edge straightness
The maximum distance between the concave side of the steel plate or strip and the line
connecting the two ends of the length, within the measured length.
a) Spheroidizing annealing treatment should be carried out, and the spheroidizing
body rating shall meet the requirements of greater than or equal to grade 5 as
specified in JB/T 5074-2007;
b) Grain size grade requirements of steel sheet and strip: micro-alloyed fine grain
steel should be grade 7 ~ 10, and other steel types should be grade 5 ~ 8;
c) Decarburization depth and carbide segregation level requirements can be
determined through negotiation between the supplier and the buyer.
4.2 Fine blanking extrusion parts
4.2.1 Dimensions
The dimensional requirements for fine blanking extrusion parts include:
a) The fine blanking dimensional tolerance and shear surface roughness
requirements shall meet the requirements of GB/T 30573, and the extrusion
tolerance shall meet the requirements of JB/T 9180.1;
b) The fine blanking shear surface verticality tolerance and the non-shear surface
flatness tolerance shall meet the requirements of GB/T 30573, and the extrusion
shear surface verticality tolerance shall not be greater than the fine blanking shear
surface verticality tolerance;
c) When extrusion is carried out under the condition of d/D >1 (d is the diameter of
the extrusion convex mold; D is the diameter of the extrusion concave mold), the
diameter l and depth h of the extrusion shrinkage cavity shall meet the
requirements of the buyer.
4.2.2 Appearance
The appearance requirements for fine blanking extrusion parts are as follows.
a) The shear surface serviceability rate grade, the shear surface allowable tear grade,
and the shear droop requirements, of fine blanking extrusion parts, shall meet the
requirements of GB/T 30573.
b) Surface quality defects on the non-shear surface of fine blanking extrusion parts
due to coining, bumping, etc. shall be determined through negotiation between
the supplier and the buyer.
c) Fine blanking extrusion parts are divided into three categories according to d/D
(for special-shaped extrusions, the calculation is based on the diameter of the
envelope circle). The common defects of the three types of fine blanking
extrusion parts are shown in Figure 1. The extrusion forming defect control of
fine blanking extrusion parts shall meet the following requirements:
a) General inspection: dimensional tolerance, shear surface serviceability rate grade,
shear surface allowable tear grade, shear surface verticality, shear droop, burr,
non-shear surface flatness and surface quality of non-shear surface, etc.;
b) Supplementary inspection: shear surface roughness and metallographic structure,
etc.
The inspection of fine blanking extrusion parts shall be confirmed through consultation
between the supplier and the buyer. If random inspection is adopted, it shall be carried
out in accordance with the provisions of GB/T 2828.1 and GB/T 2829.
6.4 The inspection of finished fine blanking extrusion parts shall be carried out by the
quality inspection department of the supplier according to the drawings of fine blanking
extrusion parts, the order contract, this document and the provisions of JB/T 9175.2.
6.5 The acceptance of finished fine blanking extrusion parts shall be carried out by the
buyer according to the quality certificate of the supplier, the drawings of fine blanking
extrusion parts, the order contract, this document and JB/T 9175.2, as agreed in the
contract or according to GB/T 2828.1, GB/T 2829 for spot check and acceptance.
6.6 The batching, s...