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Zhuhong forged round bar with DNV.GL

2019-08-22

Det norske veritas, referred to as "DNVGL, was founded in 1864, is an international company, the world's leading professional risk management services, the main business including ship and Marine products of the third party inspection, Marine facilities of the third party inspection.

DNV.GL is a very important certification for the steel industry and a symbol of product quality. It took zhuhong 20 months to successfully apply for DNV.GL. It is mainly divided into steel ingots and forging parts. Now briefly talk about the steel ingots part. Share successful experiences for manufacturers in the same industry. We tested four forged round bar at the time, C45E, S355J2G3, 42CrMo 4, 34CrNiMo 6.
 
Specifically:
 
1 applying approval scope of steel ingots
 
1.1 Ingot processing route:Induction+LF+VD+IC
 
2 approval testing plan of steel ingots
 
Referring standards
 
2.1 DNVGL-CP-0346, Approval of manufacturer scheme
 
2.2 DNVGL-CP-0242, Approval of manufacturer semi-finished steel products
 
2.3 EN 10250 Open die steel forgings for general engineering purposes
 
2.4 ASTM E381 Standard Method of Macro-etch Testing Steel Bars, Billets, Blooms, and Forgings
 
each heat no.(or each Ladle) can cast only one plate of ingots, so take 1 pc of testing sample per heat no.
 
2.5 Visual examination
 
-the surface shall not be hammered, peened or treated in any way which may obscure discontinuities
 
-examination shall be done for all applicable sides/areas, i.e. manufacturer shall ensure that lifting devices for handing and turning of the products are available.
 
-measurements shall be made on all applicable dimensions
 
-DNT such as UT and MT are not applicable
 
3 testing report of steel ingots
 
3.1  tested steel ingots
 
3.2  ladle analysis and product analysis
 
3.3  macro-etching and sulphur prints
 
3.4  visual examination
 
4 statistics of previous production of steel ingots
 
5 general documentation of manufacturing route and equipment of steel ingots
 
5.1  Introduction of company
 
5.2  Business license
 
5.3  ISO9001 certificate
 
5.4  Organization structure
 
5.5  Quality assurance system including quality control responsibilities
 
5.6  Manufacturing process description
 
5.7  Flow charts
 
5.8  Testing and inspection points
 
5.9  List of procedures for testing and inspection
 
--Procedure for materials inspection in steelmaking shop,
 
--Procedure for process inspection in steelmaking shop,
 
--Procedure for final products inspection in steelmaking shop,
 
--Procedure for take samples of ladle analysis in steelmaking shop,
 
--Procedure for chemical composition analysis in steelmaking shop,
 
5.10  List of equipment used for chemical analysis, dimensional measurements
 
5.11  Steel making process
 
1) Prepare and put crap steels into the induction furnace and supply electric power.
 
2) when temperature meets the technical requirements, analysis elements and adjust them as per the technical requirements.
 
3) Remove slag from the induction furnace.
 
4) Put new slag materials in the ladle, and then tap.
 
5) During tapping, add deoxidizing materials and Fe-alloys in the ladle.
 
6) Put the ladle into the position of ladle furnace for refining, blow Ar from bottom of ladle, supply electric power.
 
7) In LF, add CaO to make new slag and FeSi power etc. for deoxidizing, add Fe-alloy after chemical analysis.
 
8) When elements and temperature reach the technical requirements, feed Al, if necessary CaSi line into the steel, then put ladle into VD furnace for degassing.
 
9) For VD, keep enough time under vacuum level (for example ≤67pa) as per the technical requirements, then take out ladle of VD position.
 
10) Casting ingots per the technical requirements, bottom casting.
 
11) Cooling ingots for enough time as per the shop’s requirement.
 
5.12    Casting
 
5.13    Final condition of steel ingots
 
5.14    Partial hot working and heat treatment (N/A)
 
5.15    Records, test facilities and procedures
 
5.16    Test results and records
 
5.17    Calibration for relevant manufacturing and testing devices
 
5.18    Qualifications of personnel engaged in testing and inspection
 
5.19    Product identification and traceability
 
6  manufacturing summary of steel ingots
 
7  manufacturer products specification of steel ingots
 
8  manufacturers’own certificate form of steel ingots
 
9  calibration for relevant manufacturing and testing devices
 
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