Heavy Mechanical General Techniques and Standards –
Part 7: Repair Welding for Steel Castings
1 Scope
This Part of JB/T 5000 specifies such contents as the technical requirements for pre-weld preparation, the technical requirements for repair welding, the post-weld heat treatment and inspection for the repair welding of steel castings.
This Part is applicable to the repair welding of the defects of carbon steel, low alloy steel and high manganese steel castings before finishing machining.
2 Normative References
The following normative documents contain provisions which, through reference in this Part of JB/T 5000, constitute provisions of this Part. For dated references, subsequent amendments to (excluding corrections to), or revisions of, any of these publications do not apply; however, the parties who enter into agreement according to this Part are encouraged to research whether the latest editions of these documents are applied or not. For undated references, the latest edition of the normative document is applicable to this Part.
GB/T 984 Hardfacing Electrodes for Shielded Metal Arc Welding (GB/T 984-2001, eqv ANSI/AWS A5.13)
GB/T 5117 Carbon Steel Covered Electrodes (GB/T 5117-1995, eqv ANSI/AWS A5.1:1991)
GB/T 5118 Low Alloy Steel Covered Electrodes (GB/T 5118-1995, neq ANSI/AWS A5.5:1981)
GB/T 10045 Carbon Steel Flux Cored Electrodes for Arc Welding (GB/T 10045-2001, eqv ANSI/AWS A5.20:1995)
GB/T 17493 Low Alloy Steel Flux Cored Electrodes for Arc Welding (GB/T 17493-1998, eqv ANSI/AWS A5.29:1980)
GB/T 8110 Welding Wires for Gas Shielding Arc Welding of Carbon and Low Alloy Steels (GB/T 8110-1995, neq ANSI/AWS A5.18:1979)
GB/T 5680 Austenitic Manganese Steel Castings
GB/T 6417.1 Classification and Explanation of Imperfections in Fusion Welded Joints (GB/T 6417.1-2005, ISO 6520:1998,IDT)
JB/T 3223 Rules of Quality Management of Welding Materials
JB/T 5000.6 Heavy Mechanical General Techniques and Standards - Part 6: Steel Castings
JB/T 6404 Large High Manganese Steel Casting
3 Technical Requirements for Pre-weld Preparation
3.1 Defect Removal and Groove Type
3.1.1 The defect shall be removed thoroughly before repair welding; the groove face shall be made to be smooth and round, and shall be free from sharp corners.
3.1.2 According to the defects of steel castings, the defects in the repair welding area may be removed by adopting such methods as digging, grinding, carbon arc air gouging, gas cutting or machining. For steel castings with poor weldability, when carbon arc air gouging and gas cutting are adopted to remove defects, they shall be preheated according to those specified in Table 1 first, then the defects shall be removed, and the recarburization layer must be removed by polishing after carbon arc air gouging.
3.1.3 Such impurities as the sand, oil stain, water and iron rust within the repair welding area and 20mm of around the groove shall be removed thoroughly, and then the repair welding area shall be polished until the metal surface luster exposes. Especially when the basic electrode is adopted, the cleaning work shall be well done.
3.1.4 For crack defects, to prevent the crack propagation, crack-arrest hole in a diameter of no less than φ10mm may be drilled at the two endpoints of the crack, and then the groove may be made.
3.1.5 The groove type for repair welding for the defects of steel castings may be selected according to those specified in Table 2.
3.1.6 Before repair welding, the repair welding positions of steel castings shall be inspected according to the relevant requirements by adopting ultrasonic testing (UT) or magnetic particle testing (MT), penetrant testing (PT) or other methods in order to verify that the defects have been removed completely.
3.2 Weld Preheating
3.2.1 The weld preheating temperature shall comply with those specified in Table 1. The preheating temperature for the steel grades beyond those listed in Table 1 shall comply with A.2 in Appendix A.
Contents
Foreword II
1 Scope
2 Normative References
3 Technical Requirements for Pre-weld Preparation
3.1 Defect Cleaning and Groove Type
3.2 Weld Preheating
3.3 Selection and Application of Welding Materials
3.4 Welding Environment
4 Technical Requirements for Repair Welding
5 Stress Relieving Treatment after Welding
6 Inspection
Appendix A (Normative) Supplementary Regulations for Preheating Temperature
Appendix B (Normative) Evaluation on Weld
