For the welding method of the chrome molybdenum series low-alloy steel curved beam of drop weight testTechnical field
The present invention relates to a kind of welding method of low-alloy steel, be specifically related to a kind of welding method of the chrome molybdenum series low-alloy steel curved beam for drop weight test.
Background technology
The heap-type nuclear power station that China's autonomous Design manufactures, its nuclear island primary device in-pile component changes chrome molybdenum low-alloy steel forging into compared to the stainless steel forgings in pressurized-water reactor nuclear power plant.Because document rarely has the drop weight test of this type of material of display, be therefore necessary to further investigate the drop weight test of this material.
Drop weight test, full name is the nil-ductility temperature drop weight test method of ferritic steel, the difference comparing to other mechanical test method maximum is: need specimen surface built-up welding welding bead under regulatory specifications, and slot, test under determined temperature, thus investigate the material sensitiveness to crackle at such a temperature.
Existing welding method is: select the ordinary low-alloy steel surfacing welding of 4 ~ 5mm, the electric current of 190 ~ 200A directly welds sample.The shortcoming of this welding method is: on the one hand, and the heat input of the method to mother metal is comparatively large, easily produces larger heat affected area; On the other hand, the tensile strength of chrome-molybdenum steel is higher, σb>=500MPa, hardenability is comparatively strong, easily cracks in welding process.
Therefore, adopt existing welding method to implement built-up welding to chrome-molybdenum steel sample, its result of the test can not as the true RT of this materialnDT(benchmark nil-ductility temperature), therefore, is necessary to take certain technological measure to prevent the generation of this problem, thus guarantees the reliability of result of the test.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of welding method of the chrome molybdenum series low-alloy steel curved beam for drop weight test, and it can guarantee the reliability of drop weight test result.
For solving the problems of the technologies described above, the technical solution that the present invention is used for the welding method of the chrome molybdenum series low-alloy steel curved beam of drop weight test is:
Comprise the following steps:
The first step, puts into heat-treatment furnace by the Drop test pieces that chrome molybdenum series low-alloy steel is prepared into and is heated to 170 ~ 190 DEG C; Insulation; Temperature retention time is 1h/20mm (sample of every 20mm thickness is incubated 1 hour).
The chrome molybdenum series low-alloy steel adopted is 12Cr2Mo1 material.
Second step, adopt low-alloy surfacing welding, carry out built-up welding at specimen surface, speed of welding is 125 ~ 145mm/min;
Described low-alloy surfacing welding is D127 type welding rod.
Described core diameter is 4mm, predetermined current 165A.Or described core diameter is 5mm, predetermined current 180A.
3rd step, the steel plate overhead sample welded being placed in 15 ~ 20 DEG C is chilled to room temperature.
The technique effect that the present invention can reach is:
The present invention can while guarantee drop weight test validity, and prevent from producing bead crack in welding process, reduce test error, its result of the test truly can reflect the RT of materialnDT, thus make result of the test reflect the performance of material itself more realistically, with the accuracy of the reliability and result of the test that ensure drop weight test.
Detailed description of the invention
The present invention is used for the welding method of the chrome molybdenum series low-alloy steel curved beam of drop weight test, comprises the following steps:
The first step, puts into heat-treatment furnace by the Drop test pieces that chrome molybdenum series low-alloy steel is prepared into and is heated to 170 ~ 190 DEG C; Insulation, temperature retention time is that the sample of every 20mm thickness is incubated 1 hour; Object reduces the cooling velocity of weld seam, prevents welding bead from generating brinelling tissue, cracking;
Drop test pieces size is generally 130 × 50 × 20mm, then temperature retention time is 1 hour;
Second step, select diameter to be low-alloy surfacing welding, the predetermined current 165 ~ 180A of 4mm or 5mm, carry out built-up welding at specimen surface, speed of welding is 125 ~ 145mm/min (mm is sample thickness);
Low-alloy surfacing welding is D127 type welding rod;
Under the prerequisite meeting drop weight test standard-required, to reduce as far as possible, the heat of material is inputted, ensure the nature of mother metal;
3rd step, the steel plate overhead sample welded being placed in 15 ~ 20 DEG C is chilled to room temperature, reaches the object of material microstructure homogenising.
Chrome molybdenum series low-alloy steel can be 12Cr2Mo1 material.
Adopt the sample prepared by the present invention, under the impact energy of 400J, carry out the test of actual measurement nil-ductility temperature, result is RTnDT=-25 DEG C.And adopting the material of the welding method of prior art to identical working condition to test, result is RTnDT=-5 DEG C.Therefore result of the test of the present invention is much higher than the result of the test of the welding method of prior art, reduces test error.