The performance indexes of newly developed steel are better: the Charpy impact value is 7.5J/cm2 for the original steel and 13.4J/cm2 for the newly developed steel; the bending strength is 153N/mm2 and 264N/mm2 respectively; the fatigue limit is 666N/mm2 and 696N/mm2; the 107h strength of the roller pit test is 2450N/mm2 and 2695N/mm2, respectively. The main parameters determining the life of the gear are the root bending strength and the flank strength. The two indexes are higher than the original steel. Moreover, the replacement of all (or part of) Cr and Mo with B reduces the cost.
The existence of B atoms in the infiltrated C layer was observed by the peeling trace etching method: the B atom segregated in the grain boundary of the C grain; and the section of the starting point of the 3-point bending test was observed. Compared with the JIS-SCM420H original steel which is a brittle grain boundary section, the grain boundary section of the developed steel is reduced and the strength is improved, which is the result of strengthening the grain boundary by the B atom segregated at the grain boundary.
X00413 development of high-performance seamless stainless steel pipe WELD-ABLE12CR for pipelines Kawasaki Steel Co., Ltd. has developed two types of martensitic stainless steel seamless steel pipe WELDABLE12CR with excellent weldability and corrosion resistance, which is superior to corrosion resistance of 13Cr oil well pipe. 11Cr steel pipe and 12Cr steel pipe. Product target characteristics: (1) Weldability: no preheating before welding, no heat treatment after welding; (2) CO2 corrosion resistance: equivalent or higher than the original 0.2C-13Cr oil well pipe; (3) low temperature toughness: base metal and Low temperature (-40e) Charpy impact work of the weld 100J; (4) Strength: YS (yield strength) 360MPa, which is above the X52 level of the API5L standard of the American Petroleum Institute (API); (5) Hot workability: Mannesmann process can be produced; (6) SSC resistance: For martensitic stainless steel pipes used in CO2 trace H2S environment, it is required to have H2S partial pressure of 0.001 MPa, 5NaCl aqueous solution and pH=4.0. Good marks should be traced and aggregates should remain intact.
The decisive factor affecting the life of the original ladle is the loss of the nozzle brick. At the end, the wall wear resistant material still has a residual thickness of 4060 mm. In order to improve its effective utilization rate and expand the ladle volume, the core is enlarged during the building of the ladle, and the wear layer is thinned 14. And, from the middle of the side wall of the ladle, the permanent layer is made into a three-layer structure to reduce wear resistance. Layer thickness; the newly installed third layer brick was treated as an auxiliary brick, and the exposed terminal was standardized.
In use, it was found that the substrate and sidewall joints were severely damaged. The structure is therefore adjusted: the sidewalls are dropped into the bottom of the liner, thereby eliminating local damage in the lower portion of the sidewall.
(3) Improvement of castable material After taking measures to improve the effective utilization rate of the refractory material of the side wall of the ladle (to reduce the wall thickness), in order to prevent cracking, the MgO content in the material is appropriately reduced, and SiO2 is increased to reduce the thermal expansion. The coefficient has a chemical composition of 91.6Al2O3, 4.8MgO, and 0.5SiO2. As a result, the related physical properties were improved: the porosity at high temperature (1500e@3h) was changed from 20.9 to 24.2; the crush strength at low temperature (110e@24h) was increased from 11.9MPa to 22MPa; high temperature (1500e@3h) The rupture modulus is increased from 30.2 MPa to 36.3 MPa. The low expansion of the material is less prone to cracking.
(4) Improvement of ladle maintenance plan The original ladle is used for intermediate maintenance when 50 times, and 140 times after 2 times of repair; the new measure is to carry out 1 long life intermediate repair to 80 times. , the life of the ladle is extended to about 160 times. The cost of ladle refractories has dropped to 49.
It can be seen from the test results that the control of each ion content does not cause corrosion in the stainless steel pipe weld zone. Effect of purity of X00417SUS316 steel on corrosion resistance In the study of seawater corrosion resistant stainless steel SUS316, the Japan Institute of Metal Materials Technology re-melted ultra-high nitrogen and high-purity SUS316L stainless steel in a crucible to produce steel sheets (hereinafter referred to as CC steel). Corrosion resistance test to improve local corrosion resistance.
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