37results about How to "Avoid grain coarsening" patented technology

The invention discloses a novel method for preparing a nano NTC (Negative Temperature Coefficient) thermal-sensitive material. The novel method comprises the following steps: firstly, preparing nickel-manganese spinel powder of which the particle size is 50nm by using a sol-gel method; treating nano powder by using modes of tabletting and isostatic pressing so as to obtain a raw blank; sintering the raw blank for 0-60 seconds in a super-fast sintering furnace at 1000-1040 DEG C; further sintering for 5-20 hours in an air furnace at 850-950 DEG C, thereby finally obtaining the thermal-sensitiveNTC material of which the particle size is smaller than 500nm. The thermal-sensitive material has relatively high resistance and material constants.

The invention relates to a Q345R steel plate with excellent performance under high-temperature simulated post-weld heat treatment conditions. The steel plate comprises 0.16-0.20% of C, 0.25-0.45% of Si, 1.40-1.60% of Mn, 0-0.008% of P, 0-0.002% of S, 0.02-0.05% of Al, 0.02-0.05% of Nb, 0.01-0.05% of Ti, 0.10-0.30% of Ni, 0.10-0.30% of Cu and balance Fe and inevitable impurity elements, wherein thecarbon equivalent ceq is less than or equal to 0.45%. A large compression ratio design is adopted, and the main working procedures comprise smelting, two-stage rolling and normalizing heat treatment.The steel plate is in a normalizing delivery state, the delivery state surface Brinell hardness is less than or equal to 170 HB, the transverse impact energy on the 1 / 2 thickness portion of the steelplate obtained after high-temperature simulated post-weld heat treatment at -30 DEG C is larger than or equal to 100 J, the yield strength is larger than or equal to 325 Mpa, the tensile strength islarger than or equal to 500 Mpa, the elongation percentage after fracture A is larger than or equal to 25.0%, and the flaw detection of the steel plate can meet the requirements of I-grade NB / T47013.3standards.

The invention discloses a forging and molding process method for a titanium alloy tubular piece, which belongs to the technical field of forging and pressing, and is particularly suitable for tubular forging and molding of TC9 and TC11 titanium alloy materials. The method is mainly technically characterized in that methods such as pre-boring of guide through holes, hole expanding, drawing, binding and reshaping, and the like are adopted, and meanwhile, the heating temperature and heat preserving time of a TC9 or TC11 titanium alloy are controlled, so that crystal grains of the TC9 or TC11 titanium alloy can be prevented from being coarsened, the metallographic structure and mechanical performance of the TC9 or TC11 titanium alloy are prevented from being influenced, the consumption of the titanium alloy materials are lowered effectively, and the cost is saved; meanwhile, folding, corrugation and even cracks of inner holes are avoided; and the process method has the characteristics of easiness, high practicability, high product yield, and the like.

The invention belongs to the accumulator charging controlling field, wherein a diode D anode of an automatic charging stopping controlling circuit of a positive and negative combination impulse charging device is connected with a charging negative electrode, a second electric resistance R2, a variable resistance RW, a third electric resistance R3 and a fourth electric resistance R4 are connected in series in turn between a charging positive electrode and the diode D cathode, one end of a relay J or a first relay J1 is connected with a positive pole of a constant voltage power supply, the other end is connected with an anode of a silicon controlled rectifier 3CT, a cathode of the silicon controlled rectifier 3CT is respectively connected with a negative pole of the constant voltage power supply and the charging negative electrode, a controlling electrode is connected with the middle end of the variable resistance RW through the first electric resistance R1 and a constant voltage diode DW in turn, one end of a capacitance C is connected between the second resistance R2 and the variable resistance RW, the other end is connected between the fourth electric resistance R4 and the diode D cathode, a normally-closed contact J-1 or J-2 of the relay J or a second relay J2 is connected in series on the circuit that the charging anode is connected with one input end of the positive and negative impulse charging circuit, and a normally-closed contact J1-1 of the first relay J1 is connected with the second relay J2 on two input circuits of an alternating current power supply. The invention solves the technical problem that an accumulator is prevented from over charging.

The invention discloses a preparation method of a high-precision metal fibrofelt for high-temperature gas dust removal. The preparation method comprises the following steps: firstly, paving crude fibers into a crude fibrofelt blank by adopting felt paving equipment; performing vacuum high-temperature sintering treatment on the crude fibrofelt blank by adopting a high-temperature vacuum furnace, and cooling to obtain a crude fiber sintered felt; paving superfine fibers into a superfine fibrofelt blank by adopting the felt paving equipment, and then flattening the superfine fibrofelt blank by adopting a flattening machine so as to obtain a flat superfine fibrofelt blank; stacking the flat superfine fibrofelt blank and the crude fiber sintered felt, covering the surface of an obtained felt with a non-metal high-temperature-resistant material, then feeding an obtained felt blank into a high-temperature vacuum furnace for vacuum high-temperature sintering treatment, taking out the felt blank after cooling, and flattening the felt blank to obtain the high-precision metal fibrofelt. The high-precision metal fibrofelt prepared by the method is good in mechanical property, folding resistance and binding force of felt layers.

The invention discloses low-alloy steel high in strength and toughness performance and a preparing method of the low-alloy steel. The preparing method is a reasonable matching method for improving the strength and toughness performance in the manner that the aspects of component improvement, short-procedure design in which casting blank reheating is omitted, casting blank core part quality improvement, structure micronization control and rolling schedule optimization are taken into comprehensive consideration, the technical skill potential of modern material machining is fully reflected, and the actions of grain refinement, controlled rolling, rapid cooling and other technology means on steel strengthening and toughening are brought into play. It is ensured that brittle phase crack initiation of products of moderate-thickness plates is reduced and a new structure form is obtained so as to prevent crack expanding, and the breakthrough of the short-procedure technology of direct hot rolling of the ultrahigh strength and toughness steel casting blank is achieved.