371 results about "Fatigue crack propagation" patented technology

The invention discloses a high-quality steel plate capable of resisting fatigue crack growth and a manufacturing method thereof. The high-quality steel plate comprises the following constituents in percentage by weight: 0.040-0.070% of C, 0.40-0.70% of Si, 1.30-1.60% of Mn, less than or equal to 0.013% of P, less than or equal to 0.003% of S, less than or equal to 0.30% of Cu, less than or equal to 0.30% of Ni, less than or equal to 0.10% of Mo, 0.008-0.018% of Ti, 0.015-0.030% of Nb, less than or equal to 0.0040% of N, 0.0010-0.0040% of Ca, and the balance of Fe and unavoidable impurities. The manufacturing method comprises the following steps: using the ultra-low carbon C-high Si-intermediate Mn-Nb system low alloy steel as a base, controlling [%C]*[%Si] to be 0.022-0.042 and {([%C]+3.33[%Nb])*[%Si]}*V cooling velocity / T cold shutdown to be from 1.15*10<-4> to 2.2*10<-3>, carrying out Ca treatment, enabling Ca / S to be equal to 1.0-3.0 and (%Ca)*(%S)<0.28> to be smaller than or equal to 1.0*10<-3>, optimizing the TMCP technology, enabling the finished product steel plate microscopic structure to become a ferrite and uniformly dispersed bainite dual-phase structure, and allowing the average grain size of the microscopic structure to be 10 microns below.

The invention is intended to improve reliability of a thermal type air flow measuring instrument employing a molded part formed by integral molding together with a metal plate. A slot or opening allowing only a resin to pass through the same is formed in the metal plate in an area or thereabout subjected to higher stresses. A part of connector terminals, which is not required from the intrinsic object, is disposed in the vicinity of a area where the resin has a larger thickness and the temperature difference between the inside and the outside of the resin is locally increased. An injecting direction is set so as to prevent a weld line and a void from being generated in a combined way. In the molded part with the metal plate inserted therein, the occurrence of cracks and an increase of the fatigue crack growth rate can be suppressed and reliability can be improved.