shonini 썸네일형 리스트형 재료,비파괴시험 및 조직검사,금속의 응고와 결정검사 (3) 재료시험[1] 인장강도시험 재료의 외력이 정적으로 작용하여 재료가 파단 되려고 할 때 재료 단면의 단위 면적에 대한 최대 저항력을 강도라고 한다. ① 인장강도 ② 연신율 ③ 단면 수축률 ④ 내력 = 주철과 같이 항복점이 없는 재료에서는 0.2%의 영구변형이 일어날때의 응력값을 표시한 것 ＊내력 = W/A[2] 경도시험① 브리넬 경도() 지름이 D인 강구로 하중 P로 압입 후 하중을 자국의 표면적으로 나눈 값. (a) ② 비커스경도 대면각이 136°인 다이아몬드 피라미드를 사용.(b) ③ 로크웰 경도 기준하중 10kg. B스케일 하중 100k. C스케일 하중 100kg HRC : 꼭지각이 120° 인 다이아몬드 원뿔을 사용. (c) HRC = 100 – 500h HRB: 지름이 1.588(1/16”.. 더보기 금속의 조직과 변태 [금속의 조직] 금속의 원자가 규칙있게 배열된 상태를 결정체라고 하며, 이때 1개의 결정체를 결정입자라고 한다. 그리고 1개의 결정 격자를 X선으로 보면 원자들이 규칙적으로 배열되어 있는데 이것을 결정 격자라고 한다. 결정 격자에는 체심 입방 격자(B.C.C), 면심 입방 격자(F.C.C), 조밀 육방 격자 등이 있다. [금속의 변태] (1) 자기 변태(磁氣變態) 원자의 배열에는 변화가 없으나 768℃부군에서는 급격히 자기(磁氣)의 크기가 변화되는 것을 말한다. (2) 동소 변태(同素變態) 고체 내에서 결정격자의 형상 즉, 원자의 배열이 변화되는 것을 말한다. 순철(Pure Iron)에는 α, γ, δ의 3개의 동소체가 있다. α철은 910℃이하에서는 체심 입방 격자, γ철은 910~1400℃사이에서 면.. 더보기 Corrosion of Aluminum and Its Alloys: Forms of Corrosion Corrosion is the chemical reaction of a metal, in this case aluminum, with its environment, which leads to the deterioration of the properties of metals, aluminum in this case. Aluminum is a very reactive metal, but it is also a passive metal. This contradictory nature is explainable because nascent aluminum reacts with oxygen or water and forms a coherent surface oxide which impedes further rea.. 더보기 Futures FuturesA future is a contract between two parties to purchase a commodity or other asset at a later point of time, but for a price agreed on today.In a futures contract, the item being purchased is typically for a standard quality and quantity, with both parties agreeing to a price on the spot (typically called the "strike price"), with delivery at a specific future date ("delivery date").The bu.. 더보기 Spot market Spot marketThe spot market, or cash market, is where goods, equities, or other financial instruments such as currencies are exchanged for cash and delivered immediately.When something is traded in the spot market, traders (such as those involved in the forex industry) will conduct transactions ‘on the spot’, as opposed to afuture, where delivery is sometime in the future.The term spot is also us.. 더보기 Volatility VolatilityWhat is price volatility?Volatility is the price fluctuation or price change of afinancial instrument over a certain period of time.When the price fluctuation is high over a relatively short period of time, it is said that the volatility is high. When the price fluctuation is moderate over a short period of time, it is said that the volatility is low.Volatility does not measure the dir.. 더보기 Moving average Moving averageWhat is a moving average indicator?In technical analysis, the moving average is a trending indicator. It is displayed as a line on the chart and used to display the average value of an asset over a set period of time.To give an example, a simple moving average that displays the average value of the last 20 periods, is referred to as a "20 simple moving average". A 10 period simple .. 더보기 Bear, bearish trading Bear, bearish tradingWhat is a bear trader?If traders and investors think that the prices in a market will fall, they describe the market as being "bearish". A trader who wants to profit from expecting a falling or bear market trend will do so by short selling financial instruments such as commodities, stock market sharesor currencies.The opposite — expecting prices to rise — is calledbullish. h.. 더보기 Bull, bullish trading Bull, bullish tradingWhat is a bull trader?If traders and investors think that the prices in a market will rise, they describe the market as being "bullish". Bullish traders often buy stocks and commodities with the expectation of making a big profit at a later date. This is also called going long.The opposite — expecting prices to fall — is calledbearish. Traditionally, many people believe that.. 더보기 Hegemony HegemonyWhat does hegemony mean?In its historic sense, hegemony refers to the political dominance of one country or state over another (or group of others).More generally, it implies a high level of influence, authority or control over others.The word itself is thought to be derived from an ancient Greek term describing the alliance of city states beneath a single leader state ('the hegemon').In.. 더보기 이전 1 2 3 4 5 6 다음