Q345 是一种钢材的材质。它是低合金钢，广泛应用于桥梁、车辆、船舶、建筑、压力容器等。Q代表的是这种材质的屈服，后面的345，就是指这种材质的屈服值，在345左右。并会随着材质的厚度的增加而使其屈服值减小。
Q345 is a kind of steel material. It is a low alloy steel, widely used in bridges, vehicles, ships, buildings, pressure vessels, etc.. Q represents the yield of this material, followed by 345, refers to the yield value of this material, in the 345 or so. And the yield value decreases with the increase of the thickness of the material.
40Cr钢板是机械制造业使用最广泛的钢之一。调质处理后具有良好的综合力学性能，良好的低温冲击韧性和低的缺口敏感性。钢的淬透性良好，水淬时可淬透到Ф28～60mm,油淬时可淬透到Ф15～40mm。
40Cr steel plate is one of the most widely used steel in mechanical manufacturing industry. After the quenching and tempering treatment, it has good comprehensive mechanical properties, good low temperature impact toughness and low notch sensitivity. The hardenability of the steel is good, water quenching can be quenched to 28 ~ 60mm, when quenching oil quenching to 15 ~ 40mm.

这种钢除调质处理外还适于氰化和高频淬火处理。切削性能较好，当硬度为HB174～229时，相对切削加工性为60%。该钢适于制作中型塑料模具。
This kind of steel is suitable for the treatment of cyanide and high frequency quenching, besides the quenching and tempering treatment. The cutting performance is good, when the hardness is HB174 ~ 229, the relative machinability is 60%. The steel is suitable for making medium plastic mould.
低合金板经过前一段时间的快速反弹，上周国内钢材市场价格涨幅明显放缓，继续上涨动力减弱;在成交不畅的情况下，市场疲态渐现，加上期钢市场的持弱偏弱震荡，进一步加重商家观望心态，因此上周钢价窄幅震荡回落，供需双方均有一定的观望心态，因需求基本面受到南方雨水影响及商家在月底资金压力再现影响，预计短期内国内钢价还将继续震荡偏弱运行为主。
Low alloy plate after the rapid rebound in a period of time before the last week, the domestic steel market price increase is slowing down, continue to rise in power weakened; poor turnover situation, the market weakness gradually, plus the steel market to weak weak shocks, further aggravating the business mentality, so last week, steel price shocks narrow down, supply and demand the two sides have a wait-and-see attitude, and influence by rain in the south of businesses in the end of the month due to financial pressure reproduction demand fundamentals, expected short-term domestic steel prices will continue to run the main weak shock.