这些测验题适用于非热处理专业的工人和技术人员。判断以下题目所述是否正确?正确画○,错误画×: 1.铁中含碳0.03～2.0％为钢,含碳少于0.03％为纯铁,含碳超过2.0％为铸铁。 2.未经热处理的钢件,在常温下的组织是铁素体与渗碳体的混合物。 3.将钢件加热到临界温度以上,其组织全部变成奥氏体后,如果渐渐冷却,那么首先析出铁素体或渗碳体,等冷却到723℃以下,残余的奥氏体就变成珠光体。 4.将钢件加热到临界温度以上,其组织 These test questions apply to non-heat treatment professional workers and technicians. Determine whether the following questions are correct? Correct ○, Mistake ×: 1. Iron 0.03 to 2.0% of carbon steel, less than 0.03% of carbon is pure iron, more than 2.0% of carbon is cast iron. 2 without heat treatment of steel, the organization at room temperature is a mixture of ferrite and cementite. 3. The steel is heated to above the critical temperature, the organization becomes austenite, if gradually cooling, then the first precipitation of ferrite or cementite, and so cooled to 723 ℃ below the residual austenite becomes Pearlite. 4. The steel is heated to above the critical temperature, the organization