ASTM E1921-15ae1由美国材料与试验协会 US-ASTM 发布于 2015。
ASTM E1921-15ae1在国际标准分类中归属于: 77.040.10 金属材料机械试验。
ASTM E1921-15ae1 测定铁素体钢在转变范围内基准温度 (To) 的标准试验方法的最新版本是哪一版?
最新版本是 ASTM E1921-23b 。
5.1 Fracture toughness is expressed in terms of an elastic-plastic stress intensity factor, KJc, that is derived from the J-integral calculated at fracture.
5.2 Ferritic steels are microscopically inhomogeneous with respect to the orientation of individual grains. Also, grain boundaries have properties distinct from those of the grains. Both contain carbides or nonmetallic inclusions that can act as nucleation sites for cleavage microcracks. The random location of such nucleation sites with respect to the position of the crack front manifests itself as variability of the associated fracture toughness (16). This results in a distribution of fracture toughness values that is amenable to characterization using the statistical methods in this test method.
5.3 The statistical methods in this test method presume that the test materials are macroscopically homogeneous such that both the tensile and toughness properties are uniform. The fracture toughness evaluation of nonuniform materials is not amenable to the statistical analysis methods employed in the main body of this test method. For example, multipass weldments can create heat-affected and brittle zones with localized properties that are quite different from either the bulk material or weld. Thick section steel also often exhibits some variation in properties near the surfaces. An appendix to analyze the cleavage toughness properties of nonuniform or inhomogeneous materials is currently being prepared. In the interim, users are referred to (6-8) for procedures to analyze inhomogeneous materials. Metallographic analysis can be used to identify possible nonuniform regions in a material. These regions can then be evaluated through mechanical testing such as hardness, microhardness, and tensile testing to compare with the bulk material. It is also advisable to measure the toughness properties of these nonuniform regions distinctly from the bulk material.
5.4 Distributions of KJc data from replicate tests can be used to predict distributions of KJc for different specimen sizes. Theoretical reasoning (12), confirmed by experimental data, suggests that a fixed Weibull slope of 4 applies to all data distributions and, as a consequence, standard deviation on data scatter can be calculated. Data distribution and specimen size effects are characterized using a Weibull function that is coupled with weakest-link statistics (17). An upper limit on constraint loss and a lower limit on test temperature are defined between which weakest-link statistics can be used.
5.5 The experimental results can be used to define a master curve that describes......
落锤式冲击试验机主要用于测定铁素体钢(包括板材、型材、铸钢和锻钢)的无塑性转变温度。无塑性转变温度表征含有小裂纹的钢材在动态加载屈服应力下发生脆断的zui高温度。试验方法是将一定质量的锤体提升到一定高度,然后由静止释放,锤体自由落体冲击到试样表面,从而给试样进行动态加载。该试验机集机、电、自动控制技术于一体,实现了送料、提锤、冲击、出样、抓锤的全自动化过程。...
从理论上分析,由于Cr元素可以延长相变孕育期,使等温转变曲线向右移动,随着Cr含量增加,珠光体转变向高温移动,贝氏体转变向低温移动[2]。在淬火过程中,即使冷却速度较慢,在到达马氏体转变温度前,过冷奥氏体也不会产生珠光体和贝氏体转变,因此钢的淬透性明显提高,所以在钢中需要控制Cr含量,需按照其他对淬透性有重要影响的合金元素一样规定上下限。...
落锤冲击试验机是依据国家标准GB6803-86所设计,适用于测定铁素体钢的无塑性转变温度下对标准试样进行冲击试验。可分别进行试样P-1、P-2、P-3的试验。采用人机界面的控制系统,触摸屏操作方式。数据屏幕显示、读数准确,操作便捷,并配有微型打印机,实验数据输出打印。可以连续进行冲击试验。...
刚形成时是由条状铁素体合并而成的块状铁素体和小岛状富碳奥氏体组成,富碳奥氏体在随后的冷却过程中,可能全部保留成为残余奥氏体;也可能部分或全部分解为铁素体和渗碳体的混合物(珠光体或贝氏体);最可能部分转变为马氏体,部分保留下来而形成两相混合物,称为m-a组织。8.无碳化物贝氏体-板条状铁素体单相组成的组织,也称为铁素体贝氏体。形成温度在贝氏体转变温度区的最上部。...
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