1. What is nondestructive testing?

Answer: Non-destructive testing is a test method for inspecting the surface and internal quality of the parts to be inspected without damaging the working state of the workpiece or raw materials.

Second, what are the commonly used methods of flaw detection?

Answer: Commonly used non-destructive testing methods include: X-ray inspection, ultrasonic inspection, magnetic particle inspection, penetrant inspection, eddy current inspection, gamma ray inspection, fluorescent inspection, and color detection.

First, the cost of high nickel iron and nickel plate comparison

The advantage of high nickel pig iron relative to pure nickel is that it can provide steelmaking pig iron. At present, the price of steelmaking pig iron is 2,530 yuan / ton, taking 12% of high nickel pig iron as an example. The current price in Jiangsu is 1380 yuan / nickel. For high-nickel iron, the value of steel-making pig iron given by each nickel point is 181 yuan. That is to say, the high nickel pig iron price is higher than the nickel plate range of 181 yuan / nickel, then the high nickel pig iron still has a cost advantage. As far as the current situation is concerned, the spot nickel price in the Yangtze River is 126,400 yuan / ton, the difference between the two is 116 yuan / nickel, less than 181 yuan. Therefore, for smelting stainless steel raw materials, high nickel iron has a cost advantage over nickel sheets.

Second, the cost of scrap stainless steel and high nickel pig iron

Compared with high nickel pig iron, waste stainless steel contains not only nickel metal but also chromium metal. The main components of the waste stainless steel are as follows: nickel metal mass fraction is 8%, chrome metal mass fraction is 17%, iron mass fraction is 73%, and other mass fractions are 2%. For the nickel metal in scrap steel, the bidding price of the June scrap in June is 13900 yuan/ton, and the value of 8% nickel iron in the scrap is 11,120 yuan, and the price of nickel nickel in the scrap is 1390 yuan/nickel. It is basically equivalent to the current price of 12% high nickel pig iron of 1380 yuan/nickel in Jiangsu.

Xinhua News Agency Nanjing reporter learned from Hohai University on the 6th that the international standard for the evaluation of spheroidal graphite spheroidization rate, led by Professor Wang Zehua's team, was recently approved by the International Organization for Standardization (ISO).

Ductile iron is a kind of high-strength cast iron material with comprehensive mechanical properties close to steel and excellent shock absorption and wear resistance. In 2017 alone, China's production of ductile iron reached 13.75 million tons, accounting for 52% of the world's production of ductile iron.

Wang Zehua introduced that the characteristic structure of ductile iron is spheroidal graphite. The shape of graphite particles directly affects the mechanical properties of ductile iron. The quality parameter is called spheroidization rate. Previously, the International Organization for Standardization, the European Union and major industrial countries have defined the spheroidization rate and stipulated the corresponding assessment methods. However, these standards are not uniform and lack of maneuverability. Human factors are large, and disputes are easy to occur, resulting in economic loss.

“Graphite particle morphology model is the basis for evaluating the spheroidization rate of nodular cast iron. The old standard only describes the shape of graphite particles qualitatively, but it is difficult to control in actual operation.” Wang Zehua said that since the ISO project was established in September 2015, the team Relying on Zhongqi Qishuyan Locomotive and Rolling Vehicle Technology Research Institute Co., Ltd., Shenyang Foundry Research Institute and Jiangsu Hengli Hydraulic Co., Ltd., a large number of experimental studies were carried out, and the area ratio of spheroidal graphite particles was finally determined, and the spheroidization rate was obtained. The model solves the contradiction between the old standard definition and the actual operation.

Every role that nickel plays depends on its inherent characteristics, including little-known micronutrients, such as nickel-containing fertilizers; nickel metal hydride batteries and nickel-chromium batteries are less important in the public mind than lithium batteries. However, few people know that in the modern energy storage industry, nickel plays a significant role in the research of mainstream lithium chemical composition; the heat-resistant and noise-reducing nickel superalloy foam insulation materials used in jet engines can be reduced. Small aircraft noise imprints make the area around the airport more suitable for human habitation; nickel-containing stainless steel has also opened up new applications to ensure that machinery and processes operate more efficiently and longer.

Nickel is mainly used in the manufacture of stainless steel, but 8% of nickel is used in the manufacture of alloy steels, which play an important role in thousands of engineering solutions. Nickel-containing alloy steels are not classified as stainless steel. Alloy steels include a variety of iron-based materials ranging from about 0.3% (some alloy steels) to about 20% (maraging steels). Alloy steel has higher strength, hardness, wear resistance and toughness than ordinary carbon steel. It is generally used in power output, metal forming and cutting equipment, and can also be used in specific low temperature environments where carbon steel toughness is insufficient. Nickel-containing alloy steel plays a vital role in the manufacture of tools and machinery. Alloy steels can be classified according to specific properties to suit specific end uses. Although nickel is not used in these alloy steels, it is widely used and is therefore an important contributor to the industry.

Hardenable low alloy steel

Hardenable low alloy steel is a kind of iron-based material and has mechanical properties superior to ordinary carbon steel. It is made by adding alloying elements such as nickel, chromium and molybdenum, followed by quenching (rapid cooling) and tempering heat treatment. If these metal elements are dissolved in austenite before quenching, the hardenability can be effectively improved. Nickel complements the hardening effect of chromium and molybdenum and plays an important role in the toughness of the hard martensite microstructure formed by quenching and tempering heat treatment. Hardenable low alloy steels are commonly used in the manufacture of crankshafts, gears and aircraft landing gear.