Case study damage of large tool by hardening process and compensation for damage in court proceeding

1. Introduction

The heat treatment of the shaped insert made of 1.2343 ESU steel was ordered from the commercial heat treatment shop, vacuum hardening and tempering of the insert to 53 + 2 HRc. It was ordered with a heat treatment certificate; the weight of the insert is about 450 kg. The origin of the material was not specified, from the designation of the material it could be assumed that it was a material remelted under slag.

Fig.1  Insert                                                   Fig.2  Cycle record  

The process was set to heating with two steps to 650 and 850 C, austenitization temperature 1020 C, soaking time determined from Tc, cooling 2 bar overpressure. Tempering 2x 560 C. The process record shows no anomalies.

After hardening, significant cracks were found on the body of the insert. One crack was based on a sharp shape on the outer side of the insert (marked in red in Fig. 1), the other on a weld that was made before the heat treatment. Each of the cracks meant 100% deterioration of the insert without the possibility of repair.

Fig.3  Crack on outer side                             Fig.4  Crack on a weld

2. Analysis of the sales order process

 There was no contractual relationship between the two parties, the customer (complaining) and the supplier (defendant). Request for quotation, quotation and subsequently an order were issued for the execution of the work.

This is therefore a case of custom work, which does not have the character of a contract for work, but is considered to be this type of contract. The condition is that the basic requirements are met, namely the contracting parties, the subject of the work, and the price. These requirements have been met.

By the contract for the work, the contractor undertakes to perform the work at his own expense and risk for the client, and the client undertakes to take over the work and pay the price (§ 2586). If the work is performed on the basis of the contractor’s instructions, the supplier is obliged to act in accordance with them (§ 2592). However, he must stop the execution of the work or notify the client of its suspension if he finds that the instructions for the execution of the work do not comply with standard customs or conditions (§ 2594).

The question is what the supplier should ask about and to what depth so that it is possible to specify what is to be delivered and what the subject of the work is intended for (§ 2594, par. Citation of some sections of the Civil Code:

§ 2594

(1) The Contractor shall notify the Client without undue delay of the unsuitable nature of the thing which the Client handed over to him for the performance of the work or the order given to him by the Client. This does not apply if he could not determine the unsuitability even with the necessary care.

(2) If an inappropriate thing or order interferes with the proper execution of the work, the Contractor shall interrupt it to the necessary extent until the exchange of the thing or the change of the order; if the client insists on the performance of the work using the handed over item or according to the given order, the contractor has the right to request that the client do so in writing.

(4) If the contractor is retained in accordance with paragraphs 1 and 2, the client has no right to a defect in the work arising from the unsuitability of the thing or order.

 § 2902

Anyone who has breached a legal obligation, or who can and should know that he or she has breached it, shall notify the person without undue delay and shall draw his or her attention to the possible consequences. If he fulfills the notification obligation, the injured party is not entitled to compensation for the damage that he could have prevented after the notification.

 It follows that the customer (plaintiff) and the supplier (defendant) have certain obligations. The Client is obliged to truthfully communicate all necessary details that could affect the quality of the delivered work, and on the contrary, the Supplier is obliged to communicate to the Client all objections that could endanger the quality of the work.

As the cracks are of a double nature, in the case of the first crack from the weld, the customer (plaintiff) was obliged to inform the tempering plant about the welding of the liner before heat treatment, and that this weld was not performed according to the steel manufacturer’s recommendations. It was not even treated by the subsequent annealing process. The question is whether the supplier (defendant) could not find out this by taking the necessary care himself. However, since the weld was on the underside of the mold, which was not visible without turning the mold by crane, the question is whether the supplier (defendant) did not neglect his duties by not inspecting the supplied liner properly, or vice versa even from below does not exceed the limits of the usual examination.

As for the second crack, then the improperly treated shape, generating high tensile stresses when the insert cooled during hardening, was visible and should have been disputed by the supplier (defendant) prior to processing. However, since this type of crack is conditioned not only by a properly controlled hardening process, but also by the input quality of the material, in this case it is necessary to deal with the input material, whether its quality could reduce the strength properties of the material.

Heat treatment of metals belongs to the so-called special processes, which change the state of the delivered material to a new state by a thermal process according to the customer’s request. To assess the causes of damage, it is therefore necessary to know the initial state and the final state of the material after the thermal process. Knowledge of the condition of the steel before heat treatment is up to the ordering (plaintiff), whose duty is to properly order the material in the required quality, and then check this quality after delivery of the material from the steel supplier, and also at any time later, precisely due to potential complaints.

Examination of the dossier revealed that the material marked 1.2343 ESU was purchased from a supplier who purchases steel. He was not able to prove the input quality or the origin of the steel.

Knowledge of the final state can be determined only and exclusively on the basis of the assessment of the structure of the material after heat treatment, while under certain conditions, the initial state can be derived on the basis of knowledge of the final state. Samples for the assessment of the final condition must be taken directly from the mold or tool, preferably from the crack area. However, as the customer (the complainant) scrapped the insert before sampling could take place, this examination could not be performed.

4. Discussion

In examining the whole case, the following findings were made:

• The customer (plaintiff) used material that was generally correctly specified as 1.2343 ESU, but did not verify this quality during the entry control. Therefore, it can only be assumed that it was this material, given the nature of the crack, it can be seriously doubted
• The customer (plaintiff) did not restrict the steel supplier with another specification, which would precisely define the purchased state in terms of steel purity, grain size, quantity and type of primary carbides, fiber direction, or value of impact toughness, on the basis of which he could carry out an entry check to verify the quality of the delivery
• The steel supplier supplied the material without further specification and certification. While responding to the order of the insert manufacturer, which had no further specification, as a specialist in metallurgical material he should have known that for such material it is necessary to define structural properties, not only for the whole block of material but also for each piece separated from this block. He could not prove it
• After incorrect machining, the tool manufacturer (plaintiff) boiled the insert without following the prescribed procedures (electrode type, welding conditions at elevated temperatures). After welding, he did not anneal the weld and did not inform the heat treatment supplier about this fact.
• The tool manufacturer (plaintiff) has made an insert in some parts with shapes without radii or with minimum radii that generate increased tensile stresses. This puts himself at increased risk of cracking.
• The tool manufacturer (plaintiff) scrapped the damaged insert before samples could be taken for analysis. This made it virtually impossible to investigate the real causes of the damage
• The heat treatment supplier (defendant) did not warn the customer of inappropriate shapes and did not request the customer’s written consent to continue the work.
• The heat treatment supplier (defendant) selected the heat treatment parameters (hardening temperature 1020 C) in accordance with the usual conditions, ie for processing steel 1.2343 according to DIN standard, and regardless of incorrectly formulated order applied 2 tempering as the minimum treatment for this type of material. It is debatable whether a lower hardening temperature (990-1000 C) would lead to success. At the same time, it must be stated that the choice of heat treatment conditions should be based on the steel manufacturer’s regulation, which was not known !!!
• The heat treatment supplier (defendant) has chosen the heat treatment parameters in accordance with the purpose of use, a form for the manufacture of headlamps, where the required basic property is the purity of the material and its polishability, and not its maximum toughness. Therefore, he correctly chose the cooling rate of 2 bar overpressure
• With regard to critical shapes, the heat treatment supplier (defendant) should have included one or more stress relief delays during cooling (hardening). However, without knowledge of the quality of the input material, it is not possible to specify the degree of influence on the result

5. Conclusion

 On the basis of the assessment of the above facts, which clearly show the defects of the process on the part of the client (plaintiff), in the light of two expert opinions in the case, which point to these facts, the plaintiff withdrew his action. The defendant waived its right to reimbursement of the costs of the legal proceedings. The court stopped the proceedings pursuant to Section 96, paragraphs 1 and 2, of Act No. 99/1993 of the Code of Civil Procedure, and at the same time pursuant to the provisions of Section 146, paragraph 1, letter b) of the Code of Civil Procedure. decided on the costs

From the point of view of procedural acts, the plaintiff must prove to the defendant the mistakes which caused the defect or damage. In the event of damage, he must prove the causal link between the defect and the damage. In the case of an action for incorrect heat treatment, it is therefore necessary to know that the person suing (eg the tool manufacturer) must prove the fault of the heat treatment shop. For most heat treaters, which are established on the Czech market, all process and documentation procedures are in place and these entities can demonstrate the entire process from receipt of the order to invoicing step by step.

On the contrary, this is not ensured on the part of manufacturers of tools and there are many cases of so-called “failure of evidence” where a tool manufacturer is unable to prove either the purchase of steel, its quality and quality verification, or production process flow. Thus, until toolmakers are to improve their quality systems, at least to the level of all heat treatment shops, their chances of claiming compensation for defects and damages in court proceedings will be low.

Jirka Stanislav